RENOVATED?! 0F SiMULATED MUNICIPAL WAS'E'EWATER THROUGH ENTENSWE IRREGATION 0F CORN GROWN ON A TILE DRAENED CONDVER LOAN. Thesis for the Degree of M. S. MICHIGAN STATE UNIVERSITY DOUGLAS LAWRENCE KARLEN £975 Imasns LIBRARY BINDE RSI . smucronr, Mlculsmj t. ‘ ._ i2 RENOVATIOT THROW GROW}; A field 1 25, 50, 100, and com grown on a :eoovation effic by measuring nu1 recoveries thrO' soil profile. Nutrier vOlume of tile Deasuring the 1 Annual losses f M to 8.5 kg/ "eaSEd with j The y: WEI e evalua t e ABSTRACT RENOVATION OF SIMULATED MUNICIPAL WASTEWATER THROUGH INTENSIVE IRRIGATION OF CORN GROWN ON A TILE DRAINED CONOVER LOAM By Douglas Lawrence Karlen A field study to evaluate the effects of applying 25, 50, 100, and 200 cm of simulated municipal effluent to corn grown on a tile-drained loam soil was conducted. The renovation efficiency of the soil-crop system was evaluated by measuring nutrient losses through tile drainage, recoveries through plant uptake, and changes within the soil profile. Nutrient losses were calculated by measuring the volume of tile flow after each irrigation or rainfall and measuring the nutrient concentration in the drainage water. Annual losses ranged from 0.1 to 18.0, 0.01 to 0.60, and 0.2 to 8.5 kg/ha N, P, and K, respectively. Losses in- creased with increasing rates of application. The yield and nutrient uptake of seven corn hybrids ‘were evaluated under four irrigation rates. Significant differences due to loading rate and hybrid were found. The treatment hybrid interactions were non-significant, which indicated that all hybrids responded similarly at all loading rates. Nutrient recovery through plant uptake accounted for more the H, and K, respecti log rates provided tl‘ Zeooval of only the 1 recovery. Analysis of application of low I depletion of the ex lizer is applied. able sodium percenl problems due to ex The soil w losses through deg for leaching largv 3°3- PIO’file. Th following the app diluent confirm; ratios suggested Douglas Lawrence Karlen accounted for more than 40, 80, and 130% of the applied N, P, and K, respectively, at the 25, 50, and 100 cm load- ing rates provided that the entire plant was harvested. Removal of only the grain substantially reduced nutrient recovery. Analysis of soil profile samples indicated that the application of low K municipal effluents may result in a depletion of the exchangeable K unless supplemental ferti- lizer is applied. Sodium adsorption ratios and exchange- able sodium percentages indicated that there would be no problems due to excessive Na adsorption. The soil water balances indicated substantial water losses through deep percolation, and therefore a potential for leaching large quantities of the unrecovered N from the soil profile. The C1 distribution in the soil profile following the application of 100 or 200 cm of simulated effluent confirmed the leaching potential, but the Cl/NO3 ratios suggested that denitrification rather than leaching ‘was the primary mechanism for the removal of unrecovered N. RENOVATION ( TmeGH GROfllOT 1“ Patti Depar RENOVATION OF SIMULATED MUNICIPAL WASTEWATER THROUGH INTENSIVE IRRIGATION OF CORN GROWN ON A TILE DRAINED CONOVER LOAM by Douglas Lawrence Karlen A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Crop and Soil Science 1975 \ To Linda I wish to ac'. support and guidance lichigan State Unive Gratitude is any discussions am I sincerely Kidder for their as My apprecia Shields, Robert Bus chemistry staff for to Glenn Raines, D.- farm crew for thei' My thanks Fich, and the othe in these endeavors ACKNOWLEDGEMENTS I wish to acknowledge Dr. M.L. Vitosh for his support and guidance during my entire M.S. program at Michigan State University. Gratitude is expressed to Dr. R.J. Kunze for the many discussions and suggestions during this study. I sincerely thank Dr. 3.0. Ellis, and Professor E.H. Kidder for their assistance on my guidance committee. My appreciation is extended to Mrs. Elizabeth Shields, Robert Busch, and other members of the soil chemistry staff for their assistance in the laboratory, and to Glenn Raines, Dallas Hyde, and other members of the farm crew for their assistance in the field. My thanks and encouragement is extended to Russ, RiCh. and the other graduate students for their fellowship in these endeavors. ii ZERODUCTION . LITERATURE REVIEV History 1 Current ; Characte Phy Che Bic Loading Water B; Renovat TABLE OF CONTENTS INTRODUCTION . LITERATURE REVIEW METHODS RESULTS History of Land Disposal . Current Status of Land Disposal Characteristics of Municipal Effluent. Physical Characteristics Chemical Characteristics Biological Characteristics Loading Capacity Water Balance . . Renovation Capacity Particulate Matter Bacteria and Viruses Nitrogen Phosphorus . . Exchangeable Cations Chloride . . . Nutrient Content of Drainage Water . AND MATERIALS Description of Experimental Site . Soil Water Balance . . Water Sampling and Analysis Plant Sampling and Analysis Soil Sampling and Analysis Statistical Analyses AND DISCUSSION . Effluent Characteristics Site Characteristics Hydrologic Balances Drainage Water Volume and Nutrient Concentration. 44 Nutrient Loss Through tile Drainage Water Nutrient Composition and Recovery Through Plant Uptake . Soil Analysis iii 36 36 36 36 . 52 . 55 66 TABLE OF CONTENTS (Continued . SUMMARY AND CONCLUSIONS . APPENDIX . LIST OF REFERENCES . iv In. I she Effluent Cc Annual app] as influenc Simulated 1: Soil water of 25 cm 0: Soil water of 50 cm 0 on corn . 3011 water Of 100 cm on com 8011 watEI of 200 cm on corn Table 10. ll. 12. LIST OF TABLES Effluent Composition . Annual application of N, P, K, Na, and Cl as influenced by the loading rate of simulated municipal effluent ... Soil water balance for an annual loading of 25 cm of simulated municipal effluent corn Soil water balance for an annual loading of 50 cm of simulated municipal effluent on corn . Soil water balance for an annual loading of 100 cm of simulated municipal effluent on corn . . . . Soil water balance for an annual loading of 200 cm of simulated municipal effluent on corn Potassium concentrations in drainage water as influenced by the loading rate of simulated municipal effluent . SAR of drainage water and corresponding ESP as influenced by loading rate of simulated municipal effluent . Nutrient loss through tile drainage water as influenced by annual loading rate of simulated municipal effluent . Potential nutrient losses through deep percolation as influenced by annual loading rate of simulated municipal effluent . Nutrient concentration in corn ear leaf samples as influenced by hybrid . Nutrient concentration in corn ear leaf samples as influenced by annual loading rate . V Page . 37 . 38 . 39 . 40 . 41 . 42 . 53 . 53 . 56 . 56 . 58 . 59 LIST OF TABLES (Contin‘ Za'tle re.) '__a - Corn silage yi loading rate , Corn silage yi Nutrient uptal as influenced Corn grain yi loading rate Com grain yj as inf luencec Vinter ry6 a rate . DistribUtion as i1115-]-1).€I1(:e as influence 118T OF TABLES (Continued . . .) Table 13. 14. 15. 16. l7. 18. 19. 20. 21. Corn silage yields as influenced by annual loading rate . Corn silage yields as influenced by hybrid . Nutrient uptake and recovery in corn silage as influenced by annual loading rate . Corn grain yields as influenced by annual loading rate . Corn grain yields as influenced by hybrid Nutrient uptake and recovery in corn grain as influenced by annual loading rate . Yield of and nutrient concentrations in winter rye as influenced by annual loading rate . Distribution of NH --N in the soil profile as influenced by y ar, season, and depth . Distribution of N0 --N in the soil profile as influenced by y ar, season, and depth.. vi Page 61 61 62 64 64 67 68 70 70 Figure 1o. 11‘ C'COSS—g System Concen‘ (1974) Hour-1: Water Nessa Watel We ek Week 1113 app “31: Eat aP En: CZ a1 1‘; Figure 10. 