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Literature C J W / 2 9 5 substances in sea water of eggs and larvae of three genera of bivalve mollusks The Veliger 11(4) 316-323 Dovel, W L (1970), Fish eggs and larvae, in Gross physical biological effects oj overboard spoil disposal in upper Chesapeake Bay Final report to the U S Bureau of Sport Fisheries and Wildlife [Special report no 3, Contribution 397] (University of Maryland, Natural Re -sources Institute, College Park), pp 42-49 ""Flemer, D A (1970), Phytoplankton, in Gross physical biological effects of overboard spoil disposal in upper Chesapeake Bay Final report to the U S Bureau of Sport Fisheries and Wildlife [Special report no 3, Contribution 397] (University of Maryland, Natural Re-sources Institute, College Park), pp 16-25 " ' Flemer, D A , W L Dovel, H T Pfitzenmeyer, and D E Ritchie, J r (1967), Spoil disposal in upper Chesapeake Bay I I Pre-liminary analysis of biological effects, in National symposium on estuarine pollution, P L McCarty and R Kennedy, chairmen (Stanford University Press, Stanford, California), pp 152-187 ⢠« F o r d , W L and B H Ketchum (1952), Rate of dispersion in the wake of a barge at sea Transactions oj Air American Geophysical Union 33(5) 680-684 **'Gross, M G (1970), Waste removal and recychng by sedimentary processes F A O Technical Conference on Marine Pollution and I t s Effects on Living Resources, 12 pp Harrison, W , M P Lynch, and A G Altschaefii (1964), Sedi-ments of lower Chesapeake Bay, with emphasis on mass proper-ties J Sediment Petrol 34(4) 727-755 **'Holeman, J N (1968), The sediment yield of major rivers of the world Water Resour Res 4 737-747 Huet, M (1965), Water quality criteria for fish life, in Biological problems in water pollution Third seminar, C M Tarzwell, ed ( U S Department of Health, Education and Welfare, Public Health Service, Division of Water Supply and Pollution Control Cincinnati, Ohio), pp 160-167 **'Ippen, A T ed (\966), Estuary and coastline hydrodynamics CMcGraw-Hill Book Co , Inc , New York) " ' I saac , P C G (1965), The contribution of bottom muds to the depletion of oxygen in rivers and suggested standards for sus-pended solids, in Biological problems m water pollution Third semi-nar, C M Tarzwell , ed ( U S Department of Health, Educa-tion and Welfare, Public Health Service, Division of Water Supply and Pollution Control, Cincinnati, Ohio), pp 346-354 **' Jannasch, H W , K Eimhjellen, C O Wirsen, and A Farman-farmaian (1971), Microbial degradation of organic matter in the deep sea Science 171 672-675 '"Jit ts , H R (1959), The adsorption of phosphate by estuarine bottom deposits Aust J Mar Freshwater Res 10 7-21 " ' K e t c h u m , B H , A C Redfield and J P Ayers (1951), The oceanography of the New York Bight, papers in physical ocean-ography and meteorology ( M I T and W H O I , Woods Hole, Mass ), 12(1) 46 "'Loosanoff, V L (1962), Effects of turbidity on some larval and adult bivalves Gulj and Caribbean Fisheries Institute, Proc 14 80-95 "'Loosanoff, V L and F D Tommers (1948), Effect of suspended silt and other substances on rate of feeding of oysters Science 107 69-70 * " L u n z , R G (1938), Part I Oyster culture with reference to dredging operations in South Carolina Part I I T h e effects of flooding of the Santee River in April 1936 on oysters in the Cape Romain area of South Carolina Rept to the U S Engineer Oflfice, Charleston, S C " ' L u n z , R G (1942), Investigation of the effects of dredging on oyster leases in Duval County, Florida, in Handbook of oyster survey, intracoastal waterway Cumberland Sound to St Johns River Special rept U S Army Corps of Engineer, Jacksonville, Florida *"Mackin , J G (1961), Canal dredging and silting in Louisiana bays Publ Inst Mar Set Umv Tex 7 262-319 "'Manheim, F T , R H Meade, and G C Bond (1970), Sus-pended matter m surface waters of the Atlantic continental margin from Cape Cod to the Florida Keys Science 167 371-376 "'Mansueti , R J (1962), Effects of civilization on striped bass and other estuarine biota in Chesapeake Bay and tributaries Gulj and Caribbean Fisheries Institute, Proc 14 110-136 "'Marshal l , A R (1968), Dredging and filling, in Marsh and estuary management symposium proceedings, J D Newsom, ed ( T J Moran's Sons, Inc , Baton Rouge, Louisiana), pp 107-113 ^^Masch, F D and W H Espey (1967), Shell dredgingâa jactor in sedimentation in Galveston Bay [Technical report C R W R - 7 j (Center for Research in Water Resources, Hydraulic Engineering Labora-tory, University of Texas, Austin), 168 p " ' McNulty, J K , R C Work, and H B Moore (1962), Some rela-tionships between the infauna of the level bottom and the sedi-ment in South Florida Bull Mar Sci Gulj and Caribbean 12(3) 322-332 "2 Meade, R H (1969), Landward transport of bottom sediment in estuaries of the Atlantic coastal plain J Sediment Petrol 39 222-234 " ' M o c k , C R (1967), Natural and altered estuarine habitats of penaeid shrimp Gulj and Caribbean Fisheries Institute, Proc 19 86-98 *'* Municipality of Metropolitan Seattle (1965), Disposal of digested sludge to Puget Sound, the engineering and water quality as-pects July 1965 Municipality of Metropolitan Seattle, Seattle, Washington " ' Pearce, J B (1970a), The effects of solid waste disposal on benthic communities in the New York Bight FAO Technical Conjerence on Marine Pollution and its Effects on Living Resources and Fishing Rome 12 pp "'Pearce, J B (1970b), The effects of waste disposal in the New York Bight Interim report Sandy Hook Marine Laboratory, U S Bur Sport Fisheries and Wildlife Pearce, J B (1970c), Biological survey of compacted refuse sub-merged for three months in 200 meters of water off Virgin Gorda, British Virgin Islands, Sandy Hook Marine Laboratory, High-lands, N J *" Pearce, J B (1971), T h e effects of solid waste disposal on benthic communities in the New York Bight, paper E-99 in Marine pollu-tion and its effects on living resources and fishing (Food and Agri-cultural Organization of the United Nations, Rome), p 175 "'Pomeroy, L R , E E Smith, and C M Grant (1965), T h e ex-change of phosphate between estuarine water and sediments Limnol Oceanogr 10(2) 167-172 ""Pfitzenmeyer, H T (1970), Benthos, in Gross physical biological ej-jecls oj overboard spoil disposal in upper Chesapeake Bay Final report to the U S Bureau oj Sport Fisheries and Wildlife [Special report no 3, Contribution 397] (University of Maryland, Natural Re -sources Institute, College Park), pp 26-38 "'Redfield, A C and L A Walford (1951), A study of the disposal of chemical waste at sea Report of the Committee for Investiga-tion of Waste Disposal National Research CouncilâNational Academy of Sciences, Publication N R C 201, 49 p *«Sai la , S B , T T Polgar, and B A Rogers (1968), Results of studies related to dredged sediment dumping in Rhode Island Sound Annual Northeastern Regional Antipollution conference, proc July 22-24, 1968, pp 71-80 "'Sanders, H L (1956), Oceanography of Long Island Sound, 1952-1954 X The biology of marine bottom communities Bull Bingham Oceanogr Coll 15 345-414 "* Sanders, H L (1958), Benthic studies m Buzzards Bay I Animal-sediment relationships Limnol Oceanogr 3 245-258 "'Sherk, J A , J r (1971), The effects oj suspended and deposited sedt-
29e/Section IVâMarine Aquatic Life and Wildlife ments on estuarine organismsâliterature summary and research needs [Contribution 443 ] (University of Maryland, Natural Resources Institute, College Park), 73 p "â¢Smith, D D and R P Brown (1969), Marine disposal of sohd wastes an interim summary Dillingham Corporation, L a JoUa, California *" Taylor, J L and C H Saloman (1968), Some effects of hydraulic dreding and coastal development in Boca Ciega Bay, Florida US Fish Wildlife Serv Fish Bull 67(2) 213-241 ««Vacarro , R S , G D Gruce, G T Rowe, and P H Wiebe (1972), Acid iron wastes disposal and the summer distribution of standing crops in the New York Bight Water Research, 6 231-256, Perga-mon Press Weibe, P H , A D Grice and E Hoagland (1972), m press. Acid iron waste as a factor effecting the distribution and abundance of Zooplankton in the New York Bight Part I I Spatial varia-tions in the field and implications for monitoring studies Wicker, C F , ed (1965), Evaluation of present state oJ knowledge oJ Jactors affecting tidal hydraulics and related phenomena [Report no 3 ] (Committee on T ida l Hydraulics, U S Army Corps of Engi-neers, Vicksburg, Mississippi), n p *" Williams, A B (1958), Substrates as a factor in shrimp distribu-tion Limnol Oceanogr 3 283-390 Yonge, C M (1953), Aspects of life on muddy shores, m, Essays in Marine Biology, S M Marshall and A P O r r , cds (Ohver and Boyd, London), pp 29-49
Section VâAGRICULTURAL USES OF WATER TABLE OF CONTENTS Page I N T R O D U C T I O N 300 G E N E R A L F A R M S T E A D U S E S O F W A T E R . . . 301 W A T E R F O R H O U S E H O L D U S E S A N D D R I N K I N G . . 302 W A T E R F O R W A S H I N G A N D C O O L I N G R A W F A R M P R O D U C T S '⢠⢠⢠⢠302 W A T E R F O R W A S H I N G M I L K - H A N D L I N G Equip-M E N T A N D C o O L I N G D A I R Y P R O D U C T S 302 Recommendations 303 W A T E R F O R L I V E S T O C K E N T E R P R I S E S . . . . 304 W A T E R R E Q U I R E M E N T S F O R L I V E S T O C K 304 Water Consumption of Animals 305 R E L A T I O N O F N U T R I E N T E L E M E N T S I N W A T E R T O T O T A L D I E T 305 E F F E C T O F S A L I N I T Y O N L I V E S T O C K 307 Recommendation 308 T O X I C S U B S T A N C E S I N L I V E S T O C K W A T E R S . . . 309 Toxic Elements and Ions 309 Aluminum 309 Recommendation 309 Arsenic 309 Recommendation 310 Beryllium 310 Boron 310 Recommendation 310 Cadmium 310 Recommendation 311 Chromium 311 Recommendation 311 Cobalt 311 Recommendation 311 Copper 311 Recommendation 312 Fluorine 312 Recommendation 312 Iron 312 Lead 312 Recommendation 313 Manganese 313 Mercury 313 Recommendation 314 Molybdenum 314 Conclusion 314 Page . Nitrates and Nitrites 314 Recommendation 315 Selenium 316 Recommendation 316 Vanadium 316 Recommendation 316 Zinc 316 Recommendation 317 Toxic Algae 317 Recommendation 317 Radionuclides 317 Recommendation 318 P E S T I C I D E S ( I N W A T E R F O R L I V E S T O C K ) 318 Entry of Pesticides into Water 318 Pesticides Occurrence in Water 318 Toxicological Effects of Pesticides on Livestock 319 Pesticides in Drinking Water for Livestock. 319 Fish as Indicators of Water Safety 320 Recommendation 321 P A T H O G E N S A N D P A R A S F T I C O R G A N I S M S 321 Microbial Pathogens 321 Parasitic Organisms 322 W A T E R F O R I R R I G A T I O N 323 W A T E R Q U A L I T Y C O N S I D E R A T I O N S F O R I R R I G A -T I O N 324 Effects on Plant Growth 324 Crop Tolerance to Salinity 324 Nutritional Effects 326 Recommendation 327 Temperature 328 Conclusion 328 Chlorides 328 Conclusion 329 Bicarbonates 329 Conclusion 329 Sodium 329 Nitrate 329 Conclusion 329 Effects on Soils 329 Recommendation 330 298
Page Biochemical Oxygen Demand ( B O D ) and Soil Aeration 330 Acidity and Alkalinity 330 Recommendation 332 Suspended Solids 332 Effect on Animals or Humans 332 Radionuclides 332 Recommendation 332 S P E C I F I C I R R I G A T I O N W A T E R C O N S I D E R A T I O N S 333 Irrigation Water Quality for A n d and Semiarid Regions 333 Recommendation 335 Irrigation Water Quality for Humid R e -gions ^ 336 Recommendation 338 P H Y T O T O X I C T R A C E E L E M E N T S 338 Aluminum 339 Recommendations 340 Arsenic 340 Recommendations 341 Beryllium 341 Recommendations 341 Boron 341 Recommendations 341 Cadmium 342 Recommendations 342 Chromium 342 Recommendations . . 342 Cobalt 342 Recommendations 342 Copper . 342 Recommendations 343 Fluoride 343 Recommendations 343 Page Iron 343 Recommendations 343 Lead 343 Recommendations 343 Lithium 343 Recommendations 344 Manganese . . 344 Recommendations . . 344 Molybdenum 344 Recommendations 344 Nickel 344 Recommendations 344 Selenium 345 Recommendation 345 T i n , Tungsten, and Titanium 345 Vanadium 345 Recommendations 345 Zinc 345 Recommendations . 345 P E S T I C I D E S ( I N W A T E R F O R I R R I G A T I O N ) 345 Insecticides in Irrigation Water 346 Herbicides in Irrigation Water 346 Residues in Crops 347 Recommendation . . 348 P A T H O G E N S 348 Plant Pathogens 348 Human and Animal Pathogens 350 Recommendation 351 T H E U S E O F W A S T E W A T E R F O R I R R I G A T I O N 351 Wastewater From Municipal Treatment Systems 351 Wastewater From Food Processing Plants and Animal Waste Disposal Systems 353 Recommendations 353 L I T E R A T U R E C I T E D 354 299
INTRODUCTION Modern agriculture increasingly depends upon the quality of its water to achieve the fullest production of domestic plants and animals and satisfy general farmstead needs T h e quality of its water is important to modern agriculture not only in determining the productivity of plants and animals, but also as it affects the health and wel-fare of the human farm population Irrigation is one of the largest consumers of water for agricultural use Differences in crop sensitivity to salinity and toxic substances necessitate the need for evaluating water quality criteria for irrigational purposes Polluted water can be detrimental to animal health and to the safety and value of agricultural products Good water quality is an important factor in the health and comfort of rural families needing water for drinking, food preparation, bathing, and laundering Discussions of water quality requirements relate in turn to problems of pollution posed by urban, industrial, and agricultural wastes Some naturally occunng constituents, present in surface and groundwaters, can also adversely af-fect agricultural uses of water Among these substances are suspended solids, dissolved organic and inorganic substances, and living organisms such as toxic algae and organisms as-sociated with food spoilage Where undesirable natural or foreign substances interfere with optimum water use, man-agement and treatment practices must be implemented Often there are simple but effective things that a farmer or rancher can do to manage and improve the quality of his water supply Although considerations of water supply management are important, such matters are beyond the scope of this section on Agricultural Uses of Water, which is restricted to the quality requirements of water for domestic and other farmstead uses, for livestock, and for ir-rigation of crops Farmsteads typically require water at point of use, of quality equivalent to that demanded by urban populations, particularly for household uses, washing and cooling pro-duce, and production of milk Water of such high quality is frequently not readily available to the farmstead and often can be obtained only through water treatment I n the near future, water treatment facilities may be a routine installa-tion in any well-designed farmstead operation It is not the purpose of this section to elaborate upon treatment alterna-tives, but satisfactory treatment possibilities do exist for producing from most raw water a supply that will satisfy the quality needed for most agricultural uses T h e task of evaluating criteria and developing recom-mendations IS complicated by the need to consider numer-ous complex interactions For example, it is not practical to discuss water quality criteria for irrigation without con-sidering crop responses to climatic and soil factors and their interrelationships with water Evaluation of water quality requirements for livestock drinking water is also compli-cated by interactions of such variables as the quantity of water consumed and an animal's sex, size, age, and diet It should, therefore, be emphasized that evaluating criteria is a complex task, and that using the recommendations m this report made on the basis of those criteria must be guided by expert judgment 300
GENERAL FARMSTEAD USES OF WATER This section considers quality requirements of water for use by the human farm population and for other uses as-sociated with agricultural operations exclusive of livestock production and crop irrigation Included are water for household uses, drinking water, and water for preparing produce and milk for marketing For these purposes finished water of quality at least comparable to that intended for urban users is required at point of use Farmers and ranchers usually do not have access to the large, well-controlled water supplies of most municipalities and typically must make the best use of available surface or groundwater supplies But there are problems associated with the use of these waters, which often contain objection-able natural constituents These may be classified as sus-pended solids, dissolved inorganic salts and minerals, dis-solved organic constituents, and living organisms, all of which occur naturally and are not introduced by man or as a result of his activities Suspended solids are organic and inorganic particles found in water supplies They include sand, which is com-monly associated with well supplies, and silt and clay fre-quantly found in untreated surface waters Dissolved in-organic salts and minerals are found in both surface and groundwaters Most of these are soluble salts consisting of calcium, magnesium, and sodium with associated anions (i e , carbonate, bicarbonate, sulfate, and chloride) Great-est concentrations are found in the waters of and and semi-arid regions and m brackish waters along the sea coasts I n some western rivers total dissolved solids exceed 5,000 milli-grams per liter (mg/1), although many contain less than 2,000 mg/1 (Livingstone 1963) Surface waters draining from areas high in organic materials such as swamps and bogs often contain dissolved organic constituents composed mainly of hydroxy-carboxylic acids (Lamar and Goerlitz 1966,2' L a m a r 1968^°) that impart a yellow or brown color to the water Coloration often ranges from 100 to 800 platinum cobalt units compared to the 15 recommended by the federal Drinking Water Standards (Environmental Protection Agency 1972") f Living organisms in standing bodies of water that impart objectionable odors and tastes for human consumption include algae, diatoms, and proto-zoa Because these constituents even in a properly protected supply of raw water used on farmsteads cause water quality that does not satisfactorily approximate the quality of potable water, it may be necessary to resort to water treat-ment T h e wide range of quality characteristics associated with raw agricultural water supplies is matched by a broad range of water treatment methods Microbial contaminants such as pathogenic or food spoilage bacteria, often present in surface waters, indicate that treatment is required to pro-duce suitable water supplies Treatments available include the use of halogens or sodium hypochlorite (Bauman and Ludwig 1962,^ Black et al 1965,' Kjellander and L u n d 1965," Water Systems Council 1 9 6 5 - 1 9 6 6 , « Oliver 1966,'" Laubusch 1971"), ozone (O'Donovan 1965),^ silver (Shaw 1966,'2 Behrman 1968«), ultraviolet sterilization (Kristoffersen 1958," Huff et al 1965"), and heat (Shaw 1966)'^ Reviews of some of the problems associated with farmstead water supplies and possible methods of treatment are given by Wright (1956),^^ Davis ( I960) , ' Malaney et al (1962),2« James (1965),'* Water Systems Council (1965-1966) ,« Elms (1966), '° Kabler and Kreissl (1966)," Stover (1966),'' and Atherton (1970) ^ Farmers, however, should seek expert advice m selecting from various treatment alter-natives in order to achieve the desired quality of finished water A troublesome aspect of water quality for general farm-stead uses, particularly regarding the handling of produce and milk, involves nonpathogenic bacterial contaminants Many such microorganisms including algae are found even in properly protected agricultural water supplies (Thomas 1949,^^ Walters 1964),^ and various kinds contribute to problems of color, odor, taste, and to rapid spoilage of con-* Citations are listed at the end of the Section They can be located alphabetically within subtopics or by their superscript numbers which run consecutively across subtopics for the entire Section t Throughout this report, all references to the federal Drinking Water Standards are to those published by the Environmental Pro-tection Agency, 1972 " 301
302/Section VâAgricultural Uses of Water laminated products (American Water Works Assoc Com-mittee on Tastes and Odors 1970/ Mackenthun and K e u p 1970) For example, offensive odors are often attributable to sulfate-reducing bacteria (Lewis 1965) Victoreen (1969)" discussed water coloration probloms caused by Arthrobacter, a species of soil bacteria Growths of "iron bacteria" in pipes may result in slimy masses that clog pipes and produce undesirable flavors (Kabler and Kreissl 1966) Ropy milk, i e , milk that forms threads or viscous masses when poured or dipped, is a typical problem often attributable to contaminated water (Thomas 1949,'^ Davis I960') Psychrophilic bacteria can affect the storage quality of milk and other food products (Davis I960,* Malaney et al 1962,26 Ayres 1963,^ Thomas et al 1966) Similarly, thermoduric microorganisms are a problem in some farm-stead water supplies, since they can withstand milk pas-teurization temperatures and lead to spoilage (Thomas 1949,'^ Davis 1960,8 Malaney et al 1962) " Numerical recommendations for permissible levels of these and other nonpathogenic organisms have little current usefulness, because approximately 170 species of bacteria are known to occur in raw water supplies, and only half of them are ob-served during routine bacteriological examinations (Thomas 1949,'^ Malaney et al 1962^*) Similarly minimal contami-nation of perishable raw food materials with small residues of rinse water or splash can result in rapid growth under suitable temperature conditions to cause early spoilage of a high quality product Malaney et al (1962)^* stated that simple, commonly used water treatment processes render raw water supplies suitable for farmstead uses including handling of produce and milk WATER FOR HOUSEHOLD USES AND DRINKING Every farm should have a dependable water supply that is palatable and safe for domestic use This requirement dictates that the finished water be of quality comparable to that designated by the federal Drinking Water Standards for water supply systems used by interstate carriers and others subject to federal quarantine regulations These standards have been found to be reasonable in terms of both the possibility of compliance and the acceptability of such water for domestic farmstead uses Groundwater sources are generally regarded as providing a more dependable supply and as being less variable in composition than surface water sources However, many groundwater supplies contain excessive concentrations of soluble salts composed of calcium, magnesium, and associ-ated anions (carbonate, bicarbonate, sulfate, and chloride), or hydrogen sulfide They can cause taste, odor, acidity, and staining problems (Wright 1956,Ì ^ Dougan 1966,' Kabler and Kreissl 1966," K l u m b 1966," Behrman 1968«) I n the ground waters of western states high concentrations of nitrates may occur Levels may exceed the concentration of 10 mg/1 of nitrate-nitrogen recommended by Section I I on Public Water Supplies Because all supplies are subject to contamination, care must be exercised m both the installation and maintenance of water systems R a w water should be free of impurities that are offensive to sight, smell, and taste (Wright 1956)*^ and free of significant concentrations of substances and organisms detrimental to public health (see Section I I ) WATER FOR WASHING AND COOLING RAW FARM PRODUCTS Many root crops, fruits, and vegetables are washed before leaving the farm for the market Changes in fruit production associated with mechanical harvesting and bulk handling and an ever-increasing emphasis on quality have made the washing and hydrocooling of raw produce a common farm practice Water for such uses should be of the same quality as that for drinking and household pur-poses, and as such should conform to Drinking Water Standards I t is important that water for processing raw produce be of good quality bacteriologically (Geldreich and Bordner 1971)" and free of substances imparting color, ofl-flavor, and off-odor (Mercer 1971) " WATER FOR WASHING MILK-HANDLING EQUIPMENT AND COOLING DAIRY PRODUCTS Water used to clean milk utensils may gready affect the quality of milk (Atherton et al 1962),' and since modern methods of milk production require large volumes of water, its quality must not be detrimental to milk Stead-ily increasing demands for water due to intensified agri-cultural production have required many farm operators to develop secondary sources of water often of inferior quality (Esmay et al 1955,'= Pavelis and Gertel 1963) " Such supplies should be treated before use in milk-handling equipment (Thomas 1949,'^ Thomas et al 1953") T h e Grade " A " Pasteurized Milk Ordinance of the United States Public Health Service ( U S Department of Health, Education, and Welfare Public Health Service 1965)'* I S accepted as the basic sanitation standard for raw milk supplies F a r m water supplies may meet these potable standards yet have a detrimental effect on the quality of modern milk supply Rinse waters which are potable but contain psychrophylic microorganisms, excessive hard-ness, or iron or copper can have a very deleterious effect on dairy sanitation and milk quality unless properly treated to remove such contaminants (Davis I960,* Atherton et al 1962,' Atherton 1970,* Moore 197P*) T h e traditional con-cepts of potability and softness no longer suffice in this era of mechanized milk-handling systems Lengthy storage of raw milk prior to pasturization and the possible breakdown ot normal milk constituents by organisms able to grow at refrigeration temperatures may produce unacceptable changes in the quality of fluid milk or other manufactured
General Farmstead Uses of WaterfiOi dairy products (Thomas 1958,'* Davis I960,' Thomas et al 1966'") Water of quality comparable to that described m Drink-mg Water Standards typically suffices for the production of milk However, it is important that the water at point of use be clear, colorless, palatable, free of harmful micro-organisms, noncorrosive, and nonscale-forming (Moore 1971) « Recommendalions For general farmstead uses of water, including drinking, other household uses, and handling of produce and milk, it is recommended that water of the quality designated by the federal Drinking Water Standards be used. Raw water supplies not meeting these requirements should be treated to yield a finished product of quality comparable to drinking water. In general, raw waters should be free of impurities that are offensive to sight, smell, and taste. At point of use, they should be free of significant concentrations of substances and orga-nisms harmful to public health (see Section I I : Public Water Supplies) and detrimental to the market value of agricultural products.
WATER FOR LIVESTOCK ENTERPRISES Domestic animals represent an important segment of agriculture and are a vital source of food Like man and many other hfe forms, they are affected by pollutants in their environment This section is concerned primarily with considerations of livestock water quality and factors affecting it These include the presence of ions causing ex-cessive salinity, elements and ions which are toxic, bio-logically produced toxins, radionuclides, pesticide residues, and pathogenic and parasitic organisms O f importance in determining recommendations for these substances in livestock water supplies are the quantity of water an animal consumes per day and the concentration of the mineral elements in the water supply from which he consumes it Water is universally needed and consumed by farm animals, but it does not account for their entire daily intake of a particular substance Consequently, tolerance levels established for many substances in livestock feed do not accurately take into consideration the tolerance levels for those substances in water Concentrations of nutrients and toxic substances in water affect an animal on the basis of the total amount consumed Because of this, some assess-ment of the amounts of water consumed by live-stock on a daily basis and a knowledge of the probable quantity of ele-ments in water and how they satisfy daily nutritional re-quirements are needed for determining possible toxicity levels WATER REQUIREMENTS FOR LIVESTOCK T h e water content of animal bodies is relatively constant 68 per cent to 72 per cent of the total weight on a fat-free basis T h e level of water in the body usually cannot change appreciably without dire consequences to the animal, therefore, the minimal requirement for water is a reflection of water excreted from the body plus a component for growth in young animals (Robinson and McCance 1952,*' Mitchell 1962«) Water is excreted from the body in urine and feces, in evaporation from the lungs and skin, in sweat, and in pro-ductive secretions such as milk and eggs Anything that influences any of these modes of water loss affects the mini-mal water requirement of the animal T h e urine contains the soluble products of metabolism that must be eliminated T h e amount of urine excreted daily varies with the feed, work, external temperature, water consumption, and other factors T h e hormone vasopressin (antidiuretic hormone) controls the amount of urine by affecting the reabsorption of water from the kidney tubules and ducts Under conditions of water scarcity, an animal may concentrate its urine to some extent by reabsorbing a greater amount of water than usual, thereby lowering the animal's requirement for water This capacity for concen-tration, however, is usually limited I f an animal consumes excess salt or a high protein diet, the excretion of urine is increased to eliminate the salt or the end products of pro-tein metabolism, and the water requirement is thereby increased T h e amount of water lost in the feces varies depending upon diet and species Cattle, for instance, excrete feces with a high moisture content while sheep, horses, and chickens excrete relatively dry feces Substances in the diet that have a diuretic effect will increase water loss by this route Water lost by evaporation from the skin and lungs (in-sensible water loss) may account for a large part of the body's water loss approaching, and in some cases exceeding, that lost in the urine I f the environmental temperature is increased, the water lost by this route is also increased Water lost through sweating may be considerable, especially in the case of horses, depending on the environmental tem-perature and the activity of the animal Al l these factors and their interrelation make a minimal water requirement difficult to assess There is also the ad-ditional complication that a minimal water requirement does not have to be supplied entirely by drinking water T h e animal has available to it the water contained m feeds, the metabolic water formed from the oxidation ot nutrients, water liberated by polymerization, dehydration, or synthesis within the body, and preformed water associ-ated with nutrients undergoing oxidation when the energy balance is negative A l l of these may vary T h e water available from the feed will vary with the kind of feed and with the amount consumed T h e metabolic water formed 304
Water for Livestock Enterprises/305 from the oxidation of nutrients may be calculated by the use of factors obtained from equations of oxidation of typical proteins, fats, and carbohydrates There are 41, 107, and 60 grams (g) of water formed per 100 g of protein, fat, and carbohydrate oxidized, respectively I n fasting animals, or those subsisting on a protein deficient diet, water may be formed from the destruction of tissue protein I n general, it IS assumed that tissue protein is associated with three times Its weight of water, so that per gram of tissue protein metabolized, three grams of water are released It has been found by careful water balance trials that the water requirement of various species is a function of body surface area rather than weight This implies that the re-quirements are a function of energy metabolism, and Adolph (1933)'" found that a convenient hberal standard ot total water intake is 1 milliliter (ml) per calorie (cal) of heat produced This method automatically included the in-creased requirement associated with activity Cattle require somewhat higher amounts of water (1 29 to 2 05 g/cal) than other animals However, when cattle's large excretion of water in the feces is taken into account, the values are ap-proximately a gram per calorie For practical purposes, water requirements can be meas-ured as the amount of water consumed voluntarily under specified conditions This implies that thirst is a result of need Water Consumption of Animals In dry roughage and concentrate feeding programs the water present in the feed is so small relative to the animal's needs that it may be ignored (Winchester and Morris 1956) « Beef Cattle. Data calculated by Winchester and Mor-n s (1956)" indicated that values for water intake vary widely depending primarily on ambient temperature and dry matter intake European breeds consumed approxi-mately 3 5, 5 3, 7 0, and 17 liters of water daily per kilo-gram (kg) dry matter ingested at 40, 70, 90, 100 F , respec-tively Thus at an atniosphenc temperature of 21 C (70 F ) , a 450 kg steer on a 9 4 kg daily dry matter ration would consume approximately 50 liters of water per day, while at 32 C (90 F ) the expected daily water intake would be 66 liters Dairy Cattle. T h e calculations of Winchester and Morris (1956)^^ showed how water requirements varied with weight of cow, fat content of milk, ambient tempera-ture, and amount needed per kilogram of milk daily These investigations indicated that at 21 C (70 F ) a cow weighing approximately 450 kg would consume about 4 5 liters of water per kilogram dry feed plus 2 7 1/kg of milk produced Dairy heifers fed alfalfa and silage obtained about 20 per cent of their water requirements in the feed Dairy cattle suffer more quickly from a lack of water than from a shortage of any other nutrient and will drink 3 0 to 4 0 kg of water per kilogram of dry matter consumed (National R e -search Council, Committee on Animal Nutrition, hereafter referred to as N R C 1971a) Cows producing 40 kg of milk per day may drink up to 110 kg of water when fed dry feeds Sheep. Generally water consumption by sheep amounts to two times the weight of dry matter feed intake ( N R C 1968b) 'Ì But many factors may alter this value, e g , ambient temperature, activity, age, stage of production, plane of nutrition, composition of feed, and type of pasture Ewes on dry feed in winter require four liters per head daily before lambing and six or more liters per day when nursing lambs (Morrison 1959) Swine. Pigs require 2 to 2 5 kg of water per kilogram of dry feed, but voluntary consumption may be as much as 4 to 4 5 kg in high ambient temperature ( N R C 1968a) 5" Mount et al (1971)^' reported the mean water feed ratios were between 2 1 and 2 7 at temperatures between 7 and 22 C , and between 2 8 and 5 0 at 30 and 33 C T h e range of mean water consumption extended from 0 092 to 0 184 1/kg body weight per day Leitch and Thomson (1944)^* cited studies that demonstrated that a water-to-mash ratio of 3.1 gave the best results Horses. Leitch and Thomson (1944)^^ cited data that horses needed two to three liters of water per kg dry ration Morrison (1936)" obtained data of a horse going at a trot that gave off 9 4 kg of water vapor This amount was nearly twice that given off when walking with the same load, and more than three times as much as when resting during the same period Poultry. James and Wheeler (1949)''^ observed that more water was consumed by poultry when protein was increased in the diet, and more water was consumed with meat scrap, fish meal, and dried whey diets than with an all-plant diet Poultry generally consumed 2 to 3 kg of water per kilogram of dry feed Sunde (1967)*^ observed that when laying hens, at 67 percent production, were de-prived of water for approximately 36 hours, production dropped to eight per cent within five days and did not re-turn to the production of the controlled hens until 25-30 days later Sunde (personal communication 1971)'* prepared a table that showed that broilers increased on daily water consumption from 6 4 to 211 liters per 1,000 birds between two and 35 days of age, respectively Corresponding water intake values for replacement pullets were 5 7 to 88 5 liters RELATION OF NUTRIENT ELEMENTS IN WATER TO TOTAL DIET All the mineral elements essential as dietary nutrients occur to some extent in water (Shirley 1970) *° Generally the elements are in solution, but some may be present in suspended materials Lawrence (1968)*' sampled the Chat-tahoochee River system at six different reservoirs and river and creek inlets and found about 1, 3, 22, 39, 61, and 68 per cent of the total calcium, magnesium, zinc, manganese,
ZO^ISection VâAgricultural Uses of Water copper, and i ron present i n suspended materials, respec-t ively A n y given water supply requires analysis i f dietary decisions are to be most effective I n the Systems for Technical Data ( S T O R E T ) of the Wate r Programs Off ice of the Envi ronmenta l Protection Agency, data (1971)*' were accumulated f r o m surface water analyses obtained i n the U n i t e d States d u r i n g the period 1957-1969 These data included values for the mean, m a x i m u m , and m i n i m u m concentrations of the nut r ient elements (see Tab le V - 1 ) These values obviously include many samples f r o m calcium-magnesium, sulfate-chloride and sodium-potassium, sulfate-chlonde type of water as wel l as the more common calcium-magnesium, carbonate-bicarbonate type For this reason the mean values for sodium, chloride, and sulfate may appear some-wha t high Tab le V - 2 gives the estimated average intake of d r i n k i n g water of selected categories of various species of f a r m ani -mals expressed as liters per day Three values for each of ca lc ium and salt are given for i l lustrat ive purposes One co lumn expresses the Nat iona l Academy of Sciences value for dai ly requirement of the nut r ien t per day, the second gives the amount of the element contr ibuted by the average concentration of the element (calculated f r o m data i n Tab le V - 1 ) i n the average quan t i ty of water consumed da i ly , the t h i r d co lumn gives the approximate percentage of the dai ly requirements contr ibuted by the water d runk each day fo r each species of an imal Magnesium, calculated as i n Tab le V - 2 , was found to be present i n quantities that w o u l d provide 4 to 11 per cent of the requirements for beef and da i ry cattle, sheep, swine, horses, chickens, and turkeys Cobalt (Co) concentrations obtained by D u r u m et al (1971) '* were calculated, as they were more typical of water available to livestock than current values reported i n S T O R E T (1971) A sufficient amount of Co was present at the median level to supply approximately three to 13 TABLE V-1âWater Composition, United States, 1957-69 {STORET) (Collected at 140 stations) TABLE V-2âDaily Requirements of Average Concentrations of Calcium and Salt in Water for Various Animals Snbstsnce Mean Maiimum Minimum NoDetit. Phmptioras, mtfl 0 087 5 0 0 001 1,729 CalBDin, n i / l 511 173 0 11 0 510 Mainesnm, mt/l 14 3 137 0 85 1,143 Sodium, mi/l 55 1 7,500 0 0 2 1,801 PotatsDm, mi/l 43 370 0 0 06 1,104 GhlonilD, mi/I 478 0 19,000 0 0 000 37,355 SoViis, mi/l 135 3 3,313 0 0 000 30,229 Copper, p i / l 13 8 M 0 0 8 1,871 lron,ti|/l 439 4,600 0 0 10 1,836 Maii{anen,fi(/I 294 3,230 0 020 1,818 Zinc,|i|/I 51 8 1,183 0 1 0 1,883 0 016 1 0 0 01 234 loiGn»>,fi|/l 4S1 336 0 40 15 CotBIt^;l|/l 1 0 50 0 000 720 Calcium Salt<' Animal Oaili'' nter intake. I RequiteilÌ Aferaie' ami in Approi Ami in* Perceotaie dnnkini olRei|.in daily gm drinking water, gm el Rei). in water daily gm water, gm water Beet cattle 450 kt bod} w l Nuraoicow 60 28 3 4 12 25 8 5 34 FiniiMni iteer 60 21 3 4 16 24 8 5 35 Daiij cattle 450 k i bodj wl Udatini cow 30 76 5 1 7 66 12 7 19 Growini baler 60 15 3 4 22 21 8 5 40 Maintenance, cow 60 12 3 4 21 21 8 5 40 Sbeep lectatini ewe, 64 kg 6 6 8 0 3 5 13 0 9 7 Fattening lamb, 45 kg 4 3 1 0 2 7 10 0 8 6 Swine Growing, 30 kg 6 10 2 0 34 3 4 3 0 84 20 Fattening, 60 to 10O kg 8 16 5 0 46 3 4 3 1 12 26 lactating sowi, 200-250 kg 14 33 0 0 80 2 28 0 1 36 7 Honei 450 kg bod; wt Medium work 40 14 2 3 16 90 5 6 6 lattating SO 30 2 9 10 90 7 1 8 PoultiT CInckens, 8 weeks old 0 2 1 0 0 011 1 0 38 0 03 8 lejing hen 0 2 3 4 0 on <1 0 44 003 6 Torke) 0 2 1 2 0 Oil 1 0 38 0 03 8 <>Dutzi!BnandB[elind097D)>' tOnrometaL(l971)u " See disDsiion on Water Coniumption in teit lor lourcei ot these vahies. ' Sources ol nines are the National Academy el Sdentet, NRC Bulletins on Nutrient requirementL ' Calculated IromTeblel << Based on sodium in water per cent of the dietary requirements of beef and da i ry cattle, sheep, and horses T h e N R C (1971a,«« 1968b") does not state wha t the cobalt requirements were for poul t ry and swine Sulfur values demonstrated that approximately 29 per cent of beef cattle requirements were met at average con-centrations, da i ry cattle 21 to 45 per cent , sheep 10 to 11 per cent, and horses 18 to 23 per cent of their requirements T h e N R C (1971a,«51968b") do not give sulfur requirements for poul t ry and swine Iodine was not among the elements m the S T O R E T accumulat ion, but values obtained by Dan tzman and Breland ( 1 9 7 0 ) " for 15 rivers and lakes i n F lor ida can be used as i l lustrat ive values Iod ine was present i n sufficient amounts to exceed the requirements o f beef cattle and nonlactat ing horses and to meet 8 to 10 per cent of the requirements of sheep and 24 to 26 per cent o f those of hens Phosphorus, potassium, copper, i ron , zinc, manganese, and selenium, when present at mean concentrations (Tab le V - 1 ) , w o u l d supply dai ly only one to four per cent or less of that recommended by the N R C (1966,« ' 1968a," 1 9 6 8 b , « 1970,6' 1971a,'^ 1971b**) for beef and da i ry cattle, sheep, swine, horses, and poul t ry at no rma l water consumption levels I f the m a x i m u m values shown i n T a b l e V - 1 are present, some water w o u l d contain the dietary requirements of some species i n the case o f sodium chloride, sulfur , and iodine Appreciable amounts of ca lc ium, copper, cobalt , i ron ,
