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

Abstract

Abstract 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 0.01 M CaCl 2 ), acid‐extractable P (0.05 N HCl + 0.025 N H 2 SO 4 ), 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 5 years to a Norfolk soil (Site 1) and for 3 years to a Cecil soil (Site 2) also increased soluble P (in 0.01 M CaCl 2 ), 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.