title: Phosphorus saturation in spodosols impacted by manure.
abstract: Significant amounts of phosphorus (P) accumulate in soils receiving animal manures that could eventually result in unacceptable concentrations of dissolved P loss through surface runoff or subsurface leaching. The degree of phosphorus saturation (DPS) relates a soil's extractable P to its P sorbing capacity, and is reportedly a predictor of the P likely to be mobilized from a system. A DPS value (DPS-1) was derived that expressed the percentage of Mehlich 1-extractable P to the sorbing capacity of a Spodosol (expressed as the sum of oxalate-extractable Fe and Al). Values of DPS-1 were determined in various horizons of soil in current and abandoned dairy systems in South Florida's Lake Okeechobee watershed to assess P release potential. Land use within the dairies was classified as highly impacted by cattle (intensive and holding), and minimally impacted by cattle (pasture, forage, or native) areas. The A and E horizon of soils in heavily manure-impacted intensive and holding areas for both active and abandoned dairies generally had higher DPS-1 values than the pasture, forage, and native area soils, which were minimally impacted by manure. Degree of P saturation was also calculated as a percentage of Mehlich 1-extractable P to the sum of Mehlich 1-extractable Fe and Al (DPS-2). Both DPS-1 and DPS-2 were shown to be significantly (P = 0.0001) related to water-extractable P for all soil horizons, suggesting that either index can be used as an indicator for P loss potential from a soil.
authors.affiliation: Soil and Water Science Dep, Univ of Florida, Institute of Food and Agricultural Sciences, Gainesville 32611-0510, USA. vdna@mail.ifas.ufl.edu
authors.forename: V D
authors.initials: VD
authors.lastname: Nair
authors.forename: D A
authors.initials: DA
authors.lastname: Graetz
mesh_terms: D000327:Adsorption; D000818:Animals; D001682:Biological Availability; D002417:Cattle; D003612:Dairying; D004784:Environmental Monitoring; D008372:Manure; D010758:Phosphorus / Q000032:analysis* / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis*; D014872:Water Movements
chemical_list: D008372:Manure; D012989:Soil Pollutants; D010758:Phosphorus