Water /or Livestock Enterprises/2>Q1 manganese, zinc, and selenium w o u l d be present, i f water were supplied w i t h the m a x i m u m levels present O n the other hand, i f the water has only the m i n i m u m concentra-t ion of any of the elements present, i t w o u l d supply very l i t t l e of the dai ly requirements I t IS generally believed that elements i n water solution are available to the an imal that consumes the water, at least as m u c h as when present i n solid feeds or d ry salt mixes Th is was indicated when Shirley et al (1951,* ' 1957*') f ound that P'* and Ca*^ dissolved i n aqueous solu-t ion as salts and administered as a drench, were absorbed at equivalent levels to the isotopes, when they were incor-porated i n forage as fer t i l izer and fed to steers, respectively M a n y isotope studies have demonstrated that minerals i n water consumed by animals are readily absorbed, deposited i n their tissues, and excreted EFFECT OF SALINITY ON LIVESTOCK I t IS we l l k n o w n that excessively saline waters can cause physiological upset or death of livestock T h e ions most commonly involved i n causing excessive salinity are ca lc ium, magnesium, sodium, sulfate, bicarbonate, and chloride Others may contr ibute significantly i n unusual situations, and these may also exert specific toxicities separate f r o m the osmotic effects of excessive salinity (See Tox ic Elements and Ions below ) Ear ly i n this century, Larsen and Bailey (1913) ' ° re-ported that a natura l water va ry ing f r o m 4,546 to 7,369 mg/1 of total salts, w i t h sodium and sulfate ions predomi-nat ing, caused m i l d diarrhea but no symptoms of toxici ty in dairy cattle over a two-year period Later , Ramsay (1924)" reported f r o m his observations that cattle could thr ive on water containing 11,400 mg/1 of total salts, that they could l ive under certain conditions on water containing 17,120 m g / 1 , and that horses thr ived on water w i t h 5,720 mg/1 and were sustained when not worked too hard on water w i t h 9,140 mg/1 T h e first extensive studies of saline water effects on rats and on livestock were made i n Oklahoma (Hel ler and L a r -wood 1930," Hel ler 1932," 1933) " Rats were fed waters of various sodium chloride concentrations, and i t was found among other things that (a) water consumption increased w i t h salt concentrat ion but only to a point after w h i c h the animals finally refused to d r ink u n t i l thirst drove them to i t , at w h i c h t ime they drank a large amount at one t ime and then d i e d , (b) older animals were more resistant to the ef-fects o f the salt than were the young , (c) the effects of salin-i t y were osmotic rather than related to any specific i o n , (d) reproduct ion and lactat ion were affected before g r o w t h effects were noted , (e) there appeared, in t ime, to be a physiological adjustment to saline waters, and ( f ) 15,000-17,000 mg/1 of total salts seemed the m a x i m u m that could be tolerated, some adverse effects being noted at concen-trations lower than this W i t h laying hens, 10,000 mg/1 o f sodium chloride i n the d r ink ing water greatly delayed the onset of egg product ion, but 15,000 mg/1 or more were re-quired to affect g rowth over a 10-week period I n swine, 15,000 mg/1 of sodium chloride i n the d r ink ing water caused death m the smaller animals, some leg stiffness i n the larger, but 10,000 mg/1 d i d not appear par t icular ly i n -jur ious once they became accustomed to i t Sheep existed on water containing 25,000 mg/1 of sodium or ca lc ium chloride or 30,000 mg/1 of magnesium sulfate but not w i t h -out some deleterious eff"ects Cattle were somewhat less re-sistant, and I t was concluded that 10,000 mg/1 of total salts should be considered the upper l i m i t under w h i c h their maintenance could be expected A lower l i m i t was suggested for lactat ing animals I t was fur ther observed that the ani -mals wou ld not d r ink highly saline solutions i f water of low salt content was available, and that animals showing ef-fects of saline waters returned quickly to normal when a l -lowed a water of low salt content Frens ( 1 9 4 6 ) " reported that 10,000 mg/1 of sodium chloride in the d r ink ing water of dai ry cattle produced no symptoms of toxici ty , whi le 15,000 mg/1 caused a loss of appetite, decreased m i l k product ion, and increased water consumption w i t h symptoms of salt poisoning in 12 days I n studies w i t h beef heifers, Embry et al (1959)" re-ported that the addi t ion of 10,000 mg/1 of sodium sulfate to the d r ink ing water caused severe reduction i n its con-sumption, loss of weight, and symptoms of dehydrat ion Either 4,000 or 7,000 mg/1 of added sodium sulfate increased water intake but had no effect on rate o f gain or general health Similar observations were made using waters w i t h added sodium chloride or a mix ture of salts, except that symptoms of dehydrat ion were noted, and the mixed salts caused no increase in water consumption Levels of up to 6,300 mg/1 of added mixed salts increased water consump-t ion i n weanl ing pigs, but no h a r m f u l effects were observed over a three-month period I n Austral ia , Peirce (1957 , " 1959,'^ 1960,«5 1962,'* 1963," 1966,88 1968a,« ' 1968b"') conducted a number of experiments on the salt tolerance of M e r i n o wethers O n l y minor h a r m f u l effects were observed i n these sheep when they were confined to waters containing 13,000 mg/1 or less of various salt mixtures Nevada workers have reported several studies on the ef-fects of saline waters on beef heifers They found that 20,000 mg/1 of sodium chloride caused severe anorexia, weight loss, anhydremia, collapse, and certain other symp-toms, whi le 10,000 mg/1 had no effects over a 30-day period other than to increase water consumption and decrease blood urea (Weeth et al 1960) " Add i t i ona l experiments (Weeth and Haver land 1961)'* again showed 10,000 mg/1 to cause no symptoms of tox ic i ty , whi le at 12,000 m g / 1 adverse effects were noted, and these intensified w i t h i n -creasing salt concentration in the d r ink ing water A t a con-centrat ion of 15,000 mg /1 , sodium chloride increased the rat io of urine excretion to water intake (Weeth and
ZOQ/Seclwn VâAgricultural Uses of Water Lesperance ISSS),""" and a p rompt and distinct diuresis occurred when the heifers consumed water containing 5,000 or 6,000 mg/1 fo l lowing water depr ivat ion (Weeth et al 1968) W h i l e w i t h waters containing about 5,000 mg/1 (Weeth and Hunte r 1971)** or even less (Weeth and Capps 1971)'* of sodium sulfate no specific ion effects were noted, heifers drank less, lost weight, and had increased methemo-globin and sulfhemoglobin levels A later study (Weeth and Capps 1972) ' ° gave similar results, but in addi t ion suggested that the sulfate ion itself, at concentrations as low as 2150 mg/1 had adverse effects I n addi t ion to the Oklahoma work, several studies on the effects of saline water on poul t ry have been reported Selye ( 1 9 4 3 ) " found that chicks 19 days o ld when placed on experiment had diarrhea, edema, weakness, and respira-tory problems du r ing the first 10 days on water containing 9,000 mg/1 o f sodium chloride Later , the edema disap-peared, but nephrosclerotic changes were noted Water containing 3,000 mg/1 of sodium chloride was not toxic to four-week-old chicks Others (Kare and Biely 1948)" observed that w i t h two-day-old chicks on water containing 9,000 mg/1 of added sodium chloride there were a few deaths, some edema, and certain other symptoms of toxic i ty A solution w i t h 18,000 mg/1 of the salt was not toxic , however, when replaced on alternate days by fresh water, neither was i t readily con-sumed Scrivner (1946)'^ f o u n d that sodium chloride i n the d r i n k -i n g water of day-old poults at a concentration of 5,000 mg/1 caused death and vary ing degrees of edema and ascites i n over half of the birds in about two weeks Sodium bicarbo-nate at a concentration o f 1,000 mg/1 was not toxic, at 3,000 mg/1 caused some deaths and edema, and as the con-centration increased above this, the effects were more pro-nounced A solution containing 1,000 mg/1 of sodium hy-droxide caused death i n two of 31 poults by 13 days, but the remainder survived wi thou t effects, and 7,500 mg/1 of sodium citrate, iodide, carbonate, or sulfate each caused edema and many deaths South Dakota workers (Kr i s ta et al 1961)^* studied the effects of sodium chloride in water on laying hens, turkey poults, and ducklings A t 4,000 mg /1 , the salt caused some increased water consumption, watery droppings, decreased feed consumption and g rowth , and increased mor ta l i ty These effects were more pronounced at a higher concentra-t ion , 10,000 m g / 1 , causing death in a l l of the turkey poults at two weeks, some symptons of dehydrat ion i n the chicks, and decreased egg product ion i n the hens Experiments w i t h l ay ing hens restricted to water conta in ing 10,000 mg/1 o f sodium or magnesium sulfate gave results similar to those for sodium chloride I n addi t ion to the experimental work , there have been reports i n the l i terature o f field observations re la t ing to the effects of excessively saline water (Ballantyne 1957,⢠Gastler and Olson 1957," Spafford 1941"), and a number TABLE V-3âGuide to the Use of Saline Waters for Livestock and Poultry Total soluble salts content ol waters Comment Lesstlnn 1,000 1,0011-2,999 3,000-4,999 5,000-6,999 7,000-10,000 Oter10,000 Relati«elj low level of silimty Eicellent lor all classes ol livestock end poultiT Verf satisfactory lot all classes ol rimtotk and poultry May causa temporary and mild diarrhea in linstock not accustomed to tliem or watery droppints in poultry Satisfactory for livestock, but may cause temporary diarrhea or be refused at nrst by am mats not accustomed to them Poor waters for poultry, often causini water feces, increased mortahty, and decreased powth, especially In turkeys. Can be used with reasonable safety for dairy and beel cattle, for sheep, swine, and horses. Avoid use for pretnant or lactatini amnuls. Not acceptable for poultry Unlit for poultry and probably for swine. Considerable nsk m uant for preinant or lactabn; cows, horses, or sheep, or lor the youni of these speaes. In leneral, use shou Id be evoided althouf h older ruminants, horses, poultry, and swine may subsist on them under certain condibons Risks with these bigbly saline waters are so (real that they cannot be recommended lor use under any conditions. of guides to the use of these waters for livestock have been published (Ballantyne 1957,'" E m b r y et al 1959," Kr i s t a et al 1962," M c K e e and W o l f , 1963,*' Officers of the Depar tment of Agr icu l tu re and the Government Chemical Laboratories 1 9 5 0 , S p a f f o r d , 1941'") Table V-3 is based on the available published in fo rmat ion A m o n g other things, the fo l lowing items are suggested for consideration i n using this table ⢠Animals d r ink l i t t le , i f any, h ighly saline water i f water of low salt content is available to them ⢠Unless they have been previously deprived of water, animals can consume moderate amounts o f h igh ly saline water for a few days w i t h o u t being harmed ⢠A b r u p t changes f r o m water o f l ow salinity to h igh ly saline water cause more problems than a gradual change ⢠Depressed water intake is very l ikely to be accom-panied by depressed feed intake Table V-3 was developed because i n a n d or semiarid regions the use of h igh ly saline waters may often be neces-sary I t has bu i l t in to i t a very small marg in of safety, and Its use probably does not el iminate a l l risk of economic loss Cri ter ia for desirabil i ty of a livestock water are a some-what d i f ferent matter These should probably be such that the risk of economic loss f r o m using the water for any species or age of animals, lactat ing or not, on any normal feeding program, and regardless o f c l imat ic conditions, is almost nonexistent O n the other hand, they should be made no more severe than necessary to insure this small nsk Recommendation From the standpoint of salinity and its osmotic effects, waters containing 3,000 mg of soluble salts per liter or less should be satisfactory for livestock under almost any circumstance. While some minor physiological upset resulting from waters with
Water for Livestock Enterprtses/309 salinities near this limit may be observed, eco-nomic losses or serious physiological disturbances should rarely, if ever, result from their use. TOXIC SUBSTANCES IN LIVESTOCK WATERS There are many substances dissolved or suspended i n waters that may be toxic These include inorganic elements and their salts, certain organic wastes f r o m man's activities, pathogens and parasitic organisms, herbicide and pesticide residues, some biologically produced toxins, and radio-nuclides For any of the above, the concentrations at which they render a water undesirable for use for livestock is subject to a number of variables These include age, sex, species, and physiological state of the animals, water intake, diet and its composit ion, the chemical f o r m of any toxic element present, and the temperature of the environment Na tu ra l ly , i f feeds and waters both contain a toxic substance, this must be taken in to account Both short and long te rm effects and interactions w i t h other ions or compounds must also be con-sidered T h e development of recommendations for safe concentra-tions of toxic substances i n water for livestock is extremely d i f f i cu l t Careful at tent ion must be given to the discussion that follows as wel l as the recommendations and to any ad-d i t iona l experimental f indings that may develop Based on available research, an appropriate marg in of safety, under almost a l l conditions, of specific toxic substances h a r m f u l to livestock that d r ink the waters and to man who consumes the livestock or their products, is reviewed below A l t h o u g h the marg in of safety recommended is usually large, the c r i -teria suggested cannot be used as a guide in diagnosing livestock losses, since they are wel l below toxic levels for domestic animals Toxic Elements and Ions Those ions largely responsible for .salinity in water (sodium, calcium, magnesium, chloride, sulfate, and b i -carbonate) are m themselves not very toxic There are, however, a number of others that occur natura l ly or as the result of man's activities at troublesome concentrations I f feeds and water both contain a toxic ion, both must be con-sidered Interactions w i t h other ions, i f known, must be taken in to account Elements,or ions become objectionable m water when they are at levels toxic to animals, where they seriously reduce the pala tabi l i ty of the water, or when they accumulate excessively i n tissues or body fluids, rendering the meat, m i l k , eggs, or other edible product unsafe or u n f i t for human use Aluminum Soluble a l u m i n u m has been found i n surface waters of the U n i t e d States i n amounts to 3 mg /1 , but its occurrence at such concentrations is rare because i t readily precipitates as the hydroxide ( K o p p and K r o n e r 1970) Most edible grasses contain about 15-20 m g / k g of the element However, there is no evidence that i t is essential for an imal g rowth , and very l i t t l e is found deposited in ani -ma l tissues (Underwood 1971) I t is not highly toxic ( M c K e e and W o l f 1963," ' Unde rwood 1971) ,2" but Deo-bald and Elvehjem (1935) ' '* found that a level of 4,000 m g a l u m i n u m per k i logram of diet caused phosphorus de-ficiency in chicks Its occurrence in water should not cause problems for livestock, except under unusual conditions and w i t h acid waters Recommendation Livestock should be protected where natural drinking waters contain no more than 5 mg/1 aluminum. Arsenic Arsenic has long been notorious as a poison Nevertheless I t IS present i n al l l i v ing tissues i n the inorganic and m certain organic forms I t has also been used medic inal lv I t IS accepted as a safe feed addit ive for certain domestic animals I t has not been shown to be a required n u t n e n c for animals, possibly because its ub iqu i ty has precluded thp compounding of deficient diets (Frost 1967) T h e toxici ty of arsenic can depend on its chemical f o r m Its inorganic oxides being considerably more toxic than organic forms occurr ing in l i v ing tissues or used as feed additives Differences in toxicities of the various forms are clearly related to the rate of their excretion, the least tox i r being the most rapid ly el iminated (Frost 1967,''' ' Under -wood 1971) Except in unusual cases, this element should occur in waters largely as inorganic oxides I n waters carry-ing or i n contact w i t h na tura l col loidal mater ial , the soluble arsenic content may be decreased to a very low level by ad-sorption Wadswor th (1952)^*" gave the acute toxici ty of inorganic arsenic for f a r m animals as follows poul t ry , 0 05-0 10 g per a n i m a l , swine, 0 5-1 0 g per a n i m a l , sheep, goats, and horses, 10 0 - 1 5 0 g per a n i m a l , and cattle, 15-30 g per an imal Franke and M o x o n (1936)'^^ concluded that the m i n i m u m dose required to k i l l 75 per cent of rats given intraperi toneal injections of arsenate was 14â18 mg arsenic per k i logram, whi le for arsenite i t was 4 25-4 75 m g / k g of body weight W h e n mice were given d r ink ing water containing 5 m g / 1 of arsenic as arsenite f r o m weaning to natura l death, there was some accumulat ion of the element in the tissues of several organs, a somewhat shortened l ife span, but no carcinogenic effect (Schroeder and Balassa 1967) I n a similar study w i t h rats (Schroeder et al 1968b),^'* neither toxic i ty nor carcinogenic effects were observed, but large amounts accumulated i n the tissues Peoples (1964)' '^ fed arsenic acid at levels u p to 1 25 m g / kg of body weight per day for eight weeks to lactat ing cows This is equivalent to an intake of 60 liters of water
"ilQ/Section VâAgricultural Uses of Water containing 5 5 mg/1 of arsenic (10 4 m g of arsenic acid) dai ly by a 500 kg animal His results indicated that this f o r m of arsenic is absorbed and rap id ly excreted in the ur ine Thus there was l i t t l e tissue storage of the element, at no level of the added arsenic was there an increased arsenic content of the m i l k , and no toxic i ty was observed Accord ing to Frost (1967), ' '" there is no evidence that 10 parts per m i l l i o n (ppm) of arsenic in the diet is toxic to any animal Arsenicals have been accused of being carcinogenic This matter has been thoroughly reviewed by Frost (1967), '^ ' who concluded that they appear remarkably free of this property Most human foods contain less than 0 5 p p m of arsenic, bu t certain marine animals used as human food may con-centrate I t and may contain over 100 p p m (Frost 1967,''" Underwood 1971"'') Permissible levels of the element i n muscle meats is 0 5 p p m , in edible meat by-products, 1 0 p p m , and in eggs, 0 5 p p m ( U S Dept of Hea l th , Educa-t ion, and Welfare, Food and D r u g Adminis t ra t ion 1963,^" 1964"«) Federal D r i n k i n g Water Standards list 0 05 mg/1 as the upper allowable l i m i t to humans for arsenic, but M c K e e and W o l f ( 1963 ) ' " suggested 1 0 mg/1 as the upper l i m i t for livestock d r ink ing water T h e possible role of biological methyla t ion in increasing the toxici ty (Chemical Engineer-ing News 1971)'-" suggested added caution, however, and natura l waters seldom contain more than 0 2 mg/1 ( D u r u m et al 1971) '^' Recommendation To provide the necessary caution, and in view of available data, an upper limit of 0.2 mg/1 of arsenic in water is recommended. Beryllium Bery l l i um was found to occur in natura l surface waters only at very low levels, usually below 1 ( K o p p and K r o n e r 1970) '^^ Conceivably, however, i t could enter waters i n effluents f r o m certain metal lurgical plants Its salts are not h ighly toxic, laboratory rats having survived for two years on a diet that supplied the element at a level of about 18 m g / k g of body weight dai ly Pomelee (1953)^23 calculated that a cow could d r ink almost 1,000 liters of water containing 6,000 mg/1 wi thou t harm, i f these data for rats are transposable to cattle Th i s type of extrapolat ion must, however, be used w i t h caution, and the paucity of addi t ional data on the toxic i ty of be ry l l ium to livestock precludes recommending at this t ime a l i m i t for its concen-t ra t ion in livestock waters Boron T h e toxic i ty of boron, its occurrence i n foods and feeds, and I t s role i n an imal nu t r i t i on have been reviewed by M c C l u r e (1949) , "° M c K e e and W o l f (1963) , " ' and Underwood (1971) A l t h o u g h essential for plants, there IS no evidence that boron is required by animals I t has a relatively low order of toxic i ty I n the da i ry cow, 16-20 g of boric acid per day for 40 days produced no i l l effects ( M c K e e and W o l f 1963) There is no evidence that boron accumulates to any great extent m body tissues Apparent ly , most na tura l waters could be expected to contain concentrations we l l below the level of 5 0 mg/1 Th is was the m a x i m u m amount found i n 1,546 samples of r iver and lake waters f r o m various parts of the U n i t e d States, the mean value being 0 1 mg /1 ( K o p p and K r o n e r 1970) '*^ G r o u n d waters could contain substantially more than this at certain places Recommendation Experimental evidence concerning the toxicity of this element is meager. Therefore, to offer a large margin of safety, an upper limit of 5.0 mg/1 of boron in livestock waters is recommended. Cadmium C a d m i u m (Cd) is normal ly found i n natura l waters at very low levels A nat ionwide reconnaissance of surface waters of the U n i t e d States ( D u r u m et al 1971)'^' revealed that of over 720 samples, about fou r per cent contained over 10 ; x g / l of this element, and the highest level was 110 / x g / l G round water on L o n g Is land, New York , contained 3 2 mg/1 as the result of contaminat ion by waste f r o m the elec-t rop la t ing industry, and mine waters i n Missouri contained 1,000 mg/1 ( M c K e e and W o l f 1963) '» ' Research to date suggests that c a d m i u m is not an essential element I t is, on the other hand, quite toxic M a n has been sickened by about 15 p p m i n popsicles, 67 p p m in punch, 300 p p m i n a cold d r ink , 530 p p m i n gelatin, and 14 5 m g taken o ra l ly , al though a f ami ly of four whose d r i n k i n g water was reported to contain 47 p p m had no history of i l l eff"ects ( M c K e e and W o l f 1963) ' " Extensive tests have been made on the effects of various levels of c a d m i u m i n the d r i n k i n g water on rats and dogs ( M c K e e and W o l f 1963) ' " Because of the accumlat ion and retention of the element i n the l iver and kidney, i t was recommended that a l i m i t o f 100 j i g / l , or preferably less, be used for d r ink ing waters Parizek (1960)2'« found that a single dose of 4 5 m g C d / k g of body weight produced permanent steril i ty in male rats A t a level o f 5 mg /1 i n the d r i n k i n g water o f rats (Schroeder et al 1963a)"8 or mice (Schroeder et al 1963b), '"» reduced longevity was observed Intravenous in jec t ion of c a d m i u m sulfate in to pregnant hamsters at a level of 2 m g C d / k g of body weight on day eight of gestation caused mal forma-tions in the fetuses ( M u l v i h i l l et al 1970) M i l l e r ( 1971 ) " ' studied c a d m i u m absorption and dis t r i -but ion i n ruminants H e found that only a small part o f ingested c a d m i u m was absorbed, and that most of wha t was went to the kidneys and l iver Once absorbed, its turnover rate was very slow T h e cow is very efficient i n keeping
Water for Livestock Enterprises/3\ 1 c a d m i u m out of its m i l k , and M i l l e r concluded that most ma jo r an imal products, inc lud ing meat and m i l k , seemed qui te we l l protected against c admium accumulat ion Interactions of c admium w i t h several other trace ele-ments ( H i l l et al 1963,"=' G u n n and Gou ld 1967,'*' Mason and Y o u n g 1967)'*' somewhat confuse the matter of estab-lishing cri teria Recommendation From the available data on the occurrence of cadmium in natural waters, its toxicity, and its accumulation in body tissues, an upper limit of 50 Mg/l allows an adequate margin of safety for livestock and is recommended. Chromium I n a five-year survey of lake and river waters of the U n i t e d States ( K o p p and K r o n e r 1970),'82 ^y^^ highest level found in over 1,500 samples was about 0 1 m g / l , the average being about 0 001 mg/1 I n another similar survey ( D u r u m et al 1971)" ' of 700 samples, none contained over 0 05 mg /1 of c h r o m i u m V I and only 11 contained more than 0 005 mg/1 A number of industr ial processes however use the element, wh ich then may be discharged as waste in to sur-face waters, possibly at rather h igh levels Even i n its most soluble forms, the element is not readily absorbed by animals, being largely excreted i n the feces, and I t does not appear to concentrate in any part icular mammal ian tissue or to increase in these tissues w i t h age ( M e r t z 1967, '" Unde rwood 1971^4) Hexavalent c h r o m i u m is generally considered more toxic than the t r ivalent f o r m ( M e r t z 1967) However, i n their review of this element, M c K e e and W o l f ( 1963 ) ' " suggested that I t has a rather low order of toxic i ty Further , Gross and Heller (1946) '^ ' found that for rats the m a x i m u m nontoxic level, based on growth , for c h r o m i u m V I in the d r ink ing water was 500 mg/1 They also found that this concentration of the element in the water d i d not aflfect feed u t i l iza t ion by rabbits Romoser et al (\96\)^^ found that 100 p p m of c h r o m i u m V I i n chick diets had no effect on the per form-ance of the birds over a 21-day period I n a series of experiments, Schroeder et al (1963a,^" 1963b ,"» 1964,2" iges"^) administered water containing 5 mg /1 of c h r o m i u m I I I to rats and mice on low-ch romium diets over a l ife span A t this level, the element was not toxic, bu t instead i t had some beneficial efTects Tissue levels d i d not increase significantly w i t h age As a result of their review of c h r o m i u m toxici ty , M c K e e and W o l f ( 1 9 6 3 ) ' ° ' suggested that up to 5 mg/1 of c h r o m i u m I I I or V I m livestock d r i n k i n g water should not be ha rm-f u l W h i l e this may be reasonable, i t may be unnecessarily h igh when the usual concentrations of the element i n nat-u r a l waters is considered Recommendation An upper allowable limit of 1.0 mg/1 for livestock drinking waters is recommended. This provides a suitable margin of safety. Cobalt I n a recent survey of surface waters i n the U n i t e d States ( D u r u m et al 1971)' '" 63 per cent of over 720 samples were found to contain less than 0 001 mg/1 of cobalt One sample contained 4 5 mg /1 , one contained 0 11 m g / 1 , and three contained 0 05-0 10 mg/1 Underwood (1971)^^^ reviewed the role of cobalt i n an imal nu t r i t i on This element is par t o f the v i t amin B12 molecule, and as such i t is an essential nut r ient Ruminants synthesized their own v i t ami n B12 i f they were given oral cobalt For cattle and sheep a diet containing about 0 1 p p m of the element seemed nu t r i t iona l ly adequate A wide margin of safety existed between the required and toxic levels for sheep and cattle, wh ich were levels of 100 times those usually found i n adequate diets being wel l tolerated Nonruminants required preformed v i t amin Bi2 W h e n administered to these animals in amounts wel l beyond those present in foods and feeds, cobalt induced polycythemia (Underwood 1971) "Ì"Ì This was also true in calves pr ior to rumen development, about 1 1 m g of the element per kg of body weight administered daily caused depression of ap-petite and loss of weight Cobalt toxici ty was also summarized by M c K e e and W o l f (1963) ' " Recommendation In view of the data available on the occurrence and toxicity of cobalt, an upper limit for cobalt in livestock waters of 1.0 mg/1 offers a satisfactory margin of safety, and should be met by most natural waters. Copper T h e examinat ion of over 1,500 r iver and lake waters i n the U n i t e d States ( K o p p and K r o n e r 1970)'^^ yielded, at the highest, 0 28 mg/1 of copper and an average value of 0 015 mg/1 These rather low values were probably due i n par t to the relative insolubi l i ty of the copper ion in alkaline med ium and to its ready adsorbabil i ty on colloids ( M c K e e and W o l f 1963) ' " Where higher values than those reported above are found , pol lu t ion f r o m industr ial sources or mines can be suspected Copper is an essential trace element T h e requirement for chicks and turkey poults f r o m zero to eight weeks o f age is 4 p p m in the diet ( N R C 1971b) oÌs For beef cattle on rations low i n molybdenum and sulfur, 4 p p m i n the diet IS adequate, but when these elements are h igh , the copper requirement is doubled or t r ip led ( N R C 1970) A dietary level of 5 p p m i n the forage is suggested for pregnant and
^\2/Section VâAgricultural Uses of Water lactat ing ewes and their lambs ( N R C 1968b20') A level of 6 p p m i n the diet is considered adequate for swine ( N R C 1968a) Swine are apparently very tolerant of h igh levels of copper, and 250 p p m or more i n the diet have been used to improve l iveweight gams and feed efficiency ( N u t r i t i o n Reviews 1966a2"', N R C 1968a) O n the other hand, sheep were very susceptible to copper poisoning (Underwood 1971),^" and for these animals a diet containing 25 p p m was considered toxic A b o u t 9 m g per an imal per day was considered the safe tolerance level ( N R C 1968b) ^o' Several reviews of copper requirements and toxic i ty have been presented ( M c K e e and W o l f 1963 ," ' N u t n t i o n Re-views 1966a,^"' Unde rwood 1971) There is very l i t t l e ex-perimental data on the effects of copper i n the water supply on animals, and its toxic i ty must be judged largely f r o m the results of trials where copper was fed T h e element does not appear to accumulate at excessive levels i n muscle tissues, and I t IS very readi ly e l iminated once its administrat ion is stopped W h i l e most livestock tolerate rather h igh levels, sheep do not ( N R C 1968b) ^"^ Recommendation It is recommended that the upper limit for cop-per in livestock waters be 0.5 mg/1. Very few natural waters should fail to meet this. Fluorine T h e role of fluorine as a nut r ient and as a toxin has been thoroughly reviewed by Underwood (1971) (Unless otherwise indicated, the fo l lowing discussion, exclusive of the recommendation, is based upon this r e v i e w ) W h i l e there is no doubt that dietary fluoride i n appropriate amounts improved the caries resistance of teeth, the element has not yet been found essential to animals I f i t is a dietary essential, its requirement must be very low Its u b i q u i t y probably insures a continuously adequate intake by an i -mals Chronic fluoride poisoning of livestock has, on the other hand, been observed i n several areas of the w o r l d , resulting i n some cases f r o m the consumption of waters of h igh fluoride content These waters come f r o m wells i n rock f r o m w h i c h the element has been leached, and they often contain 10-15 mg /1 Surface waters, on the other hand, usually con-tain considerably less than 1 mg/1 Concentrations of 30-50 p p m of fluoride in the total ra t ion of da i ry cows is considered the upper safe l i m i t , higher values being suggested for other animals ( N R C 1971a) M a x i m u m levels of the element m waters that are tolerated by livestock are d i f f i cu l t to define f r o m available experimental work T h e species, volume, and cont inu i ty of water consumption, other dietary fluoride, and age of the animals, a l l have an effect I t appears, however, that as l i t t l e as 2 mg/1 may cause tooth mo t t l i ng under some c i r cum-stances A t least a several-fold increase i n its concentration seems, however, required to produce other in jur ious effects Fluor ide f r o m waters apparently does not accumulate i n soft tissues to a significant degree I t is transferred to a very small extent in to the m i l k and to a somewhat greater degree in to eggs M c K e e and W o l f ( 1963 ) " ' have also reviewed the mat ter of livestock poisoning by fluoride, concluding that 1 0 m g / I of the element i n their d r i n k i n g water d i d not h a r m these animals Other more recent reports presented data suggest-ing that even considerably higher concentrations of fluoride i n the water may, w i t h the exception of tooth mo t t l i ng , caused no animal health problems (Harr is et al 1963,"* Shupe et al 1964,^" N u t n t i o n Reviews 1966b,2" Saville 1967,2-'' Schroeder et al 1968a" ') Recommendation An upper limit for fluorides in livestock drinking waters of 2.0 mg/1 is recommended. Although this level may result in some tooth mottling it should not be excessive from the standpoint of animal health or the deposition of the element in meat, milk, or eggs. Iron I t is we l l k n o w n that i ron (Fe) is essential to an imal l i fe Further, i t has a low order of toxic i ty Deobald and Elveh-j e m ( 1 9 3 5 ) " ' found that i r o n salts added at a level of 9,000 m g Fe /kg of diet caused a phosphorus deficiency i n chicks This could be overcome by adding phosphate to the diet Campbel l (1961)'2'' f o u n d that soluble i r o n salt ad-ministered to baby pigs by stomach tube at a level of 600 m g F e / k g of body weight caused death w i t h i n six hours O ' D o n -ovan et al (1963)^'^ found very h igh levels of i ron i n the diet (4,000 and 5,000 m g / k g ) to cause phosphorus deficiency and to be toxic to weanl ing pigs Lower levels (3,000 m g / k g ) apparently were n o t toxic T h e intake o f water by livestock may be inh ib i t ed by h igh levels of this element (Tay lo r 1935) "^^ However, this should not be a common or a serious problem W h i l e i r o n occurs i n na tura l waters as ferrous salts wh ich are very soluble, on contact w i t h air i t is o x i -dized and I t precipitates as ferr ic oxide, rendering i t essen-t ia l ly harmless to an imal health I t IS not considered necessary to set an upper l i m i t of ac-ceptabi l i ty fo r i r o n in water I t should be noted, however, that even a few parts per m i l l i o n o f i ron can cause clogging of lines to stock water ing equipment or an undesirable stain-ing and deposit on the equipment itself Lead Lake and r iver waters of the U n i t e d States usually contain less than-0 05 mg /1 o f lead (Pb) , a l though concentrations i n excess of this have been reported ( D u r u m et al 1 9 7 1 , ' " K o p p and K r o n e r 1970) Some natura l waters i n areas where galena is found have had as much as 0 8 mg/1 of the