11. LIST OF FIGURES Cross-section of the tile flow monitoring system . Concentration of NO3-N in drainage water (1974) Nitrogen loss through drainage water (1974) Hourly concentration of P in tile drainage water (1974) Weekly concentration of P in tile drainage water (1974) Weekly P losses in tile drainage water (1974). Weekly loss in tile drainage water (1974). Distribution of N0 and Cl following the application of 25 End 50 cm of simulated municipal effluent in 1974 . . . Distribution of N03 and C1 following the application of 100 and 200 cm of simulated municipal effluent in 1974 . Cl/NO ratio in soil profile following the appliéation of 100 and 200 cm of simulated municipal effluent in 1974 . . . . . Distribution of K and Na in the soil profile before and after two years of irrigation with simulated municipal effluent at 200 cm per year . vii Page 32 46 47 49 50 51 54 72 73 74 75 The Federal 1972 encouraged the disposal techniques advanced wastewater eater pollution. I since it was first period. Large sca‘. teas, which are cu‘ liter through crOp ‘39 in need of inf 3.3th loading ra 5W Within the U “Wit? 0f the so cal properties of hes INTRODUCTION The Federal Water Pollution Control Amendments of 1.972 encouraged the development and utilization of land disposal techniques as alternatives to conventional and advanced wastewater treatment in the prevention of surface water pollution. Land disposal is not a new technique, since it was first practiced in Athens during the B.C. period. Large scale municipal wastewater renovation sys- tems, which are currently being designed to renovate waste- water through crop irrigation on limited land resources, are in need of information regarding (a) the maximum and optimum.loading rates for the various soil types and crops found within the United States, and (b) the renovation capacity of the soil and changes in the chemical and physi- cal properties of the soil system which are influenced by these management practices (Pound and Crites, 1973a; Ramsey, Wetherhill, and Duffer, 1972). The Dow Report (1972) recommends an annual applica- tion of 175 cm of municipal effluent on a loam soil with a permeability of 0.5 cm/hr. Ellis et a1. (1972) concluded that applying more than 88 to 100 cm of effluent per year would overload this type of soil, causing the entire bio- system to lose its renovation capacity. Erickson (1972) concluded that the greatest research need in land treatment 1 2 of effluents as it affects the physical changes in soils and crop yield is for field experiments with effluent application on medium to fine textured soils which have adequate artificial drainage. The objectives of this research were: (1) to field test the hydraulic capacity of a medium-textured soil which has adequate artificial drainage in land disposal of muni- cipal wastewater; (2) to determine the maximum hydraulic loading rate at which the biosystem would continue to function as a living filter, producing an economic crop yield, and making efficient use of the applied nutrients; and (3) to trace the fate of the applied N, P, and other nutrients in the effluent. Land di: Athens during t1 enich was the s: posal, was also sixteenth and n sewage farms we out creating in 1972; De'I‘urk, 1 Land di late nineteenth only for irriga Were Started in rEgions of Cali WPUIations a LITERATURE REVIEW History of Land Disposal Land disposal of wastewater was first practiced in Athens during the B.C. period. Irrigation on farmland, which was the simplest method of waste treatment and dis- posal, was also practiced in Europe and England between the sixteenth and nineteenth centuries. Properly managed, these sewage farms were able to benefit from the nutrients with- out creating insect or odor problems (Metcalf and Eddy, 1972; DeTurk, 1935). Land disposal in the United States began in the late nineteenth century. Wastewater was initially used only for irrigation; however, groundwater recharge projects were started in the early twentieth century in the semiarid regions of California and Utah. Wastewater irrigation in the East began to decline at this time because of rising pOpulations and increased land value. Today those crude sewage farms of the 1890's have been replaced by managed farms which utilize treated muni- cipal wastewater for crop production and groundwater re- charge (Pound and Crites, 1973b). Current Status of Land Disposal The Federal Water Pollution Control Act Amendments of 1972 created new interest in land disposal of waste- waters by implementing the national goal of eliminating the discharge of pollutants into navigable waters by 1985. Several points within the law encourage the utilization of land disposal techniques as alternatives to conventional and advanced wastewater treatment in the prevention of surface water pollution (Pound and Crites, 1973a). Parizek, et a1. (1967) carried out extensive studies at Pennsylvania State University to determine the degree of effluent renovation, the potential conservation of water, and the effect of municipal effluent on soils, crops, trees, and wildlife. They concluded that if properly managed, the soil system provides an effective method for effluent renovation and should be given consideration during the expansion of municipal waste treatment facilities. Day, Tucker, and Vavich (1962) concluded that ‘municipal effluent is a suitable source of irrigation water for the production of many small grains and forages in the semiarid southwest. Sopper (1970) demonstrated that municipal effluents and sludges could be used to restore strip—mined soil banks to a more esthetic and productive state. Pennypacker, Sopper, and Kardos (1967) reported that municipal effluents have been successfully disposed of by applying them.to forest land. They concluded that land disposal of municipal effluent offers a solution to both water pollution and water supply problems which plague many areas of the country. Current technology lacks sufficient information in many areas of wastewater disposal. Questions which remain unanswered include (a) the characteristics of municipal effluent, (b) the maximum and optimum loading rates for various soil types and crops found within the United States, and (c) the renovation capacity of the soil and the chemical and physical changes within the soil system which are influenced by land disposal of wastewater (Pound and Crites, 1973a; Ramsey, Wetherhill, and Duffer, 1972). Characteristics of Municipal Effluent Ellis, et a1. (1972) reported that before the impact of wastewater disposal on a soil system.can be evaluated, it is essential to know the characteristics of the effluent. The characteristics of municipal effluents may be classified as physical, chemical, and biological. Pound and Crites (1973b) found that the constituents of raw sew- age and the subsequent treatment plant effluents depend upon (1) the quality of the municipal water supply, (2) the industrial mix of the community, (3) the proportion of com- mercial to residential development, and (4) the nature of the residential community. Physical Characteristics Total dissolved solids (TDS) is the most important physical characteristic of wastewater. This includes floating, suspended, colloidal, and dissolved matter. The solids are important because they have a tendency to clog soil pores and coat the land surface. However, under proper management, these problems can be minimized (Pound and Crites, 1973b). Other physical characteristics include temperature, odor, and color. The temperature of municipal effluent ranges between 50 and 70°F which is not harmful to the soil or vegetation. Parizek, et a1. (1967) found that during the winter the wastewater had a beneficial thawing effect on the soil and that it formed an insulating ice coat which protected crops from the cold air. Effluent color had no effect when applied to crops. Odors in wastewater are caused by the anaerobic decomposition of organic matter. Hydrogen sulfide is the primary cause, although other vola- tile compounds may be present (Pound and Crites, 1973b). Chemical Characteristics Pound and Crites (1973a) divided the chemical proper- ties of wastewater into three categories: organic matter, inorganic matter, and gases. Municipal water supplies rarely contain large quantities of organic matter. Therefore, almost all of the organic compounds found in effluents either entered during 7 use or were formed during secondary treatment. Effluent organic matter is both soluble and particulate in nature (Hunter and Kotalik, 1973). Principal organic compounds found in wastewater include proteins, carbohydrates, fats, and oils. These substances are usually found in small quantities and have no short term effects on the soil or vegetation. Long term effects have not been adequately determined (Pound and Crites, 1973b). The primary inorganic constituents of wastewater include N, P, K, Ca, Mg, Na, and Cl. However, elements such as B, Cd, Cu, Ni, Pb, and Zn may be present in toxic quantities in some effluents. Gases found in wastewater, with the exception of those causing odor problems, are relatively unimportant in land application. Dissolved oxygen in the wastewater is rapidly depleted soon after application; therefore atmos- pheric oxygen must be utilized to maintain aerobic soil conditions (Pound and Crites 1973b). Biological Characteristics The biological composition of municipal effluents originates in the sewage entering the treatment plant. Bacteria are the predominant microorganisms, although viruses, fungi, protozoa, nematodes, and other miscellaneous organisms have been found in secondary effluents. 