Submitted to: Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2004
Publication Date: 1/1/2005
Citation: Akhtar, M., Mccallister, D., Francis, D.D., Schepers, J.S. 2005. Manure source effects on soil phosphorus fractions and their distributions. Soil Science. 170(3):183-190 Interpretive Summary: Applying manure to cropland as a substitute for nitrogen fertilizer is a good use of animal manure because it provides a useful blend of nutrients. Phosphorus content in manure is typically several times higher than required by crops compared to nitrogen, so application of four kinds of manure (beef and sheep feedlot, turkey, and composted paunch waste) was made in alternate year at rates adjusted to equal the total amount of phosphorus removed by the crop. Nitrogen fertilizer was applied to supplement the manure to meet crop nitrogen needs. Soils were sampled after six years of irrigated corn production (three manure applications) and analyzed for plant-available and several other types of phosphorus. Soluble and plant available phosphorus concentrations in the surface six-inches of manured soil were approximately four times higher than in non-manured soils. Surface soils of manured plots also contained about 50% higher levels of other types of adsorbed phosphorus. Although the source of applied manure had some influence on P fractionation and depth distribution, most phosphorus remained in the zone of application, emphasizing the need for conservation of the surface soil.
Technical Abstract: Manure can be applied to soils as a major source of nutrients such as phosphorus (P). The environmental chemistry and plant availability of applied P are influenced by the chemical forms of P in the solid phase. The objectives of this study were to determine the amounts, availability, and chemical forms of P in a Hord silt loam soil (fine-silty, mixed, mesic Pachic Haplustoll) amended with beef and sheep feedlot, turkey house, and composted paunch manures. Manures were applied in alternate years from 1991 to 1997. In 1996, after three manure applications, total P in the manured 0-15-cm soil depth increased up to 14% and inorganic P up to 25% compared with nonmanured. Bray and Kurtz 1-P in 0-15-cm soil depth was almost 4 times greater in manured soil than in nonmanured (47.2 mg P/kg soil versus 12.7 mg P/kg soil). Soluble P was more than 4 times higher in the 0-15-cm depth of manured soils (13.9 mg P/kg soil) compared with nonmanured soil (3.2 mg P/kg soil). Nonoccluded P was more than 1.5 times higher in manure-amended soils (78.4 mg P/kg soil than in nonmanured (46.8 mg P/kg soil) in the 0-15-cm soil depth. Occluded P in the 0-15-cm soil depth was greatest in turkey manure-amended soil (45.2 mg P/kg soil), followed by beef manure-amended soil (36.7 mg P/kg soil). In 1997, all P fractions were higher in 0-7.5-cm depth than any other amended soil depth, and the same general trends among fractions held as in 1996. Although animal source of applied manure does have some influence on P fractionation and depth distribution, most P remains in the zone of application, emphasizing the need for conservation of the surface soil.