Water for Livestock Enterprises/Z\Z element I t may also be introduced in to waters i n the ef-fluents f r o m various industries, as the result of action of the water on lead pipes ( M c K e e and W o l f 1963) ," ' or by deposition f r o m pol luted air ( N R C 1972) A nut r i t iona l need for lead by animals has not been demonstrated, bu t its toxic i ty is we l l k n o w n A rather com-plete review of the matter of lead poisoning by M c K e e and W o l f (1963)" ' suggested that fo r livestock the toxici ty of the element had not been clearly established f r o m a quan t i -tative standpoint Even w i t h more recent data (Donawick 1966, " ' L i n k and Pensinger 1966,'** Harbourne et al 1968, ' " D a m r o n et al 1969,>" H a t c h and Funnel l 1969,'** Egan and O ' C u i l l 1970 , ' " Aronson 1971), '»8 i t is d i f f i cu l t to establish clearly at what level of intake lead becomes toxic, a l though a dai ly intake of 6-7 m g P b / k g of body weight has been suggested as the m i n i m u m that eventually gave rise to signs of poisoning i n cattle ( H a m m o n d and Aronson 1964) ' ' ^ Apparent ly , cattle and sheep are considerably more resistant to lead toxicosis than are horses, being remarkably tolerant to the continuous intake of relatively large amounts of the element ( H a m m o n d and Aronson 1964,'** Garner 1967, ' '^ Aronson 1971"" , N R C 19722"') However, there is some tendency for i t to accumulate i n tissues and to be transferred to the m i l k at levels that could be toxic to man ( H a m m o n d and Aronson 1964) '** There is some agreement that 0 5 mg/1 of lead i n the d r ink ing water of livestock is a safe level ( M c K e e and W o l f 1963) , " ' and the findings of Schroeder and his associates w i t h laboratory animals are in agreement w i t h this (1963a, 1963b,"9 1964,"* 1965" ' ) Using 10 times this level, or 5 mg/1 , of lead i n the d r ink ing water of rats and mice over their l ife spans, these authors observed no obvious direct toxic effects bu t d i d f i n d an increase i n death rates i n the older animals, especially m the males Schroeder et al (1965)^'*, observed that the increased mor ta l i ty was not caused by overt lead poisoning, but rather by an increased susceptibility to spontaneous infections H e m p h i l l et al (1971) ' " later reported that mice treated w i t h subclinical doses of lead ni t rate were more susceptible to challenge w i t h Salmonella lyphmunum Recommendation In view of the lack of information concerning the chronic toxicity of lead, its apparent role in reducing disease resistance, and the very low inci-dence in natural waters of lead contents exceeding the 0.05 mg/1 level, an upper limit of 0.1 mg/1 for lead in livestock waters is recommended. Manganese ^ Like i ron , manganese is a required trace element, occurs i n natura l waters at only low levels as manganous salts, and IS precipitated i n the presence of air as manganic oxide W h i l e I t can be toxic when administered i n the feed at h igh levels (Underwood 1971),''** i t is improbable that i t w o u l d be found at toxic levels in waters I t IS doub t fu l that setting an upper l i m i t of acceptability IS necessary for manganese, but as w i t h i ron , a few m i l l i -grams per l i ter i n water can cause objectionable deposits on stock water ing equipment Mercury Natu ra l waters may contain mercury or ig inat ing f r o m the activities of man or f r o m natura l ly occurr ing geological stores (Wershaw 1970,"^ W h i t e et al 1970) ^*' T h e element tends to sorb readily on a variety of materials, inc luding the bo t tom sediments of streams, greatly reducing the levels that migh t otherwise remain in solution ( H e m 1970) '⢠Thus, surface waters in the U n i t e d States have usually been found to contain much less than 5 ^tg/1 of mercury ( D u r u m et al 1971) '*' I n areas harbor ing mercury de-posits, their biological methylat ion occurs i n bo t tom sedi-ments (Jensen and Jernelov 1969)"* resulting in a con-t inuous presence of the element i n solution (Greeson 1970) '** I n comparison to the relative instabil i ty of organic com-pounds such as salts of phenyl mercury and methoxyethyl mercury (Gage and Swan 1961,'*' M i l l e r et al 1961,"* Danie l and Gage 1969,"^ Danie l et al 1971'") a lky l mercury compounds inc lud ing methyl mercury (CHsHg*) have a high degree of stabili ty in the body (Gage 1964,'*" M i l l e r et al 1961)"* resulting in an accumulative effect Th i s relative stabili ty, together w i t h efficient absorption f r o m the gut , contributes to the somewhat greater toxic i ty of oral ly administered methyl mercury as compared to poorly absorbed inorganic mercury salts (Swensson et al 1959) T h e biological half- l i fe of methyl mercury varies f r o m about 20 to 70 days in most species (Bergrund and Berl in 1969) " ' Bra in , liver, and kidney were the organs tha t ac-cumulated the highest levels of the element, w i t h the dis t r i -but ion of methyl and other a lky l mercury compounds favor-ing nerve tissue and inorganic mercury favor ing the kidney (Malishevskaya et al 1966,"* Platonow 1968,2^ Aberg et al 1969) '"^ Transfer of methy l mercury (Curley et al 1971),"" but not mercuric mercury (Berl in and U l lbe rg 1963),"* to the fetus has been observed T h e element also appeared i n the eggs o f poul t ry ( K i w i m a e et a l 1969)'** and w i l d birds ( B o r g e t a l 1969,"* Dustman et al 1970)'*2 but d i d not seem to concentrate there m u c h above levels found in the tissues of the adul t Data concerning levels of mercury that may be detr imental to hatchabi l i ty of eggs are too meager to sup-por t conclusions at this t ime Also, data concerning transfer of mercury to m i l k is lacking T h e an imal organs representing the pr inc ipa l tissues for mercury concentration are bra in , l iver, and kidney I t is desirable that the m a x i m u m allowable l i m i t fo r mercury i n livestock waters should result i n less than 0 5 p p m of ac-cumulated mercury i n these tissues Th is is the level now i n
"ilA/Section VâAgricultural Uses of Water use as the m a x i m u m allowable i n fish used for human con-sumption Few data are available quant i ta t ively relat ing dietary mercury levels w i t h accumulat ion i n an imal tissues T h e ratios between blood and brain levels of methyl mercury appeared to range f r o m 10 for rats to 0 2 for monkeys and dogs ( In terna t ional Commit tee on M a x i m u m Al lowable Concentrations of M e r c u r y Compounds 1969) I n addi -t ion , blood levels of mercury appeared to increase approxi -mately i n propor t ion to increases in dietary intake (Birke e t a l 1967"S T e j n i n g 1967« ' ) Assuming a 0 2 or more blood-to-tissue (bra in or other tis-sue) rat io for mercury i n livestock, the maintenance of less than 0 5 p p m mercury in a l l tissues necessitates ma in ta in ing blood mercury levels below 0 1 p p m This w o u l d indicate a m a x i m u m dai ly intake of 2 3 ^tg of mercury per k i logram body weight Based upon dai ly water consumption by meat animals in the range of up to about eight per cent of body weight. I t IS estimated that water may contain almost 30 /ig/1 of mercury as methyl mercury w i thou t the l imi ts of these cri teria being exceeded Support for this approxima-t ion was provided m part by the calculations of Aberg et al (1969)""' showing that after " i n f i n i t e " t ime the body burden of mercury in man w i l l approximate 15 2 times the weekly intake of methyl mercury A p p l y i n g these data to meat ani -mals consuming water equivalent to eight per cent of body weight and containing 30 /xg/1 of mercury w o u l d result i n an average of 0 25 p p m mercury in the whole an imal body Recommendation Until specific data become available for the vari-ous species, adherence to an upper limit of 10 /ig/1 of mercury in water for livestock is recommended, and this limit provides an adequate margin of safety to humans who will subsequently not be exposed to as much as 0.5 ppm of mercury through the consumption of animal tissue. Molybdenum Underwood (1971)^" reviewed the matter of mo lyb -denum's role i n an imal nu t r i t i on W h i l e the evidence that I t IS an essential element is good, the amount of molybdenum required has not been established For cattle, for instance, no m i n i m u m requirement has been set, but i t is believed to be low, possibly less than 0 01 p p m of the d ry diet ( N R C 1970) M c K e e and W o l f ( 1 9 6 3 ) ' " reviewed the matter of toxic i ty of mo lybdenum to animals, but Unde rwood (1971)^^* pointed out that many of the studies on its toxic i ty are ot l imi t ed value because a number of factors k n o w n to influence Its metabolism were not taken in to account i n mak ing these studies These factors included the chemical f o r m ot molybdenum, the copper status and intake of the an imal , the f o r m and amount of sulfur i n the diet, and other less wel l defined matters I n spite of these, there are data to support real species differences m terms of tolerance to the element Catt le seem the least tolerant, sheep a l i t t l e more so, and horses and swine considerably more tolerant W h i l e Shirley et al ( 1 9 5 0 ) " ' f ound that drenching steers dai ly w i t h sodium molybdate i n an amount equialent to about 200 p p m of molybdenum i n the diet for a period ot seven months resulted i n no marked symptoms of toxic i ty , cattle on pastures where the herbage contained 20-100 p p m of mo lybdenum on a d ry basis developed a toxicosis k n o w n as teart Copper additions to the diet have been used to control this (Underwood 1971) Cox et al (1960)'^' reported that rats fed diets conta ining 500 and 800 p p m of added molybdenum showed toxic i ty symptoms and had increased levels of the element i n their livers Some effects of the mo lybdenum i n the diets on l iver enzymes i n the rats were not observed i n calves that had been mainta ined on diets conta ining up to 400 p p m of the element Apparent ly , na tura l surface waters very rarely contained levels of this element of over 1 mg /1 ( K o p p and K r o n e r 1970) , '^ w h i c h seemed to offer no p rob lem Conclusion Because there are many factors influencing tox-icity of molybdenum, setting an upper allowable limit for its concentration in livestock waters is not possible at this time. Nitrates and Nitrites Livestock poisoning by nitrates or nitri tes is dependent upon the intake of these ions f r o m al l sources Thus , water or forage may independently or together contain levels that are toxic O f the two, n i t r i t e is considerably more toxic Usual ly I t is fo rmed through the biological reduction of ni t rate in the rumen of cattle or sheep, i n freshly chopped forage, i n moistened feeds, or i n waters contaminated w i t h organic matter to the extent that they are capable of sup-por t ing microb ia l g r o w t h W h i l e na tura l waters of ten con-ta in h igh levels of ni trate , their n i t r i te content is usually very low W h i l e some ni t ra te was transferred to the m i l k , Davison and his associates ( 1 9 6 4 ) " ' f ound that for da i ry cattle fed 150 m g N O s N / k g of body weight the m i l k contained about 3 p p m of NO3N T h e y concluded tha t nitrates i n cattle feeds d i d not appear to constitute a hazard to human health, and that animals fed ni t ra te continuously developed some degree of adaptat ion to i t T h e L D 5 0 of ni t ra te ni t rogen for ruminants was f o u n d to be about 75 m g N O s N / k g of body weight when ad-ministered as a drench (Bradley et al 1940) ' " and about 255 m g / k g of body weight when sprayed on forage and feed (Crawfo rd and Kennedy 1960) ' " Levels of 60 m g N O s N / k g of body weight as a drench (Sapiro et al 1949)2'<' and 150 m g N O j N / k g of body weight m the diet (Prewit t and M e r i l a n 1958 ,«* Davison et al 1964" ' ) had no de-
Water for Livestock Enterprises leterious effects Lewis (1951)"^ found that 60 per cent con-version of hemoglobin to methemoglobin occurred i n mature sheep f r o m 4 0 g of NO3N or 2 0 g of NO2N placed i n the rumen, or 0 4 g NO2N injected intravenously As an ora l drench, 90 m g N O s N / k g of body weight gave peak methemoglobin levels of 5-6 g /100 m l of blood i n sheep, whi le intravenous in jec t ion of 6 m g N02N /kg of body weight gave similar results (Emerick et al 1965) ' " Nitrate- induced abortions i n cattle and sheep have generally required amounts approaching lethal levels (Simon et al 1959," ' Davison et al 1962,'3« W i n t e r and Hokanson 1964,2«« Davison et al 1965'") Some experiments have demonstrated reductions i n plasma or l iver v i t a m i n A values resulting f r o m the feeding of n i t ra te to ruminants (Jordan et al 1 9 6 1 , " ' Goodr ich et al 1964 , ' " Newland and Deans 1964,2''9 Hoar et al 1968 '") T h e destructive effect of nitrites on carotene (Olson et al 1963*") and v i t a m i n A (Pugh and Garner 1963^''*) under acid conditions that existed i n silage or i n the gastric stomach have also been noted O n the other hand, n i t ra te levels of about 0 15 per cent i n the feed (equivalent to about 1 per cent of potassium ni t rate) have not been shown to influence l iver v i t amin A levels (Hale et al 1962, '" Weichenthal et al 1963,26' M i t c h e l l et al 1967'") nor to have other deleterious eflfects in control led experiments, except fo r a possible slight decrease in produc-t ion Assuming a m a x i m u m water consumption i n da i ry cat-tle of 3 to 4 times the d ry matter intake ( N R C 1971a2"5), the concentration of ni t rate to be tolerated i n the water should be about one-fourth of that tolerated i n the feed This w o u l d be about 300 mg/1 of NO3N G w a t k i n and P lummer (1946)'*" drenched pigs w i t h potassium ni trate solutions, finding that i t required i n ex-cess of 300 m g N O a N / k g of body weight to cause erosion and hemorrhage of the gastric mucosa and subsequent death Lower levels of this salt had no effect when ad-ministered dai ly for 30 days Losses i n swine due to metho-globinemia have occurred only w i t h the consumption of preformed ni t r i te and not w i t h ni t rate ( M c i n t o s h et al 1943,'»2 G w a t k i n and P lummer 1946, '« ' Winks et al 1950^5) Ni t ra te administered oral ly as a single dose was f o u n d to be acutely toxic at 13 m g N02N /kg of body weight , 8 7 m g / k g of body weight producing moderate methemo-globinemia (Winks et al 1950) sÌs Emerick et al (1965)'^^ produced moderate methemoglobinemia i n pigs w i t h in t r a -venous injections of 6 0 m g N02N /kg of body weight and f o u n d that the animals under one week of age were no more susceptible to poisoning than older ones D r i n k i n g water conta ining 330 mg/1 NO3N fed cont inu-ously to g rowing pigs and to gilts f r o m weaning th rough two f a r rowing seasons had no adverse effects (Seerley et al 1965) 2 « Further , 100 mg /1 of N O j N m d r i n k i n g water had no effect on performance or l iver v i t amin A values of pigs over a 105-day experimental period, and methemo-globin values remained low This level of n i t r i t e greatly exceeded the m a x i m u m of 13 mg /1 NO2N f ound to f o r m i n waters i n galvanized water ing equipment and i n the presence of considerable organic matter containing up to 300 mg/1 NO3N I n special situations involv ing the presence of h igh levels of nitrates i n aqueous slurries of p lant or an ima l tissues, n i t r i t e accumulat ion reached a peak of about one-fourth to one-half the i n i t i a l ni t rate concentration ( M c i n t o s h et al 1943,'92 Winks et al 1950,265 Barnett 1952) Th is si tuation was unusual, but since wet mixtures are sometimes used for swine, i t must be considered i n establishing cr i ter ia for water Levels o f ni t rate u p to 300 mg /1 NO3N or of n i t r i t e u p to 200 mg /1 of NO2N were added to d r i n k i n g waters w i t h o u t adverse effects on the g rowth of chicks or product ion of lay ing hens (Adams et al 1966) '"^ A t 200 mg /1 NO2N, ni t r i t e decreased g rowth i n turkey poults and reduced the l iver storage of v i t a m i n A i n chicks, lay ing hens, and turkeys A t 50 mg/1 NO2N, no effects were observed on any of the birds Kienho lz et al ( 1 9 6 6 ) ' " found that 150 mg /1 of NO3N i n the d r i n k i n g water or i n the feed of chicks or poults had no detr imental effect on growth , feed efficiency, methemoglobin level, or thyro id weight, whi le Sell and Roberts ( 1 9 6 3 ) 2 « found that 0 12 per cent (1,200 ppm) of NO2N i n chick diets lowered v i t a m i n A stores i n the l iver and caused hyper t rophy of the thy ro id Other studies have shown poul t ry to tolerate levels of ni t ra te or n i t r i t e similar to or greater than those mentioned above (Adams et al 1967,'"6 C rawfo rd et al 1969'29) U p to 450 mg /1 of NO3N i n the d r ink ing water of turkeys d i d not significantly affect meat color ( M u g l e r et al 1970) '» ' Some have suggested that ni t rate or n i t r i t e can cause a chronic or subclinical toxic i ty (Simon et al 1959,2*' M c l l w a i n and Schipper 1963, '" Pfander 1961,22' Beeson 1964,"' Case 1957'25) Some degree of thy ro id hyper t rophy may occur i n some species w i t h the consumption of subtoxic levels of ni t rate or n i t r i t e (Bloomfie ld et al 1 9 6 1 , " ' Sell and Roberts 1963) ,2" but possibly not in a l l (Jainudeen et al 1965) ' " I n the h u m a n newborn, a chronic type of methe-globinemia may result f r o m feeding waters of low NO3N content (Armst rong et al 1958) I t appears, however, that a l l classes of livestock and pou l t ry that have been studied under control led experimental conditions can tolerate the cont inued ingestion of waters containing up to 300 mg /1 of NO3N or 100 m g / 1 of NO2N Recommendation In order to provide a reasonable margin of safety to allow for unusual situations such as extremely high water intake or nitrite formation in slurries, the NO3N plus NO2N content in drinking waters for livestock and poultry should be limited to 100 ppm or less, and the NO2N content alone be limited to 10 ppm or less.
ZX^/Section VâAgricultural Uses of Water Selenium Rosenfeld and Beath (1964)^ ' have reviewed the prob-lems of selenium poisoning i n livestock O f the three types of this poisoning described, the " a l k a l i disease" syndrome required the lowest level of the element in the feed for its causation M o x o n ( 1 9 3 7 ) " ' placed this level at about 5 p p m , and subsequent research conf i rmed this figure Later work established that the toxic i ty of selenium was very similar when the element was fed as i t occurs in plants, as seleno-methionine or selenocystine, or as inorganic selenite or selenate (Halverson et al 1962, Rosenfeld and Beath 1964,2" Halverson et al 1966'") R u m i n a n t animals may tolerate more as inorganic salts than do monogastnc ani -mals because of the salts' reduct ion to insoluble elemental f o r m by rumen microorganisms (Butler and Peterson 1961) ' " A studv w i t h rats (Schroeder 1967)^'^ revealed that sele-nite, bu t not selenate, i n the d r i n k i n g water caused deaths at a level of 2 mg/1 and was somewhat more toxic than selenite administered i n the diet However, the results of drenching studies w i t h cattle and sheep ( M a a g and Glenn 1967 ) ' " indicated that selenium concentration in the water should be slight, i f i t is any more toxic i n the same chemical f o r m administered in the feed I f there are differences w i t h respect to the effect o f mode o f ingestion on toxic i ty , they are probably small T o date, no substantiated cases of selenium poisoning i n livestock by waters have been reported, a l though some spring and i r r iga t ion waters have been found to conta in over 1 mg/1 of the element (Byers 1935,'^= Wi l l i ams and Byers 1935,2«< Beath 1943"") As a rule, wel l , surface, and ocean waters appeared to contain less than 0 05 m g / 1 , usually considerably less Byers et al (1938) '^ ' explained the low selenium content as a result of precipi ta t ion of the selenite ion w i t h ferr ic hydroxide M i c r o b i a l ac t iv i ty , how-ever, removed either selenite or selenate f r o m water (Abu-Erreish 1967), '" ' this may be another explanation I n add i t ion to Us toxic i ty , the essential role of selenium in an imal nu t r i t i on (Thompson and Scott 1970)^^^ must be considered Between 0 1 and 0 2 p p m i n the diet have been recommended as necessary to insure against a deficiency i n poul t ry (Scott and Thompson 1969),2^' against whi te muscle disease i n ruminants ( M u t h 1963),2"' and other diseases i n other animals (Har t ley and Gran t 1961) Selenium therapy suggests i t as a requirement for livestock i n general Inorganic selenium was not incorporated in to tissues to the same extent as i t occurred i n plant tissue (Halverson et a l 1962,'82 1966,'" Rosenfeld and Beath 19642") I t IS doub t fu l that 0 2 p p m or less of added inor-ganic selenium appreciably increased the amount found i n the tissue of animals ingesting i t T h e data of K u b o t a et al ( 1 9 6 7 ) " ' regarding the occurrence o f selenium poisoning suggested that over a good part of the U n i t e d States l ive-stock were receiving as much as 0 5 p p m or even more of na tura l ly occurr ing selenium i n their diets continuously, w i t h o u t h a r m to them and w i t h o u t accumulat ing levels of the element i n their tissues that make meats o r livestock products un f i t for human use Recommendation It is recommended that the upper limit for selenium in livestock waters be 0.05 mg/1. Vanadium V a n a d i u m has been present i n surface waters i n the U n i t e d States i n concentrations u p to 0 3 m g / 1 , a l though most o f the analyses showed less than 0 05 mg /1 ( K o p p and K r o n e r 1970) Recently, vanad ium was determined essential for the growing rat , physiologically required levels appearing to be at or below 0 1 p p m of the diet (Schwarz and M i l n e 1971) 2^ I t became toxic to chicks when incorporated in to the diet as a m m o n i u m metavanadate at concentrations over about 10 p p m of the element (Romoser et al 1961,22" Nelson e t a l 1962,2"'Berg 1963,"2 Hathcock et al 1964'"') Schroeder and Balassa (1967)2" found that when mice were allowed d r i n k i n g water containing 5 mg /1 of vanad ium as vanadyl sulfate over a l i fe span, no toxic effects were ob-served, bu t the element d id accumulate to some extent i n certain organs Recommendation It is recommended that the upper 4imit for vanadium in drinking water for livestock be 0.1 mg/1. Zinc There are many opportunit ies fo r the contamina t ion o f waters by zinc I n some areas where i t is mmed , this meta l has been found i n na tura l waters i n concentrations as h igh as 50 mg/1 I t occurs i n significant amounts i n effluents f r o m certain industries Galvanized pipes and tanks may also contr ibute zinc to acidic waters I n a recent survey of surface waters, most contained less than 0 05 m g / 1 but some exceeded 5 0 m g / 1 , the highest value being 42 mg/1 ( D u r u m et al 1971) '^' Z inc IS relatively nontoxic for animals Swine have tolerated 1,000 p p m of dietary zinc ( G r i m m e t et al 1937 , ' " Sampson et al 1942,22" Lewis et al 1957,"* B n n k et al 1959'2"), whi le 2,000 p p m or more have been found to be toxic (Br ink et al 1959) '2" S imi lar findings have been re-ported for pou l t ry (Klussendorf and Pensack 1958, '" John-son et al 1962 , ' " V o h r a and Kra t ze r 196825^) where zinc was added to the feed A d d i n g 2,320 mg /1 of the element to water for chickens reduced water consumption, egg pro-duct ion , and body weight A f t e r zinc w i t h d r a w a l there were no symptoms of toxic i ty i n chickens (Sturkie 1956) 2^' I n a number of studies w i t h ruminants , O t t et a l (1966a,2'*
Water for Livestock Enterprises/"ill b,!"* c,"" d^'*) found zinc added to diets as the oxide to be toxic, bu t at levels over 500 m g / k g o f diet W h i l e an increased zinc intake reflected an increase m level of the element i n the body tissues, the tendency for its accumulat ion was not great (Dr inker et al 1927,'** T h o m p -son et al 1927,2*' Sadasivan 1951,^^* Lewis et al 1957),'** and tissue levels fe l l r ap id ly after zinc dosing was stopped (Dr inker et al 1927,'** Johnson et al 1962'") Z inc IS a dietary requirement of a l l poul t ry and livestock Na t iona l Research Counci l recommendation for poults up to eight weeks was 70 m g / k g of diet , for chicks up to eight weeks, i t was 50 m g / k g of diet ( N R C 1971b),« '* for swine, 50 m g / k g of diet ( N R C 1968a) ^ There is no established requirement for ruminants , but zinc deficiencies were re-ported i n cattle grazing forage w i t h zinc contents ranging between 18 and 83 p p m (Underwood 1971) " * There is also no established requirement for sheep, but lambs fed a pur i f i ed diet containing 3 p p m of the element developed symptoms of a deficiency tha t were prevented by adding 15 p p m of zinc to the die t , 30 p p m was required to give max-i m u m g r o w t h ( O t t et al 1965) "* Cereal grains contained on the average 30-40 p p m and prote in concentrates f r o m 20 to over 100 p p m (Davis 1966) " * I n view of this, and i n view of the low order of tox ic i ty o f zinc and its requirement by animals, a l i m i t i n livestock waters of 25 m g zinc/1 w o u l d have a very large marg in o f safety A higher l i m i t does not seem necessary, since there w o u l d be few instances where natura l waters w o u l d car ry m excess o f this Recommendation It is recommended that the upper limit for zinc in livestock waters be 25 mg/1. Toxic Algae T h e te rm "water b l o o m " refers to heavy scums of blue-green algae that f o r m on waters under certain conditions Perhaps the first report of livestock poisoning by toxic algae was that of Francis (1878)'*' who described the problem i n southern Austral ia F i tch et al (1934)'** reviewed a number of cases of algal poisoning in f a r m animals i n Minnesota between 1882 and 1933 A l l were associated w i t h certain blue-green algae often concentrated by the w i n d at one end of the lake Losses i n cattle, sheep, and pou l t ry were re-ported T h e algae were found toxic to laboratory animals on ingestion or intraperi toneal in jec t ion Accord ing to Gorham (1964)'** six species of blue-green algae have been incr iminated , as fol lows Nodularla spumigena Microsyslis aeruginosa Coelosphaerium Kuetzingianum Gloeolnchia echinulata Anabaena flos-aquae Aphantzflmenon flos-aquae O f the above, Gorham states that Microcystis and Ana-baena have most often been blamed for serious poisonings and algal blooms consisting of one or more of these species vary considerably in their toxic i ty (Gorham 1964) '** Accord ing to Gorham (I960), '** this va r iab i l i ty seems to depend upon a number of factors, e g , species and strains of algae that are predominant , types and numbers of bac-terial associates, the conditions of g rowth , collection and decomposition, the degree of an imal starvation and sus-cept ib i l i ty , and the amount consumed T o date, only one tox in f r o m blue-green algae has been isolated and ident i f ied, only f r o m a few species and streams This was a cyclic poly-peptide containing 10 amino acid residues, one of w h i c h was the unnatura l amino acid D-serine (Bishop et al 1959) "* Th is is also referred to as F D F (fast-death fac tor ) , since I t causes death more quickly than SDF (slow-death factor) toxins produced i n water blooms Shilo (1967)2** pointed out that the sudden decomposition of algal blooms often preceded mass mor ta l i ty of fish, and similar observations were made w i t h livestock poisonings Th is suggests that the lysis of the algae may be impor tan t in the release of the toxins, but i t also suggests that i n some circumstances botulism may be involved T h e lack of oxy-gen may have caused the fish k i l l and must also be con-sidered Predeath symptoms i n livestock have not been careful ly observed and described Post-mortem examinat ion is ap-parently of no help i n diagnosis (Fi tch et al 1934) '** Feeding or in jec t ing algal suspensions or water f r o m suspect waters have been used to some extent, but the occasional fleeting toxici ty o f these materials makes this procedure o f l imi t ed value Ident i f ica t ion of any of the toxic blue-green algae species m suspect waters does no more than suggest the possibility that they caused livestock deaths I n view of the many unknowns and unresolved problems relat ing blooms of toxic algae, i t is impossible to suggest any recommendations insuring against the occurrence o f toxic algae in livestock waters Recommendation The use for livestock of waters bearing heavy growths of blue green algae should be avoided. Radionuclides Surface and groundwaters acquire radioact ivi ty f r o m natura l sources, f r o m fa l lout resulting f r o m atmospheric nuclear detonations, f r o m m i n i n g or processing u r a n i u m , or as the result of the use of isotopes in medicine, scientific research, or industry A l l radiat ion is regarded as h a r m f u l , and any unnecessary exposure to i t should be avoided Experimental work on the biological half-lives of radionuclides and their somatic and genetic effects on animals have been br ief ly reviewed by M c K e e and W o l f (1963) " ' Because the rate of decay of a radionuclide is a physical constant that cannot be changed.
3\8/Section VâAgricultural Uses of Water radioactive isotopes must be disposed of by d i lu t i on or by storage and na.tural decay I n view of the var iab i l i ty i n half-lives of the many radioisotopes, the nature of their radioac-tive emissions, and the differences in metabolism of various elements by different animals, the results of an imal experi-mentat ion do not lend themselves easily to the development of recommendations Based on the recommendations of the U S Federal Radia t ion Counci l ( I 9 6 0 , - " 1961"«) , the Envi ronmenta l Protection Agency w i l l set d r ink ing water standards for radionuclides (1972), '^ ' to establish the intake of radioac-t i v i t y f r o m waters that when added to the amount f r o m all other sources w i l l not l ikely be h a r m f u l to man Recommendation In view of the limited knowledge of the effect of radionuclides in water on domestic animals, it is recommended that the Federal Drinking Water Standards be used for farm animals as well as for man. PESTICIDES (IN WATER FOR LIVESTOCK) Pesticides include a large number of organic and inorganic compounds T h e U n i t e d States product ion of synthetic organic pesticides in 1970 was 1,060 m i l l i o n pounds con-sisting almost entirely of insecticides (501 m i l l i o n pounds), herbicides (391 m i l l i o n pounds), and fungicides (168 m i l l i o n pounds) Product ion data for inorganic pesticides was l imi ted Based on product ion, acreage treated, and use patterns, insecticides and herbicides comprise the ma jo r agr icul tura l pesticides (Fowler 1972) O f these, some can be detr imental to livestock Some have low solubi l i ty in water, but a l l cause problems i f accidental spillage pro-duces high concentrations in water, or i f they become ad-sorbed on col loidal particles subsequently dispersed in water Insecticides are subdivided into three ma jo r classes of compounds inc lud ing methylcarbamates, organophosphates and chlorinated hydrocarbons M a n y of these substances produce no serious po l lu t ion hazards, because they are non-persistent Others, such as the chlorinated hydrocarbons, are quite persistent in the environment and are the pesti-cides most f requent ly encountered in water Entry of Pesticides into Water Pesticides enter water f r o m soil runoff , direct appl icat ion, d r i f t , r a in fa l l , spills, or fau l ty waste disposal techniques Movement by erosion o f soil particles w i t h adsorbed pesti-cides IS one of the pr inc ipal means of entry in to water T h e amount carried in r u n o f f water is influenced by rates o f ap-pl icat ion, soil type, vegetation, topography, and other factors Because of strong b ind ing of some pesticides on soil particles, water po l lu t ion by pesticides is thought to occur largely through the transport of chemicals adsorbed to soil particles (Lichtenstein et al 1966) Th is mechanism may not always be a m a j o r route Bradley et al (1972)^"' ob-served that when 13 4 kg/hectare D D T and 26 8 kg/hectare toxophene were applied to cotton fields, only I 3 and 0 61 per cent, respectively, of the amounts applied were detected in natural r u n o f f water over an 8-month period Pesticides can also enter the aquatic environment by direct applicat ion to surface waters Generally, this use is to con-t ro l mosquito larvae, nuisance aquatic weeds, and, as i n several southern states, to control selected aquatic fauna such as snails (Chesters and K o n r a d 1971) Both of these pathways generally result i n contaminat ion of surface waters rather than groundwaters Precipi tat ion, accidental spills, and fau l ty waste disposal are less impor t an t entrv routes Pesticides detected i n r a i n -water include D D T , D D D , D D E , d i e ld r in , a lpha-BHC and g a m m a - B H C i n extremely minu te concentrations (i e , i n the order of 10~'^ parts or the nanograms per l i ter level) (Weibel et al 1966,2" Cohen and Pinkerton 1966,"^ T a r -rant and T a t t o n 1968^') Spills and fau l ty waste disposal techniques are usually responsible for short-term, high-level contaminat ion T h e amount of pesticide actual ly m solution, however, IS governed by a number of factors, the most impor tan t probably being the solubi l i ty o f the molecule Chlor inated hydrocarbon insecticides, for example, have low solubi l i ty i n water (Freshwater Appendix I I - D ) Cationic pesticides ( i e , paraquat and d iqua t ) are rap id ly and t i gh t ly bound to soil particles and are inactivated (Weed Society o f America 1970) Mos t arsenical pesticides f o r m insoluble salts and are inactivated (Woolson et a l 1971) ^ ' A survey of the water and soil layers in f a r m ponds indicates higher concentrates of pesticides are associated w i t h the soil layers that interface w i t h water than in the water per se I n an ex-tensive survey of f a r m water sources ( U S Dept of A g r i -cul ture, Agr i cu l t u r a l Research Service \969a,^^ hereafter referred to as Agr icu l tu re Research Service 1969a'*'), analysis o f sediment showed residues i n the magni tude of decimal fractions of a mic rogram per g ram ( j i i g / g ) to a high of 4 90 M g / g D D T and its D D E and D D D degradat ion compounds These were the p r inc ipa l pesticides found i n sediment D i e l d n n and endr in were also detected in sedi-ment i n two study areas where surface drainage water entered f a r m ponds f r o m an adjacent field Pesticides Occurrence in Water Chlor inated hydrocarbon insecticides are the pesticides most f requent ly encountered i n water They include D D T and Its degradation products D D E and D D D , d i e l d n n , endr in , chlordane, a ld r in , and l indane I n a pesticide m o n i -tor ing program conducted f r o m 1957 to 1965, Breidenbach et al ( 1 9 6 7 ) " ° concluded that d i e ldnn was present i n a l l sampled r iver basins at levels f r o m 1 to 22 nanograms (ng) / l i t e r D D T and its metabolites were found to occur i n most surface waters, whi le levels of endr in i n the lower
Water for Livestock Enterprises/319 Mississippi decreased f r o m a h i g h o f 214 ng/1 i n 1963 to a range of 15 to 116 ng/1 i n 1965 Results of mon i to r ing studies conducted by the U S Depar tment of Agr icu l tu re (Agr i cu l tu ra l Research Service 1969a)2»' f r o m 1965 to 1967 indicated that only very small amounts of pesticides were present i n any of the sources sampled T h e most preva-lent pesticides i n water were D D T , its metabolites D D D and D D E , and d ie ld r in Levels detected were usually below one par t per b i l l i o n T h e D D T fami ly , d i e ld r in , endnn , chlordane, l indane, heptachlor epoxide, t r i f l u r a l i n , and 2 , 4 - D , were detected i n the range of 0 1 to 0 0 1 ng/\ I n a ma jo r survey o f surface waters m the U n i t e d States con-ducted f r o m 1965 to 1968 for chlorinated hydrocarbon pesti-cides (Lichtenberg et al 1969),282 d ie ld r in and D D T ( i n -c lud ing D D E and D D D ) were the compounds most f re -quent ly detected throughout the 5-year period A f t e r reach-i n g a peak i n 1966, the total number of occurrences of a l l chlor inated hydrocarbon pesticides decreased sharply i n 1967 and 1968 A list o f pesticides most l ikely to occur i n the environ-ment and, consequently, recommended for inclusion i n m o n i t o r i n g studies, was developed by the former Federal Commit tee on Pesticide Cont ro l (now W o r k i n g Group on Pesticides) Th i s list was revised (Schechter 1971)2«' and expanded to include those compounds (1) whose persistence IS of relatively long-term dura t ion , (2) whose use patterns is large scale in terms of acreage, or (3) whose inherent tox ic i ty IS hazardous enough to mer i t close surveillance T h e p r imary list includes 32 pesticides or classes of pesticides ( i e arsenical pesticides, mercur ia l pesticides, and several di thiocarbamate fungicides) recommended to be moni tored i n water A secondary list of 17 compounds was developed fo r consideration, i f mon i to r ing activities are expanded i n the fu tu re T h e pesticides found on the p r imary list w o u l d be those most l ikely to be encountered in f a r m water sup-plies (see Freshwater Append ix I I - D ) Toxicological Effects of Pesticides on Livestock M a m m a l s generally have a greater tolerance to pesticides than birds and fish However, the increased use of pesticides i n agricul ture, par t icu lar ly the insecticides, presents a poten-t i a l hazard to livestock Some compounds such as the or-ganophosphorous insecticides can be extremely dangerous, especially when mishandled or wrongly used T o date, how-ever, there actually have been very few verif ied cases of livestock poisoning f r o m pesticides (Papworth 1967) I n the few instances reported, the cause of livestock poisoning usually has been a t t r ibuted to human negligence For l ive-stock, pesticide classes that may pose possible hazards are the acaricides, fungicides, herbicides, insecticides, mollus-cides, and rodenticides (Papworth 1967) 2 " Acaricides intended f o r use on crops and trees usually have low toxici ty to livestock Some, such as technical chlorobenzilate, have significant toxici ty for mammals T h e acute oral L D 5 0 i n rats is 0 7 g / k g of body weight (Pap-w o r t h 1967) 28' W i t h fungicides, the m a i n hazard to l ive-stock apparently is not f r o m the water route, but f r o m their use as seed dressings f o r g ram O f the types used, the organo-mercury compounds and th i r am are potential ly the most dangerous (McEntee 1950,2S3 Weibel et al I9662'*) T h e use of al l organomercury fungicides is restricted by the Envi ronmenta l Protection Agency (Off ice of Pesticides, Pesticides Regulat ion Div is ion 1972) 2" Consequently, the possible hazard to livestock f r o m these compounds has, for most purposes, been el iminated O f the herbicides in current use, the d i n i t r o compounds pose the greatest hazard to livestock Dini t roorthocresol ( D N C or D N O C ) is probably the most used member of this group I n ruminants , however, D N C is destroyed rap id ly by the rumen organisms (Papwor th 1967) 28' These compounds are very persistent, up to two years, and for livestock the greatest hazard is f r o m spillages, contamina-t ion of vegetation, or water I n contrast, the phenoxyacetic acid derivatives ( 2 , 4 - D , M C P A ) are comparat ively ha rm-less Fert ig (1953)2'8 states that suspected poisoning of livestock or wi ld l i f e by phenoxy herbicides could not be substantiated in a l l cases careful ly surveyed T h e hazards to livestock f r o m hormone weed killers are discussed by Rowe and Hymas (1955) ,2*' and dini t rocompounds by M c G i r r and Papworth (1953)28" and Edson (1954) 2 " T h e possible hazards f r o m other herbicides are reviewed by Papwor th (1967)28' Radelef f (1970) 288 O f the classes of insecticides i n use, some pose a potential hazard to livestock, whi le others do not Insecticides o f vegetable or ig in such as pyrethrins and rotenones, are prac-t ical ly non-toxic to livestock Most chlorinated hydrocarbons are not h igh ly toxic to livestock, and none is k n o w n to ac-cumulate in v i t a l organs D D T , D D D , d i lan , methoxychlor, and perthane are not h ighly toxic to mammals, bu t some other chlorinated hydrocarbons are qui te toxic (Papworth 1967,28' Radelefl" 1970288) T h e insecticides that are poten-t ia l ly the most hazardous are the organophosphorus com-pounds causing chlorinesterase inh ib i t ion Some, such as mipafax, induce pathological changes not d i rect ly related to cholinesterase inh ib i t i on (Barnes and Denz 1953) 2*8 L i q u i d organophosphorus insecticides are absorbed by a l l routes, and the lethal dose for most of these compounds is low (Papworth 1967,2" Radeleff 19 7 0288) Pesticides in Drinking Water for Livestock T h e subgroup on contaminat ion m the Report o f the Secretary's Commission on Pesticides and T h e i r Rela t ion-ship to Envi ronmenta l Hea l th ( U S Dept of Hea l th , E d u -cation, and Welfare 1969)2" examined the present k n o w l -edge -on mechanisms for dissemination of pesticides in the environment , i nc lud ing the water route There have been no reported cases of livestock toxic i ty resulting f r o m pesti-cides i n water However, they conclude that the possibility of contaminat ion and toxic i ty f r o m pesticides is real because of indiscriminate, uncontrol led and excessive use
