Location: Soil Dynamics Research2010 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 (Watkinsville and Auburn) and crop land (Oxford). 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)
Watkinsville and 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. Use of similar treatments at Auburn and Watkinsville is to evaluate differences in treatment effects associated with differences in soil and climate at the two locations. 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. Soil aggregate stability would be measured yearly to evaluate impacts of FGD gypsum on soil structural stability. 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. Oxford - Two studies will be conducted at the Northeast Mississippi Experiment Station at Verona. In one study, we will evaluate the effects of FGD gypsum on an existing set of notill cotton plots. FGD gypsum application rates of 0, 1, 1.5, 2, and 3 tons/acre would be applied on a replicated plot experiment. The other study will evaluate the effects of tillage-gypsum interactions on soybean yields. The three tillage treatments are no-till, fall chisel-harrow, and conventional. Plot sizes, gypsum application rates, and replications are identical to those for no-till cotton. Crop yields will be measured by the experiment station personnel responsible for all agronomic practices. Following harvest each growing season, soil cores will be collected to a depth of 36 inches from each plot and characterized for water dispersible clay as a measure of erodibility, particle size distribution, organic carbon content, pH, exchangeable Al, exchangeable bases, total calcium, sulfur, nitrogen, and phosphorus.
3. Progress Report
A field study was initiated to evaluate flue-gas desulfurization (FGD) gypsum uses as soil amendment for reducing phosphorus (P) losses from poultry litter applied in a forage based production system. Flue-gas desulfurization gypsum influences on soil physical properties, water conservation, and forage production are being investigated. This project also includes the use of rainfall simulations to quantify the impacts that FGD gypsum has on reducing the loss of P in surface water runoff. Forage cuttings for this study were collected 4 times throughout the growing season. Treatment effects on forage production and nutritive value are in the process of being determined for each cutting, 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 Carbon (C), Nitrogen (N), particulate C, aggregate stability). The first rain simulation was conducted 6 weeks after fertilization to evaluate fate and transport of P, heavy metals, and arsenic.