2009 Annual Report 1a.Objectives (from AD-416) We propose to evaluate FGD gypsum influences soil physical properties and losses of P from poultry litter on pastures. The research would help establish proper combinations of rates of FGD gypsum and poultry litter to reduce losses of P in runoff and improve soil productivity and provide documentation of water quality improvements associated with FGD gypsum needed to help qualify practices for use as a BMP and water quality improvement credits. 1b.Approach (from AD-416) Auburn – FGD gypsum and poultry litter will be applied at four rates (0, 2, 4, 6 Mg ha-1) to bermudagrass pasture to evaluate changes in available soil P over three years. FGD gypsum and poultry litter would be applied annually and measurements of soil P fractions (Total P, water soluble P, Mehlich P, and organic P) would be made at 6 month intervals. In addition we would evaluate FGD gypsum and poultry litter effects on forage production and quality along with the potential for nutrient removal by grazing and haying which is important for management of high P soils. Forage would be harvested at regular intervals to simulate haying and evaluated for P content (P removal) and forage quality. Results would establish potential for using FGD gypsum as an amendment to increase poultry litter application rates and improve water use efficiency on pasture and hay land. 3.Progress Report This research project was initiated to evaluate the use of flue-gas desulfurization (FGD) gypsum as soil amendment to reduce losses of phosphorus (P) from poultry litter in forage based production systems. Influences of FGD gypsum on soil physical properties affecting water infiltration, water conservation, and forage production are being investigated. The project uses rainfall simulation studies to quantify the impacts that FGD gypsum has on soil and forage quality. This study is evaluating proper rate combination of FGD gypsum and poultry litter needed to reduce P losses in surface water runoff and forage yields. Treatment effects on forage production and nutritive value are being determined for each cutting throughout growing season, along with nutrient removal in the hay. Soils are being analyzed to determine; changes in soil P fractions (total P, water soluble P, Mehlich P, and organic P); changes in heavy metal content ( such as mercury); and changes in soil quality (soil C, N, particulate C, aggregate stability). The first rain simulation was conducted 6 weeks after fertilization to evaluate fate and transport of P, and heavy metals.