ZlO/Section VâAgricultural Uses of Water Pesticide residues m f a r m water supplies fo r livestock and related enterprises are undesirable and must be reduced or el iminated whenever possible T h e p r imary problem of reducing levels of pesticides i n water is to locate the source of contaminat ion Once located, appropriate steps should be taken to eliminate the source Some of the properties and concentrations of pesticides found m water are shown i n Table V - 4 A l t h o u g h many pesticides are readily broken d o w n and e l iminated by l ive-stock w i t h no subsequent toxicological effect, the inherent problems associated w i t h pesticide use include the accumu-la t ion and secretion of either the parent compound or its degradation products i n edible tissues and m i l k (Kutches et al 1970) 2^" Consequently, pesticides consumed by l ive-stock through d r ink ing water may result i n residues in fa t and certain produce (mi lk , eggs, wool ) , depending on the level of exposure and the nature of the pesticide There is also a possibility of interactions between insecticides and drugs, especially in animal feeds (Conney and Hi tchings 1969) 2 " Nonpolar l ipophi l ic pesticides such as the chlorinated hydrocarbon inhecticides ( D D T , l indane, endr in , and others) tend to accumulate i n fa t ty tissue and may re-sult i n measurable residues Polar, water soluble pesticides and their metabolic derivatives are generally excreted i n the urine soon after ingestion Examples of this class wou ld include most of the phosphate insecticides and the acid herbicides ( 2 , 4 - D , 2 , 4 , 5 - T , and others) Approx ima te ly 96 per cent of a dose of 2 , 4 - D fed to sheep was excreted unchanged in the urine and 1 4 per cent i n the feces i n 72 hours (Clark et al 1964) 2 " Feeding studies (Claborn et al 1960)2'2 have shown that when insecticides were fed to beef cattle and sheep as a contaminant in their feed at dosages that occur as residues on forage crops, a l l except methoxy-chlor were stored i n the fat T h e levels of these insecticides i n fa t decreased after the insecticides were removed f r o m the animals ' diets W h e n poul t ry were exposed to pesticides either by ingestion of contaminated food or through the use of pesticides i n poul t ry houses. Whi tehead (1971)2^" ob-TABLE V-4âSome Properties, Criteria, and Concentrations of Pesticides Found in Water Solubility ;it/liter Toxicity LD50 mg/k{ Maumum concentrabon" Ml/I aldnn 38 0 OSS dieldnn 110 46 0 407 endnn 160 10 0 133 heptachlor 56 130 0 048 heptachlor eponde 3S0 0 067 DDT 1 2 113 0 316 DDE 0 050 DDD 0 840 2,4 D> 60,000 30D-1000 <⢠Maumum concentration of pesbade found in surface waters in the United Statss, from Lchtenberi! etat (t969)M> ' Refers to the herbiade family 2,4-D, 2,4,S-T, and 2,4,5 TP served that the toxicities to birds of the substances used varied greatly However, nonlethal doses may affect g rowth rate, feed conversion efficiency, egg product ion , egg size, shell thickness, and v i a b i l i t y o f the young A l t h o u g h the ef-fects of large doses may be considerable. Whi tehead con-cluded that l i t t l e IS known about the impa i rmen t of produc-t ion at low rates commonly used i n agr icul tura l practice E l imina t ion of fa t soluble pesticides f r o m contaminated animals is slow U r i n a r y excretion is insignif icant and e l iminat ion m feces is slow T h e p r imary route of excretion in a lactat ing an imal is through m i l k T h e lowest concentra-tions of pesticides i n feeds that lead to detectable residues in animal tissues or products exceed the amounts found i n water by a factor o f 10,000 However, at the comparat ively h igh dosage rates given i n feeds, certain trends are apparent Cows fed D D T i n their diet at rates of 0 5, 1 0, 2 0, 3 0, and 5 0 m g / k g exhibited residues in m i l k at a l l feeding levels except at 0 5 m g / k g As the D D T feed levels increased, contaminat ion increased (Zweig et a l 1961) 2"^ W h e n cows were removed f r o m contaminated feeds, the amount of t ime required for several pesticides to reach the non-detect-able level was recorded ( M o u b r y et al 1968) 2*6 D i e l d n n had the longest retention t ime in m i l k , approximate ly 100 days D D T and its analogs, B H C , hndane, endr in , and methoxychlor fo l lowed i n that order I t should be empha-sized that levels found i n f a r m water supplies do not make a significant con t r ibu t ion to an imal body burdens of pesticides compared to amounts accumulated in feeds Table V - 4 shows the tox ic i ty o f some impor t an t pesti-cides Assuming the average concentration of any pesticide i n water is 0 1 / ig /1 , and the average dai ly consumption of water by da i ry or beef cattle is 60 liters per day, then the average da i ly intake of D D T w o u l d be 0 006 m g Further , assuming that the average body weight fo r da i ry or beef cat-tle IS 450 kg and the L D 5 0 fo r D D T is 113 m g / k g (Table V - 4 ) , then 50 grams w o u l d have to be consumed to approach the dose that w o u l d be le thal to 50 per cent o f the animals I f a steer were mainta ined on this water for 1,000 days, then i t w o u l d have ingested about 1/10,000 of the reported L D 5 0 For e n d n n ( L D 5 0 = 10 m g / k g ) , cattle w o u l d ingest 1/1,000 of the established L D 5 0 T h e safety marg in is probably greater than indicated, because the calculations assume that a l l of the insecticide is retained unaltered d u r i n g the total ingestion period D D T is k n o w n to be degraded to a l imi t ed extent by bovine rumen fluid and by rumen microorgan-isms For sheep, swine, horses, and poul t ry , the average da i ly water intake i n liters is about 5, 10, 40, and 0 2, re-spectively Consequently, their intake wou ld be substantially less Fish as Indicators of Water Safety T h e presence of fish may be an excellent mon i to r f o r toxic levels of pesticides i n livestock water supplies There are numerous and wel l documented examples i n the l i tera-ture o f the biological magnif ica t ion of persistent pesticides
Water for Livestock Enterprises/32\ TABLE V-5-âExamples of Fish as Indicators of Water Safety for Livestock Matenal TOXIC levels mg/1 lor fish Toxic effects on animals Aldnn 0 02 3mg/kglood (poultry) Chlordane 1 O(sunnsh) 91 mg/kg body weight rn food (cattle) Dieldrin 0 025 (trout) 25 mg/kg food (rats) Dipterei 500 10 0 mg/kg body weight in lend (calves) Endnn 0 003 (bass) 3 5 mg/kg body weight In lood (chicks) Ferhan, lermate 1 0 to 4 0 Methoiychlor 0 2 (bass) 14 mg/kg allalla hay, not toxic (cattle) Parathron 2 0 (goldfish) 75 mg/kg body weight in lood (cattle) Pentachlorophenol 0 35(bloegill) CO mg/1 dnnking water not toxic (cattle) Pyrethrum (sllethnn) 2 OtolO 0 1,400 to 2,800 mg/kg body weight in food (rats) Silvex 5 0 500 to 2,000 mg/kg body weight in food (chicks) Touphene 0 1 (bass) 35 to 110 mg/kg body weight in food (cattle) McKee and Woll,1363"> by fish and other aquatic organisms (See Sections I I I and I V on Freshwater and M a r i n e Aquat ic L i f e and W i l d l i f e ) Because of the lower tolerance levels of these aquatic organisms for persistent pesticides such as chlorinated hy-drocarbon insecticides, mercuria l compounds, and heavy metal fungicides, the presence of l i v ing fish in agr icul tura l water supplies wou ld indicate their safety for livestock ( M c K e e and W o l f 1963) =** Some examples of ind iv idua l effects of pesticides upon fish compared to an imal species are shown in Tab le V-5 These data indicate that fish gen-erally have much lower tolerance for commonly used pesti-cides than do livestock and pou l t ry Recommendation Feeding studies indicate no deleterious effects of reported pesticide residues in livestock drinking water on animal health. To prevent unacceptable residues in animal products, the maximum levels proposed in the pesticide section of the Panel of Public Water Supplies are recommended for farm animal water supplies. PATHOGENS AND PARASITIC ORGANISMS Microbiol Pathogens One of the most significant factors in the spread of infec-tious diseases of domesticated animals is the qua l i ty of water wh ich they consume I n many instances the only water available to livestock is f r o m surface sources such as ponds, waterholes, lakes, rivers and creeks N o t infrequent ly these sources are contaminated by animals wh ich wade to d r ink or stand in them seeking refuge f r o m pests Con-tamina t ion w i t h potential disease-producing organisms comes f r o m surface drainage or ig inat ing in corrals, feed lots, or pastures in w h i c h either sick or carrier animals are kept Direc t evidence relat ing the occurence of an imal patho-gens in surface waters and disease outbreaks is l imi ted However, water may be a source for listeriosis caused by Listeria monocytogenes (Larsen 1964)'*^ and erysipelas caused by Erysipelothnx rhusiopathiae (Wood and Packer i n press 1972) "* Tu la remia of animals is not normal ly waterborne, but the organism Pasteurella tularensis has been isolated f r o m waters in the U n i t e d States (Parker et al 1951, '* ' Seghetti 1952) '"* Enteric microorganisms, inc lud ing the vibrios (Wilson and Miles 1966)'** and amoebae, have a long record as water po l lu t ing agents T h e Escliericlna-Enterobacter-Klebscilla group of enterics are widely distr ibuted in feed, water, and the general en-v i ronment (Breed et al 1957) They sometimes cause ur inary disease, abscesses, and mastitis i n livestock Sal-monella are very invasive and the carrier state is easily pro-duced and persistent, often wi thou t any general evidence of disease Spread of the enterics outside the yards, pens, or pastures of infected livestock is a possibility, bu t the epi-demiology and ecology of this problem are not clear I n the U n i t e d States, leptospirosis is probably the most in t imate ly water-related disease problem (Gillespie et al 1957,"" Crawford et a 1 1969'**) T h e pathogenic leptospira leave the infected host through ur ine and lack protection against d ry ing Direc t animal- to-animal spread can occur through urine splashed to the eyes and nostrils of another animal Infect ion by leptospirosis f r o m water often is d i rec t , that IS, contaminated water infects animals that consume i t or come in to contact w i t h i t V a n T h i e l (1948)'** and Gillespie et al (1957)'*' pointed out that minera l composition and p H of water are factors affect ing continued mob i l i t y of voided leptospira Mos t episodes of leptospirosis can be traced to ponds, ricefields, and natura l waters of suitable p H and minera l composition For leptospira control , livestock must not be allowed to wade in contaminated water Indi rec t contaminat ion of water through sewage is unl ikely , al though free- l iving leptospira may occur in such an environment T h e Genus Clostridium is comprised of many species (Breed et al 1957),^** some of wh ich have no pathogenic characteristics Some such as Clostridium perfngens and CI tetani may become adapted to an enteric existence in an i -mals Almost a l l of them are soil adapted Water has a v i t a l role in environments favorable for anaerobic infections caused by Clostridia Management of water to avoid oxygen depletion serves to control the anaerobic problem Tempora ry or permanent areas of anaerobic water environment are dangerous to livestock Domestic animals should be prevented f r o m con-suming water not adequately oxygenated One of the best examples of water-related disease is baci l -lary hemoglobinuria , caused by an organism CI hemolyticum found i n western areas of N o r t h and South America I t has been l inked w i t h l iver fluke i n j u r y , but is not dependent on the presence of flukes O f par t icular concern has been the spread of this disease to new areas i n the western states As described by V a n Ness and Erickson (1964) , ' " each new
ZTllSection VâAgricultural Uses of Water premise is an endemic area wh ich has an alkahne, anaerobic soil-water environment suitable for the organism This disease has made its appearance i n new areas of the West when these areas are cleared of brush and irr igated T o avoid this problem, western i r r iga t ion waters should be managed to avoid cat tai l marshes, hummock grasses, and other environments of prolonged saturation A n t h r a x i n livestock is a disease of considerable concern T h e organism causing anthrax. Bacillus anthracis, may occur i n soils w i t h p H above 6 0 T h e organism forms spores w h i c h , i n the presence of adequate soil nutrients, vege-tate and grow T h e spread of disease by d r i n k i n g water containing spores has never been proved Bits of hide and hai r waste may be floated by water downstream f r o m manu-fac tur ing plants, but very few outbreaks have been reported f r o m these sources T h e disease is associated w i t h the water f r o m pastures where the grass has been ki l led ( V a n Ness 1971) ""^The ki l led grass is b rown rather than blackened, a significant difference f r o m water drowned vegetation in general T h e epidemiology of virus infections tends to incr iminate direct contact , e g , fomites, mechanical, and biological vectors, but seldom water supplies Water used to wash away manure pr ior to the use of disinfectants or other bio-logical control procedure may carry viruses to the general environment Viruses are classified by size, type of nucleic acid, struc-ture, ether sensitivity, tissue effects (which includes viruses long known to cause recognizable diseases, such as pox and hog cholera), and by other cri teria O n l y the ether-resistant viruses, such as those causing polio and foot and m o u t h disease i n cattle, appear to present problems in natural water (Prier 1966) Parasitic Organisms Parasitic protozoa include numerous forms wh ich are capable of causing serious livestock losses Most outbreaks fo l low direct spread among animals Water contaminated w i t h these organisms or their cysts becomes an indirect factor in spread of infect ion Some of the most impor tan t parasitic forms are the various flukes w h i c h develop as adul t forms in man and livestock I m p o r t a n t ecological factors include presence of snails and vegetation i n the water, or vegetation covered by in te rmi t -tent overflow This problem is very serious in i rr igated areas, but only when snails or other intermediate hosts are avai l -able for the complete l ife cycle Fluke eggs passed by the host, usually in the manure (some species, i n the ur ine) , enter the water and hatch in to miracidia These seek out a snail or other invertebrate host where they develop in to sporocysts These transform into redia wh ich in t u rn may f o r m other redia or several cercariae T h e cercariae leave the snail and swim about the water where they may find the f ina l host, or may encyst on vegetation to be eaten later T h e l ife cycle is completed by ma tu r ing i n a suitable host and establishment of an exit for eggs f r o m the site of the at-tachment Roundworms include numerous species wh ich may use water pathways in their l ife cycle Free-l iving nematodes can sometimes be found i n a piped water supply, but are probably of l i t t l e health significance Mois ture is an i m -portant factor i n the l ife cycle of many parasitic roundworms and livestock are maintained in an environment where con-taminat ion of water supplies f requent ly occurs I t is usually thought that r oundworm eggs are eaten but water-saturated environments provide ideal conditions for main ta in ing popu-lations of these organisms and their eggs Parasitic roundworms probably evolved through evolu-t ionary cycles exemplified by the behavior of the genus Slrongyloides Slrongyloides spread along drainageways through the washdown of concrete feeding platforms and other housing facilities for livestock T h e Guinea w o r m , Dracimculus, is dependent upon water, because the adul t lays eggs only when the host comes in contact w i t h water M a n , dogs, cats, or various w i l d m a m -mals may harbor the adult , and the larvae develop i n Cyclops T h e l ife cycle is thus maintained in a water environ-ment when the Cyclops is swallowed by another suitable host Eggs of "horsehair worms" are la id by the adul t i n water or moist soil T h e larvae encyst and i f eaten by an appropr i -ate insect w i l l continue development to the adul t stage Worms do not leave the insect unless they can enter water T h e prevention of water-borne diseases and parasitisms i n domestic animals depends on in te r rup t ion of the orga-nisms' l ife cycle T h e most effective means is to keep l ive-stock out of contaminated water Trea tment for the removal of the pathogen or parasite f r o m the host and destruction of the intermediate host are measures of control
WATER FOR IRRIGATION I r r i g a t i o n f a r m i n g increases produc t iv i ty o f croplands and provides flexibility m al ternat ing crops to meet market demands Ear ly i r r iga t ion developments i n the a n d and semiarid West were largely along streams where only a small par t o f the total annual flow was put to use Such streams contained dissolved solids accumulated through the no rma l leaching and weathering processes w i t h on ly slight additions or increases in concentrations resulting f r o m man's activities A d d i t i o n a l uses of water resources have i n many cases concentrated the existing dissolved solids, added new salts, contr ibuted toxic elements, microbiological ly pol luted the streams, or in some other way degraded the qua l i ty of the water for i r r iga t ion Water qua l i ty cr i ter ia for i r r iga t ion has become increasingly significant as new developments i n water resources occur Soil , plant , and cl imate variables and interactions must be considered i n developing cr i ter ia for evaluation of i r r iga-t ion water qua l i ty A wide range o f suitable water charac-teristics IS possible even when only a few variables are con-sidered These variables are impor t an t m de te rmin ing the qua l i ty of water that can be used for i r r iga t ion under specific conditions T h e physicochemical properties of a soil determine the root environment that a p lant encounters f o l l o w i n g i r r iga -t ion T h e soil consists of an organo-mineral complex that has the ab i l i t y to react both physically and chemical ly w i t h constituents present in i r r iga t ion water T h e degree to wh ich these added constituents w i l l leach out of a soil, re-m a i n available to plants in the soil, or become f ixed and unavailable to plants, depends largely on the soil charac-teristics Evapotranspirat ion by plants removes water f r o m the soil leaving the salts behind Since uptake by plants is negligible, salts accumulate in the soil i n a n d and semiarid areas A favorable salt balance i n the root zone can be ma in -tained by leaching, through the use of i r r iga t ion water i n excess o f p lant needs Good drainage is essential to prevent a rising water table and salt accumulat ion i n the soil surface and to ma in ta in adequate soil aeration I n i r r igated areas, a water f requent ly exists at some depth below the g round surface, w i t h an unsaturated condi t ion existing above i t D u r i n g and immediately fo l l owing periods of precipi ta t ion or i r r iga t ion , water moves d o w n w a r d through the soil to the water table A t other times, water is lost th rough evaporation f r o m the soil surface, and trans-p i ra t ion f r o m plants (evapotranspiration) may reverse the direct ion of flow in the soil, so that water moves u p w a r d f r o m the water table by capi l lary flow T h e rate o f move-ment IS dependent upon water content, soil texture, and structure I n h u m i d and subhumid regions, this capi l lary rise of water i n the soil is a valuable water source fo r use by crops d u r i n g periods of drought Even under favorable conditions of soil, drainage, and environmental factors, too sparing applications o f h i g h qua l i ty water w i t h to ta l dissolved solids of less than 100 mg/1 w o u l d u l t imate ly damage sensitive crops such as citrus f r u i t , whereas w i t h adequate leaching, waters containing 500 to 1,000 mg/1 m i g h t be used safely Under the same conditions, certain salt-tolerant field crops migh t produce economic re-turns using water w i t h more than 4,000 mg/1 Cr i te r ia fo r j u d g i n g water qua l i ty must take these factors in to account T h e need for i r r iga t ion for o p t i m u m plant g rowth is de-termined also by ra in fa l l and snow d i s t r ibu t ion , and by temperature, radia t ion, and h u m i d i t y I r r i g a t i o n must be used for intensive crop product ion i n a n d and semiarid areas and must supplement ra in fa l l i n h u m i d areas (See Specific I r r i ga t i on Wate r Considerations b e l o w ) T h e effects of water qua l i ty characteristics on soils and on plant g rowth are direct ly related to the frequency and amount o f i r r iga t ion water applied T h e rate at w h i c h water IS lost f r o m soils through evapotranspiration is a direct func t ion of temperature, solar radia t ion, w i n d , and h u m i d -i t y Soil and p lan t characteristics also influence this water loss Aside f r o m water loss considerations, water stress i n a plant, as affected by the rate of evapotranspiration, w i l l determine the plant 's reaction to a given soil condi t ion For example, i n a saline soil at a given water content, a p lant w i l l usually suffer more i n a hot, d ry cl imate than i n a cool, h u m i d one Considering the wide var ia t ion m the c l imat ic and soil variables over the U n i t e d States, i t is apparent that water qual i ty requirements also vary considerably Successful sustained i rr igated agriculture, whether m a n d 323
324/Sectton VâAgricultural Uses of Water regions or i n subhumid regions, or other areas, requires sk i l l fu l water applicat ion based upon the characteristics of the land, water, and the requirements of the crop T h r o u g h proper t i m i n g and adjustment o f frequency and volumes of water applied, detr imental effects of poor qual i ty water may of ten be mit igated WATER QUALITY CONSIDERATIONS FOR IRRIGATION Effects on Plant Growth Plants may be adversely affected direct ly by either the development of h igh osmotic conditions i n the plant sub-strate or by the presence of a phytotoxic constituent in the water I n general, plants are more susceptible to i n j u r y f r o m dissolved constituents du r ing germinat ion and early growth than at ma tu r i ty (Bernstein and H a y ward 1958) Plants affected du r ing early g rowth may result i n complete crop fa i lure or severe yield reductions Effects of undesirable constituents may be manifested i n suppressed vegetative growth , reduced f r u i t development, impaired qua l i ty of the marketable product, or a combinat ion of these factors T h e presence of sediment, pesticides, or pathogenic or-ganisms i n i r r iga t ion water, wh ich may not specifically affect plant g rowth , can affect the acceptabili ty of the product Another aspect to be considered is the presence of elements in i r r iga t ion water that are not detr imental to crop product ion but may accumulate in crops to levels that may be h a r m f u l to animals or humans Where sprinkler i r r iga t ion is used, fo l ia r absorption or adsorption of constituents i n the water may be detr imental to plant g rowth or to the consumption of affected plants by m a n or animals Where surface or sprinkler i r r iga t ion is practiced, the effect of a given water qua l i ty on plant g rowth IS determined by the composition o f the soil solu-t ion This IS the g rowth med ium available to roots after soil and water have reacted Plant g rowth may be affected indirect ly through the i n -fluence of water qua l i ty on soil For example, the absorption by the soil of sodium f r o m water w i l l result i n a dispersion of the clay f rac t ion T h e degree of dispersion w i l l depend on the clay minerals present This decreases soil permeabil-i ty and often results in a surface crust fo rmat ion that deters seed germinat ion and emergence Soils i r r igated w i t h h ighly saline water w i l l tend to be flocculated and have relatively h igh i n f i l t r a t i on rates (Bower and W i l c o x 1965) A change to waters of sufficiently lower salt content reduces soil permeabil i ty and rates of i n f i l t r a t i on by dispersion of the clay f rac t ion i n the soil This hazard increases when com-bined w i t h h igh sodium content i n the water M u c h de-pends upon whether a given i r r iga t ion water is used con-tinuously or occasionally Crop Tolerance to Salinity T h e effect of salinity, or total dissolved solids, on the os-mot ic pressure of the soil solution is one of the most i m -por tant water qua l i ty considerations Th is relates to the avai lab i l i ty of water for plant consumption Plants have been observed to w i l t i n fields apparendy having adequate water content This is usually the result of high soil salinity creating a physiological drought condi t ion Specifically, the ab i l i ty of a plant to extract water f r o m a soil is determined by the fo l l owing relationship TSS = MS-t-SS I n this equation, ( U S Department of Agr icu l tu re , Sal ini ty Labora tory Staff 1954 ' " hereafter referred to as Sal ini ty Labora tory 1954''*) the total soil suction (TSS) represents the force w i t h which water in the soil is wi thhe ld f r o m plant uptake I n s implif ied f o r m , this factor is the sum of the matr ic suction ( M S ) or the physical at t ract ion of soil for water, and the solute suction (SS) or the osmotic pressure of the soil water As the water content of the soil decreases due to evapo-transpirat ion, the water film surrounding the soil particles becomes thinner and the remaining water is held w i t h i n -creasingly greater force ( M S ) Since only pure water is lost to the atmosphere du r ing evapotranspiration, the salt concentration of soil solution increases rapid ly du r ing the d ry ing process Since the ma tnc suction of a soil i n -creases exponentially on d ry ing , the combined effects of these two factors can produce cr i t ica l conditions w i t h re-gard to soil water avai labi l i ty I n assessing the problem of plant g rowth , the salinity level of the soil solution must be evaluated I t is d i f l i c u l t to extract the soil solution f r o m a moist soil w i t h i n the range of water content available to plants I t has been demonstrated, however, that salinity levels of the soil solution and their resultant effects upon plant g rowth may be correlated w i t h salinity levels of soil moisture at saturation T h e quan t i ty of water held in the soil between field capacity and the w i l t i n g point varies considerably f r o m relatively low values for sandy soils to high values for soils h igh in clay content T h e U S Salini ty Labora tory Staff (1954)335 developed the technique of using a saturation extract to meet this need Demineralized water is added to a soil sample to a point at w h i c h the soil paste glistens as i t reflects l igh t and flows slightly when the container is t ipped T h e amount of water added is reasonably related to the soil texture For many soils, the water content of the soil paste is roughly twice tha t o f the soil at field capacity and four times that at the w i l t i n g point This water content is called the saturation percentage W h e n the saturated paste is filtered, the result-ant solution IS referred to as the saturation extract T h e salt content of the saturation extract does not give an exact mf l ica t ion o f sal ini ty m the soil solution under field condi-tions, because soil structure has been destroyed, nor does i t give a true picture of salinity gradients w i t h i n the soil result-ing f r o m water extraction by roots A l though not t r u ly de-pic t ing salinity i n the immediate root environment, i t does give a usable parameter that represents a soil salinity value that can be correlated w i t h plant g rowth
Water for IrngaUon/Z25 TABLE V-6âRelative Tolerance of Crop Plants to Salt, {Listed tn Decreasing Order of Tolerance") Hi|li salt tolerance Mediam salt tolerance Low salt tolerance VEGHABLE CROPS ECeX1II'=12 ECeX1P=10 ECcX1P=4 Garden beets Tomato Radish Kale Broccoli Celery Asparatus Cabbage Green beans Spinach Bell pepper Caulillower Lettuce Sweet corn Potatoes (White Rose) Carrot Onion Peas Squash Cucumber ECcX10'=4 ECcX1ff'=3 FIELD CROPS ECeXl(P=16 ECcXI0'=10 Barley (gram) Rye ((ram) Hold beans Su(ar beet Wheal (tram) Rape Oats (gram) Cotton RICO Sorghum (gram) Corn (Held) Flax Sunllower Castorbeans E C X 1 P = 1 0 ECcXI0»=6 FRUIT CROPS Date palm Pomegranate Pear Fig Apple Olive Orange Grape Grapelruit Cantaloupe Prune Plum Almond Apricot Peach Strawberry Lemon Avocado ECrX1P=IS Alkali sacaton Saltgrass Nulla II alkahgrass Bermuda grass Rhodes grass Rescue grass Canada wildrye Western wheatgrass Barley (hay) Bridsfoot trefoil E C e X l P ^ l J FORAGE CROPS On decreasing order tolerance) ECtXlP=12 White sweet clover Yellow sweet clover Perenraal ryegrass Mountain brome Strawberry clover Dalbs grass Sudan grass Hubam clover ECeX10'=4 White Duteh clover Meadow foitail Alsike clover Red clover Ladino clover Burnet ECcXII) '=4 ECcX1II»=2 Salinity is most readily measured by determining the electrical conduct ivi ty ( E C ) of a solution This method re-lates to the ab i l i ty of salts i n solution to conduct electricity and results are expressed as mi l l imhos ( m h o s X l O " ' ) per centimeter (cm) at 25 C Salini ty of i r r iga t ion water is ex-pressed in terms of E C , and soil salinity is indicated by the electrical conduct iv i ty of the saturation extract (ECe) See Tab le V -6 Temperature and w i n d effects are especially impor tan t as they direct ly affect evapotranspiration Periods of h igh temperature or other factors such as d ry winds, wh ich i n -crease evapotranspiration rates, not only tend to increase soil salinity but also create a greater water stress i n the plant T h e effect of c l imate conditions on plant response to salinity was demonstrated by Magistad and his associates (1943) Some of these effects can be alleviated by more frequent i r r iga t ion to main ta in safer levels of soil salinity Plants vary in their tolerance to soil salinity, and there are many ways in w h i c h salt tolerance can be appraised Ha>ward and Bernstein (1958)32' po,nt three (1) Test the abi l i ty of a plant to survive on saline soils Salt tolerance based p r imar i l y on this cr i ter ion of survival has l imi t ed ap-pl icat ion m i r r iga t ion agriculture but is a method of ap-praisal that has been used widely by ecologists (2) Test the absolute yield of a plant on a saline soil This cr i ter ion has the greatest agronomic significance (3) Relate the yie ld on saline soil to nonsaline soil This cr i ter ion is useful for compar ing dissimilar crops whose absolute yields cannot be compared direct ly T h e U S Sal ini ty Laboratory Staff (1954) has used the t h i r d cr i ter ion in establishing the list of salt tolerance of various crops shown in Table V -6 These salt tolerance values are based upon the conduct iv i ty of the saturation ex-tract ( E C c ) expressed i n mmhos /cm at wh ich a 50 per cent decrement in yield mav be expected when compared to TABLE V-7âSotl Salmities tn Root Zone at which Yield Reductions become Significant Crop Electrical conducbnty of saturabon eitracts (ECg) at which yields decrease by about 10 per cent" Allella (Calilornia common) Tall fescue mmh/cm at 25 C Rye (hay) Date palm 8 Wheat (hay) Pomegranate 1 Oats (hay) FiJ > 4-S' Orchardgrass orive j Blue grama Grape 4 Meadow fescue Muskmelon 3 5 Reed canary Orange, grapefruit, lemon° 3-2 5 Big trefoil Apple, pear 2 S Smooth brome Plum, prune, peach, apricot, almond 2 S Tall meadow oatgrass Boysenberry, btackbeny, raspbeny< 2 5-1 5 Cicer milkvetch Avocado 2 Sourclover Strawberry 1 5 Sickle milkvetch » The numbers following EC xÌ 10' are the electrical conducbnty values of the sabirabon eitract in miDimbos per eenbmeter at 25 C associated with 50 per cent decrease in yield Sabnity Laboratory Staff 1954>» ° In gypsiferous soils, ECe readings for given soil saDmbes are about 2 mmb/«n higher than lor nongypsifenns soils. Date palm would be affected at 10 mmh/cm, grapes at 6 mmh/cm, etc. on gypsiferous sols. " Esbmated ' Lemon is more sensibve than orange and grapefruit, raspberry more than boysenbenj and bbcUnny Bernstein 19SSb>i<
Z2&/Section VâAgricultural Uses oj Water TABLE VSâSalt Tolerance of Ornamental Shrubs (Mainnuiii ECo'itolented) Tobniit Moderateli tolerant Senalife Ver; sensibve 6-10 4-S 2 Carlia (nndinon Dracaena endinta Hitasais rosa sinensis llai comuta Bnrtord (Natal plan) nr BnlDante (Burford boll)) BooplnnDea spettaUDi Thuja orientaCs Nandina domestica Hedera cananensis (BotaimlDea) (arbor ntae) (heannlj bamboo) (Alpnan nrj) Norioin oleander Juniptm chineniii Tratbelospermom las Fajoa sellowlana (oleander) (ttireadjnt luniper) mnoides (star jasnune) (pineapple tnan) Rosmarinoi bdiwoodl Eooninius iaponica yibumum tinos roliustuni Rosasp (nr Grenoble (Resmarji) (randiflora rose on Dr Hnsi root) Dodonea noon atroimr lantana cantara pnrea Elaeapui puniens (slnrterTT) CalDitemon itmlnaBi XTloima nntcoa (Intttelmisli) Pittotporum tobira Prraeantta Graben Liiuitmm luodum (Tout pn«et) Buiui microplqilla laponica (Japaneu boiwood) Bermtein 19Ga><< yields of that plant g rown on a nonsaline soil under com-parable g rowing conditions W o r k has been done by many investigators, based upon both field and greenhouse re-search, to evaluate salt tolerance of a broad variety o f plants I n general, where comparable cri teria were used to assess salt tolerance, results obtained were most often in agreement Recent work on the salt tolerance of f r u i t crops is shown i n Tab le V - 7 , and for ornamentals i n Tab le V - 8 Bernstein (1965a '") gave E C e values causing 10, 25, and 50 per cent yield decrements for a variety of field and forage crops f r o m late seeding stage to matur i ty , assuming that sodium or chloride toxic i ty was not a g rowth deterrent These values are shown i n Figures V - 1 , V - 2 , and V -3 T h e data suggested that the effects of E C c values producing 10 to 50 per cent decrements ( w i t h i n a range of E C e values of 8 to 10 m m h / c m for many crops) may be considered ap-proximate ly linear, but for nearly al l crops the rate of change E C e Ay AECe either steepens or flattens slightly as the yie ld decrements increase f r o m less than 25 to more than 25 per cent Bernstein (1965a) ' " also pointed out that most f r u i t crops were more sensitive to salinity than were field, forage, or vegetable crops T h e data also il lustrated the h igh ly variable effect o f E C e values upon dif ferent crops and the nonlinear response of some crops to increasing con-centrations o f salt I n considering salt tolerances of crops, E C e values were used These values were correlated w i t h yields at field moisture content I f soils were allowed to d ry out excessively between irrigations, yie ld reductions were much greater, since the total soil water stress is a func t ion of both matr ic suction and solute suction and increases exponentially on EC^. in mmho/cm, at 25 C 0 2 4 6 8 10 12 14 16 18 20 22 r I I I Barley'' Sugartjcels'^ . Cotto Safflowcr Rye Wheal" _ Oals Sorghum . Soybean Sesbania'' Rice" " I â I â r 12 1 Broadbean Flax Sunflower Castor bean Beans Yield Reduction J L ^ h e indicated salt tolerances apply to the period of rapid plant growth and maturation from the late seeding stage upward Crops in each category are ranked in order of decreasing salt tolerance Width of the bar next to each crop indicates the effect of increasing salinity on yield Crosslines are placed at 10 25 and 50 per cent yield reductions Approximate rank in order of decreasing salt tolerance is indicated for additional crops for most of which complete data are lacking (Bower personal communication 1972)238 ^Less tolerant during seec'ling stage Salinity at this stage should not exceed 4 or 5 mmho/cm ECe *^Sensilive during germination Sahnity should not exceed 3 mmho/cm during germination **Less tolerant during flowering and seed set as well as during the seedling stage SaUnity at sensitive suges should not exceed 4 mmho/cm ECe of soil water FIGURE V-lâSalt Tolerance oj Field Crops' d r y i n g (Bernstein 1965a) ' " Good i r r iga t ion management can min imize this hazard Nutritional Effects Plants require a blanced nut r ient content i n the soil solution to ma in ta in o p t i m u m growth Use o f saline water for i r r iga t ion may or may not significantly upset this n u t r i -t ional balance depending upon the composit ion, concentra-t ion , and volume of i m g a t i o n water applied
Water for Irrtgatton/327 Some o f the possible nu t r i t i ona l effects were summarized by Bernstein (1965a) ' '3 as follows H i g h concentrations of ca lc ium ions i n the solution may prevent the plant f r o m absorbing enough potas-sium, or h igh concentrations of other ions may affect the uptake o f suflScient ca lc ium Di f fe ren t crops vary wide ly i n their requirements for given nutrients and i n their ab i l i t y to absorb them N u t r i t i o n a l effects of salinity, therefore, appear only i n certain crops and on ly when a par t icular type o f saline condi t ion exists Some varieties o f a par t icular crop may be immune to nu t r i t iona l disturbances, wh i l e other varieties are severely affected H i g h levels o f soluble sulfate cause internal b rowning (a ca lc ium deficiency symptom) in some lettuce varieties, but not i n others S imi la r ly , Bermuda grass Alkali sacaion, Saltgrass Nuttallalkali grass Tall wheatgrass Qrested wheatgrass Rhodes grass, Rescue grass. Canada wild rye Western wheatgrass Tall fescue Barley hayb Sweet clovers Perennial rye Mountain bromc 0 2 4 6 I â 1 â I â r - c ECe in mmho/cm at 25 C 8 10 12 14 16 18 20 22 - I 1 1 1 1 1 1 1 1£ Hardinggrass ⢠Beets'" Asparagus Kale Spinach Tomato Broccoli Cabbage Cauliflower Potato Corn Sweetpotato Lettuce â Bell pepper Onion Carrot Cucumber, Peas Squash, Radish Celery Beans ECe mmho/cm at 25 C 0 2 4 6 8 10 12 14 16 -1 1 1 1 5 0 * Yield Reduction 25% 10% L _ J IâI 1 1 - - L _ l *See Figure V-1 (Bower personal communication 1972)338 ''sensitive during germination SaLnity should not exceed 3 mmho/cm ECe during germination Birdsfoot trefoil ⢠Beardless wildrye Strawberry clover Dallis grass, Sudan grass Hubam clover Alfalfa Rye hay. Oat hay Wheat hay I" Orchardgrass Blue grama Meadow foxtail Reed canary, Big trefoil Smooth brome, Milkvetch Tall meadow oatgrass, Burnet Clovers, alsike , red FIGURE V-3âSalt Tolerance of Vegetable Crops" 50% Yield Reduction 25% 10% 1 L . -1 L . _ L _ J L _ J "See Figure V I (Bower personal communication 1972)338 â¢"Less tolerant during seedling stage Salinity at this sute should not exceed 4 or 5 mmho/cm ECe FIGURE V-2âSalt Tolerance of Forage Crops" h igh levels of ca lc ium cause greater nu t r i t i ona l dis-turbances i n some carrot varieties than i n others Chemical analysis o f the p lant is useful i n diagnosing these effects A t a given level o f salinity, g rowth and y ie ld are depressed more when n u t r i t i o n is disturbed than when n u t r i t i o n is no rma l N u t r i t i o n a l effects, for tunate ly , are not impor tan t i n most crops under saline con-di t ions, when they do occur, the use o f better adapted varieties may be advisable Recommendation Crops vary considerably in their tolerance to soil salinity in the root zone, and the factors affecting
