%0 Journal Article
%T Effect of Land Application of Phosphorus-Saturated Gypsum on Soil Phosphorus in a Laboratory Incubation
%A Karen L. Grubb
%A Joshua M. McGrath
%A Chad J. Penn
%A Ray B. Bryant
%J Applied and Environmental Soil Science
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/506951
%X Agricultural drainage ditches can deliver high loads of phosphorus (P) to surface water. Installation of filter structures containing P sorbing materials (PSMs), including gypsum, is an emerging practice that has shown promise to reduce these P loads. The objective of this study was to evaluate what effect soil amendment with gypsum would have on soil P concentrations and forms in a laboratory incubation experiment. Gypsum was saturated at two levels with P, and applied to a silt loam and a sandy loam at two rates. The treated soils were incubated in the laboratory at 25¡ãC, and samples were collected on eight dates between 0 and 183 days after amendment. Spent gypsum application did not significantly increase soil water-extractable or Mehlich 3 P when applied at typical agronomic rates. This appears to be a viable strategy to remove P from agricultural drainage waters but does not appear to provide any additional P fertilizer value. 1. Introduction Accelerated eutrophication of the Chesapeake Bay has been identified as a priority natural resource concern [1]. According to the Chesapeake Bay Program Watershed Model Phase 4.3 agricultural sources account for 45% of the total phosphorus (P) delivered to the Chesapeake Bay [2]. The Delmarva Peninsula is comprised of the nine counties of the eastern shore of Maryland, Accomack and Northampton counties in Virginia, and the state of Delaware. The Delmarva Peninsula is home to a large concentration of poultry production, leading to a regional surplus of phosphorus (P). In the past, poultry manure was land applied based on crop nitrogen (N) requirements. However, because the P£¿:£¿N ratio found in manure is much higher than the P£¿:£¿N ratio required by plants, excessive P application has occurred resulting in elevated soil P concentrations [3]. The lower portion of the Delmarva Peninsula is dominated by coarse textured soils, shallow groundwater tables, and agricultural drainage ditches. Phosphorus leaching to groundwater is greatly increased in sandy soils with limited capacity to retain P, in soils with high P saturation, and in ditch drained soils containing preferential flow pathways [4]. This combination of hydrology and agricultural practices has led to P loading to surface water through shallow subsurface pathways and environmental quality issues [5]. One possible way to reduce phosphorus loss is to use by-product materials that can sorb phosphorus [6]. Phosphorus sorption is the process of adsorption and precipitation of P from dissolved to solid forms [7]. Phosphorus sorbing materials (PSMs) can provide a
%U http://www.hindawi.com/journals/aess/2012/506951/