8 Secondary treatment removes some bacteria and viruses by flocculation and secondary sedimentation. Dis- infection using heat, ozone, bromine, iodine, or, most commonly, chlorine is the primary method of reducing the number of organisms in the effluent (Hunter and Kotalik, 1973; Pound and Crites, 1973b). The biological composition of wastewater leads to some public apprehension about land disposal because of the potential for spreading pathogenic organisms. Foster and Engelbrecht (1973) found very little information on irriga- tion-caused epidemics when reviewing the microbial hazard of applying wastewater to soil. They concluded that waste- water should not be applied where underlying bedrock con- tains fractures or channels which would allow pathogens to move long distances, and that there should be at least two months between the last irrigation and the harvesting of edible crops. Loading_Capacity Pound and Crites (1973a) found that the loading capacity of a land disposal system could be exceeded by excessive hydraulic, nitrogen, or organic loading rates. The hydraulic capacity of a land disposal system is determined by the texture and structure of the soil, the depth to the existing water table, the crOp, the cli- mate, and the wastewater characteristics. 9 Hydraulic overloading will result in lower crop yields, anaerobic soil conditions, odors, and reduced renovation of the wastewater. If the soil filter ceases to function because of overloading, it may be rejuvenated by allowing it to drain and dry out. Usually after such a rest period, the soil filter will function adequately, provided the loading rates are reduced (Kunze, 1972). The importance of not overloading the soil system was demonstrated by Shields, Ellis, Kunze, and Wolcott (1972, paper presented at the Annual ASA Meetings, Miami, Florida). The wastewater which was used for their study was spent (NH4)ZSO3 liquor from the Menasha Paper Company. The effluent contained about 1% solids which is much higher than normal secondary effluent; however, the problems which they observed in a 60-day study may be applicable to long term sewage disposal projects. The effluent was applied to a Spinks loamy sand and a Morley silty clay loam at rates of 0.25, 0.5, and 1.0 inches per day. Both soils accepted the maximum loading rate for 3 to 5 weeks. How- ever, as the soil became overloaded surface slimes developed and the aggregates of the Morley soil were dispersed. The dispersion resulted in surface clogging, reduced infiltra- tion rates, anaerobic conditions, and crop failure. Run- off approached 85% of the daily input toward the end of the experiment. Pound and Crites (1973a) found that municipal effluents usually contain very small quantities of organic 10 matter. Therefore, the problems associated with the dis- posal of paper mill waste probably will not be present for land disposal of municipal effluents, unless the soil sys- tem becomes hydraulically overloaded and anerobic conditions develop. Excessive organic loading can be prevented by following an intermittent application schedule and allowing time for the aerobic decomposition of organic matter. Coarse textured soils tend to have greater in- filtration and percolation rates. Therefore, N loading rather than hydraulic loading will limit wastewater disposal on these soils. Nitrogen loading has been defined as the pounds of applied N per acre per year. It has been calculated because of the potential build-up of nitrate in soils, drainage waters, and groundwater. This build-up can be minimized by limiting the pounds of total N applied to the amount removed by cover crops (Pound and Crites, 1973a). Medium-and fine-textured soils have smaller hydraulic conductivities; however they also have a greater surface area. Therefore, the water has a longer residence time and the soils have a greater capacity to adsorb nutrients and filter wastes from the water (Kunze, 1972). V Various rates of effluent application have been reported. Pound and Crites (1973a) reported that loading rates for sprinkler irrigation of municipal wastewater ranged from.l.5 to 4.0 inches per week. Parizek et al. (1967) 11 applied effluent at rates of 1,2, and 4 inches per week on forest and agronomic land. An established gamelands area, having mixed hardwood vegetation, received rates of 2 and 4 inches per week throughout the summer and 6 inches per week during the winter. Bauer and Matsche (1973) reported that the Muskegon Project was being designed for a 30 week irrigation season with an average loading of 3 inches per week, however maximum applications of 4 inches per week were anticipated. R.L. Cook (personal communication) observed that under these loading rates the corn crop suffered from a severe N deficiency. He suggested that this was probably due to a low nitrogen effluent (5 ppm) being applied at rates sufficient to leach the nitrate nitrogen from.the profile before the plant could recover it. Water Balance The water balance in the soil profile influences the hydraulic loading capacity of the soil system. In its simplest form.the soil water balance in a given volume of soil is merely the difference between water gains and losses (Hillel, 1971). When water is applied to the land surface through rainfall or irrigation it may follow many paths. It may be intercepted by vegetation and returned to the atmosphere, infiltrate the soil surface, or run off along the ground surface (Carey, 1972). 12 Kunze (1972) defined infiltration as the movement of water into the soil. Water which enters the soil is then held in capillary pores or percolates through the profile and becomes a part of an existing water table. This water eventually flows into a nearby drain tile or ditch; how- ever if no impermeable strata exist near the soil surface the water will eventually become a part of a deeper aquifer. The rate of infiltration varies with soil, soil moisture, sprinkling intensity, and time. The infiltration rate decreases with time until the final infiltration capacity is reached. If this rate is exceeded, water will begin to pond on the surface or to trickle downslope as run off. The final infiltration rate will be profile- controlled if sprinkling intensity exceeds the infiltration capacity; however, if the intensity does not exceed this capacity, infiltration will be controlled by the supply rate (Kunze, 1972). Carey (1972) defined percolation as the movement of water in soil beneath the ground surface but above the water table. Percolation may occur as either saturated or as unsaturated flow. Saturated flow is governed by the same parameters as groundwater flow, namely hydraulic con- ductivity and gradient. Unsaturated flow is essentially two-phase fIOW‘With both water and gas occupying the pores. The presence of air in the pores reduces the specific permeability by a factor between 0 and 1 depending upon the percent satur shown that 80 specific perm Both upon permeabi structure. T percolation . In a percolation 1 Various soil Ederlies a II develOp, Thi gradients and larger area. the Surface 11 1972), EVapc cesses throng E~,raP0ratiOn ( Kass eXceedS severally hig 13 percent saturation of the soil. Experimental data has shown that 80% saturation was required before the unsaturated specific permeability reached 50% of the saturated value. Both saturated and unsaturated flow are dependent upon permeability which is determined by pore size and soil structure. Therefore, soil type ultimately controls percolation. In a heterogeneous medium such as glacial till, percolation is dependent upon the stratification of the various soil types. If a soil having a lower permeability underlies a more permeable material a recharge mound may develop. This will result in the development of radial gradients and the spreading of the percolate over a much larger area. Similarly, a layer with low permeability near the surface may result in surface ponding and runoff (Carey 1972). Evaporation and transpiration are the primary pro- cesses through which water returns to the atmosphere. Evaporation occurs whenever the vapor pressure of a water mass exceeds the vapor pressure in the adjacent