Location: Southeast Watershed Research2012 Annual Report
1a. Objectives (from AD-416):
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 identify practices for use as a Best Management Practices and to qualify for water quality improvement credits.
1b. Approach (from AD-416):
At 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. At Oxford - Two studies will be conducted. At the Northeast Mississippi Experiment Station at Verona the effects of FGD gypsum on an existing set of no-till cotton plots will be evaluated. FGD gypsum application rates of 0, 1, 1.5, 2, and 3 tons/acre would be applied on a replicated plot experiment. A Study at Milan, TN will evaluate the effects of tillage-gypsum interactions on cotton yields. 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:
This project contributes to research objective 1 of this in-house project: Determine the effects of legume cover crops and soil amendments (e.g., poultry litter and flue gas desulfurization gypsum) on nutrient cycling and other soil processes in cropping systems. This cooperative project with the Tennessee Valley Authority investigates the effects of flue gas desulfurized gypsum (FGD-gypsum) on forage production, soil properties, and movement of phosphorus in association with land applications of poultry litter as a source of nutrients for southeastern soils. The overall project involves three Agricultural Research Service (ARS) locations (Auburn, Alabama, Oxford, Mississippi, and Watkinsville, Georgia). The United States Environmental Protection Agency’s (USEPA) Office of Resource Conservation and Recovery is cooperating in the project for risk assessment. In 2012 Watkinsville was one of 10 ARS locations closed on the basis of the U.S. Department of Agriculture (USDA) full-year appropriation for FY2012 signed by the President on November 18, 2011. All field and laboratory research activities ceased as of that date. The research team continued data processing and analysis and has submitted two journal manuscripts for publication. The project was transferred to USDA-ARS Southeast Watershed Research Lab after mid-June 2012. We contributed to a risk assessment for FGD-gypsum in cooperation with USEPA with sample analysis conducted at ARS’ Environmental Management and Byproducts Utilization Laboratory in Beltsville, Maryland. Annual reports were given to participating utilities and USEPA.