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United States Department of Agriculture

Agricultural Research Service

Research Project: Management Practices to Mitigate Global Climate Change, Enhance Bio-Energy Production, Increase Soil-C Stocks & Sustain Soil Productivity...

Location: Soil Plant Nutrient Research (SPNR)

Title: A GIS Assessment to Identify and Reduce Nitrate Loads That Contribute to Hypoxia in the Gulf of Mexico

Authors
item Bunch, Theodis -
item Delgado, Jorge
item Shumway, Cal -
item Hansen, Leroy -
item Ribaudo, Marc -

Submitted to: Soil and Water Conservation Society
Publication Type: Abstract Only
Publication Acceptance Date: April 26, 2011
Publication Date: N/A

Technical Abstract: Nitrate leaching has been reported as one of the main pathways contributing to the nitrate flux out of the Mississippi River watershed into the Gulf of Mexico. This out-flux of nitrogen has been identified as one of the factors that contribute to the hypoxia problem in the Gulf of Mexico. The Arkansas Delta is a key productive agricultural region of the Mississippi River watershed, and it has been reported that while it is not as large as other agricultural areas of the Midwest that are more susceptible because of their tile drainage, the Arkansas Delta still contributes nitrates to the out-flux of the Mississippi River watershed via leaching losses. The new Nitrogen Loss and Environmental Assessment Package with GIS capabilities (NLEAP-GIS) was used to assess the spatial and temporal variability of these leaching losses on selected farm areas for different counties. Although the analysis did not include the entire watershed of the Arkansas Delta, we suggest that this GIS analysis for different farm fields can be used to help us assess the benefits of implementing best management practices (BMPs) across selected counties for the study. Maximum potential loads for nitrate leaching were estimated by conducting an assessment across corn-soybean and cotton rotations when high nitrogen rates were applied. An analysis was then conducted at the same locations using BMPs, and the potential reduction in nitrate loads was assessed. Additionally, to support this GIS assessment, calibration and validation studies were conducted from 2008 to 2009 for three selected farms. This long-term GIS analysis shows, among other preliminary findings, that rotations of soybeans into corn systems significantly reduces emissions of N2O across this region and reduces NO3-N leaching losses at the field level. Results from improvement in method, time and rate of nitrogen applications will also be presented.

Last Modified: 12/19/2014