air. It is generally higher with increasing air and water temperatures, however only because of greater vapor pressure differences. Wind usually favors evaporation by removing saturated air and replacing it with air capable of taking up more water; however, it may reduce evaporation by hindering the transfer of the latent heat of vaporization (Carey, 1972). l4 Evaporation from moist soils requires more energy than evaporation from open water bodies due to the forces between the water and the soil particles. In an un- saturated soil, evaporation will cease when a thin layer of soil at the surface has lost its moisture. However, when the soil is saturated moisture migration under capillary forces continues to replace the water and evaporation con- tinues as long as vapor pressure differences exist (Carey, 1972). Transpiration is the same phenomena as evaporation except that the water escapes from moist pores and membranes in plants. Most transpiration occurs through leaves where it operates to bring nutrients and to maintain favorable leaf temperatures. Shaw and Laing (1965) defined evapotranspiration as the Water used by a crop. This consisted of both soil evaporation and plant transpiration. They found that the quantity of water used by a crop is dependant upon the amount of plant cover. Under a partial canOpy, water use was usually much lower due to a reduction in the water available for surface evaporation. Climatic factors such as temperature, solar radi- ation, and wind, along with the amount of available soil moisture ultimately determine the amount of water returned to the atmosphere. The amount of solar radiation an area receives is the primary climatic control, however, the Great Lakes and variation climate. rental an season is hated thr about 31 the relat the Slime Gilly node Curing ch. litter (M later. I" oxidatiOn 15 variations in topography greatly influence Michigan's climate. The climate at Lansing alternates between conti- nental and semimarine. The average length of the growing season is 154 days. Precipitation is fairly well distri- buted throughout the year with an annual accumulation of about 31 inches. During the winter cloudiness prevails and the relative humidity remains rather high, however, during the summer sunshine is abundant and relative humidity is only moderate. Winds are predominantly southwesterly during the summer and west to northwesterly during the winter (Michigan Weather Service, 1971). Renovation Capacity The soil system is a complex treatment zone where many physical, chemical, and biological processes and inter- actions contribute to the renovation of the applied waste- water. The major renovation mechanisms include plant uptake, oxidation, reduction, adsorption, precipitation, ion ex- change, and filtration (Pound and Crites, 1973a). The solubility of various mineral phases in the soil ultimately controls the compositions of the soil solution; however, kinetic and thermodynamic factors must also be considered for many reactions which have sufficiently slow rates of precipitation and dissolution (Lindsey, 1973). Particulate Matter The filtration mechanism of the soil matrix separates the suspended organics from.wastewater as it 16 infiltrates the soil. McGauhey and Krone (1967) found the inert and organic particulate matter was effectively removed by the top 5 to 6 inches of soil. Bacterial oxida- tion then destroys the trapped particles, thus eliminating the biodegradable organics from the percolate (Pound and Crites, 1973a). Refractory organics such as phenols, fats, tannins, pesticides, and humic substances are broken down more slowly; however, physical entrapment and chemical adsorption of these compounds within the soil matrix should provide the necessary retention time for effective microbial degradation (Miller, 1973). Bacteria and Viruses Bacteria found in wastewater behave like other particulate matter and are removed by straining, sediment- ation, entrapment, and adsorption. They are also subject to die-off when introduced into an unfavorable environment. Enteric pathogens, however, may survive and retain their virulence for about 2 months provided there is sufficient organic matter in the soil (McGauhey and Krone, 1967). Viruses are removed by the soil matrix primarily by adsorption; however, the survival times of adsorbed viruses have not been explored (McGauhey and Krone, 1967). Nitrogen Ammonia and NH4--N in wastewater are formed by the hydrolysis of urea and the biological decomposition of N containing organic compounds (Hunter and Kotalik, 1973). 17 When sewage effluent is applied in small amounts, the soil will remain predominantly aerobic and the NH3 or NH+4 will be oxidized by microorganisms to No-3. Under these conditions the fate of this N will be about the same as fertilizer N, i.e., about 50% taken up by plants, 25% lost through denitrification, and the remaining 25% lost through processes such as biological immobilization, NH3 volatilization, or leaching (Bouwer and Chaney, 1974, unpublished manuscript). The U.S. Department of Health, Education, and Welfare (1962) established a limit of 10 mg/l NO3--N as the safe level for N03 in drinking water. Therefore, the efficiency of wastewater renovation.with respect to N has been measured by determining the N03 concentration in the soil percolate. Kardos and Sopper (1973a) used suction lysimeters to sample the soil solution. They reported that at hydraulic loading rates greater than 1 inch per week the N03 concen- tration 48 inches beneath a corn crop exceeded 10 mg/l. Plants can recover substantial amounts of the applied nitrogen. Allison (1966) found recoveries in the crop varied widely with growth conditions and cropping sys- tems. Recoveries in a single harvested crop, grown under optimum field conditions, usually will not exceed 50 to 70% of the applied N and are often below these values. Sopper and Kardos (1973) reported that two corn hybrids recovered more than two times the amount of N applied at the 1 inch per week irrigation rate, and more I. J the crop the: coat cf? 11g 1974 18 than 100% of the applied N at the 2 inch per week rate. They also reported that reed canary grass, wheat, oats, alfalfa, and red clover could recover significant amounts of N provided that the loading rates were not much higher than the fertilizer requirements of the crop. This was also true for a mixed hardwood forest, plantations of red pine and white spruce, and an abandoned field with a vegetative cover of herbaceous annuals and perennials. Denitrification is the most important process for the removal of N applied with the wastewater in excess of crap requirements (Lance, 1972). Losses may be higher where wastewater is more frequently applied than under normal agricultural practices. The higher soil moisture content inhibits diffusion of 02 and organic C in the effluent may be used as an energy source by the denitrify- ing bacteria (Broadbent and Clark, 1965; Bouwer and Chaney, 1974, unpublished manuscript). Denitrification requires the presence of N03 and organic C under anaerobic conditions. Therefore, since most N in wastewater is in the NH3 form an aerobic phase in the soil is essential for the conversion of the N to N03. During this process, the organic C in the effluent will also be oxidized by hetertrophic aerobic bacteria. Secondary municipal effluents usually contain relatively small amounts of C. This may limit denitrification when the wastewater moves into an anaerobic zone since 19 approximately one milligram of organic C is required for each milligram of NO3 that is denitrified. If organic C is limiting, it may be added by incorporating crop residues or adding C sources to the wastewater (Bouwer and Chaney, 1974, unpublished manuscript). The effect of organic matter on denitrification is twofold. It serves as an energy source for the denitrify- ing bacteria, and its decomposition influences the 02 demand within the soil. Root secretions by living plants also influence denitrification. The rhizosphere organisms which break down these secretions consume 02 and the secretions themselves may serve as H2 donors in denitrifica- tion (Broadbent and Clark, 1965). The actual quantity of N lost through denitrifica- tion is difficult to determine. Allison (1966) reported . that several lysimeter studies indicated losses of 15% of the fertilizer N; however, this included volatilization losses in addition to denitrification losses. Broadbent and Clark (1965) reported that denitrification losses in excess of 50% of the applied N have