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United States Department of Agriculture

Agricultural Research Service

Research Project: DEVELOPMENT OF ALTERNATIVE PRACTICES FOR IMPROVED WATERSHED MANAGEMENT Title: Assessment of Herbicide Transport in Central Missouri Watersheds Using a Process-Based Index Model

Authors
item Willett, Cammy -
item Lerch, Robert
item Milner, M -
item Bernards, M -
item Shea, P -

Submitted to: Soil and Water Conservation Society
Publication Type: Abstract Only
Publication Acceptance Date: January 19, 2009
Publication Date: July 18, 2010
Citation: Willett, C.D., Lerch, R.N., Milner, M., Bernards, M.L., Shea, P.J. 2010. Assessment of Herbicide Transport in Central Missouri Watersheds Using a Process-Based Index Model [abstract]. Soil and Water Conservation Society, July 18-22, 2010, St. Louis, Missouri. Available: http://www.swcs.org/documents/filelibrary/10ac/2010_Oral_Presentation_Abstracts_566DF5164F928.pdf.

Technical Abstract: Identification of areas at risk for pesticide loss is a necessary requirement for targeting best management practices (BMPs) to the most vulnerable areas within watersheds. To work toward that goal, a process-based index model was developed to assess relative landscape vulnerability to hydrologic losses of pesticides. The model applies mathematical functions to assign scores (i.e., degree of risk) on the basis of pesticide, soil, and landscape properties relevant to the environmental fate of pesticides. The model uses the NRCS county SSURGO database as the input source of soils data. The risk of pesticide transport is considered for three hydrologic pathways, or scenarios: leaching, solution runoff, and particle adsorbed runoff. The model is used to compute the relative risk of pesticide transport for a given pesticide for each hydrologic pathway, providing the spatial and temporal risk of transport. The model is being applied to the Youngs Creek watershed in the Central Claypan Region of Missouri, a watershed with known herbicide contamination problems. The risk of herbicide loss for each hydrologic pathway was determined for each of four corn herbicides (atrazine, metolachlor, isoxaflutole, and glyphosate). By computing area-weighted scores at the watershed scale, a score for each herbicide and hydrologic pathway scenario combination was determined. Area-weighted scores were used to evaluate the potential spatial and temporal risk of applying these herbicides in the Youngs Creek watershed. This information can then be used to make recommendations regarding the choice of herbicides that minimize the risk of hydrologic transport for this watershed.

Last Modified: 10/22/2014
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