32Q/Section VâAgricultural Uses of Water the soil solution and crop tolerance are varied and complex. Therefore, no recommendation can be given for these. For specific crops, however, it is recommended that the salt tolerance values (ECe) for a saturation extract established by the U.S. Salinity Laboratory Staff be used as a guide for production. Temperature T h e temperature of i r r iga t ion water has a direct and indirect effect on plant g rowth Each occurs when p lan t physiological functions are impaired by excessively high or excessively low temperatures T h e exact water temperatures at which g rowth is severely restricted depends on method of water applicat ion, atmospheric conditions at the t ime of applicat ion, frequency o f applicat ion, and plant species A l l plant species have a tempeature range in wh ich they develop best These temperature l imits vary w i t h plant species Direct effect on plant g rowth f r o m extreme temperature of the i r r iga t ion water occurs when the water is first applied Plant damage results only f r o m direct contact Norma l ly , few problems arise when excessively w a r m water is applied by sprinkler i r r iga t ion T h e effect of the temperature of the water on the temperature of the soil is negligible I t has been demonstrated that w a r m water applied through a sprinkler system has attained ambient temperatures at the t ime I t reaches the soil surface (Cline et al 1969) Water as w a r m as 130 F can be safely used i n this manner Cold water is h a r m f u l to plant g rowth when applied through a sprinkler system I t does not change in temperature nearly so much as the w a r m water However, its effect is rarely lethal Surface applied water that is either very cold or very w a r m poses greater problems Excessive w a r m water can-not be used for surface i r r iga t ion and cold water affects plant g rowth T h e adverse effects of cold water on the g rowth o f rice were suddenly brought to the at tention of rice growers when cold water was first released f r o m the Shasta Reservoir i n Cal i forn ia (Raney 1963) Summer water temperatures were suddenly dropped f r o m about 61 F to 45 F Research is st i l l proceeding, and some of the available in format ion was recently reviewed by Raney and M i h a r a (1967) Dams such as the Orov i l l e D a m are now being planned so that water can be w i t h d r a w n f r o m any reservoir depth to avoid the cold-water problem W a r m i n g basins have been used (Raney 1959) ' ' ^ There are oppor-tunities i n p lanning to separate watersâthe w a r m waters for recreation and agricul ture, the cold waters for cold-water fish, salmon spawning, and other uses T h e exact nature of the mechanisms by w h i c h damage occurs is not completely understood Indi rec t effect of the temperature o f i r r iga t ion water on p lan t g rowth occurs as a result of its influence on the tem-perature of the soil T h e latter affects the rate of water uptake, nut r ient uptake, translocation o f metabolites, and, indirect ly , such factors as stomatal opening and plant water stress A l l these phenomena are wel l documented T h e effect of the temperature of the applied i r r iga t ion water on the temperature o f the soil is not wel l described This effect is probably qui te small Conclusion Present literature does not provide adequate data to establish specific temperature recommendations for irrigation waters. Therefore, no specific recom-mendations can be made at this time. Chlorides Chlorides in i r r iga t ion waters are not generally toxic to crops Cer ta in f r u i t crops are, however, sensitive to chlorides Bernstein (1967)3'^ indicated that m a x i m u m permissible chloride concentrations i n the soil range f r o m 10 to 50 mill iequivalents ( m e q ) / l for certain sensitive f r u i t crops (Table V - 9 ) I n terms of permissible chloride concentra-tions i n i r r iga t ion water, values up to 20 meq/1 can be used, depending upon environmental conditions, crops, and i r r iga-t ion management practices Foliar absorption of chlorides can be of importance m sprinkler i r r iga t ion (Eaton and H a r d i n g 1959," ' Eh l ig and Bernstein 1959'^") T h e adverse effects vary between evapo-TABLE V-9âSalt Tolerance of Fruit Crop Varieties and Rootstocks and Tolerable Chloride Levels in the Saturation Extracts Tolerablsletelsol Crop Rootitocli or nnet; chlonde in aturation extract Rootstotki meq/l Ronipur lime, Cleopatra nundinn 2S btnii Routh lemon, tanielo, sour oranp IS , Sweet orange, dtrange 10 Mananna 25 Stone (nut Loiell, ShaGI 10 Yunnan 7 Afoado f West Indian 8 1 [ Mencan S Vanetiet (V) and Rootstodu (R) Salt Creek, 1E13 3 R 40 Grape Dot Ridge 30 Thompson Seedless, Perlette Â¥ 20 Cardinal, Bbck Rosa 10 Vanetiei Boysenben; 10 Bemoi Olallie bbckberrj 10 Indian Summer nspberr; 5 Strawliertj Lassen 8 1 Shasta S Beroslein 19S]">
Water for Irrtgation/329 rative conditions of day and night and the amount of evaporation that can occur between successive wettings ( i e , t ime after each pass w i t h a slowly revolving sprinkler) There is less effect w i t h n ight ime spr inkl ing and less effect w i t h fixed sprinklers (applying water at a rap id rate) Concentrations as low as 3 meq/1 of chloride i n i r r iga t ion water have been found h a r m f u l when used on citrus, stone frui ts , and almonds (Bernstein 1967) Conclusion Permissible chloride concentrations depend upon type of crop, environmental conditions and man-agement practices. A single value cannot be given, and no limits should be established, because detri-mental effects from salinity per se ordinarily deter crop growth first. Bicarbonates H i g h bicarbonate water may induce i ron chlonsis by mak ing i ron unavailable to plants (Brown and Wadle igh 1955) Problems have been noted w i t h apples and pears (Prat t 1 9 6 6 ) a n d w i t h some ornamentals ( L u n t et al 1956) A l though concentrations of 10 to 20 meq/1 of bicarbonate can cause chlorosis in some plants, i t is of l i t t l e concern m the field where precipi tat ion o f ca lc ium carbo-nate minimizes this hazard Conclusion Specific recommendations for bicarbonates can-not be given without consideration of other soil and water constituents. Sodium T h e presence of relatively high concentration of sodium i n i r r iga t ion waters affects irr igated crops i n many ways I n addi t ion to its effect on soil structure and permeabil i ty, sodium has been found by Li l le land et al (1945)'22 and Ayers et al (1952)^' ' to be absorbed by plants and cause leaf burn i n almonds, avocados, and i n stone f rui ts g rown in cul ture solutions Bernstein (1967) ' " has indicated that water having S A R * values of four to eight may in ju re sodium-sensitive plants I t is d i f f i cu l t to separate the specific toxic effects of sodium f r o m the effect of adsorbed sodium on soil structure (This factor w i l l be discussed later ) As has been noted, the complex interactions of the total and relative concentrations of these common ions upon various crops preclude their consideration as ind iv idua l components for general i r r igat ion use, except for sodium and possibly chlorides in areas where f r u i t would be i m -portant Nitrate T h e presence o f n i t ra te in natura l i r r iga t ion waters may be considered an asset rather than a l i ab i l i t y w i t h respect * For definition of SAR, Sodium Adsorption Ratio, see p 330 to p lant g rowth Concentrations h igh enough to adversely affect p lant g r o w t h or composition are seldom, i f ever, found I n a n d regions, h igh nitrate water may result i n ni trate accumulations in the soil i n much the same manner as salt accumulates T h e same soil and water management practices that min imize salt accumulation w i l l also min imize nitrate accumulat ion There is some concern over the h igh nitrate content of food and feed crops M a n y factors such as plant species characteristics, cl imate conditions, and growth stage are just as significant in determining ni t rate accumulations in plants as the amount present i n the soil I t is unl ikely that any nitrate added i n natural i r r iga t ion water could be a significant factor Problems may arise where waste waters containing rela-tively large amounts of nitrogenous materials are used for i r r igat ion Larger amounts are usually applied than that actually required for plant g rowth These wastes, however, usually contain nitrogen i n a f o r m that is slowly converted to ni trate Nevertheless, i t is possible that h igh nitrate ac-cumulations in plants may occur al though l i t t l e evidence is available to indicate this Conclusion Since nitrate in natural irrigation waters is usually an asset for plant growth and there is little evidence indicating that it will accumulate to toxic levels in irrigated plants consumed by animals, there appears to be no need for a recom-mendation. Effects on Soils Sodium Hazard Sodium in i r r igat ion water may be-come a problem in the soil solution as a component of total salinity, wh ich can increase the osmotic concentration, and as a specific source o f i n j u r y to frui ts T h e problems o f sodium main ly occur in soil structure, i n f i l t r a t ion , and per-meabi l i ty rates Since good drainage is essential for manage-ment of salinity in i r r igat ion and for reclamation of saline lands, good soil structure and permeabil i ty must be ma in -tained A h igh percentage of exchangeable sodium i n a soil containing swelling-type clays results i n a dispersed condi-t ion , wh ich IS unfavorable for water movement and plant g rowth A n y t h i n g that alters the composition of the soil solution, such as i r r iga t ion or fer t i l izat ion, disturbs the equ i l i b r ium and alters the dis t r ibut ion of adsorbed ions in the soil W h e n ca lc ium is the predominant cation adsorbed on the soil exchange complex, the soil tends to have a granular structure that is easily worked and readily perme-eable When the amount o f adsorbed sodium exceeds 10 to 15 per cent of the total cations on the exchange complex, the clay becomes dispersed and slowly permeable, unless a h igh concentration o f total salts causes flocculation Where soils have a h igh exchangeable sodium content and are flocculated because o f the presence of free salts in solution, subsequent removal of salts by leaching w i l l cause sodium
ZZO/Section VâAgricultural Uses of Water dispersal, unless leaching is accomplished by adding ca lc ium or calc ium-producmg amendments Adsorpt ion o f sodium f r o m a given i r r iga t ion water is a func t ion of the proport ion of sodium to divalent cations (calcium and magnesium) i n that water T o estimate the degree to w h i c h sodium w i l l be adsorbed by a soil f r o m a given water when brought in to equ i l ib r ium w i t h i t , the Salini ty Labora tory (1954)' '* proposed the sodium adsorp-t ion rat io (SAR) Na+ 4 Ca++- | -Mg++ Expressed as me/1 As soils tend to dry , the S A R value of the soil solution i n -creases even though the relative concentrations of the ca-tions remain the same This is apparent f r o m the S A R equation, where the denominator is a square-root func t ion This is a significant factor i n estimating sodium effects on soils T h e S A R value can be related to the amount of ex-changeable cation content This latter value is called the exchangeable sodium percentage (ESP) F r o m empir ical determinations, the U S Salinity Laboratory ( 1 9 5 4 ) " ' obtained an equation for predict ing a soil ESP value based on the S A R value of a water i n equ i l ib r ium w i t h i t This is expressed as follows ESP = [100 a- t -b(SAR)] [ l - f - a - l - b ( S A R ) ] T h e constants " a " (intercept representing experimental er-ror) and " b " (slope o f the regression line) were deter-mined statistically by various investigators who found " a " to be i n the order o f â0 06 to 0 01 and " b " to be w i t h i n the range of 0 014 to 0 016 This relationship is shown in the nomogram (Figure V-4) developed by the U S Salini ty Labora tory (1954) For sensitive frui ts , the tolerance l i m i t for S A R of i r r iga t ion water is about four For general crops, a l i m i t o f eight to 18 is generally considered w i t h i n a usable range, a l though this depends to some degree on the type o f clay minera l , electrolyte concentration in the water, and other variables T h e ESP value that significantly affects soil properties varies according to the propor t ion of swelling and non-swelling clay minerals A n ESP of 10 to 15 per cent is considered excessive, i f a h igh percentage of swelling clay minerals such as montmor i l loni te are present Fair crop growth of alfalfa, cotton, and even olives, have been ob-served m soils of the San Joaquin Val ley (Cal i fornia) w i t h ESP values ranging f r o m 60 to 70 percent (Schoonover 1963) Prediction o f the equ i l i b r ium ESP f r o m S A R values of i r -r igat ion waters is complicated by the fact that the salt con-tent of i r r iga t ion water becomes more concentrated i n the soil solution Accord ing to the U S Salinity Labora tory (1954),"* shallow ground waters 10 times as saline as the i r r iga t ion waters may be found w i t h i n depths of 10 feet, and a salt concentration two to three times that o f i r r iga t ion water may be reasonably expected in the first-foot depth Under conditions where precipi ta t ion of salts and ra infa l l may be neglected, the salt content of i r r iga t ion water w i l l increase to higher concentrations in the soil solution wi thou t change in relative composition T h e S A R increases in propor t ion to the square root of the concentrat ion, there-fore, the S A R applicable for calculat ing equ i l i b r ium ESP i n the upper root zone may be assumed to be two to three times that of the i r r iga t ion water Recommendation To reduce the sodium hazard in irrigation water for a specific crop, it is recommended that the SAR value be within the tolerance limits determined by the U.S. Soil Salinity Laboratory Staff. Biochemical Oxygen Demand (BOD) and Soil Aeration T h e need for adequate oxygen in the soil for o p t i m u m plant g rowth is wel l recognized T o meet the oxygen re-quirement of the plant, soil structure (porosity) and soil water contents must be adequate to permi t good aeration Conditions that develop immediately fo l lowing i r r iga t ion are not clearly understood Soil aeration and oxygen avai labi l i ty normal ly present no problem on well-structured soils w i t h good qua l i ty water Where drainage is poor, oxygen may become l i m i t i n g U t i l i z a t i on o f waters having high B O D or Chemical Oxygen Demand ( C O D ) values could aggravate the condi t ion by fur ther depleting available oxygen Aside f r o m det r imenta l effects of oxygen deficiency for plant g rowth , reduction o f elements such as i ron and manganese to the more soluble divalent forms may create toxic conditions Other biological and chemical equi l ibr ia may also be affected There is very l i t t l e in fo rmat ion regarding the effect of using i r r iga t ion waters w i t h h igh B O D values on plant g rowth Between source of contaminat ion and point of i r -r igat ion, considerable reduction in B O D value may result Sprinkler i r r iga t ion may fur ther reduce the B O D value of water I n f i l t r a t i o n in to well-drained soils can also decrease the B O D value of the water w i thou t serious depleting the oxygen available for plant g rowth Acidity and Alkalinity T h e p H of normal i rnga t ion water has l i t t le direct sig-nificance Since water itself is unbuffered , and the soil is a buffered system (except for extremely sandy soils low in organic mat ter ) , the p H of the soil w i l l not be significantly affected by appl icat ion of i r r iga t ion water There are, how-ever, some extremes and indirect effects Water having p H values below 4 8 applied to acid soils over a period of t ime may possibly render soluble i ron .
Water for Irrigation/iiX Ca^"+Mg Salinity Laboratory 1954 335 FIGURE V-4âNomogram for Determining the SAR Value of Irrigation Water and for Estimating the Corresponding ESP Value of a Soil That is at Equilibrium with the Water
332/&c/jon VâAgricultural Uses of Water a l u m i n u m , or manganese in concentrations large enough to be toxic to plant g rowth Similar ly , additions of saline waters to acid soils could result i n a decrease in soil p H and an increase i n the solubil i ty of a l u m i n u m and manganese I n some areas where acid mine drainage contaminates water sources, p H values as low as 1 8 have been reported Waters having unusually low p H values such as this wou ld be strongly suspect of containing toxic quantities of certain heavy metals or other elements Waters having p H values i n excess of 8 3 are h ighly alkaline and may contain high concentrations of sodium, carbonates, and bicarbonates These constituents affect soils and plant g rowth directly or indirect ly , (see "Effects on Plant G r o w t h " above) Recommendation Because most of the effects of acidity and alka-linity in irrigation waters on soils and plant growth are indirect, no specific pH values can be recom-mended. However, water with pH values in the range of 4.5 to 9.0 should be usable provided that care is taken to detect the development of harmful indirect effects. Suspended Solids Deposition o f colloidal particles on the soil surface can produce crusts that i nh ib i t water in f i l t r a t ion and seedling emergence This same deposition and crusting can reduce soil aeration and impede plant development H i g h col-lo ida l content in water used for sprinkler i r r iga t ion could result m deposition of films on leaf surfaces that could re-duce photosynthetic ac t iv i ty and thereby deter g rowth Where sprinkler i r r iga t ion is used for leafy vegetable crops such as lettuce, sediment may accumulate on the growing plant affect ing the marketabi l i ty of these products I n surface i r r iga t ion , suspended solids can interfere w i t h the flow of water i n conveyance systems and structures Deposit ion o f sediment not only reduces the capacity of these systems to carry and distribute water but can also decrease reservoir storage capacity For sprinkler i r r iga t ion , suspended mineral solids may cause undue wear on i r r iga-t ion pumps and sprinkler nozzles (as wel l as plugging up the la t ter ) , thereby reducing i r r iga t ion efficiency Soils are specifically affected by deposition of these sus-pended solids, especially when they consist p r imar i ly of clays or colloidal material These cause crust formations that reduce seedling emergence I n addi t ion, these crusts reduce in f i l t r a t i on and hinder the leaching of saline soils T h e scouring action of sediment i n streams has also been found to affect soils adversely by cont r ibu t ing to the dissolu-t ion and increase o f salts i n some areas (Pil lsbury and Blaney 1966) Conversely, sediment h igh i n silt may improve the texture, consistency, and water-holding capacity of a sandy soil EfTect on Animals or Humans T h e effects of i r r iga t ion water qua l i ty on soils and plants has been discussed However, since the qua l i ty o f i r r iga t ion water is variable and originates f r o m di f fe ren t sources, there may be natural or added substances in the water wh ich pose a hazard to animals or humans consuming irr igated crops These substances may be accumulated in certain cereals, pasture plants, or f r u i t and vegetable crops w i thou t any apparent i n j u r y O f concern, however, is that the concen-t ra t ion of these substances may be toxic or h a r m f u l to humans or animals consuming the plants M a n y substances i n i r r iga t ion waters such as inorganic salts and minerals, pesticides, human and animal pathogens have recommenda-tions to protect the desired resource For radionuclides no such recommendation exists Radionuclides There are no generally accepted standards for control of radioactive contaminat ion in i r r iga t ion water For most radionuclides, the use of federal D r i n k i n g Water Standards, should be reasonable for i r r iga t ion water T h e l i m i t i n g factor for radioactive contaminat ion i n i r -r igat ion IS I t s transfer to foods and eventual intake by humans Such a level of contaminat ion wou ld be reached long before any damage to plants themselves could be ob-served Plants can absorb radionuclides f r o m i r r iga t ion water i n two ways direct contaminat ion of foliage th rough sprinkler i r r iga t ion , and indirect ly through soil contamina-t ion T h e latter presents many complex problems since eventual concentration i n the soil w i l l depend on the rate of water applicat ion, the rate of radioactive decay, and other losses of the radionuclide f r o m the soil Some studies, relat ing to these factors have been reported (Menzel et al 1963,326 M o o r b y and Squire 1963,'28 Perrin \963,''-' Menze l 1965,3" M i l b o u r n and Tay lo r 1965'") I t IS estimated that concentrations of strontium-90 and radium-226 i n fresh produce w o u l d approximate those i n the i r r iga t ion water for the crop i f there was negligible up-take of these radionuclides f r o m the soil W i t h flood or fu r -row i r r iga t ion only, one or more decades of continuous i r -r igat ion w i t h contaminated water w o u l d be required before the concentrations of strontium-90 or radium-226 in the produce equalled those in the water (Menzel personal com-munication 1972) Recommendation In view of the lack of experimental evidence con-cerning -the long-term accumulation and avail-ability of strontium-90 and radium-226 in irrigated soils and to provide an adequate margin of safety, it is recommended that Federal Drinking Water Standards be used for irrigation water.
Water for Irrigation/333 SPECIFIC IRRIGATION WATER CONSIDERATIONS Irrigation Water Quality for Arid and Semiarid Regions Climate Cl imat ic var iab i l i ty exists in and and semiarid re-gions There can be heavy winter precipi ta t ion, generally i n -creasing f r o m south to nor th and increasing w i t h elevation Summer showers are common, increasing nor th and east f r o m Cal i fornia C o m m o n through the western part of the country is the inadequacy of precipi tat ion du r ing the grow-ing season I n most areas of the West, intensive agriculture is not possible wi thou t i r r iga t ion I r r iga t ion must supply at least one-half of a l l the soil water required annual ly for crops for periods ranging f r o m three to 12 months Annua l precipi ta t ion varies in the western U n i t e d States f r o m practical ly zero in the southwestern deserts to more than 100 inches in the upper western slope of the Pacific Northwest T h e dis t r ibut ion of precipi tat ion throughout the year also varies, w i t h no ra infa l l du r ing extended periods in many locales O f t e n the ra infa l l occurs du r ing nongrowing seasons T h e amount of precipi tat ion and its d is t r ibut ion is one of the pr inc ipal variables in determining the diversion require-ment or demand for i r r igat ion water Land Soils in the semiarid and and regions were developed under dry c l imat ic conditions w i t h l i t t l e leaching of weather-able minerals in the surface horizon Consequently, these soils are better supplied w i t h most nutr ient elements T h e p H of these soils varies f r o m being slightly acidic to neutral or alkaline T h e presence of silicate clay minerals of the montmor i l lon i te and hydrous mica groups in many of these soils gives them a higher exchange capacity than those of the southeast, wh ich contain kaolini te minerals of lower ex-change capacity However, organic matter and nitrogen contents of a n d soil are usually lower Plant deficiencies of trace elements such as zinc, i ron , manganese are more fre-quent ly encountered Because of the less frequent passage of water through and soils, they are more apt to be saline T h e nature of the surface horizon (plow layer) and the subsoil IS especially impor tan t for i r r igat ion D u r i n g soil fo rmat ion a prof i le can develop consisting of various ho r i -zons T h e horizons consist of genetically related layers of soil or soil material parallel to the land surface, and they d i f f e r i n their chemical, physical, and biological properties T h e produc t iv i ty of a soil is largely determined by the na-ture of these horizons Soils available for i r r iga t ion w i t h restrictive or impervious horizons present management problems (e g , drainage, aeration, salt accumulat ion m root zone, changes in soil structure) and consequently are not the best for i rr igated agriculture Other land and soil factors of importance to i r r iga t ion are topography and slope, which may influence the choice of i r r iga t ion method, and soil charactenstics T h e latter are extremely impor tan t because they determine the usable depth of water that can be stored in the root zone of the crop and the erodabil i ty and intake rate of the soil Water Each river system w i t h i n the a n d and semiarid por-t ion of the U n i t e d States has qual i ty characteristics peculiar to Its geologic or ig in and cl imat ic environment I n consider-ing water qua l i ty characteristics as related to i r r iga t ion , both historic and current data for the stream and location in question should be used w i t h care because of the large seasonal and sporadic variations that occur T h e range of sediment concentrations of a r iver through-out the year is usually much greater than the range of dis-solved solids concentrations M a x i m u m sediment concentra-tions may range f r o m 10 to more than a thousand times the m i n i m u m concentrations Usually, the sediment concentra-tions are higher du r ing high flow than du r ing low flow This differs inversely f r o m dissolved-solids concentrations that are usually lower du r ing high flows Four general designations o f water have been used (Rainwater 1962)3^' based on their chemical composition ( I ) calcium-magnesium, carbonate-bicarbonate, (2) cal-cium-magnesium, sulfate-chloride, (2) sodium-potassium, carbonate-bicarbonate, and (4) sodium-potassium, sulfate-chloride This type of classification characterizes the chem-ical properties of the water and wou ld be indicat ive of re-actions that could be expected w i t h soil when used for i r -r igat ion Al though a l ist ing of data for each stream and t r ibu ta ry is beyond the scope of this report, an indicat ion of ranges in dissolved-solids concentrations, chemical type, and sediment concentration IS given i n Table V - I O (Rainwater 1962) Customari ly, each i r r iga t ion project diverts water at one point i n the river and the re turn flow comes back into the mainstream somewhere below the system This re turn flow consists in the ma in o f ( I ) regulatory water, w h i c h is the unused part of the diverted water required so that each farmer i r r iga t ing can have the exact flow he has ordered. TABLE V-10âVariations in Dissolved Solids, Chemical Type, and Sediment in Rivers in Arid and Semiarid United States Region Dissolved solids conceiilJdIiona, mg/l Prevalent chemical tnie° Sediment concentrations, rag/l* From To From To Columbia River Basin <100 3Q0 Ca l»{ Cb <200 300 Northern California <100 700 Ca Mg,Cb <200 +500 Southern Cablorma <100 +2,000 Ca Mg, C b, Ca Mg,SC <200 +15,000 Colorado Rivei Basin <100 +2,500 Ca Mg. S C. Ca Mg,C-b <200 +15,000 Rio Grande Basin <10O +2,000 Ca Mg. C b. Ca Mg,SC +300 +50,000 Pecos River Basin 100 +3,000 Ca Mg,SC +300 +7,000 Western Gull ol Menco Basins 100 +3,000 Ca Mg, C b, Ca Mg. S C, Na P, S C <200 +30,000 Red River Basm <100 +2,500 Ca Mg, S C, Na P,SC +300 +25,000 Arkansas River Basin 100 +2,000 Ca Mg, S C, Ca Mg, C-b, NaP.SC +300 +30,000 Platte River 100 +1,500 Ca Mg. C-b, Ca Mg,SC +300 +7.000 Upper Missouri River Basin 100 +2.000 Ca Mg, S C, Na P, C-b, Na P, C b <200 +15.000 °Ca Mg.C-&=Calciom magnesium, carbonate bicarbonate. Ca Mg,$-C=Calciiim magnesium, sulfate-diioride. Na P, C b= Sodium potassum, carbonate-bicarbonate. Na P, S C=Sodium potassum, suHate chloride. ^ Sediment concen1ratioo= Rainwater 1982"! Annual Uad Annual Streamdow
334/Sectton VâAgricultural Uses of Water (2) ta i l water, w h i c h is that por t ion of the water that runs o f f the ends of the fields, and (3) underground drainage, required to provide adequate applicat ion and salt balance i n a l l parts of the fields T h e in i t i a l flush of ta i l water may be somewhat more saline than later but rapidly approaches the same qua l i ty as the applied water (Reeve et al 1955) Drainage and Leaching Requirements I n al l i r r iga t ion agri-cul ture some water must pass through the soil to remove salts brought to the soil i n the water I n semiarid areas, or i n the transition zone between a n d and h u m i d regions, this drainage water is usually obtained as a result of ra in fa l l du r ing periods of low evapotranspiration, and no excess i r r iga t ion water is needed to provide the drainage required I n many a n d regions, the needed leaching must be ob-tained by adding excess water I n al l cases, the required drainage volume is related to the amount of salt i n the i r -r igat ion water T h a t drainage volume is called the leaching requirement ( L R ) I t IS possible to predict the approximate salt concentra-t ion that wou ld occur i n the soil after a number of i r r iga-tions by estimating the propor t ion of applied water that w i l l percolate below the root zone I n any steady-state leaching fo rmula , the fo l lowing assumptions are made ⢠N o precipi tat ion of salts occurs in the soil , ⢠I o n uptake by plants is negligible, ⢠There is u n i f o r m dis t r ibut ion of soil moisture through the prof i le and u n i f o r m concentration of salts i n the soil moisture, ⢠Complete and u n i f o r m m i x i n g of i r r iga t ion water w i t h soil moisture takes place before any of the mois-ture percolates below the root zone and ⢠Residual soil moisture is negligible A steady state leaching requirement fo rmula has been developed by the U S Salini ty Labora tory ( 1 9 5 4 ) ' " de-signed to estimate that f rac t ion of the i r r iga t ion water that must be leached through the root zone to control soil salin-i t y at any specified level This is given as Ddw E C , â L R = ECdw where L R is the leaching requirement , Ddw, the depth of drainage water , D,w, the depth of i r r iga t ion water , EC,w, the salinity of i r r iga t ion water , and ECdw, the salinity of water percolating past root zone Hence, i f ECdw is determined by the salt tolerance of the crop to be g rown, and the salt content of the i r r iga t ion water EC,w is known, the desired L R can be calculated This leaching f rac t ion w i l l then be the rat io of depth of drainage volume to the depth of i r r iga t ion water applied Because the permissible values for ECdw for various yie ld decrements for various crops are not known , the E C e for 50 per cent yield reduction has been substituted for ECdw T h e actual yield reduction w i l l probably be less than 50 per cent (Bernstein 1966) This E C e is the assumed aver-age electrical conduct iv i ty for the soil water at saturation for the whole root zone W h e n i t is substituted for the ECdw, the actual E C e encountered in the root zone w i l l be less than this value because, i n many near steady state situa-tions, the salinity increases progressively w i t h increase in depth in the prof i le and is m a x i m u m at the bo t tom of the root zone Bernstein (1967 ) " ' has developed a leaching f rac t ion fo rmula that takes into consideration factors that control leaching rates such as in f i l t r a t ion rate, c l imate (evapotrans-p i ra t ion) , frequency and dura t ion of i r r iga t ion , and, of course, the salt tolerance of the crops H e defines the leaching f rac t ion as L F = 1 â E T c / I T i where L F is the leach-ing f rac t ion or propor t ion of applied water percolating below the root zone, E , the average rate o f evapotranspira-t ion du r ing the i r r iga t ion cycle, T c , and I , the average i n -filtration rate du r ing the period of i n f i l t r a t i on , T i By u t i l i z -ing both the required leaching derived f r o m the steady state fo rmula L R = E C , ECdw and the leaching f rac t ion based upon in f i l t r a t i on rates and evapotranspiration du r ing the i r r iga t ion cycle, i t is possible to estimate whether adequate leaching can be attained or whether adjustments must be made in the crops to be grown to permi t higher salinity concentrations I n addi t ion to determinat ion of crops to be g rown, leaching requirements may be used to indicate the total quantities of water required For example, i r r iga t ion water w i t h a conduct ivi ty of two mmhos requires one-sixth more water to main ta in root zone salt concentrations w i t h i n eight mmhos than w o u l d water w i t h a salt concentration o f one mmhos under the same conditions of use There are a number of problems in apply ing the leaching requirement concept i n actual practice Some of these relate to the basic assumptions involved and others derive f r o m water applicat ion problems and soil va r iab i l i ty ⢠Considerable precipi tat ion of ca lc ium carbonate oc-curs as many i r r iga t ion waters enter the soil causing a reduction in the total soluble salt load I n many crops, o r crop rotations, crop removal o f such ions as chloride was a significant f rac t ion of the total added i n waters of med ium to low salinity (Pratt e t a l 1967) ⢠I t IS not practical to apply water w i t h complete u n i -fo rmi ty ⢠Soils are far f r o m u n i f o r m , par t icu lar ly w i t h respect to vert ical hydraul ic conduct iv i ty ⢠T h e eff luent f r o m t i le o r d i t c h drains may not be representative of the salinity of water at the bo t tom of the root zones Also, there is a considerable var ia t ion i n drainage ou t f low that has no relat ion to leaching requirement when di f ferent
Water for Irrigation/3'55 crops are irr igated (Pillsbury and Johnston 1965) This results f r o m variations i n i r r iga t ion practices for the d i f ferent crops T h e leaching requirement concept, wh i l e very useful, should not be used as a sole guide in the field T h e leaching requirement is a long-period average value that can be departed f r o m for short periods w i t h adequately drained soils to make temporary use of water poorer i n qua l i ty than customarily applied T h e exact manner i n w h i c h leaching occurs and the ap-propriate values to be used i n leaching requirement formulas require fu r the r study T h e many variables and as-sumptions involved preclude a precise determinat ion under field conditions Salinity Hazard Waters w i t h total dissolved solids ( T D S ) less than about 500 mg/1 are usually used by farmers w i t h -ou t awareness o f any salinity problem, unless, o f course, there is a h igh water table Also, w i thou t d i l u t i on f r o m precipi ta t ion or an alternative supply, waters w i t h T D S of about 5,000 mg/1 usually have l i t t l e value for i r r iga t ion (Pil lsbury and Blaney 1966) W i t h i n these l imi ts , the value of the water appears to decrease as the salinity increases Where water is to be used regularly for the i r r iga t ion of relatively impervious soil, its value is l imi ted i f the T D S IS i n the range of 2,000 mg/1 or higher Recommendation In spite of the facts that (1) any TDS limits used in classifying the salinity hazard of waters are somewhat arbitrary; (2) the hazard is related not only to the TDS but also to the individual ions involved; and (3) no exact hazard can be assessed unless the soil, crop, and acceptable yield reduc-tions are known, Table Y - l l suggests classifications for general purposes for arid and semiarid regions. Permeability Hazard T w o cri teria used to evaluate the ef-fect of salts m i r r iga t ion water on soil permeabil i ty are (1) the sodium adsorption rat io ( S A R ) and its relat ion to the exchangeable sodium percentage, and (2) the bicarbo-nate hazard that is par t icu lar ly applicable to waters o f a n d regions Another factor related to the permeabil i ty hazard is tha t the permeabi l i ty tends to increase, and the s tabi l i ty o f a sod at any exchangeable sodium percentage (ESP) increases as the sal ini ty of the water increases ( Q u i r k and Schofield 1955) Eaton ( 1 9 5 0 ) , ' " Doneen ( 1 9 5 9 ) , ' " and Christiansen and T h o r n e (1966)'** have recognized that the permeabil i ty hazard of i r r iga t ion waters containing bicarbonate was greater than indicated by their S A R values Bower and W i l c o x ( 1 9 6 5 ) ' " f ound that the tendency for ca lc ium carbonate to precipitate i n soils was related to the Langelier index (Langelier 1936)'*' and to the f rac t ion of the i r r iga-t ion water evapotranspired f r o m the soil Bower et al ( 1 9 6 5 , ' « 1 9 6 8 ) ' « modif ied the Langeher index or precipita-TABLE V-11âRecommended Guidelines for Salinity in Irrigation Water Cbssiflcation TDS mt/1 EC mmhos/cm Water lor which no iletrimental efletti are usually notceil 500 0 75 Water that can have detnmental effects on sensitive crops 500-1,000 0 75-1 50 Water that can have adverse oDects on man; crops, requires careful 1,000-2,000 1 50-3 00 nunaiement practices 3 00-7 50 Water that can be used tor tolerant plantt on permeable soils w ith care 2,000-5,000 ful manaiement practices t ion index ( P I ) to the soil system and presented s impl i f ied means for calculat ion T h e P I was 8 4-pHc, where 8 4 was the pH o f the soil and pHc, the pH that wou ld be found i n a ca lc ium carbonate suspension that wou ld have the same ca lc ium and bicarbonate concentrations as those m the i r -r igat ion water For the soil system p H , = p K j - p K â + p ( C a + M g ) + p A l k where pK2 and pKc are the negative logarithms, respec-tively, of the second dissociation constant for carbonic acid and the solubil i ty constant for calcite, p ( C a + M g ) and p A l k are the negative logarithms, respectively, of the molar concentrations of ( C a + M g ) and the t i t rable a lka l in i ty Magnes ium is included p r imar i ly because i t reacts, through cation exchange, to main ta in the ca lc ium concentration i n solution The P I combines empir ical ly w i t h the S A R i n the fo l lowing equation SARse = SARi« \/C(\+Pl) where SARse and SAR,â are for the saturation extract and the i r r iga t ion water, respectively, C is the concentration factor or the reciprocal of the leaching f ract ion, and P I is 8 4-pHc Bower e t a l ( 1 9 6 8 ) ' « and Pratt and Bair (1969), '*» using lysimeter experiments, have shown a h igh correlation between the predicted and measured SARse w i t h waters of various bicarbonate concentrations T h e in format ion avai l-able suggested a h igh u t i l i t y of this equation for calculat ing permeabi l i ty or sodium hazard of waters I n cases where C IS not known, a value of 4, corresponding to a leaching frac-t ion of 0 25, can be used to give relative comparisons among waters I n this case the equation is SAR,e = 2 S A R , w ( l + P I ) Da ta can be used to prepare graphs, f r o m which the values for p K j â p K c , p ( C a + M g ) , and p A l k can be ob-tained fo r easy calculat ion of pHc T h e calculation of pHo IS described by Bower et al (1965) Soils have ind iv idua l responses i n reduction i n permeabil-i ty as the S A R or calculated S A R values increase, bu t ad-verse effects usually begin to appear as the S A R value passes through the range f r o m 8 to 18 Above an S A R of 18 the effects are usually adverse Suspended Solids Suspended organic solids in surface water supplies seldom give trouble m d i t ch d is t r ibut ion