been encountered. Broadbent (1973) reported that in an uncropped column study using tagged (NH4)ZSO4 and applying 3 inches of water per week, more than 85% of the soluble N was unaccounted for. Therefore, he concluded that the N in the soil solution which is not intercepted by plant roots probably would not move into the water table, but would be denitrified. fin I i 41 20 Nitrogen losses may also occur through NH3 volatili- zation, or biological immobilization and incorporation into organic matter. The amount of N which is lost through NH3 volatili- zation is difficult to determine, however, Gardener (1965) reported that this loss has been found to be related to the loss of water through evaporation. The upward movement of water helps transport NH3 to the soil surfaces, where the conditions which favor evaporation also favor the volatili- zation of NH3. The decomposition of plant materials usually results in changes in the quantity of organic N within the residue. Low N residues tend to increase in organic N content if N is available in excess of that contained in the residue; however, high N residues such as legumes may decline in organic N content (Bartholomew, 1965). Corn stalks, cereal straws, and grasses are inter- mediate in N content, ranging between 0.5 and 1.5%. The organic N content of these materials usually increases during the early stages of decomposition. After a short period a residue containing organic N is formed. This organic N appears to be biologically stable since net mineralization is very slow. The magnitude of this immobili- zation can be estimated as follows. Corn stover and cereal straws may contain about 0.75% N or 15 pounds per ton of residue. During decomposition 20 to 25 pounds of N may be required to satisfy the needs of the microbes which effect 21 the decay. Therefore, this biological process results in a net tie-up of 5 to 10 pounds of the N which is added or be- comes mineralized from.the organic matter (Bartholomew, 1965). Phosphorus Municipal effluents usually contain about lOmg/l total P. Orthophosphate is the primary form found in wastewater. Condensed polyphosphates and organic forms are rapidly con- verted to this form during primary and secondary wastewater treatment or when applied to the soil (Murrman and Koutz, 1972). Phosphorus renovation occurs primarily by adsorption, precipitation, or plant uptake. Soils should adsorb P until their adsorption capacity has been reached; however, Ellis and Erickson (1969, unpublished report to the Michigan Water Resource Commission) reported that the level of P in waste- water was not sufficient to utilize the entire adsorption capacity of many soils. Precipitation mechanisms may control the amount of P in solution at both high and low pH ialues. Lindsey and Moreno (1960) utilized the solubility products of various P compounds to predict the formation and stability of various Ca, Fe, and Al phosphates that may form.under various soil conditions. Iron and Al phosphates are precipitated in acid soils and therefore control P solubility at low pH, however, most wastewaters have pH values greater than 7.0 and therefore P solubility will probably be controlled by m Vi. ‘1“ A :‘n\ EEC Ab l'Ec cite Elli] II .11 II.) a. i‘ f H‘ 22 calcium phosphates such as dicilcium phosphate and octa- calcium phosphate. Ellis (1973) reported that hydroxy- apatite and fluorapatite form too slowly to have any effect on the precipitation of P from.wastewaters. Hook, Kardos, and Sopper (1973) and Sopper and Kardos (1973) reported that the amount of P taken up by cover crops accounts for a large part of the total P applied during irrigation with municipal effluents. They reported that when corn was used as a cover crop, annual P recoveries at the l in/wk loading rate ranged between 39 and 230% of the applied, while at the 2 in/wk loading rate recoveries ranged from between 21 and 143% of the applied. When reed canary grass was used as a cover crop it removed slightly more P than the agronomic craps; however, the recoveries accounted for only 24 to 63% of the applied P due to a greater hydraulic loading rate which increased the annual P application. Kardos and Sopper (1973a) reported that below 6 inches, there was no significant increase in the P concen- tration of the soil profile. Soil water samples taken with suction lysimeters at the 48 inch depth showed that the P concentration had decreased 98.6 to 99.8% at the l in/wk loading rate and 98.1 to 99.6% at the 2 in/wk loading rate. This confirmed that the P in the wastewater was being removed through plant uptake, precipitation, or adsorption, and that it was not moving out of the soil profile into surface or ground waters. 23 Exchangeable Cations The principal exchangeable cations in municipal effluents are Ca, Mg, K, and Na. These ions with the ex- ception of Na are not expected to constitute any great hazards, since they are abundantly present under natural soil conditions. Various ion exchange reactions in the soil slow the downward movement of these ions; however, with continued leaching some will eventually enter the drainage water (Lindsey, 1973). The recovery of these cations is not too important because of their natural abundance and their relatively unimportant role in the eutrophication of surface waters; however, Sopper and Kardos (1973) have computed the annual uptake of these ions by silage corn and reed canary grass. They found that at the l in/wk loading rate uptake in the corn crop accounted for 195 to 280% of the K, 25 to 38% of the Ca, 41 to 53% of the Mg, and l to 2% of the Na applied during the year. At the 2 in/wk loading rate up- take by the corn crop accounted for 114 to 130% of the K, 16% of the Ca, 28% of the Mg, and 1% of the Na applied during the year. Reed canary grass which received effluent at 2 in/wk throughout the year recovered 117% of the K, 9% cf the Ca, 19% of the mg, and 1% of the Na applied during the year. Potassium recoveries greater than 100% indicate a potential for the depletion of exchangeable and interlayer .K. Therefore, since wastewater usually contains very little K, 193. Tea] Rate 24 supplemental fertilization may be required to maintain optimum plant growth. The level of salt in sewage effluent is not high enough to affect more than the most sensitive plants. Corn, bromegrass, reed canary grass, and other medium salt tolerant crops should encounter no salinity hazard from wastewater irrigation (Ellis, et al. 1972). The physical properties of the soil may be suscept- able to degradation due to excess adsorption of monovalent ions from the wastewater. The exchange of Na for Ca is particularly important in the irrigation of soils. If the cation exchange complex becomes sufficiently saturated ‘with Na, dispersion of the soil will occur. This results in decreased infiltration rates and lower soil permeability (Ellis, et a1. 1972). Sodium.adsorption ratios (SAR) have been used to evaluate the possible hazards of irrigation water, and can easily be applied to wastewaters used for irrigation. The ratio predicts the Na hazard by comparing the relative con- centrations of Na, Ca, and Mg in the water. Continued irrigation with water having a high SAR value may lead to an accumulation of exchangeable Na and the formation of a soil having poor structure and low permeability (Richards, 1954). Day, Stroehlein, and Tucker (1972) reported that 14 3years of irrigating a Grabe silt loam with municipal waste- lwater resulted in a slight reduction in infiltration, and he] 9‘12 Ia C01 ('1') ..1 25 an accumulation of soluble salts, N03, and P04; however, the yields of various small grains were not reduced and minor changes in field crop culture were sufficient to correct any problems. The exchangeable sodium percentage (ESP) is an estimate of the exchangeable Na when a soil and a wastewater have reached a steady state. Exchangeable Na percentages greater than 15 would be considered very serious; however, even lower values may seriously impede infiltration and percolation in fine textured soils (Ellis, 1973). Henery, et a1. (1954) reported that in a three year study, municipal effluent containing 680 ppm Na increased the exchangeable Na to 2.37 meq per 100 grams of soil. Exchangeable Ca and Mg decreased significantly, however, exchangeable K remained unchanged. Reduced infiltration rates were not mentioned despite the high exchangeable Na content. Kardos and Sopper (1973b) reported a significant increase in exchangeable Mg and Na when wastewater was applied to a corn rotation. Exchangeable K and Ca showed no significant increases. Increases in exchangeable Mg, Na, and Ca were found in the forested areas, however, the effects of wastewater on exchangeable K were small and non- significant. Chloride The C1 concentration of municipal effluent is sufficient to result in excessive annual applications. 