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United States Department of Agriculture

Agricultural Research Service


Location: Southeast Watershed Research

Project Number: 6602-11130-003-03-T
Project Type: Trust Fund Cooperative Agreement

Start Date: Feb 28, 2008
End Date: Feb 27, 2013

We propose to evaluate FGD gypsum influences on soil physical properties and losses of P from poultry litter applied to pastures (Watkinsville),crop land (Oxford), and hay land (Auburn). 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.

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. Auburn - Research will be conducted at the ARS National Soil Dynamics Laboratory, Auburn AL that will contribute to the overall project goals. Scientists at the NSDL will investigate the effects of FGD gypsum and poultry litter on soil physical properties, nutrient use, and forage production on a Coastal Plain soil. The experimental approach and methods will be nearly the same as those at the Watkinsville research location using the same rates of gypsum and poultry litter. Rainfall simulations will also be conducted at the Auburn location to determine the effects of the FGD gypsum and poultry litter treatments on runoff and sediment losses.

Last Modified: 06/27/2017
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