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United States Department of Agriculture

Agricultural Research Service


Location: Water Quality and Ecology Research

2013 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 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; one at the Northeast Mississippi Experiment Station at Verona will evaluate the effects of FGD gypsum on an existing set of no-till cotton plots. 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:
A cotton experiment was begun in 2009 comparing no-tillage and tilled cotton with five gypsum rates, 0, 1, 2, 3 and 5 tons per acre. The experiment is a randomized complete block design with four replications. Initial soil data to a depth of 4 feet in 6 inch increments was taken on each plot prior to gypsum application. Additional soil samples were collected in fall 2011 after three crop years. These samples are being processed and analyzed for various chemical constituents. Chemical measurements have included soil pH; citrate-bicarbonate-dithionite (CBD) extractable iron (Fe), aluminum (Al), and manganese (Mn); oxalate extractable Fe, Al, and Mn; cation and anion exchange capacity (CEC and AEC); and exchangeable cations and anions. Plot yields were measured each year. Soil penetrometer resistance was measured in spring 2012. Collaborative efforts were maintained through routine site visits, email, and telephone communications with collaborators and a meeting in Auburn, Alabama.

4. Accomplishments

Last Modified: 06/21/2017
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