Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 6/12/1998
Publication Date: N/A
Technical Abstract: Animal manure is used to add nutrients and organic matter to improve physical and biochemical conditions of agricultural lands. Although manure is considered an organic amendment, the release of phosphorus (P) is of interest because of the high proportion of inorganic P in cattle feedlot wastes and the stabilization of manure nutrients upon composting. Bulk samples of stockpiled and composted manure were obtained from a commercial feedlot located near Hereford, TX. Water-soluble P readily desorbed from both manures when incubated alone or with a Torrertic Paleustoll and an Aridic Paleustalf. Phosphorus desorption followed a double-exponential kinetic model, showing a large P pool with a decay rate of 0.08 and 0.31 mg/kg/d for stockpiled and composted manure. No apparent increased stability of P occurred with composted manure. Trends in P extractability were similar in both soils amended at the rate of 40 mg/kg although higher amounts of P were desorbed from the Paleustoll. Soil mediation of the P turnover processes were affected by highly variable waste nutrient characteristics.