336/&c/zon VâAgricultural Uses of Water systems except for occasional clogging of gates They can also carry weed seeds onto fields where their subsequent g rowth can have a severely adverse effect on the crop or can have a beneficial effect by reducing seepage losses Where surface water supplies are distr ibuted through pipelines, i t is often necessary to have self-cleaning screens to prevent clogging of the pipe system appliances Finer screening is usually required where water enters pressure-pipe systems for sprinkler i r r iga t ion There are waters diverted for i r r iga t ion that carry heavy inorganic sediment loads T h e effects that these loads migh t have depend in part on the particle size and dis t r i -but ion of the suspended material For example, the ab i l i ty of sandy soils to store moisture is greatly improved after the soils are i rr igated w i t h muddy water for a period of years M o r e commonly , sediment tends to fill canals and ditches, causing serious cleaning and dredging problems I t also tends to fur ther reduce the already low in f i l t r a t i on charac-teristics o f slowly permeable soils Irrigation Water Quality For Humid Regions Climate T h e most s t r iking feature of the climate of the h u m i d region that contrasts w i t h that of the far West and in te rmounta in areas is the larger amount of and less season-able d is t r ibut ion of the precipi ta t ion Abundan t ra in fa l l , rather than lack of i t , is the normal expectation Yet , droughts are common enough to require that at tention be given to supplemental i r r iga t ion These times of shortage o f water for o p t i m u m plant g rowth can occur at i rregular i n -tervals and at almost any stage of plant g rowth Water demands per week or day are not as h igh i n h u m i d as i n a n d lands But ra infa l l is not easily predicted Thus a crop may be i r r igated and immediately thereafter receive a ra in of one or two inches Supplying the proper amount of supplemental i r r iga t ion water at the r ight t ime is not easy even w i t h adequate equipment and a good water supply There can be periods of several successive years when supplemental i r r iga t ion is not required for most crops i n the h u m i d areas There are times however, when supplemental water can increase yield or avert a crop fa i lure Supplemental i r r iga t ion for high-value crops w i l l undoubt-edly increase i n h u m i d areas in spite of the fact that much capital IS t ied u p i n i r r iga t ion equipment du r ing years i n w h i c h l i t t l e or no use is made of i t T h e range of temperatures i n the h u m i d region i n w h i c h supplemental i r r iga t ion is needed is almost as great as that for a n d and semiarid areas I t ranges f r o m that of the short g rowing season of upstate New Y o r k and M i c h i g a n to the continuous g rowing season of southern Flor ida Bu t in the whole o f this area, the most unpredictable factor i n crop product ion is the need for addi t ional water for o p t i m u m crop product ion Soils T h e soils o f the h u m i d region contrast w i t h those of the West p r i m a r i l y in being lower i n available nutrients They are generally more acid and may have problems w i t h exchangeable a l u m i n u m T h e texture o f soils is similar to that found i n the West and ranges f r o m sands to clays Some are too permeable, whi le others take water very slowly Soils of the h u m i d region generally have clay minerals of lower exchange capacity than soils of the a n d and semiarid regions and hence lower buffer capacity They are more easily saturated w i t h anions and cations Th is is an i m -portant consideration i f i r r iga t ion w i t h brackish water is necessary to supplement na tura l ra in fa l l Organic matter content ranges f r o m pract ical ly none on some of the F lor ida sands to 50 per cent or more i n i r r igated peats One of the most impor tan t characteristics of many of the soils of the h u m i d Southeast is the unfavorable root environ-ment of the deeper horizons conta ining exchangeable a l u m i n u m and having a strong acid reaction I n fact, the lack o f root penetration of these horizons by most f a r m crops IS the p r imary reason for the need for supplemental i r r iga-t ion d u r i n g short droughts Specific Difference Between Humid and Arid Regions T h e effect of a specific water qua l i ty deterrent on plant g rowth is governed by related factors Basic principles involved are almost universally applicable, bu t the u l t imate effect must take in to consideration these as-sociated variables Water qua l i ty cr i ter ia for supplemental i r r iga t ion in h u m i d areas may d i f f e r f r o m those indicated for a n d and semiarid areas where the water requirements of the g rowing plant are met almost entirely by i r r iga t ion W h e n i r r iga t ion water conta ining a deterrent is used, its effect on p lant g rowth may vary, however, w i t h the stage of g rowth at wh ich the water is applied I n a n d areas, plants may be subjected to the influence of i r r iga t ion water qua l i ty continuously f r o m germinat ion to harvest Where water is used for supplemental i r r iga t ion only, the effect on plants depends not only upon the g r o w t h stage at w h i c h applied, but to the length of t ime that the deterrent remains i n the root zone ( L u n i n et al 1963) 3^2 Leaching effects o f inter-vening ra in fa l l must be taken in to consideration Cl imat ic differences between h u m i d and a n d regions also influence cr i ter ia for use of i r r iga t ion water T h e amount o f ra in fa l l determines i n par t the degree to w h i c h a given constituent w i l l accumulate i n the soil Other factors as-sociated w i t h salt accumulat ion i n the soil are those c l imat ic conditions relat ing to evapotranspiration I n h u m i d areas, evapotranspiration is generally less than i n a n d regions, and plants are not as readily subjected to water stress T h e importance o f c l imat ic conditions i n relat ion to salinity was demonstrated by Magis tad et al (1943) I n general, cr i ter ia regarding salinity for supplemental i r r iga t ion i n h u m i d areas can be more flexible than fo r a n d areas Soil characteristics represent another significant difference between a n d and h u m i d regions These were discussed previously Minera logica l composit ion w i l l also vary T h e composi-t ion o f soil water available for absorption by plant roots
ZZ(>/Section VâAgricultural Uses of Water systems except for occasional clogging of gates They can also carry weed seeds onto fields where their subsequent g rowth can have a severely adverse effect on the crop or can have a beneficial effect by reducing seepage losses Where surface water supplies are distr ibuted through pipelines, i t IS often necessary to have self-cleaning screens to prevent clogging of the pipe system appliances Finer screening is usually required where water enters pressure-pipe systems for sprinkler i r r iga t ion There are waters diverted for i r r iga t ion that carry heavy inorganic sediment loads The effects that these loads migh t have depend i n part on the particle size and dis t r i -but ion of the suspended material For example, the ab i l i ty of sandy soils to store moisture is greatly improved after the soils are i rr igated w i t h muddy water for a period of years M o r e commonly, sediment tends to fill canals and ditches, causing serious cleaning and dredging problems I t also tends to fur ther reduce the already low in f i l t r a t i on charac-teristics of slowly permeable soils Irrigation Water Quality For Humid Regions Climate T h e most s t r iking feature of the climate of the h u m i d region that contrasts w i t h that of the far West and in te rmounta in areas is the larger amount of and less season-able d is t r ibut ion of the precipi ta t ion Abundan t ra in fa l l , rather than lack o f i t , is the normal expectation Yet , droughts are common enough to require that at tention be given to supplemental i r r iga t ion These times of shortage of water for o p t i m u m plant g rowth can occur at i rregular i n -tervals and at almost any stage of plant g rowth Water demands per week or day are not as h igh in h u m i d as in a n d lands Bu t ra infa l l is not easily predicted Thus a crop may be i r r igated and immediately thereafter receive a ra in o f one or two inches Supplying the proper amount of supplemental i r r iga t ion water at the r ight t ime is not easy even w i t h adequate equipment and a good water supply There can be periods o f several successive years when supplemental i r r iga t ion is not required for most crops in the h u m i d areas There are times however, when supplemental water can increase yield or avert a crop fa i lure Supplemental i r r iga t ion for high-value crops w i l l undoubt -edly increase in h u m i d areas i n spite of the fact that much capital IS t ied u p i n i r r iga t ion equipment du r ing years i n w h i c h l i t t l e or no use is made of i t T h e range of temperatures i n the h u m i d region in w h i c h supplemental i r r iga t ion is needed is almost as great as that for a n d and semiarid areas I t ranges f r o m that of the short g rowing season of upstate New York and M i c h i g a n to the continuous g rowing season of southern Flor ida But in the whole of this area, the most unpredictable factor i n crop product ion is the need for addi t ional water for o p t i m u m crop product ion Soils T h e soils of the h u m i d region contrast w i t h those of the West p r i m a r i l y i n being lower i n available nutrients They are generally more acid and may have problems w i t h exchangeable a l u m i n u m T h e texture of soils is similar to that found i n the West and ranges f r o m sands to clays Some are too permeable, whi le others take water very slowly Soils of the h u m i d region generally have clay minerals of lower exchange capacity than soils of the a n d and semiarid regions and hence lower buffer capacity T h e y are more easily saturated w i t h anions and cations This is an i m -portant consideration i f i r r iga t ion w i t h brackish water is necessary to supplement na tura l ra in fa l l Organic matter content ranges f r o m pract ical ly none on some of the F lor ida sands to 50 per cent or more in i r r igated peats One o f the most impor tan t characteristics of many of the soils of the h u m i d Southeast is the unfavorable root environ-ment of the deeper horizons conta ining exchangeable a l u m i n u m and having a strong acid reaction I n fact, the lack of root penetration o f these horizons by most f a r m crops IS the p r imary reason for the need for supplemental i r r iga-t ion d u r i n g short droughts Specific Difference Between Humid and Arid Regions T h e effect of a specific water qua l i ty deterrent on plant g rowth is governed by related factors Basic principles involved are almost universally applicable, but the u l t imate effect must take into consideration these as-sociated variables Water qua l i ty cr i ter ia for supplemental i r r iga t ion i n h u m i d areas may d i f f e r f r o m those indicated for a n d and semiarid areas where the water requirements of the g rowing plant are met almost entirely by i r r iga t ion W h e n i r r iga t ion water conta ining a deterrent is used, its effect on p lant g rowth may vary, however, w i t h the stage of g rowth at w h i c h the water is applied I n a n d areas, plants may be subjected to the influence of i r r iga t ion water qua l i ty continuously f r o m germinat ion to harvest Where water is used for supplemental i r r iga t ion only, the effect on plants depends not only upon the g rowth stage at w h i c h applied, but to the length of t ime that the deterrent remains i n the root zone ( L u n i n et al 1963) 'Ì 'Ì Leaching effects o f inter-vening ra in fa l l must be taken in to consideration Cl imat ic differences between h u m i d and a n d regions also influence cr i ter ia for use of i r r iga t ion water T h e amount o f r a in fa l l determines i n par t the degree to wh ich a given constituent w i l l accumulate i n the soil O the r factors as-sociated w i t h salt accumulat ion i n the soil are those cl imat ic conditions relat ing to evapotranspiration I n h u m i d areas, evapotranspiration is generally less than i n a n d regions, and plants are not as readily subjected to water stress T h e importance o f c l imat ic conditions i n relat ion to salinity was demonstrated by Magis tad et al (1943) ' " I n general, cr i ter ia regarding salinity for supplemental i r r iga t ion i n h u m i d areas can be more flexible than for a n d areas Soil characteristics represent another significant difference between a n d and h u m i d regions These were discussed previously Minera logica l composit ion w i l l also vary T h e composi-t ion o f soil water available for absorption by plant roots
Water for Irrigation/337 represents the results of an interact ion between the constitu-ents of the i r r iga t ion water and the soil complex T h e final result may be that a given qua l i ty deterrent present in the water could be rendered harmless by the soil ( remaining readily available), or that the dissolved constituents of a water may render soluble toxic concentrations of an element that was not present in the i r r iga t ion water A n example of this wou ld be the addi t ion of a saline water to an acid soil resulting in a decrease i n p H and a possible increase in solubil i ty of elements such as i ron , a l u m i n u m , and manga-nese (Eriksson 1952) General relationships previously derived for S A R and ad-sorbed sodium in neutral or alkaline soils of a n d areas do not apply equally wel l to acid soils found in h u m i d regions ( L u n i n and Batchelder 1960) '^^ Furthermore, the effect of a given level of adsorbed sodium (ESP) on plant g rowth is determined to some degree by the associated adsorbed cations T h e amount of adsorbed ca lc ium and magnesium relative to adsorbed sodium is of considerable consequence, especially when compar ing acidic soils to ones that are neutral or alkaline Another example w o u l d be the presence of a trace element i n the i r r iga t ion water that migh t be rendered insoluble when applied to a neutral or alkaline soil, but retained i n a soluble, available f o r m in acid soils For these reasons, soil characteristics, w h i c h d i f fe r greatly between a n d and h u m i d areas, must be taken into consideration Certain economic factors also influence water qua l i ty cri teria for supplemental i r r iga t ion A l t h o u g h the u l t imate objective of i r r iga t ion is to insure efficient and economic crop product ion , there may be instances where an adequate supply of good qua l i ty water is unavailable to achieve this A farmer may be faced w i t h the need to use i r r iga t ion water of infer ior qua l i ty to get some economic re turn and prevent a complete crop fai lure This can occur i n h u m i d areas du r ing periods of prolonged drought Water qua l i ty cri teria are generally designed for o p t i m u m product ion, but con-sideration must be given also to supplying guidelines for use of water of inferior qua l i ty to avert a crop fa i lure Specific Quality Criteria for Supplemental Irri-gation A previous discussion (see " W a t e r Q u a l i t y Con-siderations for I r r i g a t i o n " above) of potential qual i ty deter-rents contained a long list of factors indica t ing the current state of our knowledge as to how they migh t relate to plant g rowth Cri ter ia can be established by determining a con-centrat ion of a given deterrent, wh ich , when adsorbed on or absorbed by a leaf du r ing sprinkler i r r igat ion, results in adverse plant g rowth , and by evaluating the direct or i n -direct effects (or both) that a given concentration of a qual -i ty deterrent has on the p lant root environment as i r r iga-t ion water enters the soil Neither evaluation is simple, but the latter is more complex because so many variables are involved Since sprinkler applicat ion in h u m i d areas is most common for supplemental i r r iga t ion , both types of evalua-t ion have considerable significance T h e fo l lowing discus-sion relates only to those qua l i ty cr i ter ia that are specifically applicable to supplemental i r r iga t ion Salinity General concepts regarding soil salinity as pre-viously discussed are applicable Ac tua l levels of salinity that can be tolerated for supplemental i r r iga t ion must take into consideration the leaching effect of ra infa l l and the fact that soils are usually nonsaline at spring p lant ing T h e amount of i r r iga t ion water having a given level of salinity that can be applied to the crop w i l l depend upon the n u m -ber of irrigations between leaching rains, the salt tolerance of the crop, and the salt content of the soil p r ior to i r r iga-t ion Since I t IS not realistic to set a single salinity value or even a range that wou ld take these variables in to consideration, a guide was developed to aid farmers in safely using saline or brackish waters ( L u n i n and Gal la t in 1960) T h e fo l lowing equation was used as a basis for this guide F P - F P I where ECc(f) is the electrical conduct iv i ty of the saturation extract after i r r igat ion is completed, E C e ( i ) , the electrical conduct ivi ty of the soil saturation extract before i r r iga t ion , EC,w, the electrical conduct ivi ty of the i r r iga t ion water, and n , the number of irrigations T o ut i l ize this guide, the salt tolerance of the crop to be grown and the soil salinity level (ECe(f)) that w i l l result in a 15 or 50 per cent yie ld decrement for that crop must be considered Af t e r evaluating the level of soil salinity pr ior to i r r iga t ion (ECc(,)) and the salinity of the i r r iga t ion water, the m a x i m u m number of permissible irrigations can be calculated These numbers are based on the assumption that no intervening ra infa l l occurs m quantities large enough to leach salts f r o m the root zone Should leaching ra infa l l occur, the situation could be reevaluated using a new value for E C e o Categorizing the salt tolerance of crops as highly salt tolerant, moderately salt tolerant, and slightly salt tolerant, the guide shown i n Table V-12 was prepared to indicate TABLE V-12âPermtsstbte Number of Irrigatwns in Humid Areas with Salme Water between Leachmg Rams for Crops of Different Salt Tolerance" Imtation water Numtwr at Imiations lor crops bannf Total salt! m t / l Elettncal conductiinty Low saR tolcrann Moderate salt Hijfi salt tolerante mmhos/cn at 29 C toleraim 640 1 7 15 1,280 2 4 7 11 1,920 3 2 4-5 7 2,S50 4 2 3 5 3,200 5 1 2-3 4 3,840 6 1 2 3 4,480 7 1-2 2-3 S,120 8 1 2 " Based on a SO per cent j ield deaement. LnmnetaL I380u<
Section VâAgricultural Uses of Water the number of permissible irrigations using water of vary ing salt concentrations This guide is based on two assumptions ⢠no leaching ra in fa l l occurs between irrigations ⢠there is no salt accumulat ion i n the soil at the start o f the i r r iga t ion period I f leaching rains occur be-tween irrigations, the effect o f the added salt is min imized I f there is an accumulat ion of salt i n the soil in i t i a l ly , such as m i g h t occur when i r r iga t ing a fa l l crop on land to wh ich saline water had been ap-plied du r ing a spring crop, the soil should be tested for salt content, and the i r r iga t ion recommendations modif ied accordingly Recommendation Since it is not realistic to set a single salinity value or even a range that would take all variables into consideration, Table V-12 developed by Lunin et al. (1960),'Ì should be used as a guide to aid farmers in safely using saline or brackish waters for supplemental irrigation in humid areas. SAR values and exchangeable sodium T h e principles relat ing to S A R values and the degree to w h i c h sodium is adsorbed f r o m water by soils are generally applicable in both a n d and h u m i d regions Some evidence is available ( L u n i n and Batchelder 1960),'^" however, to indicate that, for a given water qual i ty , less sodium was adsorbed by an acid soil than by a base-saturated soil For a given level of exchange-able sodium, pre l iminary evidence indicated more de t r i -mental effects on acid soils than on base-saturated soils ( L u n i n et al 1964) Experimental evidence is not conclusive, so the de t r i -mental l imits for S A R values listed previously should also apply to supplemental i r r iga t ion i n h u m i d regions (See the recommendation i n this section fo l lowing the discussion of sodium hazard under Water Q u a l i t y Considerations for I r -r igat ion ) Acidity and alkalinity T h e only consideration not pre-viously discussed relates to soil acidity, wh ich is more prevalent in h u m i d regions where supplemental i r r iga t ion IS practiced A n y factor that drops the p H below 4 8 may render soluble toxic concentrations of i ron , a l u m i n u m , and manganese This migh t result f r o m applicat ion of a h ighly acidic water or f r o m a saline solution applied to an acidic soil (See the recommendation in this section fo l lowing the discussion of acidity and alkal ini ty under Water Q u a l i t y Considerations for I r r iga t ion ) Trace elements Cr i ter ia and related factors discussed i n the section on Phytotoxic Trace Elements are equally ap-plicable to supplemental i r r iga t ion in h u m i d regions Cer-ta in related qualifications must be kept i n m i n d , however First, fo l iar absorption of trace elements in toxic amounts is direct ly related to sprinkler i r r iga t ion Cr i t i ca l levels estab-lished for soil or cul ture solutions w o u l d not apply to direct fo l ia r i n j u r y Regarding trace element concentrations i n the soil resulting f r o m i r r iga t ion water appl icat ion, the volume of the water applied by sprinkler as supplemental i r r iga t ion IS much less than that applied by f u r r o w or flood i r r iga t ion i n and regions I n assessing trace element concentrations i n i r r iga t ion water, total volume of water applied and the physicochemi-cal characteristics of the soil must be taken in to considera-t ion Both factors could result i n d i f ferent cri teria for supple-mental i r r iga t ion as compared w i t h surface i r r iga t ion in a n d regions Suspended solids Certain factors regarding suspended solids must be taken in to consideration for sprinkler i r r iga t ion T h e first deals w i t h the plugging up of sprinkler nozzles by these sediments Size of sediment is a defini te factor, bu t no specific particle size l i m i t can be established I f some larger sediment particles pass through the sprinkler, they can often be washed o f f certain leafy vegetable crops Some of the finer fractions, suspended col loidal material , could accumulate on the leaves and, once dry , become extremely d i f f i cu l t to wash off , thereby i m p a i r i n g the qua l i ty of the product PHYTOTOXIC TRACE ELEMENTS I n addi t ion to the effect of total salinity on plant g rowth , ind iv idua l ions may cause growth reductions Ions of both major and trace elements occur in i r r iga t ion water Trace elements are those that normal ly occur i n waters or soil solutions i n concentrations less than a few mg/1 w i t h usual concentrations less than 100 microgram { f i g ) / \ Some may be essential for plant g rowth , whi le others are nonessential W h e n an element is added to the soil, i t may combine w i t h i t to decrease its concentration and increase the store of that element i n the soil I f the process of adding i r r iga t ion water containing a toxic level of the element continues, the capacity of the soil to react w i t h the element w i l l be saturated A steady state may be approached i n wh ich the amount of the element leaving the soil i n the drainage water equals the amount added w i t h the i r r iga t ion water, w i t h no fu r the r change i n concentration in the soil Removal i n harvested crops can also be a factor i n decreasing the ac-cumula t ion of trace elements i n soils I n many cases, soils have high capacities to react w i t h trace elements Therefore, i r r iga t ion water containing toxic levels of trace elements may be added for many years before a steady state is approached Thus, a situation exists where toxicities may develop in years, decades, or even centuries f r o m the continued addi t ion of pollutants to i r r iga t ion waters T h e t ime wou ld depend on soil and plant factors as wel l as on the concentration of trace elements in the water V a r i a b i l i t y among species is wel l recognized Recent i n -vestigations by Foy et al (1965),^'^ and Kerr idge et al (1971)"^ work ing w i t h soluble a l u m i n u m i n soils and i n nut r ient solutions, have demonstrated that there is also var iab i l i ty among varieties w i t h i n a given species
Water for Irrtgatton/Z39 Comprehensive reviews of l i terature dealing w i t h trace element effects on plants are provided by M c K e e and W o l f ( 1 9 6 3 ) , " ' Holland and Butler ( 1 9 6 6 ) , ' " and Chapman (1966) 3 " Hodgson ( 1 9 6 3 ) " ' presented a review dealing w i t h reactions of trace elements i n soils I n developing a workable program to determine accept-able l imits f o r trace elements i n i r r iga t ion waters, three considerations should be recognized ⢠M a n y factors affect the uptake of and tolerance to trace elements T h e most impor tan t of these are the na tu ra l va r i ab i l i t y i n tolerances o f plants and o f animals that consume plants, i n reactions w i t h i n the soil, and i n nu t r ien t interactions, par t icu lar ly i n the p lant ⢠A system of tolerance l imi ts should provide sufficient f l e x i b i l i t y to cope w i t h the more serious factors listed above ⢠A t the same t ime, restrictions must be defined as precisely as possible using presently available, but l i m i t e d , research in fo rmat ion Both the concentrat ion of the element in the soil solution, assuming that steady state may be approached, and the total amount o f the element added i n relat ion to quantities tha t have been shown to produce toxicities were used i n ar-r i v i n g at recommended m a x i m u m concentrations A water appl icat ion rate of 3 acre feet/acre/year was used to calcu-late the yearly rate of trace elements added i n i r r iga t ion water T h e suggested m a x i m u m trace element concentrations for i r r iga t ion waters are shown i n Tab le V-13 T h e suggested m a x i m u m concentrations for continuous use on a l l soils are set for those sandy soils that have low capacities to react w i t h the element i n question They are generally set at levels less than the concentrations tha t pro-duce toxicities when the most sensitive plants are g rown i n nu t r ien t solutions or sand cultures This level is set, recog-n iz ing that concentration increases i n the soil as water is evapotranspired, and that the effective concentration i n the soil solution, at near steady state, is higher than i n the i r r iga-t ion water T h e cri teria for short-term use are suggested for soils that have h igh capacitites to remove f r o m solution the element or elements being considered T h e work o f Hodgson (1963)^" showed that the general tolerance of the soil-plant system to manganese, cobalt, zmc, copper, and boron increased as the p H increased, p r i m a r i l y because of the positive correlat ion between the capacity o f the soil to inactivate these ions and the p H This same relationship exists w i t h a l u m i n u m and probably exists w i t h other elements such as nickel (Prat t et al 1964)*^' and boron (Sims and Bingham 1968) However, the ab i l -i t y o f the soil to inactivate molybdenum decreases w i t h i n -crease i n p H , such that the amount of this element that could be added wi thou t producing excesses was higher i n acid soils TABLE V-13âRecommended Maximum Concentrations of Trace Elements in Irrigation Waters' Etement For waten used continnouilr For use up to 20 rears on One on an HDl teituredsnlsofpHO OtoS 5 m i / l m i / l AlDininum 5 0 200 Amnic 0 10 2 0 Benrinuin 0 10 0 SO Boron 0 75 2 0 Cadmium 0 010 0 050 Chromium 0 10 1 0 Cobalt 0 050 5 0 Coppsr 0 20 5 0 Flaorido 1 0 15 0 Iron 5 0 200 lead 5 0 10 0 UUiium 2 5* 2 5* Mansanoss 0 20 10 0 Molfbdonum 0 010 0 050^ Nickel 0 20 2 0 Selenium 0 020 0 020 Tln= Titanium' Tunisten< Vanadium 0 10 1 0 Zinc 2 0 10 0 ' These M s will normaDj not adiersel; allect plants or soils. » Recommended maumum concentration lor i m i a b o i atrus is 0.075 m f A ' See test lor a discussion of these elements. <> For only sad One teitured soils or and soils with retativelj hi|b iron onde contents. I n addi t ion to p H control ( i e , l i m i n g acid soils), another impor tan t management factor that has a large effect on the capacity of soils to adsorb some trace elements w i t h o u t de-velopment of plant toxicities is the available phosphorus level Large applications o f phosphate are k n o w n to induce deficiencies of such elements as copper and zinc and greatly reduce a l u m i n u m toxic i ty (Chapman 1966) T h e concentrations given i n Table V-13 are for ionic and soluble forms of the elements I f insoluble forms are present as part iculate matter, these should be removed by filtration before the water is analyzed Aluminum T h e toxic i ty of this ion is considered to be one of the m a i n causes o f nonproduc t iv i ty i n acid soils (Coleman and Thomas 1 9 6 7 , R e e v e and Sumner 1970,^" H o y t and N y b o r g 1 9 7 1 a « ' ) A t p H values f r o m about 5 5 to 8 0, soils have great capacities to precipitate soluble a l u m i n u m and to el iminate Its tox ic i ty Mos t i r r igated soils are na tura l ly alkaline, and many are h ighly buffered w i t h ca lc ium carbonate I n these situations a l u m i n u m toxici ty is effectively prevented W i t h only a few exceptions, as soils become more acid ( p H < 5 5) , exchangeable and soluble a l u m i n u m develop by dissolution o f oxides and hydroxides or by decomposition of clay minerals Thus , w i thou t the in t roduct ion of a l u m i -n u m , a toxic i ty o f this element usually develops as soils are acidif ied, and limestone must be added to keep the soil productive
3W/Section VâAgricultural Uses of Water I n nu t r ien t solutions toxicities are reported f o r a number of plants at a l u m i n u m concentrations o f 1 mg/1 (Pratt 1966)/^* whereas wheat is reported to show g rowth reduc-tions at 0 1 mg/1 (Barnette 1923) L ieb ig et al {\942y^ found g rowth depressions o f orange seedlings at 0 1 mg/1 L igon and Pierre (1932)^" showed growth reductions o f 60, 22, and 13 per cent for barley, corn, and sorghum, re-spectively, at 1 m g / I I n spite of the potential toxic i ty of a l u m i n u m , this is not the basis fo r the establishment o f m a x i m u m concentrations i n i r r iga t ion waters, because ground limestone can be added where needed to control a l u m i n u m solubi l i ty m soils Nevertheless, two disadvantages remain One is that the salts that are the sources of soluble a l u m i n u m in waters ac id i fy the soil and contr ibute to the requirement for ground limestone to prevent the accumulat ion or develop-ment of soluble a l u m i n u m This is a disadvantage only i n acid soils T h e other disadvantage is a greater fixation o f phosphate fert i l izer by freshly precipitated a l u m i n u m hydroxides I n de termining a recommendation for m a x i m u m levels of a l u m i n u m in i r r iga t ion water using 5 0 mg/1 for waters to be used continuously on al l soils and 20 mg/1 for up to 20 years on fine-textured soils, the fo l lowing was considered A t rates of 3 acre feet of water per acre per year the ca lc ium carbonate equivalent of the 5 mg/1 concentration used fo r 100 years wou ld be 11 5 tons per acre, the 20 mg/1 concen-t ra t ion fo r 20 years wou ld be equivalent to 9 tons o f CaCOs per acre I n most i rr igated soils this amount of limestone w o u l d not have to be added, because the soils have sufficient buf fer capacity to neutralize the a l u m i n u m salts I n acid soils that are already near the p H where limestone should be used, the a l u m i n u m added i n the water w o u l d contr ibute these quantities to the l ime requirements Amounts of limestone needed fo r control o f soluble a l u m i -n u m i n acid soils can be estimated by a method that is based on p H control (Shoemaker et al 1961) A method based on the amount of soluble and exchangeable a l u m i n u m was developed by K a m p r a t h (1970) «^ Recommendations Recommended maximum concentrations are 5.0 mg/1 aluminum for continuous use on all soils and 20 mg/1 for use on fine textured neutral to alkaline soils over a period of 20 years. Arsenic A l b e r t and A r n d t ( 1 9 3 1 ) ' " f o u n d that arsenic at 0 5 m g / 1 i n nutr ient solutions reduced the g rowth of roots of cowpeas, and at 1 0 mg/1 i t reduced the g rowth of both roots and tops They reported that 1 0 mg/1 of soluble arsenic was fre-quently found i n the solution obtained f r o m soils w i t h demonstrated toxic levels o f arsenic Rasmussen and H e n r y (1965) ' '" found that arsenic at 0 5 mg/1 i n nut r ien t solu-tions produced toxic i ty symptoms i n seedlings o f the pine-apple and orange Below this concentrat ion no symptoms of tox ic i ty were found Clements and Heggeness (1939)^*" re-ported that 0 5 mg/1 arsenic as arsenite i n nut r ient solu-tions produced an 80 per cent y ie ld reduct ion i n tomatoes L ieb ig et al ( 1 9 5 9 ) « ' f ound that 10 mg /1 of arsenic as arsenate or 5 mg /1 as arsenite caused marked reduct ion in g rowth of tops and roots of citrus g rown in nut r ien t solu-tions Machl is (1941)'"^ found that concentrations o f 1 2 and 12 mg/1 caused g rowth suppression i n beans and sudan grass respectively However, the most def ini te work w i t h arsenic tox ic i ty i n soils has been aimed at de te rmining the amounts that can be added to various types o f soils w i t h o u t reduct ion i n yields of sensitive crops T h e experiments o f Cooper et al ( 1 9 3 2 ) , " ' Vandecaveye et al (1936), Crafts and Rosenfels ( 1 9 3 9 ) , ' " D o r m a n and Co lman (1939),396 D o r m a n et al ( 1 9 3 9 ) , ' " Clements and Munson (1947),'9' Benson (1953),"^ Chis-h o l m et al (1955) , '«8 Jacobs et al (1970) ,^» Woolson et al (1971)^*' showed that the amount o f total arsenic that pro-duced the i n i t i a t i on of tox ic i ty varied w i t h soil texture and other factors that inf luenced the adsorptive capacity As-suming that the added arsenic is mixed w i t h the surface six inches of soil and tha t i t is i n the arsenate f o r m , the amounts that produce tox ic i ty for sensitive plants vary f r o m 100 pounds ( lb ) /acre fo r sandy soils to 300 lb /acre for clayey soils Data f r o m Crafts and Rosenfels (1939)"^ fo r 80 soils showed that for a 50 per cent y ie ld reduct ion w i t h barley, 120, 190, 230, and 290 l b arsenic/acre were required f o r sandy loams, loams, clay loams, and clays, respectively These amounts of arsenic indicated the amounts adsorbed in to soils of d i f fe ren t adsorptive capacities before the toxic i ty level was reached W i t h long periods of t ime involved, such as w o u l d be the case w i t h accumulations f r o m i r r iga t ion water, possible leaching in sandy soils (Jacobs et al 1970)^^ and reversion to less soluble and less toxic forms of arsenic (Crafts and Rosenfels 1939) ' ' ' ' a l low extensions o f the amounts required for toxic i ty Perhaps a factor of at least two could be used, g iv in g a l i m i t o f 200 l b m sandy soils and a l i m i t o f 600 l b i n clayey soils over many years Us ing these l imi ts , a con-centrat ion o f 0 1 m g / 1 could be used for 100 years on sandy soils, and a concentrat ion of 2 mg /1 used for a period of 20 years or 0 5 m g / 1 used f o r 100 years on clayey soils w o u l d provide an adequate m a r g i n of safety Th i s is assuming 3 acre feet of water are used per acre per year (1 mg /1 equals 2 71 lb /acre foot o f water or 8 13 l b / 3 acre feet), and that the added arsenic becomes mixed i n a 6-inch layer o f soil Removal of small amounts m harvested crops provides an addi t iona l safety factor T h e only effective management practice k n o w n for soils that have accumulated toxic levels o f arsenic is to change to more tolerant crops Benson and Reisenauer ( 1 9 5 1 ) ' " developed a list o f plants o f three levels of tolerance W o r k by Reed and Sturgis (1936)^*2 suggested tha t rice on flooded soils was extremely sensitive to small amounts of arsenic, and
that the suggested m a x i m u m concentrations listed below were too h igh for this crop Recommendations Recommendations are that maximum concen-trations of arsenic in irrigation water be 0.10 mg/1 for continuous use on all soils and 2 mg/1 for use up to 20 years on fine textured neutral to alkaline soils. Beryllium Haas (1932)'"" reported that some varieties of citrus seed-lings showed toxicities at 2 5 mg/1 of bery l l ium whereas others showed toxic i ty at 5 mg/1 in nutr ient solutions Romney et al (1962)^" found that be ry l l ium at 0 5 mg/1 i n nutr ient solutions reduced the growth of bush beans Romney and Childress (1965)"=^ found that 2 mg/1 or greater i n nut r ient solutions reduced the g rowth of toma-toes, peas, soybeans, lettuce, and alfalfa plants Addi t ions of soluble be ry l l ium salts at levels equivalent to 4 per cent o f the cation-adsorption capacity of two acid soils reduced the yields of ladino clover Bery l l i um carbonate and be ry l l ium oxide at the same levels d id not reduce yields These results suggest that be ry l l i um in calcareous soils migh t be much less active and less toxic than in acid soils Wi l l i ams and LeRiche (igeS)"'" found that be ry l l i um at 2 mg/1 m nutr ient solu-tions was toxic to mustard, whereas 5 mg/1 was required for g rowth reductions w i t h kale I t seems reasonable to recommend low levels of beryl-l i u m in view o f the fact that , at 0 1 m g / 1 , 80 pounds o f be ry l l i um w o u l d be added in 100 years using 3 acre feet of water per acre per year I n 20 years, at 0 5 m g / 1 , water at the same rate wou ld add 80 pounds Recommendations In view of toxicities in nutrient solutions and in soils, it is recommended that maximum concen-trations of beryllium in irrigation waters be 0.10 mg/1 for continuous use on all soils and 0.50 mg/1 for use on neutral to alkaline fine textured soils for a 20-year period. Boron Boron is an essential element fo r the g rowth o f plants O p t i m u m yields of some plants are obtained at concentra-tions o f a few tenths m g / l i n nut r ien t solutions However, at concentrations of 1 mg/1 , boron is toxic to a number of sensitive plants Eaton {\935,">« 1944^'") determined the boron tolerance of a large number of plants and developed lists o f sensitive, semitolerant, and tolerant species These lists, slightly modi f ied , arc also given in the U S D A Handbook 60 (Sal ini ty Labora tory 1954)^^9 g^e pre-sented i n Tab le V - I 4 I n general, sensitive crops showed toxicities at 1 mg/1 or less, semitolerant crops at 1 to 2 m g / 1 , and tolerant crops at 2 to 4 mg/1 A t concentrations above Water for Irrigation/34:1 TABLE V-t4âRelative Tolerance of Plants to Boron (In each roup tlisplantinntnameilaroconaieredailiEinj mors tolerant and tlie last named more sensitive) Tolerant Semitolerant Sensihve Athel (Tamani asptiylla) Sunflower (native) Pecan Asparapis Potato Black Walnut Palm (Phoenli cananensis) Acala cotton Persian (EngTish) walnut Date palm (P dactjSlera) Pima cotton Jerusalem artichoke Sugar lieet Tomato Navy bean Mangel Sweetpea American elm Garden beet Radish Plum AHalla Field pea Pear Gladiolus Ragnd Robin rose Apple Broadbean Olive Grape (Sultanlna and Malaga) Onion Barley Kadota flg Turnip Wheat Persimmon Cabtiage Corn Cherry lettuce Milo Peach Canot Oat Apricot Zinma Thomless blackberry Pumpkin Orange Bell pepper Avocado Sweet potato Grapefruit l ima bean lemon Salinity Uboratory Staff 19M«> 4 mg/1 , the i r r iga t ion water was generally unsatisfactory fo r most crops Bradford (1966) , " ' i n a review of boron deficiencies and toxicities, stated that when the boron content of i r r iga t ion waters was greater than 0 75 mg/1 , some sensitive plants, such as citrus, begin to show i n j u r y Chapman ( 1 9 6 8 ) ' " concluded that citrus showed some m i l d toxic i ty symptoms when i r r iga t ion waters have 0 5 to 1 0 mg /1 , and that when the concentration was greater than 10 mg/1 pronounced toxicities were found Biggar and Fireman ( I 9 6 0 ) ' ' * and Hatcher and Bower (1958)^" showed that the accumulat ion o f boron i n soils is an adsorption process, and that before soluble levels of 1 or 2 mg /1 can be f o u n d , the adsorptive capacity must be saturated W i t h neutral and alkaline soils of h igh adsorption capacities water of 2 mg /1 m i g h t be used for some t ime wi thou t i n j u r y to sensitive plants Recommendations From the extensive work on citrus, one of the most sensitive crops, the maximum concentration of 0.75 mg boron/1 for use on sensitive crops on all soils seems justified. Recommended maximum concentrations for semitolerant and tolerant plants are considered to be 1 and 2 mg/1 respec-tively. For neutral and alkaline fine textured soils the recommended maximum concentration of boron in irrigation water used for a 20-year period on sensitive crops is 2.0 mg/1. With tolerant plants or for shorter periods of time higher boron concen-trations are acceptable.