26 Kardos and Sopper (1973b) reported that the Cl concentration in the soil solution.was almost five times higher in the wastewater treated area than in the control area. Soils do not adsorb C1 to any extent. Ellis, et a1. (1972) suggested that a minimum hydraulic loading rate of l in/wk would be sufficient for leaching the C1 from the profile. Chloride is also removed by plant uptake. Sopper and Kardos (1973) reported that corn recovered 20 to 26% of the C1 at the 1 in/wk loading rate and 11 to 14% at the 2 in/wk loading rate. Reed canary grass removed 20% of the applied chloride. Nutrient Content of Drainage Water The quantity of nutrients found in the drainage water can be used to measure the renovation efficiency of land disposal systems. The N and P concentrations are of major concern from the standpoint of pollution. Nitrogen is important because it is a potential health hazard if large amounts of N03 enter potable water supplies. Phosphorus is important because of its influence on algal growth at concentrations as low as 10 ppb (Ellis, 1971). Ellis and Erickson (1971) found that very small .amounts of K leach despite its relatively high solubility. 'The quantities of Ca and Mg which are leached are primarily due to the weathering of limestone. 27 Ellis and Erickson (1971) and Johnston, et a1. (1965) reported that N03--N accounted for the largest amounts of N found in drainage water; however, N losses also occurred in the NH3 form, as N02, and organic N. The amount of N03 reaching the drainage tile is a product of three different processes: (a) the production of N03 in the soil, (b) the utilization of NO3 by the plant or other microorganisms, and (c) the movement of the N03 through the soil by percolating water. Ellis and Erickson (1971) found a greater fluctuation in the quantity of N leached, than in the concentration of N in the drainage 'water. They concluded that this could be attributed to the 'variability in the amount of drainage water. Thomas and Barfield (1974) reported that the NO3--N concentrations found in tile effluent may be an unreliable estimate of N losses from soils if the volume of tile flow does not account for the largest proportion of the total ‘water flow; Using a mass N balance to determine the N03 concentration in seepage water compared to the concentration in the tile effluent, they concluded that the N03 concen- tration in the nontile drainage was much lower than in the tile effluent. The results of their study suggested that there was an oxidized zone close to the tile lines which protected the N03 from denitrification. In the water that did not flow through the tiles the N03 concentration was apparently lower initially, or else it was reduced through denitrification as the water flowed through the soil. c'eoi ‘te T1115 28 Cast, Nelson, and MacGregor (1974) reported that denitrification rather than leaching or tile drainage was the primary mechanism responsible for the disappearance of unused fertilizer nitrogen. Johnston, et a1. (1965) concluded that the quantity of N and P discharged was related to the amount of applied fertilizer and the quantity of tile flow. Ellis and Erickson (1971) reported the level of P in drainage water was very low. They concluded that when soils were fertilized at recommended rates, nutrient losses through tile drainage would be very small. METHODS AND MATERIALS Description of Experimental Site The study was conducted on a Conover loam at the iMichigan State University Soils Research Farm at East Lansing. This soil which developed from loamy, calcareous till is nearly level with slopes of 0 to 2%, has slow surface runoff, has moderate to moderately slow permeability, and is somewhat poorly drained with water table fluctuations between 60 and 300 cm. The site had been tiled in 1970 at a depth of 105 cm and at spacings of 15m. Secondary municipal effluent was not available for this study. Therefore, a simulated effluent was prepared by injecting a solution of NaCl and 12-6-6 liquid fertilizer into irrigation water. Four rates of effluent irrigation (25, 50, 100, and 200 cm per year) and six corn hybrids (Michigan (M) 396, 'M402, or Pioneer 3780, M500, M511, M572, and Funks 4444) ‘were replicated three times in a split-plot design. The treatments were established over three adjacent tile lines to compensate for possible lateral flow. Each tile line and its drainage area of 557 square meters was then treated as a replicate. Effluent was applied at 0.78 cm/hour through a solid set irrigation system. Risers were placed every 9 meters 29 U! 30 along the laterals which were placed in the center of each replicate directly above the tile lines. Therefore, sprinkler spacings were approximately 9 x 15 meters. Two types of Rainbird sprinklers were used to give a uniform distribution over the entire plot. The three central sprinklers were full-circle heads with 9/64 inch nozzles while the end sprinklers were semi-circle heads with 3/32 inch nozzles. In 1973, a preplant mixture of paraquat and atrazine 'was applied to kill the bromegrass sod. To maintain optimum soil structure, the corn was no-till planted in 28 inch rows on May 14. Plant populations for the various hybrids are given in Appendix Table 22. A 16-16-16 starter fertilizer was applied at 280 kg/ha. This supplied the crop 'with 45 kg/ha N, P205, and K20. All additional nutrients ‘were supplied by the simulated effluent. Winter rye was planted following the harvest of silage corn. The rye which provided a nutrient sink for the fall and spring irrigations was mowed and plowed down as green manure in May of 1974. The field was disced, harrowed, and planted to corn on May 23. A 12-12-12 starter fertilizer was applied at 375 kg/ha and a pre-emergence lnixture of atrazine and alachlor was applied for weed control. Soil Water Balance A.soil water balance was determined by measuring 'water gains and losses throughout the growing season. Cla den ihr 31 Water gains included rainfall and the quantity of effluent an area received, while water losses included evapotrans- piration (ET), tile drainage, deep percolation and water storage. Rainfall was measured with a standard U.S. Weather Bureau rain gauge. The quantity of effluent which was applied was determined by the number of hours of irrigation. Evapotranspiration losses were estimated from Class A open pan evaporation according to the procedures developed by Shaw and Laing (1965). The volume of tile drainage was measured by replacing a clay tile with a plastic tube equipped with a 600 V-notch 'weir. This tube was connected to a plastic pail which functioned as a still well for a Stevens Water Stage Recorder (Figure l). A calibration curve developed for each weir was used to convert the change in head to the volume of flow. Water Sampling_and Analysis The tile drainage water was sampled several times throughout each flow period. These samples were analyzed for NOB-N, P, K, Ca, Mg, Na, and C1. The N03 concentrations were measured with an Orion specific ion electrode during 1973 and early 1974. However, 'when the Technicon Auto-Analyser became available, N03 was 1measured colorimetrically using the cadmium reduction method 32 Figure 1. Cross-section of the tile flow monitoring system. #4 4” N A Plastic Tile with 60 ° V - Notch Weir Q Pl as tic Pall fx, as S till Well _6_ Ste vans Water Stage Recorder in 33 of Henriksen and Selmer-Olsen (1970). This method was more desirable since it was more sensitive and it eliminated any potential Cl interference. The P concentration was measured colormetrically using ammonium molybdate and ascorbic acid for color development (Watanabe and Olsen, 1965). The K and Na concentrations were determined photo- metrically using a Coleman flame photometer while Ca and Mg concentrations were determined by atomic absorption using a Perkin-Elmer 303 spectophotometer. The Cl concentration was determined by using an Orion Cl specific electrode. Plant Sampligg and Analysis Ear leaf samples were taken at first silking to measure the nutritional status of the actively growing plant according to the sufficiency guidelines published by Jones (1973). Corn silage yields were determined by chopping a 15 meter row of each hybrid, and grain yields were deter- mined by picking and shelling two 15 meter rows. Winter rye yields were determined by chopping a 7.5 meter strip on each side of the irrigation line. Samples were oven dried for moisture determination, and then ground to pass a 40-mesh sieve for laboratory analysis. 