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ARS Home » Southeast Area » Tifton, Georgia » Southeast Watershed Research » Research » Research Project #412350


Location: Southeast Watershed Research

2008 Annual Report

1a. Objectives (from AD-416)
We propose to evaluate FGD gypsum influences on soil physical properties and losses of P from poultry litter applied to pastures (Watkinsville) and crop land (Oxford). The research will help establish proper combinations of rates of FGD gypsum and poultry litter to reduce losses of P in runoff and improve soil productivity. We will also 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 – FGD gypsum and poultry litter will be applied at four rates (0, 1, 2, 3 tons/acre) to bermudagrass pasture to evaluate changes in available soil P over three years. The FGD gypsum and poultry litter will be applied annually and measurements of soil P fractions (Total P, water soluble P, Mehlich P, and organic P) will be made at 6 month intervals. Soil aggregate stability will be measured yearly to evaluate impacts of FGD gypsum on soil structural stability. In addition we will 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 will be harvested at regular intervals to simulate haying and evaluated for P content (P removal) and forage quality. Results will 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 no-till cotton plots. The FGD gypsum application rates of 0, 1, 1.5, 2, and 3 tons/acre will 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
This project contributes to research objective 2 of this in-house project: Quantify key system components of mixed cropped and grazed systems that can be optimized to improve whole-farm economic and natural resource sustainability in the Southern Piedmont. This project investigates the effects of flue gas desulfurized gypsum on forage production, soil properties, and movement of phosphorus in association with land applications of poultry litter as a source of nutrients for piedmont soils. The overall project involves three ARS locations (Auburn, Oxford, and Watkinsville). At Watkinsville we are in the initial stages of establishing the field plots and beginning the research. We will collect soil samples this fall to establish background soil physical and chemical data. The Authorized Departmental Officer’s Designated Representative monitored the project through coordination of information with the cooperator and with the other ARS locations through email and phone conversations. An overview of the project was presented to participants of an United States Environmental Protection Agency sponsored workshop on use of recycled materials.

4. Accomplishments