ZA2/Seciton VâAgricultural Uses of Water Cadmium Data by Page et al in press (1972)"^ showed that the yields of beans, beets, and turnips were reduced about 25 per cent by 0 10 m g cadmium/1 i n nutr ient solutions, whereas cabbage and barley gave yield decreases o f 20 to 50 per cent at 1 0 mg/1 Corn and lettuce were intermediate i n response w i t h less than 25 per cent yield reductions at 0 10 mg/1 and greater than 50 per cent at 1 0 mg/1 Cad-m i u m contents of plants g rown in soils containing 0 11 to 0 56 mg/1 acid extractable c a d m i u m (Lagerwerf f 1971)" ' were o f the same order of magnitude as the plants g rown by Page et al i n control nutr ient solutions Because of the phytotoxici ty of c admium to plants, its accumulat ion in plants, lack of soils in format ion , and the potential problems w i t h this element i n foods and feeds, a conservative approach is taken Recommendations Maximum concentrations for cadmium in irriga-tion waters of 0.010 mg/1 for continuous use on all soils and 0.050 mg/1 on neutral and alkaline fine textured soils for a 20-year period are recom-mended. Chromium Even though a number o f investigators have found small increases i n yields w i t h small additions of this element, i t has not become recognized as an essential element T h e p r imary concern of soil and plant scientists is w i t h its toxic-i t y Soane and Saunders (1959)^«« found that 10 mg/1 of c h r o m i u m i n sand cultures was toxic to corn, and that for tobacco 5 mg/1 of c h r o m i u m caused reduced g rowth and 1 0 mg/1 reduced stem elongation Scharrer and Schropp (1935)'"' found that chromium, as chromic sulfate, was toxic to corn at 5 mg/1 in nutr ient solutions H e w i t t (1953)'"^ found that 8 mg/1 c h r o m i u m as chromic or chromate ions produced i ron chlorosis on sugar beets grown i n sand cultures H e w i t t also found that the chromate ion was more toxic than the chromic ion Hun te r and Vergnano (1953)^' ' f ound that 5 mg/1 of ch romium in nut r ient solu-tions produced i r o n deficiencies i n plants T u r n e r and Rust (1971)''⢠found that c h r o m i u m treatments as low as 0 5 mg/1 i n water cultures and 10 m g / k g in soil cultures significantly reduced the yields of two varieties of soybeans Because l i t t l e is known about the accumulat ion of c h r o m i u m i n soils i n relat ion to its toxic i ty , a concentration of less than 1 0 mg/1 in i r r iga t ion waters is desirable A t this concentration, using 3 acre feet water /acre /yr , more than 80 l b of c h r o m i u m w o u l d be added per acre i n 100 years, and using a concentration of 1 0 mg/1 for a period of 20 years and applying water at the same rate, about 160 pounds of c h r o m i u m would be added to the soil Recommendations In view of the lack of knowledge concerning chromium accumulation and toxicity, a maximum concentration of 0.1 mg/1 is recommended for con-tinuous use on all soils and 1.0 mg/1 on neutral and alkaline fine textured soils for a 20-year period is recommended. Cobalt Ahmed and T w y m a n (1953)'^* found that tomato plants showed toxici ty f r o m cobalt at 0 1 mg /1 , and Vergnano and Hunte r (1953) found that cobalt at 5 mg/1 was h ighly toxic to oats Scharrer ancl Schropp (1933)' '^ found that cobalt at a few mg/1 in sand and solution cultures was toxic to peas, beans, oats, rye, wheat, barley, and corn, and that the tolerance to cobalt increased i n the order listed Vanse-low (1966a ) " ' found additions of 100 m g / k g to soils were not toxic to citrus T h e l i terature indicates that a concentration of 0 10 mg /1 for cobalt is near the threshold toxic i ty level i n nut r ient solutions Thus, a concentration of 0 05 mg/1 appears to be satisfactory for continuous use on a l l soils However, because the reaction o f this element w i t h soils is strong at neutral and alkaline p H values and i t increases w i t h t ime (Hodgson 1960),^'^ a concentrat ion of 5 0 mg/1 m i g h t be tolerated by fine textured neutra l and alkaline soils when i t is added i n small yearly increments Recommendations Recommended maximum concentrations for co-balt are set at 0.050 mg/1 for continuous use on all soils and 5.0 mg/1 for neutral and alkaline fine textured soils for a 20-year period. Copper Copper concentrations of 0 1 to 1 0 mg/1 in nut r ient solutions have been found to be toxic to a large number of plants (Piper 1939 ," ' L ieb ig et al 1942 ,«2 Frol ich et al 1966,^0' Nollendorfs 1969,"^ Struckmeyer et al 1969,«» SeiUac 1 9 7 1 « 2 ) Westgate ( 1 9 5 2 ) " « found copper toxici ty in soils that had accumulated 800 lb /acre f r o m the use of Bordeaux sprays Field studies i n sandy soils o f Flor ida (Reuther and Smi th 1954)^" showed that toxic i ty to citrus resulted when copper levels reached 1 6 m g / m e q of cation-exchange capacity per 100 g o f d ry soil T h e management procedures that reduce copper toxic i ty include l i m i n g the soil i f i t is acid, using ample phosphate ferti l izer, and adding i ron salts (Reuther and Labanauskas 1966) Tox i c i t y levels in nut r ient solutions and l imi ted data on soils suggest a concentration of 0 20 mg/1 for continuous use on a l l soils This level used at a rate of 3 acre feet o f water per year w o u l d add about 160 pounds of copper i n 100 years, wh ich is approaching the recorded levels of
Water for Irrigation/3A3 tox ic i ty i n acid sandy soils A safety marg in can be obtained by l i m i n g these soils A concentration o f copper at 5 0 mg /1 applied i n i r r iga t ion water at the rate of 3 acre feet of water per year for a 20-year period w o u l d add 800 pounds of copper i n 20 years Recommendations Based on toxicity levels in nutrient solutions and the limited soils data available, a maximum con-centration of 0.20 mg/1 copper is recommended for continuous use on all soils. On neutral and alkaline fine textured soils for use over a 20-year period, a maximum concentration of 5.0 mg/1 is recom-mended. Fluoride Applicat ions of soluble fluoride salts to acid soils can produce toxic i ty to plants Prince et al (1949)^^° found that 360 pounds fluoride per acre, added as sodium fluoride, reduced the yields of buckwheat at p H 4 5, but at p H values above 5 5 this rate produced no i n j u r y M a c l n t i r e et al (1942)"'= found that 1,150 pounds of fluoride i n superphosphate, 575 pounds of fluoride i n slag, or 2,300 pounds of fluoride as calc ium fluoride per acre had no detr imental effects on germinat ion or plant g rowth on wel l - l imed neutral soils, and that vegetation grown on these soils showed only a slight increase i n fluoride as compared to those g rown in acid soils However, Shirley et al (1970)"°' ' found that bones of cows that had grazed pastures fert i l ized w i t h raw rock and col loidal phosphate, w h i c h contained ap-proximately two to three per cent fluorides, for seven to 16 years averaged approximately 2,900 and 2,300 m g of fluorine per k i logram of bone, respectively T h e bones of cows that had grazed on pastures fert i l ized w i t h relatively fluorine free superphosphate, concentrated superphosphate, and basic slag fert i l izer contained only 1400 m g / k g fluorine Recommendations Because of the capacity of neutral and alkaline soils to inactivate fluoride, a relatively high maxi-mum concentration for continuous use on these soils is recommended. Recommended maximum concentrations are 1.0 mg/1 for continuous use on all soils and 15 mg/1 for use for a 20-year period on neutral and alkaline fine textured soils. Iron I r o n m i r r iga t ion waters is not l ikely to create a p roblem of p lan t toxicities I t is so insoluble i n aerated soils at a l l p H values i n w h i c h plants grow wel l , that i t is not toxic I n fact, the problems w i t h this element are deficiencies in alkaline soils I n reduced (flooded) soils soluble ferrous ions develop f r o m inherent compounds i n soils, so that quantities that m i g h t be added i n waters wou ld be o f no concern However, Rhoads (1971)"*' found large reductions in the qua l i ty of cigar wrapper tobacco when plants were sprinkler i r r igated w i t h water conta ining 5 or more m g soluble i r o n / 1 , because of precipi tat ion of i ron oxides on the leaves Rhoad's ex-perience w o u l d suggest caut ion when i r r iga t ing any crops using sprinkler systems and waters hav ing sufficient reducing conditions to produce reduced and soluble ferrous i ron T h e disadvantages of soluble i ron salts i n waters are that these w o u l d contr ibute to soil acidif icat ion, and the precipi-tated i ron w o u l d increase the fixation of such essential ele-ments as phosphorous and molybdenum Recommendations A maximum concentration of 5.0 mg/1 is recom-mended for continuous use on all soils, and a maximum concentration of 20 mg/1 is recom-mended on neutral to alkaline soils for a 20-year period. The use of waters with large concentrations of suspended freshly precipitated iron oxides and hydroxides is not recommended, because these materials also increase the fixation of phosphorous and molybdenum. Lead T h e phytotoxici ty of lead is relatively low Berry (1924) ' ' " found that a concentration of lead ni t rate o f 25 mg/1 was required for toxic i ty to oats and tomato plants A t a concen-t ra t ion of 50 mg /1 , death of plants occurred Hopper (1937)"!* found that 30 mg/1 o f lead m nut r ien t solutions was toxic to bean plants Wi lk ins (1957)"^' found that lead at 10 mg/1 as lead nitrate reduced root g rowth Since soluble lead contents i n soils were usually f r o m 0 05 to 5 0 m g / k g (Brewer 1966), '*' l i t t l e toxic i ty can be expected I t was shown that the pr inc ipa l entry of lead in to plants was f r o m aerial deposits rather than f r o m absorption f r o m soils (Page et al 1971)""* indica t ing that lead that falls onto the soil is not available to plants I n a summary on the effects of lead on plants, the C o m -mittee on the Biological Effects of Atmosphere Pollutants ( N R C 1972)""' concluded that there is not sufficient evidence to indicate that lead, as i t occurs i n nature, is toxic to vege-tat ion However, i n studies using roots o f some plants and very h igh concentrations of lead, this element was reported to be concentrated i n cell walls and nuclei du r ing mitosis and to inh ib i t cell prol i fera t ion Recommendations Recommended maximum concentrations of lead are 5.0 mg/1 for continuous use on all soils and 10 mg/1 for a 20-year period on neutral and alkaline fine textured soils. Lithium Most crops can tolerate l i t h i u m i n nut r ient solutions at concentrations u p to 5 mg /1 ( O e r t l i 1962,""' B ingham et a l 1964 , ' " Bol la rd and Butler 1966 '") But research revealed
ZA^/Section VâAgricultural Uses of Water that citrus was more sensitive ( A l d r i c h et al 1951, '^ ' Brad-fo rd 1963b, ' " H i lgeman et al 1970"*) Hi lgeman et al (1970)^'* found that grapefrui t developed severe symptoms of l i t h i u m toxic i ty when irr igated w i t h waters containing l i t h i u m at 0 18 to 0 25 mg/1 Bradford (1963a)'*' reported that experience i n Cal i fornia indicated slight toxic i ty of l i t h i u m to citrus at 0 06 to 0 10 mg/1 in the water L i t h i u m IS one o f the most mobile of cations in soils I t tends to be replaced by other cations i n waters or fertilizers and IS removed by leaching O n the other hand, i t is not precipitated by any k n o w n process Recommendations Recommendations for maximum concentrations of lithium, based on its phytotoxicity, are 2.5 mg/1 for continuous use on all soils, except for citrus where the recommended maximum concentration is 0.075 mg/1 for all soils. For short-term use on fine textured soils the same maximum concentra-tions are recommended because of lack of inactiva-tion in soils. Manganese Manganese concentrations at a few tenths to a few m i l l i -grams per l i ter i n nut r ient solutions are toxic to a number of crops as shown by M o r r i s and Pierre (1949),''^'' Adams and Wear ( 1 9 5 7 ) , ' " H e w i t t (1965),'"* and others However, toxicities o f this element are associated w i t h acid soils, and applications o f proper quantities o f ground limestone suc-cessfully el iminated the problem Increasing the p H to the 5 5 to 6 0 range usually reduced the active manganese to below the toxic level (Adams and Wear 1957) '^^ H o y t and N y b o r g (1971b)" ' ' f ound that available manganese i n the soil and manganese content o f plants were negatively cor-related w i t h soil p H However, the defini te association of toxic i ty w i t h soil p H as found w i t h a l u m i n u m was not found w i t h manganese, wh ich has a more complex chemistry Thus, more care must be taken in setting water qua l i ty c r i -teria for manganese than for a l u m i n u m ( i e , management for control of toxicities is not certain) Recommendations Recommended maximum concentrations for manganese in irrigation waters are set at 0.20 mg/1 for continued use on all soils and 10 mg/1 for use up to 20 years on neutral and alkaline fine textured soils. Concentrations for continued use can be in-creased with alkaline or calcareous soils, and also with crops that have higher tolerance levels. Molybdenum This element presents no problems of toxici ty to plants at concentrations usually found i n soils and waters T h e prob-lem IS one of toxic i ty to animals f r o m molybdenum i n -gested f r o m forage that has been grown m soils w i t h rela-t ively h igh amounts of avaiable mo lybdenum Dye and O ' H a r a ( 1 9 5 9 ) ' " reported that the mo lybdenum concentra-t ion i n forage that produced toxic i ty in ruminants was 5 to 30 m g / k g Lesperance and Bohman (1963)^'" found that toxic i ty was not s imply associated w i t h the molybdenum content of forage but was influenced by the amounts of other elements, par t icular ly copper Jensen and Lesperance ( 1 9 7 1 ) " ' found that the accumulat ion of mo lybdenum in plants was propor t ional to the amount o f the element added to the soil K u b o t a et al (1963)"^ found that molybdenum concen-trations of 0 01 mg/1 or greater i n soil solutions were as-sociated w i t h an imal toxic i ty levels of this element in alsike clover B ingham e t a l ( 1 9 7 0 ) ' " reported that molybdosis of cattle was associated w i t h soils that had 0 01 to 0 10 mg /1 of molybdenum in saturation extracts of soils Recommendations The recommended maximum concentration of molybdenum for continued use of water on all soils, based on animal toxicities from forage, is 0.010 mg/1. For short term use on soils that react with this element, a concentration of 0.050 mg/1 is recommended. Nickel Accord ing to Vanselow (1966b)," ' ' many experiments w i t h sand and solution cultures have shown that nickel at 0 5 to 1 0 mg/1 IS toxic to a number of plants Chang and Sherman (1953)'** found that tomato seedlings were i n -j u r e d by 0 5 mg/1 M i l l i k a n ( 1 9 4 9 ) « ' found that 0 5 to 5 0 mg/1 were toxic to flax Brenchley (1938)"^ reported toxic-i ty to barley and beans f r o m 2 mg/1 Crooke (1954)'^* found that 2 5 mg/1 was toxic to oats Legg and Ormerod (1958)''^' found that 1 0 mg/1 produced toxic i ty in hop plants Vergnano and H u n t e r (1953)'"* found that 1 0 mg/1 in solutions flushed through sand cultures was toxic to oats Soane and Saunders (1959)''*' f ound that tobacco plants showed no toxic i ty at 30 m g / 1 , and that corn showed no toxic i ty at 2 m g / 1 but showed toxic i ty at 10 mg /1 W o r k by M i z u n o ( 1 9 6 8 ) " ' and Halstead et al (1969)^<« and the review of Vanselow (1966b)"^ showed that increas-ing the p H of soils reduces the toxic i ty of added nickel Halstead et al ( 1 9 6 9 ) f o u n d the greatest capacity to ad-sorb nickel w i t h o u t development of toxic i ty was by a soil w i t h 21 per cent organic mat ter Recommendations Based on both toxicity in nutrient solutions and on quantities that produce toxicities in soils, the recommended maximum concentration of nickel in irrigation waters is 0.20 mg/1 for continued use on all soils. For neutral fine textured soils for a period up to 20 years, the recommended maximum is 2.0 mg/1.
Water for Irngatton/Z^b Selenium Selenium is toxic at low concentrations i n nut r ient solu-tions, and only small amounts added to soils increase the selenium content of forages to a level toxic to livestock Broyer et al (1966)' '^ found that selenium at 0 025 mg/1 in nutr ient solutions decreased the yields of alfalfa T h e best evidence for use i n setting water qual i ty cr i ter ia for this element is appl icat ion rates i n relation to toxici ty in forages Amounts of selenium i n forages required to prevent selenium deficiencies i n cattle (AUaway et al 1967)'^^ ranged between 0 03 and 0 10 m g / k g (depending on other factors), whereas concentrations above 3 or 4 m g / k g were considered toxic (Underwood 1966) A number of investi-gators ( H a m i l t o n and Beath 1963,""' Grant 1965,'"" AUaway et al 1 9 6 6 ) h a v e shown that small applications of selenium to soils at a rate of a few kilograms per hectare produced plant concentrations of selenium that were toxic to animals Gissel-Nielson and Bisbjerg (1970)'""' found that applica-tions of approximately 0 2 kg/hectare of selenium produced f r o m 1 0 to 10 5 m g / k g in tissues of forage and vegetable crops Recommendation With the low levels of selenium required to pro-duce toxic levels in forages, the recommended maximum concentration in irrigation waters is 0.02 mg/1 for continuous use on all soils. At a rate of 3 acre feet of water per acre per year this concen-tration represents 3.2 pounds per acre in 20 years. The same recommended maximum concentration should be used on neutral and alkaline fine textured soils until greater information is obtained on soil reactions. The relative mobility of this element in soils in comparison to other trace elements and slow removal in harvested crops provide a sufficient safety margin. Tin, Tungsten, and Titanium T i n , tungsten, and t i t a n t i u m are effectively excluded by plants T h e first two can undoubtedly be introduced to plants under conditions that can produce specific toxicities However, not enough is known at this t ime about any of the three to prescribe tolerance l imits (This is t rue w i t h other trace elements such as s i lve r ) T i t a n t i u m is very insoluble, at present i t is not of great concern Vanadium Gericke and Rennenkampff (1939)"°* found that vanad-i u m at 0 1, 10 , and 2 0 mg/1 added to nutr ient solutions as ca lc ium vanadate slightly increased the g rowth of barley, whereas at 10 mg /1 vanadium was toxic to both tops and roots and that vanadium chloride at 1 0 mg /1 o f vanad ium was toxic War ing ton (1954," '« 1956"") found that flax, soy-beans, and peas showed toxici ty to vanad ium i n the con-centrat ion range of 0 5 to 2 5 mg/1 C h i u ( 1 9 5 3 ) ' " found that 560 pounds per acre of vanad ium added as a m m o n i u m metavanadate to rice paddy soils produced toxici ty to rice Recommendations Considering the toxicity of vanadium in nutrient solutions and in soils and the lack of information on the reaction of this element with soils, a maxi-mum concentration of 0.10 mg/1 for continued use on all soils is recommended. For a 20-year period on neutral and alkaline fine textured the recom-mended maximum concentration is 1.0 mg/1. Zinc Toxicit ies of zinc i n nutr ient solutions have been demon-strated for a number of plants H e w i t t (1948)"" found that zinc at 16 to 32 mg/1 produced i ron deficiencies in sugar beets Hun te r and Vergnano (1953)"^' found toxic i ty to oats at 25 mg/1 M i l l i k a n (1947)"'^ found that 2 5 mg /1 produced i ron deficiency i n oats Barley (1943)'^' found that the Peking variety of soybeans was ki l led at 0 4 mg /1 , whereas the M a n c h u variety was ki l led at 1 6 mg/1 T h e toxic i ty of zinc in soils is related to soil p H , and l i m i n g acid soil has a large effect i n reducing toxici ty (Barnette 1936," ' Ga l l and Barnette 1940,""" Peech 1941,""« Staker and Cummings 1941,"«» Staker 1942,"" Lee and Page ] 957428Ì Amounts of added zinc that produce toxic i ty are highest i n clay and peat soils and smallest i n sands O n acid sandy soils the amounts required for toxic i ty w o u l d suggest a recommended m a x i m u m concentration of zinc o f 1 mg/1 for continuous use This concentration at a water appl icat ion rate of 3 acre feet/acre/year w o u l d add 813 pounds per acre in 100 years However, i f acid sandy soils are l imed to p H values of six or above, the tolerance level IS increased by at least a factor of two (Gal l and Barnette 1940) "»" Recommendations Assuming adequate use of liming materials to keep pH values high (six or above), the recom-mended maximum concentration for continuous use on all soils is 2.0 mg/L For a 20-year period on neutral and alkaline soils the recommended maxi-mum is 10 mg/1. On fine textured calcareous soils and on organic soils, the concentrations can exceed this limit by a factor of two or three with low probability of toxicities in a 20-year period. PESTICIDES (IN WATER FOR IRRIGATION) Pesticies are used widely i n water for i r r iga t ion on com-mercial crops in the U n i t e d States (Sheets 1967) ^ Figures on product ion, acreage treated, and use patterns indicate insecticides and herbicides comprise the ma jo r agr icul tura l pesticides There are over 320 insecticides and 127 herb i -cides registered for agr icul tura l use (Fowler 1972) " ' '
3^/Section VâAgricultural Uses of Water A l o n g w i t h the many benefits to agriculture, pesticides can have detr imental effects O f concern for i rr igated agr i -cul ture is the possible effects of pesticide residues in i r r iga-t ion water on the g rowth and market qua l i ty of forages and crops Pesticides most l ikely to be found in agr icul tural water supplies are listed i n the Freshwater Appendix I I - D Insecticides in Irrigation Water T h e route of entry of insecticides in to waters is discussed i n the pesticide section under Water for Livestock Enter-prises For example. M i l l e r et al (1967)*°*' observed the movement of parathion f r o m treated cranberry bogs in to a nearby i r r iga t ion d i t ch and drainage canal, and Sparr et al (1966)*° ' moni tored endrin i n waste i r r iga t ion water used three days after spraying I n moni to r ing pesticides in water used to irr igate areas near T u l e Lake and lower K l a m a t h Lake W i l d l i f e Refuges i n nor thern Cal i fornia , Godsil and Johnson (1968)"' ' detected h igh levels of endrin compared to other pesticides They observed that the concentrations of pesticides i n i r r iga t ion waters varied direct ly w i t h agr i -cu l tu ra l activities I n moni to r ing pesticides residues f r o m 1965 to 1967 (Agr icu l tu ra l Research Service 1969a),"8'the U S Depart-ment of Agr icu l tu re detected the fo l lowing pesticides in i r -r igat ion waters at a sampling area near Y u m a , Ar izona the D D T complex, d i e ldnn , methyl parathion, endrin, endosulfan, ethyl parathion, dicofol , s ,s ,s , - t r i b u t y l phos-phorotr i th ia te ( D E F ) , and demeton Insecticides most com-monly detected were D D T , endr in , and d i e ldnn For the most part, a l l residues in water were less than 1 0 /xg/l A fur ther examinat ion of the i r r iga t ion water at the Y u m a sampling area showed that water entering i t contained rela-tively low amounts of insecticide residues whi le water leav-ing contained greater concentrations I t was concluded that some insecticides were picked up f r o m the soil by i r r iga t ion water and carried out of the fields Crops at the same location were also sampled for insecti-cide residues W i t h the exception of somewhat higher con-centrations o f D D T and dicofol m cotton stalks and canta-loupe vines, respectively, residues in crop plants were rela-t ively small T h e mean concentrations, where detected, were 2 6 /xg/g combined D D T , 0 01 ^ g / g endrin, 0 40 ^ig/g d i e ldnn , 0 05 Mg/g lindane, 5 0 / ig/g dicofol , and 1 8 Mg/g combined para thion T h e larger residues for D D T and dicofol were apparently f r o m foliage applications Sampling of harvested crops showed that residues were generally less than 0 30 /xg/g and occurred p r i m a r i l y i n lettuce and in cantaloupe pulp , seeds, and n n d D D T , dicofol , and endr in were applied to crops du r ing the survey, and f r o m 2 0 to 6 0 lb /acre of D D T were applied to the soil before 1965 Some crops do not absorb measurable amounts of insecti-cides but others translocate the chemicals in various amounts A t the levels (less than 1 0 | i g / l ) moni tored by the U S Depar tment of Agr icu l tu re in i r r iga t ion waters ( A g r i -cu l tura l Research Service 1969a),"" there is l i t t l e evidence indicat ing that insecticide residues in the water are det r i -mental to plant g rowth or accumulate to undesirable or i l -legal concentrations i n food or feed crops Herbicides in Irrigation Water I n contrast to insecticides, misuse of herbicides can pre-sent a greater hazard to crop growth Herbicides are l ikely to be found in i r r iga t ion water under the fo l lowing c i r cum-stances (1) d u r i n g their purposeful in t roduct ion in to i r r iga-t ion water to control submersed weeds, of (2) incidental to herbicide treatment for control of weeds on banks of i r r iga-t ion canals Attempts are seldom made to prevent water containing herbicides such as xylene or acrolein f r o m being diverted onto cropland d u r i n g i r r iga t ion I n most instances, however, water-use restrictions do apply when herbicides are used in reservoirs of i r r iga t ion water T h e herbicides used in reservoirs are more persistent and inherently more phytotoxic at low levels than are xylene and acrolein The tolerances of a number of crops to various herbicides used in and around water are listed in Tab le V-15 Residue levels tolerated by most crops are usually much higher than the concentrations found in water fo l lowing normal use of the herbicides Aromat ic solvent (xylene) and acrolein are widely used in western states for keeping i r r iga t ion canals free of submersed weeds and algae and are not h a r m f u l to crops at concentrations needed for weed control ( U S Department of Agr icul ture , Agr i cu l tu ra l Research Service 1963,*°" hereafter referred to as Agr icu l tu ra l Research Service 1963) "*- Xylene , wh ich is non-polar, is lost rap id ly f r o m water (50 per cent in 3 to 4 hours) by vola t i l i ty (Frank et al 1970) Acrole in , a polar compound, may remain i n flowing water for periods of 24 hours or more at levels that are phytotoxic only to submersed aquatic weeds Copper sulfate IS used frequent ly to control algae I t has also been found effective on submersed vascular weeds when applied continuously to i r r iga t ion water at low levels (Bartley 1969) "8' T h e herbicides that have been used most widely on i r r iga-t ion ditchbanks are 2 , 4 - D , dalapon, T C A , and silvex T h e appl icat ion of herbicides may be restricted to a swath o f a few feet along the margin of the water, or i t may cover a swath 15 feet or more wide A variable overlap of the spray pat tern at the water marg in is unavoidable and accounts for most of the herbicide residues that occur in water d u r i n g di tchbank treatments Rates of applicat ion vary f r o m 2 l b per acre for 2 , 4 - D to 20 lb per acre for dalapon For ex-amples of residue levels that occur in water f r o m these treatments see Tab le V-16 T h e residues generally occur only d u r i n g the periods when ditchbanks are treated T h e rates of dissipation of herbicides in i r r iga t ion water were reported recently by Frank et al (1970) " " T h e herbi-cides and formulat ions commonly used on ditchbanks are readily soluble in water and not extensively sorbed to soil or other surfaces Reduct ion in levels of residues i n flowing i r r iga t ion water is due largely to d i l u t i on I r r i ga t i on canals
Water for Irrigation/"i^l TABLE V-15âTolerance of Crops to Various Herbicides Used In and Around Waters' Heibade Sits o1 HIS Fomulil ion Trealmsnt rate Concentration Uat not actor in impbon water' Crop iniur j thretliolil in impt ion water (m|/ l)« Acrolein Aronutctol«entj(qlene) Copper sutlate Dalapon Diquat Diuron DichlobemI EndotlDll Endothall amine salts Fenac Monuron S l i m TCA 2,4 Damme Impt ion canals l i i imd nowint water in canals or drains Emulsillabls liquid Canals or reservoirs Banks ol canals and ditches Injected into water or sprayed over surface Banks and bottoms of small dry powder ditches Bottoms ol dry canals Ponds and reservoirs Reservoirs and static water canals Bottoms of dry canals Banks and bottoms of small diy powder ditches Woody plants and brambles on floodways, alont canal, stream, or reservoir banks Floatint and emersed weeds in southern waterways Banks of canals and ditches On banks ol canals and ditches Pentahydrate crystals Water soluble salt Imuid Wettable powder Granules or wettable powder Water soluble Na or K salts Liquid or tranules Lquid or tranules Wettable powder Esters in liquid form Water soluble salt Uquid Picloram noating and emersed weeds i n southern canals and ditches For control of brush on water Lqmds or granules sheds 15 m t / l for 4 hours 0 6mt / l fo r8hours 0 1 m| / l for 48 hours 5 to10ga l /c ts (3Mlo750mj /D apphed in 3I)-C0 minutes Continuous treatment 0 5 to 3 0 m i / l , slui treatment ! ^ to 1 lb (0 15too 45kg)percfswater flow 15 to 30 lb/A or 17 to 34 kt/ha 3 l o 5 m | / l , t t o 1 5tbs/A,or 1 2 t o 1 7k t /ha Up to 64 lb/A or 72 kg/ha 7 to10 lb /Aor7 9 to t2 Skt/ba 1 to 4 m i / l 0 5 to2 5 m ! / l 10 to 20 lb/A or 12 6 to 25 2 k|/ha Up to 64 lb/A or72k| /ha 2 t o 4 l b / A o r 2 2 to4 4k | /ha lOtoO t m i / l 0 4 to0 02m{ / l 0 05to0 1 m { / l 700 m| / l or less 0 04too 9mg/1 duringOrst 10 miles, 0 08 to 9 Omg/ldonng Orst 10 to 20 miles. Loss than 0 2 mg/1 Usually less than 0 I mg/1 No data No data Absent or only traces Absent or only trans Absent or only traces No data No data Probably well under 0 1 mg/I 2 to 8 lb/A or 2 2 to 8 8 kg/ha O O l t o l 6 mg/11 day after appO Up to 64 lb/A or 72 kg/ha 1 to 4 lb/A or 1 1 to 4/4 kg/ha 2 t o 4 l b / A o r 2 2 to4 4kg/ha 1 t a 3 l b / A o r 1 1to3 3kg/ha cabon Usually less than 0 1 mg/I 0 01 to 0 10 mg/I No data Probably less than 0 1 mg/I No data Flood or furrow, beans 60, com 60, cotton 80, soybeans 20, sugar beets-6a Sprinkler, com 60, soybeans IS, sugar beets 15 Alfalfa>l,600, beans 1,200, carrob 1,600, com 3,000 cotton 1,600, gram sorghum > 800, oats 2,400, potatoes 1,300, wheat > 1,200 Threshold is above these levels. Beets>7 O,com>0 35 Beans 5 O,corn 125 No data Alfalfa 10,com>10, soybeans 1 0. sugar beets 1 OtolO Com 25, neld beans 1 0,Alfalla >10 0 Com>25, soybeans>25, sugar beets 25 Allalfa 1 0, corn 10, soybeans 0 1 , sugar beets 0 1 to 10 No data Com>S 0, sugar beets and soybeans > 0 02. No injury observed at levels used Heldbeans>1 0,grapes-0 7, sugar beets>0 2,soybeans>0 02, com 10, cucumbers, potatoes, sorghum, alfalfa, poppers>1 0 Corn>10, field beans 0 1, sugar beeU>1 0 "Sources of data included in this table are US Departmentof Agriculture, Agncultural Research Service (1969)'i», Arte and McHae(1959,<w 1960<»), Bnins(I9S4, '»» 1957,<» 1 9 6 4 , " i 1969'"), Bruns and Clore (1958V» Brans and Dawson (1959),<" Brans et al (1955,<» 1 9 H , < M unpublished data 1971»â¢) Frank et a l ( 1 9 7 0 ) , » ' Yeo (1959)"" !> Herbicide concentrabons given in this column are the highest concentrabons that have been found in impbon water, but these levels seldom remain in the water when i t reaches the crop. ' Unless indicated otherwise, all crop tolerance data were obtained by flood or furrow imjabon Threshold of inlory is Uie lowest coneentrabon causing temporary or permanent injury to crop plants even though, in many instances, neither crop yield nor quality was aHetted are designed to deliver a certain volume of water to be used on a specific area of cropland Water is diverted f r o m the canals at regular intervals, and this systematically reduces the volume of flow Consequently, l i t t le or no water re-mains at the ends of most canals where disposal of water conta ining herbicides might be troublesome Residues in Crops Successful application of herbicides for control of algae and submersed vascular weeds in i r r iga t ion channels is dependent upon a continuous flow of water Because i t is impract ica l to in te r rupt the flow and use of water du r ing the applicat ion of herbicides in canals or on canal banks, the herbicide-bearing water is usually diverted onto croplands Under these circumstances, measurable levels of certain herbicides may occur i n crops Copper sulfate is used most frequently for control o^ algae at concentrations that are often less than the suggested tolerance for this herbicide i n potable water App l i ca t ion rates may range f r o m one t h i rd pound of copper sulfate per cubic-feet-second (cfs) of water flow to two pounds per cfs of water flow (Agr icul ture Research Service 1963) '"^ Xylene is a common fo rmula t ing ingredient for many pesti-cides and as such is often applied directly to crop plants T h e dis t r ibut ion by f u r r o w or sprinkler of i r r iga t ion water con-ta in ing acrolein contributes to the rap id loss of this herbi -cide Copper sulfate, xylene, and acrolein are of minor i m -portance as sources of objectionable residues i n crops Phenoxy herbicides, dalapon, T C A , and amit role are most persistent i n i r r iga t ion water (Bartley and H a t t r u p 1970) I t IS possible to calculate the m a x i m u m amount of a herbicide such as 2 , 4 - D that migh t be applied to crop-
SAS/Sectton VâAgricultural Uses of Water TABLE V-16âMaximum Levels of Herbicide Residues Found in Irrigation Water as a Result of Dttchbank Treatment' Hertncide and canaf treated Treatment rate, lb/A Water flow in ds Maumom contentrabon of residue, f ig/1 DAIAPON Five mile lateral n ts 365» Lateral No 4 6 7 290 23 Manard lateral 9 6 37 39 Yolo lateral 10 5 26 162 TCA Lateral No. 4 3 t 290 12 Manard Lateral 5 4 37 20 Yolo lateral 5 9 26 69 2,4 D AMINE SALT lateral No 4 1 9 290 5 Manard lateral 2 7 37 13 Yolo lateral 3 0 26 36 ° Frank etal (1970)4" <> High level of residue probably due to atypical treatmenl land fo l lowing its use on an i r r iga t ion bank A four-mile-long body of i r r iga t ion water contaminated w i t h 2 , 4 - D and f lowing at a velocity of one mile per hour, would be diverted onto an adjacent field for a period of 4 hours A diversion rate o f two acre inches of water in 10 hours wou ld deliver 0 8 inch of contaminated water per acre I f this amount of water contained 50 /xg/l of 2 , 4 - D (a higher con-centrat ion than IS usually observed), i t w o u l d deposit slightly less than 0 009 lb of 2 , 4 - D per acre of cropland Levels of 2 , 4 - D residues of greater magnitude h^ve not caused i n -j u r y to irr igated crops (see Table V-15) T h e manner in which i r r iga t ion water containing herbi-cides IS applied to croplands may influence the presence and amounts of residues m crops (Stanford Research Ins t i -tute 1970) ^ For example, residues in leafy crops may be greater when sprinkler irr igated than when f u r r o w i r r i -gated, and the converse may be true w i t h root crops I f there is accidental contaminat ion of field, forage, or vegetable crops by polluted i r r igat ion water, the t ime inter-val between exposure and harvesting of the crop is i m -portant , especially w i t h crops used for human consumption Factors to be considered w i t h those mentioned above i n -clude the intensity of the applicat ion, stage of g rowth , d i l u -t ion , and pesticide degradabil i ty in order to assess the amount of pesticide that may reach the u l t imate consumer ( U S Depar tment of Heal th , Education and Welfare 1969) '"^ Pesticides applied to g rowing plants may affect the market qua l i ty by causing changes i n the chemical com-position, appearance, texture, and flavor of the product harvested for human consumption ( N R C 1968) Recommendation Pesticide residues in irrigation waters are variable depending upon land and crop management prac-tices. Recent data indicate pesticide residues are declining in irrigation waters, with concentrations less than 1.0 /xg/1 being detected. To date there have been no documented toxic effects on crops irrigated with waters containing insecticide resi-dues. Because of these factors and the marked variability in crop sensitivity, no recommendation is given for insecticide residues in irrigation waters. For selected herbicides in irrigation water, it is recommended that levels at the crop not exceed the recommended maximum concentration listed in Table V-16. PATHOGENS Plant Pathogens T h e avai labi l i ty of " h i g h q u a l i t y " i r r iga t ion water may lead to the reuse of r u n o f f water or tai lwater and subse-quent ly lead to a serious bu t generally unrecognized prob-lem, that of the d is t r ibut ion of plant pathogenic organisms such as bacteria, f ung i , nematodes, and possibly viruses This IS most serious when i t occurs on previously nonfarmed lands Distribution of Nematodes Wide d is t r ibut ion of plant-nematodes in i r r iga t ion waters of south central Wash-ington and the Columbia Basin of eastern Washington was demonstrated by Faulkner and Bolander (1966,*'* 1970*'«) When surface drainage f r o m agr icul tura l fields is collected and reintroduced in to i r r iga t ion systems, w i thou t first being impounded in settling basins, large numbers of nematodes can be transferred Faulkner and Bolander's data indicated that an acre of land i n the Lower Y a k i m a Val ley may re-ceive f r o m 4 m i l l i o n to over 10 m i l l i o n plant-parasitic nematodes w i t h each i r r iga t ion Numbers of nematodes transported vary w i t h the growing season, but some that were detectable in i r r iga t ion water and demonstrated to be infective were Melotdogyne liapla, Helerodera schachtii, Pratylen-chus sp , and Tylenchorhynchus sp Meagher (1967)*^^ found that plant-parasitic nematodes such as the citrus nematode, Tylenctmlus semipenelrans, may be spread by subsoil drainage water reused for i r r iga t ion Thomason and V a n Gundy (1961)*'" showed another means by wh ich nematodes may possibly enter i r r iga t ion supplies T w o species of rootknot nematode, Meloidogyne incognita and M javanica, were found reproducing on arrow-weed, Pluchea sericea, at the edge of sandbars in the Colorado River at Blythe, Cal i fornia N o conclusive evidence that nematodes entered the river was presented, but infested soil and infected roots were in direct contact w i t h the water Plant-parasitic nematodes are essentially aquatic animals and may survive for days or weeks immersed in water Unless provisions are made for excluding them f r o m or settling them out of i r r iga t ion water, they may seriously deteriorate water qua l i ty in areas of the U n i t e d States de-pendent on i r r iga t ion for crop product ion Distribution of Fungi Surveys were conducted to de-termine the origins and prevalence of Phytophtliora sp , a