34 Total N was determined by semimicro Kjeldahl analysis (Bremner, 1956b). The silage samples from 1973 and the winter rye samples were analyzed for P, Ca, Mg, Na, and K following a wet oxidation with nitric and perchloric acid (Jackson, 1958). The P concentration was determined colorimetrically utilizing ammonium molybdate and ascorbic acid for color development (Watanabe and Olsen, 1965). The K and Na concentrations were determined photo- metrically using a Coleman flame photometer, while Ca and Mg concentrations were determined by atomic absorption using a Perkin-Elmer 303 spectophotometer. Soluble C1 was determined by potentiometric titration 'with AgNO3 (La Croix, et a1. 1970). The ear leaf samples, grain samples, and the silage samples from.l974 were sent to the International Minerals and Chemical Corporation where they were analyzed specto- graphically for P, K, Ca, Mg, Na, Cu, Fe, Zn, B, Mn, Al, and Ba. Soil Sampling and Analysis Soil samples were taken in April and November of each year. Two cores per plot were taken to a depth of 270 cm and divided into the following increments for analysis (0-15, 15-30, 30-60, 60-90, 90-120, 120-150, 150- 210, and 210-270 cm). ' 35 The samples were air dried, sieved through a 10 mesh screen, and analyzed for NH4-N, NO3 + NO2 - N, extractable P, exchangeable Na, K, Ca, and Mg, and soluble C1. The NHa-N and N03 + N02-N concentrations were determined by direct steam distillation (Bremner, 1965a). Extractable P was measured colorimetrically with a Technicon Auto-Analyser II. The samples were extracted with 0.025 N NHAF-HCI as outlined by Bray and Kurtz (1945). However, the procedure was modified by using a 1:4 soil- solution ratio and by shaking for 5 minutes. Color develop- 'ment was accomplished by using ammonium molybdate and 1,2, 4-aminonaphthosu1fonic acid (Jackson, 1958). Exchangeable K, Na, Ca, and Mg were extracted with 1N NHAOAc. The K and Na concentrations were determined photometrically using a Coleman flame photometer, while Ca and Mg concentrations were determined by atomic absorption using a Perkin-Elmer 303 spectrophotometer. Soluble Cl was measured by shaking the samples with saturated CaSO4 for 30 minutes, and then measuring the conductivity with an Orion C1 specific electrode. Statistical Analyses All statistical analyses were performed on an CDC 6500 computer at the Michigan State Computer laboratory. The least significant differences (LSD) were calculated according to the procedures given by Steel and Torrie (1960). RESULTS AND DISCUSSION Effluent Characteristics The simulated municipal effluent had approximately the same inorganic nutrient composition as the secondary effluent produced at East Lansing's municipal waste treat- ment plant (Table 1). The concentration of heavy metals, organic and total carbon, and susPended solids in the secondary effluent was sufficiently IOW'SO that no attempt was made to simulate the potential effects of these con- stituents. The annual application rates of N, P, K, Na, and Cl are given in Table 2. Site Characteristics The experiment was established on one of the most uniform sites available, but measurements with piziometer tubes indicated large variations in the drainage character- istics of the soil profile. These variations can probably be accounted for by the natural heterogeneity of soils developed from glacial till and the very non-uniform drain- age patterns which often result. Hydrologic Balances Hydrologic balances were determined to trace the fate of the applied effluent at the various annual loading rates (Tables 3 to 6). 36 37 TABLE 1. Effluent composition. Constituent East Lansing's Secondarya Simulated ---------- mg/1'"-'-'_'-""'---"---'-'- Total N 15.2 15.0 Nitrate N 3.1 3.5 Total P 4.9 3.3 Soluble P 1.1 2.2 K 8.6 6.2 Na 130 130b Ca 100 200 Mg 25 62 Cl 260 zoobc a D'itri, F.M. (1973). b C In 1973 the simulated effluent contained 210 ppm Na and 324 ppm Cl. This was the amount of Cl added. The irrigation water had an additional 25 ppm Cl from natural sources. 38 TABLE 2. Annual application of N, P, K, Na, and Cl as influenced by the loading rate of simulated municipal.effluent. Treatment Ni"l Pa Ka Nab Clbc -------------- kg/ha --------------------- 25 cm 83 28 53 330 507 50 cm 121 36 69 660 1014 100 cm 197 52 100 1320 2029 200 cm 349 85 163 2640 4058 a Includes 45 kg/ha N, P205, K20 starter fertilizer. b In 1973 the Na applications were 319, 909, 1780, 3343 kg/ha, and the Cl applications were 492, 1401, 2744, and 5154 kg/ha at the 25, 50, 100, and 200 cm.loading rates, respectively. c Based on the amount of Cl added. . IV I HhuiHCPU H.~AIV ...U-hlwIHaNuh‘,lNrr‘ uvzfln fl....v Fun-inn- Ilvcn' 1051-.v-IP-suq “E .h Pi nII,.U Air-tad 154.4 #ufi-II-IINA;‘v~. ll"IdI-l.h!~ FlII‘ .fifll' h theiA-IH‘ IHAE ,Q'ULOH53 .§ \nvrad. II. .v.‘lN.H§l\l-‘., 39 .oHsHHmw aoumxm on one wouoafiummo .%QSoHowmmo aogumwwuuw Nooa wnflESmms n .amma .NH Honouoo was an HHHQ< consume osma.muaoEoH5mmmzu mm.“ mw.o mm.~m om.¢~ w~.¢m Hmuoy oo.o m¢.au oo.o mn.o oo.o mN.o mu oo.o Hm.0u oo.o aw.o oo.o ¢~.N «N oo.o Hm.mu oo.o mo.H oo.o NH.H mm oo.o mn.Ha oo.o mm.H mn.o oo.o Nu oo.o mm.on oo.o mo.H mm.o wn.H Hm oo.o mm.Hu oo.o mo.H wn.o .mm.a om oo.o um.uu oo.o mm.~ on.H mN.m ma oo.o Hw.¢u oo.o om.m om.H wo.o ma oo.o mn.~u oo.o mm.~ mm.H mw.m 5H oo.o Hm.mu oo.o «N.N om.a H¢.o 0H 00.0 an.¢n oo.o om.m om.a n¢.a ma oo.o ne.mu oo.o mn.~ om.H mm.o «H 00.0 ma.mu oo.o H~.¢ om.H oo.o ma oo.o mn.ou oo.o mm.~ cm.H mw.o NH mn.H oo.o oo. mn.~ on.a mm.~ HH oo.o o¢.on oo.o om.H on.H oo.o 0H mH.H oo.o oo.o 5H.H om.H Hw.o m oo.o no.0- oo.o wm.a wn.o mn.o m mm.o oo.o oo.o mm.a mn.o mm.H n mm.o oo.o oo.o mm.o om.H om.H o oo.o um.au oo.o No.H 00.0 00.0 m mN.m oo.o omm.o wo.H oo.o No.9 a 00.0 ou.o: oo.o no.a mn.o ¢¢.N m oo.o nn.Hu oo.o mN.N om.a om.o N 00.0 No.au oo.o No.H oo.o oo.o H IIIIII IIIII IIII...IIIIIIIIIIIIIIIIIIIIIIIII BU IIIII ... IIIIIIIIIIIIIIIIIIIIIIII coaumaooumm moon owmnoumaa 30am mafia Hm cowumeHHH Hawmcaum sums n m.anoo no uamsammo Homaoacsa smumaaanm mo 80 mm mo wsfismoa Houses am now dosages nouns Hwom .m mqmIM/r/6m o.H H.H .m ousmHm 51 some oumu mcHoMOH Eo oo~ moon mcHoooH EU ooH .anmHo Hopes omooHoHo oHHu :H mommoH m memoB OH om om ov om cm on om om .o ouomHm xM/eq/mfi 52 volume of tile flow than variations in concentration. Severe structural problems may result if the ex- changeable sodium percentage (ESP) is greater than 15 (Richards, 1954). The sodium adsorption ratio (SAR) of the simulated municipal effluent was approximately 3.0, which indicated that this water would have a very low sodium hazard. The SAR values of the drainage water support this, indicating that after two years of irrigation with this effluent the maximum.ESP was only 3.4 (Table 8). These values may increase slightly after more years of irrigation, however infiltration and percolation of rainfall and snow melt should insure that no structural problems will develop due to excessive sodium adsorption. Nutrient Loss Through Draingge Water Nutrient loss through the tile drainage water accounted for only a small amount of the applied N, P, and K (Table 9). Since tile flow accounted for only 1, 5, 13, and 8% of the rainfall and applied effluent at the 25, 50, 100, and 200 cm loading rates, respectively, there may have been a substantial nutrient loss through deep percola- tion. An estimate of this potential loss can be made by assuming (a) a uniform nutrient concentration in all of the soil water, (b) an irrigation efficiency of 100%, and (c) a uniform soil moisture content before and after the irrigation season. Therefore, deep percolation losses accounted for 13, 34, 48, and 70% of the rainfall and applied effluent at the 25, 50, 100, and 200 cm loading rates, 53 TABLE 7. Potassium concentrations in drainage water as influenced by the loading rate of simulated municipal effluent. Treatment 1973 1974 50 .. 12:; """ mg“ """"" 15:3" 100 cm 5.7 2.4 200 cm 9.8 4.3 TABLE 8. SAR of drainage water and corresponding ESP as influenced by loading rate of simulated municipal effluent. Treatment SAR ESPa 50 cm 1.4 0.8 100 cm 2.4 2.3 200 cm. 3.2 3.4 aEstimated from.SAR values using Figure 22, USDA Handbook No. 60. Weekly K loss in tile drainage water (1974). Figure 7. 