Improving swine effluent management practices requires understanding of the fate of nutrients derived from swine effluent in soil quality. This study was conducted to evaluate the effects of long-term swine lagoon effluent application on nutrient distribution in an alkaline Okolona silty clay, an acidic Vaiden silty clay, and a Brooksville silty clay loam. Swine effluent has been applied using a center-pivot irrigation system at a total rate ranging from 10 to 15 cm ha(-1) of effluent per year since 1990. In October 2005, soil samples were taken from the irrigated and nonirrigated sites at the following depths: 0 to 5, 5 to 15, 15 to 30, 30 to 60, and 60 to 90 cm. Soils were air-dried, ground to pass 2-mm sieve, and analyzed for selected chemical properties. Sorption isotherms were also performed on the soil samples to determine P sorption capacity and strength. Long-term application of swine effluent resulted in a decrease in soil pH and an increase in soil electrical conductivity in all three soils. Total soil C and microbial biomass C increased in irrigated sites for all soils. Soil ammonium, nitrate, acid-extractable P, water-soluble P, and Zn concentrations were elevated at the 0- to 5-cm and 5- to 15-cm depths, and their values were extremely lower in the alkaline Okolona soil than in the Brooksville and Vaiden soils. No clear effect was observed for P sorption strength and capacity. Low N and P accumulation in alkaline Okolona soil may prolong the capacity of this soil in receiving swine effluent particularly if threshold water-soluble P and soil test P levels are used as part of swine effluent management program.
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