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United States Department of Agriculture

Agricultural Research Service


Location: Southeast Watershed 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 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 the above 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 Duke Energy Corporation investigated the effects of flue gas desulfurized gypsum (FGD-gypsum) on forage production, row-crop (soybean and cotton) production, soil properties, and movement of phosphorus in runoff in association with land applications of poultry litter as a source of nutrients for southeastern soils. The overall project involved three Agricultural Research Service (ARS) locations (Auburn, Alabama, Oxford, Mississippi, and Watkinsville, Georgia). The U.S. Environmental Protection Agency’s (USEPA) Office of Resource Conservation and Recovery cooperated in the project on risk assessment by providing separate but direct funding for sample analysis to the ARS Environmental Management and Byproducts Utilization Laboratory in Beltsville, Maryland. The Watkinsville Lab closed in fall 2012. A new Authorized Departmental Officer’s Designated Representative (ADODR) managed the remaining project from the Southeast Watershed Research Lab in Tifton after being relocated there in June 2012. The term date of 03/31/2013 was extended for another year. The start date was 05/26/2009. A total of $100,000 was provided by Duke Energy through Watkinsville and split among locations during the project period. Duke Energy failed to provide another $50,000 it initially promised. Activities focused on analyses of soil and water samples collected previously toward completion of our data base and/or to answer questions raised by reviewers for two manuscripts submitted for publication. The manuscripts were subsequently accepted and published online 03/01/2013 (ARIS#283415 and #280367). Throughout the period the ADODR monitored the project through coordination of information with the cooperator and with the other ARS locations and the Beltsville Lab through email and phone conversations. Research updates were conducted via conference calls. Revisions for manuscripts were provided through contacts with coauthors and the research locations. Two important face to face meetings were also held. The first was a project progress meeting held in Auburn Alabama (5/16 & 17, 2013) with all three entities (Tennessee Valley Authority, Duke Energy & Southern Company) involved in funding the larger overall core project, in which each location, including the Beltsville Lab, submitted a full progress report, including all data analyses and conclusions and recommendations to date. The second was a meeting held in Beltsville, Maryland, with top Natural Resources Conservation Service (NRCS) personnel instrumental in making decisions about national NRCS nutrient management policies. Representatives from the three ARS locations made presentations about findings from the 5-yr project. The NRCS representatives expressed willingness to move forward on making a “National NRCS Standard” for the use of gypsum in agriculture. This is as good as it gets as far as NRCS accepting gypsum as a Best Management Practice.

4. Accomplishments

Last Modified: 06/28/2017
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