100 cm loading rate 200 cm loading rate 0.9 54 CD I O I‘m In fl' OO O O 0.3 0.2 0.1 XM/PH/BX 24 12 l4 16 18 20 22 Week 10 55 respectively. By using the measured nutrient loss in the tile drainage, an estimate of the potential loss through deep percolation can be made (Table 10). These estimates may be'much greater than the real leaching losses. Mechanisms such as biological immobiliza- tion and denitrification often reduce NO3 concentrations in the percolate to a much lower concentration than is found in the tile drainage. The findings of Thomas and Barfield (1974) indicated that unless the overall picture of drainage is known, estimating N loss in this manner may be very unreliable. Estimates of P loss may also be significantly higher due to the short circuiting of some effluent into the tile lines and therefore a much higher mean P concentration in the drainage water than in the soil percolate. Irrigation efficiencies are rarely 100% due to losses through drift and evaporation. If these losses sub- stantially reduced the amount of water applied, i.e. 70 to 80% efficiency, less water would have been attributed to deep percolation. Therefore, the nutrient losses through leaching would also be reduced. Nutrient Composition and Recovery Through Plant Uptake The 1973 ear leaf analyses (Table 11) indicated that the corn hybrids were slightly deficient in K, within the normal range for N, Ca, Mg, Zn, B, and Mn, and slightly above the sufficiency range in P according to the guidelines 56 TABLE 9. Nutrient loss through tile drainage water as influenced by annual loading rate of simulated municipal.effluent. Treatment N P K -------------- kg/ha---------------------- 25 cm. 0.1 0.01 0.2 50 cm 1.3 0.05 2.9 100 cm. 14.8 0.28 4.9 200 cm 18.0 0.60 8.5 TABLE 10. Potential nutrient losses through deep percolation as influenced by annual loading rate of simulated municipal effluent. Treatment N P K ------------- kglha------------------------ 25 cm, 1.3 0.13 2.5 50 cm 8.8 0.34 19.7 100 cm. 101. 1.90 33.3 200 cm 153. 5.10 72.2 57 published by Jones (1973). The 1974 analyses indicated that the hybrids were deficient in both N and K, within the normal range for Ca, Mg, Zn, B, and Mn, and above the sufficiency range in P. The nutrient concentrations in the ear leaves showed significant treatment responses (Table 12). The N, P, Ca, Na, Zn, B, and Mn concentrations increased with in- creasing rates of simulated effluent, while K concentrations decreased and Mg concentrations remained constant. In 1973 N, Ca, Mg, Zn, B, and Mn concentrations were within the sufficiency range at all loading rates. The P levels were above the sufficiency range, while K levels were deficient at all rates of application. In 1974 N was deficient at all loading rates, but K was deficient only at the 100 and 200 cm.rates. The P concen— trations were within the normal range at the 25 and 50 cm loading rates, but slightly above at the 100 and 200 cm rates. The Ca, Mg, Zn, B, and Mn concentrations were with- in their sufficiency ranges at all loading rates. The treatment x hybrid interactions showed no significant differences. Corn silage yields (Table 13) showed significant treatment differences in both 1973 and 1974. Yields were maximized at the 50 cm.loading rate, with only a slight reduction at the 200 cm rate of application. The 100 cm loading rate resulted in a significant yield reduction in 58 mammaoo comm oonHuuoo cmmHoonuuz .mamaaoo comm HmoGOHmusmo .zamqaoo ovum mxadmuumu n .muaoaumouu HHm mmouom omwmno>. \. ....~ \ _ _ , .r // . .... / o 0000 // /o toss”. / / / .Hmmh Hmm EU com um ucmsammm HmmfimHGSE wmumHflfiwm nuHB coaummfluufl mo mummw oBu Hmumm 6cm mHommn mHHmon HHOm may CH mz cam M «0 aoflusnfinumwo Ohm mNN omH mma om mv .HH mnnmflm 1110 76 snow melt had reduced it during the winter months. This indicates that the soil system had reached an equilibrium with the applied effluent, and that as the SAR had indicated there probably would not be any structural problems due to sodium. The progressive decline in exchangeable K indicates that if municipal effluents which are usually low in K are to be renovated through land disposal, supplemental K must be applied to maintain optimum plant growth and nutrient uptake. SUMMARY AND CONCLUSIONS A field study was conducted to determine the possible effects of renovating municipal effluents through intensive irrigation of corn grown on a tile drained loam soil. Municipal effluent was not available at the experimental site, therefore a simulated effluent having an inorganic nutrient composition similar to that of East Lansing's munici- pal effluent was used. The effluent was applied at graduated weekly rates so that the total application would be 25, 50, 100, or 200 cm per year. Seven corn hybrids were evaluated for silage and grain yield, and for nutrient uptake under these management practices. From the results of this study the following conclusions can be made. 1. To insure efficient utilization of the applied nutrients through plant uptake, the annual loading rates should not exceed 100 cm of supplemental effluent. If the entire corn plant was harvested, uptake accounted for at least 40, 80, and 130% of the applied N,P, and K, respectively, at the 25, 50, and 100 cm loading rates. 2. The renovation of municipal effluents applied to soils formed from glacial till may be complicated by the natural variability of these soils and the non-uniform drainage patterns which often results.A short circuiting of the effluent through the sand smears may result in substantial 77 78 nutrient loss through the drainage water. 3. The annual nutrient recoveries were increased significant- ly if the entire corn plant was harvested. 4. Although significant differences were found among the hybrids, the treatment x hybrid interaction was not sig- nificant indicating that all hybrids responded similarly across all treatments. 5. For accurate monitoring of the nutrient loss through the drainage water from a land disposal system, both nutrient concentration and flow volume must be measured continuously. 6. The application of IOW’K effluents may result in a depletion of the exchangeable K unless supplemental K fert- ilizers are applied. 7. The application of an effluent whose SAR is less than 5 is not likely to cause structural problems due to excess Na adsorption. 8. Although C1/NO3 ratios indicate that the unrecovered N was being lost through denitrification, a series of shallow wells should be monitored to determine if N is being lost by denitrification or through deep percolation. 9. Land disposal of secondary municipal effluent is a vi- able alternative to tertiary chemical treatment if the system is managed for maximum yield and nutrient recovery through plant uptake. APPENDIX 79 xmmz ma ma HH m l mumu mcflpmoH EU oom mpmu mcflcmoH E0 ooa .Amnmav Hmum3 mmmcwMHw ca zlmoz mo zoflumuucmocoo haxmmz OH ON on ov om .NH musmsm HM/I/fim 80 ma x663 ma HH a A m m H 0 ’Illlllllllllll. \ GHQ“ mGHvMOH EU CON ............... mumu mcflvmoH So ooa .Amhmav Hmpm3 mmmcflmuw Ga A no coflumnuamocoo maxmmz mN.o om.o mh.o XM/I/5m oo.H mN.H om.H .mH magmas 81 TABLE 22-. Mean.plant population of.the corn hybrids.a Hybrid 1973. 1974 ------ plants/ha -------- M 396b 20,950 27,800 M 402 18,150 ------ P 3780c ------ 26,050 _, M 500 27,100 23, 250 Fla“ M 511 23,650 24,750 ' M 572 22,450 26,300 ,, F 4444d 30,750 27,150 Jj ‘ aAveraged across all treatments. bM--Michigan Certified Seed Company. cP--Pioneer Seed Company. dF--Funks Seed Company. 82 TABLE 23. Weekly volumes of tile drainage as influenced by annual loading rate. Week 50 mm 100 cm. 200 cm ----------- liters ----------------------- 1 2 63 158 1398 3 102a 1961a 5111b g 14277 14277 14277 6 314 103 7 354 8 1872 556 9 140 415 3093 10 3410 2887 11 919 20056 8013 12 2137 14072 22470 13 43 7220 19985 14 656 15318 26680 15 167 19502 30448 16 1326 19655 26724 17 33736 71285 53415 18 274 25094 28717 19 16445 53770 53117 20 571 20224 19086 21 65 2184 2073 22 130 1275 945 23 399 211 24 84 13131 2746 25 1214 3807 aEstimated flow bMeasured flow 83 mawvmoa Hmsncm he umocmaamnw fill r F .J. .mufiun%£ cuoo Ham Hm>o meowumuucmocoo mwmum>¢m q H m mo. No. No. no. mz «o. Ha. Ano.v 9mg mu 0H ma as. ea. mm. mm. om.H «a. on. .50 com mm 0 ma mu. mo. HN. mm. om.a «m. mo. So ooa me n ma an. no. om. mm. NN.H on. on. .80 on mg m mm we. no. mm. om. m~.H mm. on. Ho mm qmma no. Ho. mz «o. «a. «o. co. Amo.v 9mg mm. mm. mm. 56. mm.H ma. mm. 80 com um. ma. mm. mm. om.H m¢. mm. 80 00H mm. ma. mm. mm. 6H.H mm. Hm. Bo on on. co. «m. mm. mm.H mm. mm. 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