Water for Irrigation/349 fungus pathogenic to citrus, i n open i r r iga t ion canals and reservoirs in five southern Cal i fornia counties by K l o t z et a l (1959) Phylophlhora progagules were detected by t rap-p ing them on healthy lemon f ru i t s suspended i n the water O f the 12 canals tested f r o m September 1957 to Septem-ber 1958, a l l yielded Phytophlhora sp at one t ime or another, some more consistently than others Phylophthora citrophthora was the most common and was recovered f r o m 11 canals I n the five canals where i t was possible to set the lemon traps at the source of the water, no Phylophthora sp were recovered However, as the canals passed through citrus areas where excess i r r iga t ion water or ra in r u n o f f could d r a m in to the canals, the f u n g i were readily isolated Soil samples collected f r o m paths of r u n o f f water that drained in to i r r iga t ion canals yielded P citrophthora, ind ica t ing that Phytophlhora zoospores f r o m infested citrus groves can be i n -t roduced in to canals One of three reservoirs was found to be infested w i t h P parasitica App l i ca t ion of copper sulfate effectively con-t ro l led the fungus under the static condi t ion of the water i n the reservoir Chlor ina t ion (2 m g / 1 for 2 minutes) effectively ki l led the infective zoospores of Phylophthora sp under laboratory conditions M c i n t o s h (1966)"* established that Phytophlhora cacto-rum, wh ich causes collar-rot of f r u i t trees in Bri t ish Co-lumbia , contaminates the water of many i r r iga t ion systems i n the Okanagan and Similkamen Valleys T h e fungus was isolated f r o m 15 sources inc lud ing ponds, reservoirs, rivers, creeks, and canals I t had been established previously that P cactorum was widespread i n i r r igated orchard soils of the area, but could not be readily detected i n non-i r r igated soils M a n y plant-pathogenic f u n g i normal ly produce f r u i t i n g bodies that are widely disseminated by w i n d A number do not, however, and these could easily be disseminated by i r r iga t ion water Distribution of Viruses Most plant pathogenic v i -ruses do not remain infestive in the soil outside the host or vector T w o exceptions may be tobacco mosaic virus ( T M V ) and tobacco necrosis virus ( T N V ) There is some evidence that these persist i n association w i t h soil colloids and can gain entry to plant roots th rough wounds H e w i t t et al (1958)*^'' demonstrated that f an leaf virus of grape is t ransmitted by a dagger nematode, Xiphmema index T o date, three genera o f nematodes, Xtphinema, Longidorus, and Tnchodorus are k n o w n to transmit viruses T h e first two of these genera transmit polyhedral viruses of the Arabis mosaic group Tnchdorus spp transmit tubular viruses of the Tobacco Rattles group Infect ive viruses are known to persist i n the nematode vector fo r months in the absence of a host plant Th i s i n fo rma t ion , coupled w i t h Faulkner and Bolander's (1966,^'* 1970)*'^ proof of the d is t r ibut ion of nematodes in i r r iga t ion water, suggested the possibility that certain plant viruses could be dis t r ibuted in their nematode vectors i n i r r iga t ion water T o date, no direct evidence for this has been pub-lished Several other soil-borne plant-pathogenic viruses are transmitted to hosts by soil f u n g i T h e ab i l i ty of the fungus Olpidium brassicae to carry and transmit Lettuce Big V e i n Vi rus ( L B V V ) was recently demonstrated (Grogan et al 1958, *" Campbel l 1962,*" Teakle 1969*«) I t is carried w i t h i n the zoospore in to fresh roots and there released ^ h e most l ikely vehicle for its d is t r ibut ion i n i r r iga t ion water w o u l d be resting sporangia carried in r u n o f f water f r o m infested fields T h e resting sporangia are released into the soil f r o m decaying roots of host plants Another economically impor tan t virus transmitted by a soil fungus IS Whea t Mosaic Vi rus carried by the fungus Polymyxa gramims (Teakle 1969) *» Another means of spread of plant viruses (such as T o -bacco Rattles Vi rus and Arabis Mosaic Viruses that are vectored by nematodes) is th rough virus-infected weed seed carried in i r r iga t ion water Distribution of Bacteria Bacterial plant pathogens w o u l d appear to be easily transported i n i r r iga t ion water However, relatively few data have been published con-cerning these pathogens K e l m a n (1953)*^ reported the spread of the bacterial w i l t organism of tobacco in drainage water f r o m fields and in water f r o m shallow wells H e also noted spread of the disease along an i r r iga t ion canal carry-ing water f r o m a forested area, but no direct evidence of the bacter ium m the water was presented Loca l spread m r u n o f f water is substantiated but not in ma jo r i r r iga t ion systems Cont ro l l ing plant disease organisms i n i r r iga t ion water should be preventive rather than an at tempt to remove them once they are introduced I n assuring that i r r iga t ion water does not serve for the dispersal of impor tan t plant pathogens, efforts should be directed to those organisms that are not readily disseminated by w i n d , insects, or other means At t en t ion should be focused on those soil-borne nematodes, f u n g i , viruses, and bacteria that do not spread rapidly i n nature T w o major means of in t roduct ion of plant pathogens in to i r r iga t ion systems are apparent T h e most common is natura l r u n o f f f r o m infested fields and orchards du r ing heavy ra in fa l l and floods T h e other is collection o f i r r i ga -t ion r u n o f f or tailwater and its re turn to i r r iga t ion canals I f I t IS necessary to trap surface water, either f r o m ra in fa l l or i r r iga t ion drainage, provisions should be made to i m -pound the water for sufficient t ime to al low settling out of nematodes and possibly other organisms Water may be assayed for plant pathogens, but there are thousands, or perhaps mil l ions of harmless microorgan-isms for every one that causes a plant disease However, plant pathogenic nematodes, and perhaps certain f u n g i , can be readi ly trapped f r o m i r r iga t ion water, easily iden t i -fied, and used as indicators of contaminat ion ( K l o t z et al 1959, Faulkner and Bolander 1966,*'* M c i n t o s h 1966*")
350/Section VâAgricultural Uses of Water Plant infect ion is not considered serious unless an eco-nomical ly impor tan t percentage of the crop is affected T h e real danger is that a trace of plant disease can be spread by water to an uninfected area, where i t can then be spread by other means and become impor tan t I t is unl ike ly that any method of water examinat ion w o u l d be as effective in preventing this as wou ld the prohibi t ions such as those suggested above Human and Animal Pathogens M a n y microorganisms, pathogenic for either animals or humans, or both, may be carried i n i r r iga t ion water, par t icu lar ly that derived f r o m surface sources T h e list comprises a large variety of bacteria, spirochetes, protozoa, helminths, and viruses wh ich find their way in to i r r iga-t ion water f r o m munic ipa l and industr ial wastes, inc lud ing food-processing plants, slaughterhouses, poultry-processing operations, and feedlots T h e diseases associated w i t h these organisms include baci l lary and amebic dysentery. Sal-monella gastroenteritis, typhoid and para typhoid fevers, leptospirosis, cholera, vibriosis, and infectious hepatitis Other less common infections are tuberculosis, brucellosis, listeriosis, coccidiosis, swine erysipelas, ascariasis, cysti-cercosis and tapeworm disease, fascioliasis, and schisto-somiasis O f the types of i r r iga t ion commonly practiced, spr inkl ing requires the best qua l i ty of water f r o m a microbiological point of a view, as the water and organisms are frequent ly apphed direct ly to that por t ion of the plant above the g round , especially f ru i t s and leafy crops such as straw-berries, lettuce, cabbage, alfalfa, and clover wh ich may be consumed raw by humans or animals F looding the field may pose the same microbiological problems i f the crop is eaten wi thou t thorough cooking Subirr igat ion and f u r r o w i r r iga t ion present fewer problems as the water rarely reaches the upper portions of the p lant , and root crops, as wel l as no rma l leafy crops and f ru i t s , o rd inar i ly do not permi t penetration o f the plant by animal and human pathogens Cr i te r ia for these latter types may also depend upon the characteristics of the soil, c l imate and other variables w h i c h affect survival of the microorganisms Benefits can be obtained by coordinat ing operation of reservoir releases w i t h downstream inflows to provide sedimentation and d i lu t i on factors to markedly reduce the concentrations of pathogens in i r r iga t ion water (Le-Bosquet 1945,*" Camp et al 1949*'2) T h e common l iver fluke, Fasctola hepattca, the ova of w h i c h are spread f r o m the feces of many animals, com-mon ly affects cattle and sheep (All ison 1930,*'° U S Dept Agr icu l tu re 1961*"), and may affect man T h e intermediate hosts, certain species of snails, l ive i n springs, slow-moving swampy waters, and on the banks of ponds, streams, and i r r iga t ion ditches A f t e r development i n the snail, the cer-carial forms emerge and encyst on grasses, plants, bark, or sod Catt le and sheep become infected by ingestion ot grasses, plants, or water m damp or i r r iga ted pastures where vegetation is infested w i t h metacercariae M a n contracts the disease by ingesting plants such as watercress or lettuce containing the encysted metacercariae Ascarts ova are also spread f r o m the feces of infected an i -mals and man and are found i n i r r iga t ion water (Wang and D u n l o p 1954) * ' 2 Catt le and hogs are commonly infected, where the adul t worms mature in the intestinal tract, some-times blocking the bile ducts Ascarts ova have been re-ported to survive for 2 years i n i r r igated soil and have been found on irr igated vegetables even when chlorinated ef-fluent was used for i r r iga t ion (Gaertner and M u e t m g 1951) *" Schistosomiasis, a l though not yet prevalent in the U n i t e d States except in immigrants f r o m areas where the disease exists, should be considered because infected individuals may move about the country and spread the disease T h e l i fe cycle of these schistosomes is similar to that of the l iver fluke, i n that eggs f r o m the feces or ur ine of infected i n d i -viduals are spread f r o m domestic wastes and may reach surface i r r iga t ion water where the mi rac id ia l forms enter certain snails and m u l t i p l y , releasing cercariae A l t h o u g h these cercariae may produce disease i f ingested by man, the more common method of infect ion is th rough the skin o f individuals work ing m infested streams and i r r iga t ion ditches Such infections are most common i n Egypt (Barlow 1937)*" and other i r r igated areas where workers wade i n the water w i thou t boots I t is unl ikely that the cercariae w o u l d survive long on plants after harvest L i t t l e is known of the possibility that enteric viruses such as polioviruses, Coxsackie, E C H O , and infectious hepatitis viruses may be spread through i r r iga t ion practices M u r p h y and his co-workers ( M u r p h y et al 1958)*^' tested the sur-v iva l of polioviruses i n the root environment of tomato and pea plants i n modif ied hydroponic cul ture I n a second paper. M u r p h y and Syverton (1958)*^' studied the recovery and d is t r ibut ion o f a variety of viruses i n growing plants T h e authors conclude that i t is unl ikely that plants or p lant f ru i ts serve as reservoirs and carriers of poliovirus H o w -ever, their findings of significant absorption of a m a m m a l i a n virus i n the roots of the plants suggest that more research is needed i n this area M a n y microorganisms other than those specifically men-tioned i n this section may be transmitted to plants, animals, and humans through i r r iga t ion practices One of the more serious of these is vibriosis I n some cases, def ini t ive in for -mat ion on microorganisms is lacking A l t h o u g h others, such as the cholera organisms, are significant i n other parts o f the w o r l d , they are no longer impor t an t i n the U n i t e d States Direc t search for the presence of pathogenic micro-organisms i n streams, reservoirs, i r r iga t ion water, or on i r -rigated plants IS too slow and cumbersome for rout ine con-t ro l or assessment of qua l i ty Instead, accepted index organisms such as the co l i fo rm group and fecj i l col i (Kab le r
Water for Irrigation/351 et al 1964),'^' w h i c h are usually far more numerous f r o m these sources, and other biological or chemical tests, are used to assess water qua l i ty Recent studies have emphasized the value of the fecal cohform i n assessing the occurrence of salmonella, the most common bacterial pathogen i n i r r iga t ion water Geldreich and Bordner ( 1 9 7 1 ) " ' reviewed field studies invo lv ing i r -r igat ion water, field crops, and soils, and stated that when the fecal cohform density per 100 m l was above 1,000 organisms i n various stream waters, Salmonella occurrence reached a frequency of 96 4 per cent Below 1,000 fecal coliforms per 100 m l (range 1-1000) the occurence of Salmonella was 53 5 per cent Fur ther support for the l i m i t of 1,000 fecal coliforms per 100 m l of water is shown in the recent studies of Cheng et al (1971),"^ who reported that as the fecal coliforms density reached less than 810 per 100 m l downstream f r o m a sewage treatment p lant . Salmonella were not recovered Recommendation Irrigation waters below the fecal coliform den-sity of 1,000/100 ml should contain sufficiently low concentrations of pathogenic microorganisms that no hazards to animals or man result from their use or from consumption of raw crops irrigated with such waters. THE USE OF WASTEWATER FOR IRRIGATION A n expanding populat ion requires new sources o f water for i r r iga t ion of crops and development of disposal systems for mun ic ipa l and other wastewaters that w i l l not result i n the contaminat ion of streams, lakes, and oceans I r r i g a t i o n of crops w i t h wastewater w i l l probably be widely practiced because i t meets both needs simultaneously Wastewater From Municipal Treatment Systems Various human and animal pathogens carried in m u n i c i -pa l wastewater need to be nu l l i f i ed Pathogens carried i n mun ic ipa l wastewater include various bacteria, spirochetes, helminths , protozoa, and viruses (Dunlop 1968) Tanner (1944)668 and Rudolfs et a l ( 1 9 5 0 ) " ' have reviewed the l i tera ture on the occurrence and survival of pathogenic and nonpathogenic enteric bacteria i n soil, water, sewage, and sludges, and on vegetation i r r igated or fe r t i l ized w i t h these materials I t w o u l d appear f r o m these reviews that f ru i t s and vegetables g rowing i n infected soil can become con-taminated w i t h pathogenic bacteria and that these bacteria may survive fo r periods o f a few days to several weeks or more i n the soil, depending upon local conditions, weather, and the degree o f contaminat ion However, Geldreich and Bordner ( 1 9 7 1 ) " ' noted that pathogens are seldom detected on f a r m produce unless the plant samples are grossly con-taminated w i t h sewage or are observed to have fecal particles c l inging to them T h e level of pathogen recovery depends upon the incidence of waterborne disease i n the area, the soil type, soil p H , soil moisture content, soil nut r ient levels, antagonistic eflfects of other organisms, temperature, humid i t y , and length of exposure to sunlight No r man and Kab le r ( 1 9 5 3 ) ' " made cohform and other bacterial counts in samples of sewage-contamination river and d i t ch waters and of soil and vegetable samples i n the fields to wh ich these waters were applied They found that a l though the bacterial contents of both river and d i t ch waters were very high, both soil and vegetable washings had much lower counts For example, where i r r iga t ion water had cohform counts of 230,000/100 m l , leafy vegetables had counts of 39,000/100 grams and smooth vegetables, such as tomatoes and peppers, only 1,000/100 grams H i g h entero-coccus counts accompanied h igh cohform counts in water samples, but enterococcus counts d i d not appear to be cor-related m any way w i t h cohform counts in soil and vegetable washings D u n l o p and W a n g (1961)^' ' have also endeavored to study the problem under actual field conditions i n Colorado Salmonella, Ascarts ova, and Entamoeba colt cysts were re-covered f r o m more than 50 per cent of i r r iga t ion water samples contaminated w i t h either raw sewage or p r imary-treated, chlorinated effluents O n l y one of 97 samples of vegetables irr igated w i t h this water yielded Salmonella, but Ascans ova were recovered f r o m two of 34 of the vegetable samples A l though cysts of the human pathogen. Entamoeba histolytica, were not recovered in this work , probably due to a low carrier rate in Colorado, their similar resistance to the environment w o u l d suggest that these organisms wou ld also survive i n i r r iga t ion water for a considerable period of t ime I t should be pointed out, however, that this work was done entirely w i t h f u r r o w i r r iga t ion on a sandy soil i n a semiarid region, and the low recoveries f r o m vegetables cannot necessarily be applied to other regions or to sprinkler i r r iga t ion of similar crops I n fact, M u l l e r (1957)**" has re-ported that two places near H a m b u r g , Germany, where sprinkler i r r iga t ion was used. Salmonella organisms were iso-lated 40 days after spr inkl ing on soil and on potatoes, 10 days on carrots, and 5 days on cabbage and gooseberries M u l l e r ( 1 9 5 5 ) " ' has also reported that 69 of 204 grass samples receiving raw sewage by spr inkl ing were positive for organisms of the typhoid-para typhoid group (Salmonella) T h e bacteria began to die off" 3 weeks after sewage applica-t ion , bu t 6 weeks after appl icat ion, 5 per cent o f the sam-ples were sti l l infected These findings emphasize the i m -portance of having good qua l i ty water for sprinkler i r r iga-t ion Tubercle baci l l i have apparendy not been looked for on i r r igated crops i n the U n i t e d States However, Sepp ( 1 9 6 3 ) " ' stated that several investigations on tuberculosis infect ion of cattle pasturing on sewage-irrigated l and have been carried out i n Germany T h e investigators are i n gen-eral agreement that i f sewage applicat ion is stopped 14 days before pasturing, there is no danger that the cattle w i l l con-
352/Section VâAgricultural Uses of Water t ract bovine tuberculosis through grazing I n contrast, Dedie (1955)*" reported that these organisms can remain infective for 3 months i n waste waters and up to 6 months i n soil T h e recent findings of a typical mycobacteria i n intestinal lesions of cattle w i t h concurrent tubercul in sensi-t i v i t y in the Un i t ed States may possibly be due to ingestion of these organisms either f r o m soil or i r r igated pastures Both animals and human beings are subject to he lmin th infectionsâascariasis, fascioliasis, cysticerosis and tapeworm infection, and schistosomiasisâall of w h i c h may be trans-mi t ted through surface i r r iga t ion water and plants infected w i t h the ova or intermediate forms of the organisms T h e ova and parasitic worms are quite resistant to sewage treatment processes as wel l as to chlor inat ion (Borts 1949)*" and have been studied quite extensively in the applicat ion of sewage and i r r iga t ion water to various crops (Ot ter 1951,**' Sehtrennikova and Shakhurina 1953,**« W a n g and D u n l o p 1954*^) Epidemics have been traced to crop con-taminat ion w i t h raw sewage but not to i r r iga t ion w i t h treated effluents (Dunlop 1968) * " T h e chances of contaminat ion of crops can be fur ther re-duced by using f u r r o w or subirr igat ion instead of sprinklers, by stopping i r r iga t ion as long as possible before harvest begins, and by educating f a r m workers on sanitation prac-tices for harvest (Geldreich and Bordner 1971) *â¢" I t is better to restrict i r r iga t ion w i t h sewage water to crops that are adequately processed before sale and to crops that are not used for human consumption Standards are needed to establish the point where i r r iga-t ion waters that contain some sewage water must be re-stricted and to indicate the level to wh ich wastewater must be treated before i t can be used for unrestricted i r r iga t ion T h e direct isolation of pathogens is too slow and com-plicated for routine analyses of water qua l i ty (Geldreich and Bordner 1971) *â¢" A quant i ta t ive method for Salmonella detection has been developed recently (Cheng et al 1971) However, the m i n i m u m number of Salmonella required to cause infect ion are not known , and data are not available to correlate incidence of Salmonella w i t h the inc i -dence of other pathogens (Geldreich 1970) * 'Ì' T h e fecal co l i fo rm group has a h igh positive correlation w i t h fecal contaminat ion f r o m warm-blooded animals and should be used as an indicator of po l lu t ion u n t i l more direct methods can be developed I n f o r m a t i o n is available indica t ing the levels of fecal co l i fo rm at which pathogens can no longer be isolated f r o m i r r iga t ion water Salmonella were consistently recovered in the Red River of the nor th when fecal co l i fo rm levels were 1000/100 m l or higher, but were not detected at fecal col i -f o r m levels of 218 and 49/100 m l ( O R S A N C O Water Users Committee 1971) **« Cheng et al (1971)*'« reported n u m -bers of fecal co l i fo rm at various distances downstream, and Salmonella was not isolated f r o m samples containing less than 810 fecal col i forms/100 m l Geldreich and Bordner (1971)*^' presented data f r o m nat ionwide field investiga-tions showing the relationship between Salmonella oc-currence and fecal co l i fo rm densities Salmonella occur-rence was 53 5 per cent for streams w i t h less than 1,000 fecal coliforms per 100 m l and 96 4 per cent for streams w i t h more than 1,000 fecal coliforms per 100 m l A m a x i m u m level of 1,000 fecal coliforms per 100 m l of water appears to be a realistic standard for water used fo r unrestricted i r -r igat ion Secondary sewage effluent can be chlorinated to reduce the fecal co l i fo rm bacteria below the 1,000 per m l l i m i t , but viruses may survive chlor inat ion Wastewater used for un -restricted i r r iga t ion should receive at least p r imary and biological secondary treatment before chlor ina t ion F i l t r a -t ion through soil is another effective way to remove fecal bacteria ( M e r r e l l et al 1967,*« Bouwer 1968,*'^ Bouwer and Lance 1970,*'* Lance and Whisler 1972) *Ì ^ T h e e l iminat ion of health hazards has been the p r imary consideration regulat ing the use of sewage water in the past But control of nut r ient loads must also be a pr ime con-cern T h e nutrients applied to the land must be balanced against the nut r ient removal capacity of the soil-plant sys-tem to min imize groundwater contaminat ion Kardos (1968)*^^ reported that various crops removed only 20 to 60 per cent of the phosphorus applied in sewage water, bu t the total removal by the soil-plant system was about 99 per cent M a n y biological reactions account for nitrogen removal f r o m wastewater, but heavy applications of sewage water can result m the movement of nitrogen below the root zone (Lance*" in press 1972) W o r k w i t h a high-rate groundwater recharge system u t i -l iz ing sewage water resulted i n 30 per cent nitrogen removal f r o m the sewage water (Lance and Whisler 1972) *Ì ^ Ni t ra te can accumulate i n plants supplied w i t h ni trogen i n excess of their needs to the point that they are a hazard to livestock Ni t ra te usually accumulates in stems and leaves rather than in seeds (Viets 1965) **' T h e concentration of trace elements i n sewage water used for i r r iga t ion should meet the general requirements estab-lished for other i r r iga t ion waters Damage to plants by toxic elements has not yet been a problem on lands i r r igated w i t h sewage water i n the U n i t e d States Problems could develop in some areas, however, i f industries release potential ly toxic elements such as zinc or copper in to sewage treatment sys-tems i n large quantities T h e concentration of boron i n sewage water may become a problem i f the use of this ele-ment i n detergents continues to increase T h e guidelines for salinity in i r r iga t ion water also apply to sewage water used for i r r iga t ion T h e organic matter content of secondary sewage water does ncft appear to be a problem l i m i t i n g its use i n i r r iga t ion Secondary sewage effluent has been inf i l t ra ted into r iver sand at a rate of 100 meters per year i n Ar izona (Bouwer and Lance 1970) *'* T h e C O D of this water was consistently reduced f r o m 50 mg /1 to 17 mg/1 or the same C O D as the
Water for Irrigation/353 native groundwater of the area T h e organic load might be a factor in causing clogging of soils used for maximum irri-gation to promote groundwater recharge Suspended solids have not been reported to be a problem during irrigation with treated effluents Wastewater From Food Processing Plants and Animal Waste Disposal Systems Wastewater from food processing plants, dairy plants, and lagoons used for treatment of wastes from feedlots, poultry houses, and swine operations, may also be used for ir-rigation Some food processing wastewater is high in salt content and the guidelines for salinity control concerning unrestricted irrigation in the Section, Irrigation Quality for A n d Regions, should be followed (Pearson tn press 1972"'') Effluents from plants using a lye-peeling process are gen-erally unsuitable for irrigation due to their high sodium content Al l of the wastewaters mentioned above are usually much higher in organic content than secondary sewage effluent This can result in clogging of the soil surface, if application rates are excessive (Lawton et al 1960,5^' L a w 1968, L a w et al 1970) s « Only well drained soils should be irrigated, and runoff should be pre-vented unless a closely managed spray-runoff treatment system is used T h e nutrient content of the wastewaters varies considerably T h e nutrient load applied should be balanced against the nutrient removal capacity of the soil Food processing wastes present no pathogenic problem and may be used for unrestricted irrigation Since some animal pathogens also infect humans, water containing animal wastes should not be applied with sprinkler systems to crops that are consumed raw Recommendations ⢠Raw sewage should not be used in the United States for irrigation or land disposal. ⢠Sewage water that has received primary treat-ment may be used on crops not used for human consumption. Primary effluents should be free of phytotoxic materials. ⢠Sewage water that has received secondary treat-ment may also be used to irrigate crops that are canned or similarly processed before sale. ⢠Fecal coliform standard for unrestricted irri-gation water should be a maximum of 1,000/100 ml. ⢠The amount of wastewater that can be applied is determined by balancing the nutrient load of the wastewater against the nutrient removal capacity of the soil. ⢠Phosphorus will probably not limit sewage appli-cation because of the tremendous adsorption capacity of the soil. ⢠The nitrogen load should be balanced against crop removal within 30 per cent unless additional removal can be demonstrated.
LITERATURE CITED GENERAL FARMSTEAD USES ⢠Amencan Water Works Association Committee on Tastes and Odors (1970), Committee report research on tastes and odors J Amer Water Works Ass 62(1) 59-62 ' Atherton, H V (1970), Comparison of methods of sanitizing water A S A E Paper 70-759 1970 Winter Meeting Arrt Soc Ag Eng Chtcago 'Atherton, H V , D A Klein, and R N Mullen (1962), 5ym/>o«um 071 water treatment and use Farm water supplies, their influence on milk quality [Paper 62-206] (American Society of Agricultural E n -gineers, St Joseph, Michigan), 9 p * Ayres, J C (1963), Low temperature organisms as indexes of quality of fresh meat, in Microbiological quality o] foods, L W Slaneu, C O Chichester, A R Gaufin, and Z J Ordal , eds (Academic Press, New York), pp 132-148 'Baumann, E R and D D Ludwig (1962), Free available chlorine residuals for small nonpublic water supplies J Amer Water Works Ass 54(11) 1379-1388 â¢Behrman, A S (1968), Water is everybody's business the chemistry of water purification (Doubleday and Company, Inc , Garden City, New York), pp 1-18 ' Black, A P , R N Kinman, W C Thomas, J r , G F Freund, and E D Bird (1965), Use of iodine for disinfection J Amer Water Works Ass 57(11) 1401-1421 'Davis , J G (1960), The microbiological control of water in dairies and food factories I I Dairy Ind 25(12) 913-918 'Dougan, R S (1966), T h e quantity-quality challenge of water in rural areas, in Proceedings, Farmstead water quality improvement seminar [PROC-167] (American Society of Agricultural Engineers, St Joseph, Michigan), pp 47-48 " E l m s , D R (1966), Neutrahzation, sequestration, oxidation and adsorption, in Proceedings, farmstead water quality improvement semi-nar [PROC-167] (American Society of Agricultural Engineers, St Joseph, Michigan), pp 24-26, 50 " Environmental Protection Agency draft. Drinking Water Standards, 1972 revision " Esmay, M L , B E Guyer, M D Shanklin, and L H Tempel (1955), Treatment of surface water supplies for the farm home Mo Agr Exp Sta Res Bull no 589, 36 p "Geldreich, E E and R H Bordner (1971), Fecal contamination of fruits and vegetables during cultivation and processing for market A review J Milk Food Technol 34(4) 184-195 » Huff, C B , H F Smith, W D Boring, and N A Clark (1965), A study of ultraviolet disinfection of water and factors in treatment efficiency Public Health Reports 80 695-704 "James, G V {\<3(ib). Water treatment, Zvd cd (The Technical Press, Ltd , London), 307 p " K a b l e r , P W and J F Kreissl (1966), Biological and radiological properties of water, in Proceedings, farmstead water quality improve-ment seminar [PROC-167] (American Society of Agricultural Engineers, St Joseph, Michigan), pp 9-11, 17 "Kjel lander, J O , and E Lund (1965), Sensitivity of escherichia coll and poliovirus to different forms of combined chlorine J Amer Water Works Ass 57(7) 893-900 " K l u m b , G H (1966), Nature of water physical and chemical properties, in Proceedings, farmstead water quality improvement seminar [PROC-167] (American Society of Agricultural Engineers, St Joseph, Michigan), pp 5-8 " Kristoffersen, T (1958), A psychrophilic strain relatively resistant to hypochlorite-type sanitizers J Dairy Set 41(7) 1003 Lamar, W L Evaluation of organic color and iron in natural sur-face waters [Geological Survey professional paper 600-D ] (Govern-ment Printing Office, Washington, D C ) , pp 24-29 Lamar, W L and D F Goerlitz (1966), Organic acids in naturally colored surface waters [Geological Survey water supply paper 1817-A] (Government Printing Office, Washington, D C ) , 17 p Laubusch, E J (1971), Chlorination and other disinfection proc-esses, in Water quality and treatment, 3rd ed , prepared by the American Water Works Association (McGraw-Hil l Book C o , New York), pp 158-224 Lewis, R F (1965), Control of sulfate-reducing bacteria J Amer Water Works Ass 57(8) 1011-1015 "Livingstone, D A (1963), Chemical composition of rivers and lakes [Geological Survey professional paper 400-G], in Data of geochemistry, 6th ed , M Fleischer, ed (Government Printing Office, Washington, D C ) , 64 p Mackenthun, K M and L E Keup (1970), Biological problems encountered in water supplies J Amer Water Works Ass 62 520-526 " Malaney, G W , H H Weiser, R O Turner, and M Van Horn (1962), Coliforms, enterococci, thermophiles, and psychrophiles in untreated farm pond waters Appl Microbiol 10(1) 44-51 " Mercer, W A (1971), Food processing without pollution Presented at the 64th convention of the National Canners Association, January 26, 1971 "Moore, M J (1971), Rura l water supplies Vermont Extension Cir 145 "O'Donovan, D C (1965), Treatment with ozone J Amer Water Works Ass 57(9) 1167-1194 ""Oliver, R P (1966), Comparison of chlorine, bromine and iodine for use in Farmstead water treatment A S A E Conference Pro-ceedings Farmstead Water Quality Improvement Seminar, Columbus, Ohio A S A E Publ Proc-167 " Pavelis, G A and K Gertel (1963), T h e management and use of water, in A place to live the yearbook of agriculture 1963 (Govern-ment Printing Office, Washington, D C ) , pp 88, 90 "Shaw, M D (1966), Water disinfecting processes Heat, silver, and ultraviolet, in Proceedings, farmstead water quality improvement seminar 354
Literature Ctted/355 [PROC-167] (American Society of Agricultural Engineers, St Joseph, Michigan), pp 18-20 "Stover, H E (1966), Farm pond water-treatment system, in Pro-ceedwgSj farmstead water quality improvement seminar [PROC-167] (American Society of Agricultural Engineers St Joseph, Michi-gan), p 49 Thomas, S B (1949), The types of bacteria commonly found in farm and creamery water supplies and their action on rmlk and milk products Soc Dairy Technol J 2 224-232 "Thomas , S B (1958), Psychrophilic micro-organisms in milk and dairy products Dairy Set Abstr 20(6) 4 4 7 ^ 8 "Thomas , S B , R G Druce, and A Davies (1966), The signifi-cance of psychrotrophic bacteria in raw milk Dairy Indust 31(1) 27-32 "Thomas, S B , B F Thomas, and P M Frankhn (1953), Bac-teriology of farm water supplies a study of the colony count in 48 hours at 37° Proc Soc Appl Bad 14(2) 121-130 " U S Department of Health, Education and Welfare Public Health Service (1965), Grade "A" pasteurized mild ordinance 7965 recom-mendation of the Public Health Service [PHS Pub 229] (Government Printing Office, Washington, D C ), 184 p "Victoreen, H T (1969), Soil bacteria and color problem in dis-tribution systems J Amer Water Works Ass 61(9) 429-431 Walters, A H (1964), The hidden danger in water Dairy Ind 29 (9) 678-679 " W a t e r Systems Council (1965-66), Water system and treatment hand-book, 4th ed (Water Systems Council, Chicago), 108 p « Wright, F B (1956), Rural water supply and sanitation, 2nd ed (John Wiley & Sons, Inc , New York), 347 p WATER REQUIREMENTS FOR LIVESTOCK "Adolph, E F (1933), The metabolism and distribution of water in body and tissues Physiol Rev 13 336-371 "James , E C , J r and R S Wheeler (1949), Relation of dietary protein content to water intake, water elimination and amount of cloacal excreta produced by growing chickens Poultry Sci 28 465-467 Leitch, I and J S Thomson (1944), The water economy of farm animals Nulr Abstr Rev 14(2) 197-223 *'Mitchell, H H (1962), The water requirements for maintenance, in Comparative nutrition of man and domestic animals (Academic Press, New York), vol 1, pp 192-224 "Morrison, F B (1936), Feeds and feeding, 20th ed (The Morrison Publishing Co , Ithaca, New York), 1959 « Morrison, F B (1959), Feeds and feeding (The Morrison Publishing Co , Ithaca, New York) « M o u n t , L E , C W Holmes, W H Close, S R Morrison, and I B Start (1971), A note on the consumption of water by the growing pit at several environmental temperatures and levels of feeding Anim Prod 13(3) 561-563 " National Research Council Committee on Animal Nutrition (1968a), Nutrient requirements of swine, 6th rev ed (The National Academy of Sciences, Washington D C ) , 69 p " National Research Council Committee on Animal Nutrition (1968b), Nutrient requirements of sheep, 4th rev ed (The National Academy of Sciences, Washington, D C ), 64 p " National Research Council Committee on Animal Nutntion (I97\a), Nutrient requirements of dairy cattle, ith rev ed (The Na-tional Academy of Sciences, Washington, D C ) , 54 p "Robinson, J R and R A McCance (1952), Water metabolism Annu Rev Physiol 14 115-142 "Sunde, M L (1967), Water is important Feedstuffs 39(5\) 32-3^ "Winchester, C F and M J Morris (1956), Water intake rates of cattle J Anim Set 15 722-740 References Cited "Sunde, M L (1971), personal communications. Poultry Department, University of Wisconsin, Madison Wisconsin RELATION OF NUTRIENT ELEMENTS IN WATER TO TOTAL DIET "Dantzman, C L and H L Breland (1970), Chemical status of some water sources in south central Florida Soil Crop Set Soc Fla Proc 29 18-28 " D u r u m , W H , J D Hem, and S G Heidel (1971), Reconnais-sance of selected minor elements in surface waters of the United States, October 1970 [Geological Survey circular 643] (Government Printing Office, Washington, D C ) , 49 p "Lawrence , J M (1968), Aquatic weed control in fish ponds, paper no E-1 in Proceedings of the world symposium on warm-water pond fish cultures [ F A O fisheries report 44] (Food and Agricultural Organization of the United Nations, Rome), vol 5, pp 76-91 so National Research Council Committee on Ammal Nutrition (1966), Nutrient requirements of horses (The National Academy of Sciences, Washington, D C ) , 25 p " National Research Council Committee on Animal Nutrition {\9S%!i), Nutrient requirements of swine,&thTcv ed (The National Academy of Sciences, Washington, D C ) , 69 p ^ National Research Council Committee on Animal Nutrition (1968b), Nutrient requirements of Sheep, 4th rev ed (The National Academy of Sciences, Washington, D C ) , 64 p " National Research Council Committee on Animal Nutrition (1970), Nutrient requirements of beef cattle, 4th rev ed (The Na-tional Academy of Sciences, Washington, D C ) , 55 p " National Research Council Committee on Animal Nutrition (1971 a), Nutrient requirements of dairy cattle, (The National Academy of Sciences, Washington, D C ) , 54 p "National Research Council Committee on Animal Nutrition (1971b), Nutrient requirements of poultry, 6th rev ed (The National Academy of Sciences, Washington, D C ), 54 p "Shirley, R L (1970), Nutrients in water available for economic animals, in Proceedings Nutrition Council's 30th annual meeting (Ameri-can Feed Manufacturers Association, Chicago), pp 23-25 "Shirley, R L , G K Davis, and J R Neller (1951), Distribution of P '2 in the tissues of a steer fed grass from land that received labelled ferulizer J Anim Sci 10 335-336 " Shirley, R L , W K Robertson, J T McCaU, J R Neller, and G K Davis (1957), Distribution of C a " in tissues of a steer fed grass from land that received labelled fertihzer Quart J Fla Acad Sci 20(2) 133-138 "Systems for Technical Data ( S T O R E T ) (1971), Water Programs Office, Environmental Protection Agency, Washington, D C EFFECT OF SALINITY ON LIVESTOCK ⢠Ballantyne, E E (1957), Drinking waters toxic for hvestock Can J Comp Med 21(7) 254-257 " Embry, L B , M A HoeUcher, R C Wahlstrom, C W Carlson, L M Krista, W R Brosz, G F Gastler, and O E Olson (1959), Salinity and livestock water quality 5 Dak Agr Exp Sta Bull no 481 1-12 "Frens , A M (1946), Salt drinking water for cows Tijdschr Dier-geneesk 71(1) 6-11 "Gastler , G F and O E Olson (1957), Dugout water quality 5 Dak Farm Home Res 8(2) 20-23 "Hel ler , V G (1932), Sahne and alkahne drinking waters J Nutr 5 421^29 "Hel ler , V G (1933), The effect of saline and alkahne waters on domestic animals Okla Agr Exp Sta Bull no 217 3-23
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V I The tolerance of wethers in pens for drinking waters of the types ob-tained from underground sources in Australia Aust J Agr Res 17 209-218 "Peirce, A W (1968a), Studies on salt tolerance of sheep V I I The tolerance of ewes and their lambs in pens for drinking waters of the types obtained from underground sources in Australia Aust J Agr Res 19 577-587 «« Peirce, A W (1968), Studies on salt tolerance of sheep V I I I The tolerance of grazing ewes and their lambs for drinking waters of types obtained from underground sources in Australia Aust J Agr Res 19 589-595 Ramsay, A A (1924), Waters suitable for livestock Analyses and experiences in New South Wales Agr Gaz N S W 35 339-342 ''Scrivner, L H (1946), Experimental edema and ascites in poults J Amer Vet Med Ass 108 27-32 " Selye, H (1943), Production of nephrosclerosis in the fowl by sodium chloride J Amer Vet Med Ass 103 140-143 '^SpafTord, W J (1941), South Australian natural waters for farm livestock J Dep Agr South Australia 44 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