Phosphorus Adsorption-Desorption Characteristics of Two Soils Utilized for Disposal of Animal Wastes

The purpose of this study was to determine the effect of animal waste loading rates on P adsorption-desorption characteristics of two soils. In a laboratory incubation study, Norfolk soil was treated with beef, poultry, or swine wastes; and allowed to decompose under optimum moisture conditions for a period of 30 days. Phosphorus adsorption-desorption characteristics of the soil were measured at the end of the incubation period. Application of beef, poultry, and swine wastes to a Norfolk soil decreased adsorption capacity of the soil and increased soluble P (in 0.01A/ CaCU), acid-extractable P (O.OS/V HCI + 0.025/V H,SO«), equilibrium P concentration (EPC), and P desorption (after four 1-hour extractions). In a field study, increased rates of swine lagoon effluent application over a period of S years to a Norfolk soil (Site 1) and for 3 years to a Cecil soil (Site 2) also increased soluble P (in 0.01M CaCU), acid extractable P, P desorbed, and EPC values, and decreased the adsorption capacity. At high loading rates of swine lagoon effluent, soluble P movement occurred to a depth of 75 and 30 cm at Site 1 and 2, respectively. Phosphorus adsorption increased with depth, and EPC values decreased with increasing depths of soil profile. A significant relationship was observed between EPC values, and soluble and acid extractable P. Additional Index Words: equilibrium P concentration, loading rate, swing lagoon effluent, beef waste, poultry waste, swine waste, P migration. 'Contribution from the Dep. of Biolog. and Agric. Eng., and North Carolina Agric. Exp. Stn., Raleigh, NC 27607, as Journal Article no. 5833. The use of trade names in this publication does not imply endorsement by the North Carolina Agric. Exp. Stn. of the products named, nor criticism of similar ones not mentioned. This research was supported in part by the U.S. Environ. Prot. Agency on a grant, no. R-805011-01-0. Received 16 Oct. 1978. 2 Assistant Research Scientist, Univ. of Florida, Agric. Res. and Educ. Center, Sanford, FL 32771; and Associate Professor, Research Associate, and Assistant Professor, Dep. of Biolog. and Agric. Eng., North Carolina State Univ., Raleigh, respectively. Reddy, K. R., M. R. Overcash, R. Khaleel, and P. W. Westerman. 1980. Phosphorus adsorption-desorption characteristics on two soils utilized for disposal of animal wastes. J. Environ. Qual. 9:86-92. Application of animal wastes on farm land is usually regulated according to N requirement of crops to preclude nitrate leaching and ground water contamination, resulting in no control or consideration of P application rates. When soils are utilized for disposal purposes, P application rates of animal wastes are considerably higher than crop uptake, resulting in greater accumulation of P in the soil. Accumulation of P in soil increases with increasing waste application rates as measured for beef wastes (Herron and Erhart, 1965; Murphy et al., 1972; Vitosh et al., 1973), dairy wastes (Olsen et al., 1970), swine wastes (Collins et al., 1978; Sutton et al., 1974; Cummings et al., 1975), and poultry wastes (Perkins et al., 1964; Shortall and Leibhardt, 1975)." These researchers concluded that application of animal wastes increases plant available P in acid or alkaline soils. A few studies have observed significant amounts of P movement in the soil profile (Adriano et al., 1975; Bielby et al., 1973). The movement of P in the soil profile is dependent on the rate of P application, type of waste, and P reaction with the soil. Several researchers have observed a P sorption by soils in the presence of organic residues (Dalton et al., 1952; Gaur, 1969; A. L. Sutton, D. W. Nelson, J. J. Moeller, and L. F. Huggins. 1974. Application of anaerobic liquid dairy waste on slopping frozen land. Presented at 69th Annu. Meet., Am. Dairy Sci. Assoc., 23-26 June 1974, Univ. Guelph, Canada. 'S. R. Crane. 1978. A laboratory investigation of the short-term chemical and microbial transformations in the soil following surface land application of poultry manure. M.S. Thesis, North Carolina State Univ., Raleigh, N.C. 86 J. Environ. Qual., Vol. 9, no. 1,1980 Struthers and Sieling, 1950; Vyas, 1964). It was concluded from these studies that during decomposition of organic residues, organic acids form stable complexes with Fe and Al, and consequently block P retention in the soil. However, increased retention due to organic residue application has also been observed (Fokin and Chistova, 1964; Harter, 1969; Jackman, 1955; Larsen et al., 1959; Rennie and McKercher, 1958). So far, very little is known about the effect of animal waste application on P sorption by soils. The objectives of this study were to determine the effect of various animal waste loading rates on: (i) the phosphorus adsorption-desorption characteristics of the soils treated with fresh beef, poultry, and swine wastes (studied under laboratory conditions), and swine lagoon effluent (studied under field conditions); and (ii) characteristics of P movement in the soils treated with long-term application of swine lagoon effluent. MATERIALS AND METHODS The soils used in this study belong to the Norfolk and Cecil series (Table 1). Norfolk series, a loamy sand, typical of th.e Coastal Plains region, is a member of fine loamy siliceous, thermic family of typic paleudults. These soils often consist of a deep, well-drained profile formed in a loamy Coast Plains sediments, with a grayish brown Ap horizon (0 to 22 cm) and a light yellowish brown A2 layer (22 to cm). The Cecil series, a sandy loam typical of the Piedmont regions, is a member of the clayey, kaolinitic, thermic family of typic Hapludults. The soils have dark grayish brown or brown sandy loam A horizons (0 to 15 cm) and red Bt horizons. In all experiments, animal waste application rates were based on the N content. EXPERIMENT I (LABORATORY) Laboratory incubations were carried out in 400-ml plastic containers, which received 200 g of Norfolk soil (0 to 15 cm layer) incorporated separately with fresh beef, swine, or poultry wastes at 600 #g of total N/g soil. Incorporation of the waste into the soil was achieved by mixing soil-waste complex for a period of 5 min with a spatula. Some of the selected characteristics of the wastes used in this study are presented in Table 2. The moisture content of the soil-waste system was adjusted to field capacity (10% soil moisture). Duplicate incubations were carried out for a period of 30 days at 25°C. At the end of incubation, soil was dried at 40°C for a period of 48 hours and stored at 4°C in tightly sealed containers. EXPERIMENT !I (FIELD) Soil samples were obtained to a depth of 105 cm, from two experimental sites, where swine lagoon effluent was applied at a rate of 650 and 1,300 kg N/ha per year for a period of 3 years (at the Unit II station) and at a rate of 325,650, and 1,300 kg N/ha per year for period of 5 years (at the Central Crops Research Station, Clayton). the Unit II station, soil samples were also obtained from plots receiving 31 kg P/ha per year as fertilizer P only. At the Unit II station, Table 2--Selected chemical characteristics of fresh animal wastes used in Experiment I.