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United States Department of Agriculture

Agricultural Research Service

Title: Apex Model Assessment of Variable Landscapes on Runoff, Dissolved Herbicides and Nutrients

item Mudgal, Ashish
item Baffaut, Claire
item Anderson, Stephen
item Sadler, Edward - John

Submitted to: ASABE Annual International Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 6/29/2008
Publication Date: 6/29/2008
Citation: Mudgal, A., Baffaut, C., Anderson, S.H., Sadler, E.J. 2008. Apex Model Assessment of Variable Landscapes on Runoff, Dissolved Herbicides and Nutrients [abstract]. In: Proceddings of the American Society of Agricultural and Biological Enginners Annual International Meeting, June 29 - July 02, 2008, Providence, Rhode Island. Paper No. 084498

Interpretive Summary:

Technical Abstract: Variability in soil landscapes and their associated properties can have significant effects on erosion and deposition processes that affect runoff and transport of pesticides and nutrients. Simulation models are one way in which the effects of landscapes on these processes can be assessed. This study evaluated the effects of variations in landscape position on runoff, dissolved nutrients and dissolved herbicides using a calibrated APEX model. Fourteen agricultural plots (18 x 189 m2) in the Goodwater Creek watershed, a 7250 ha agricultural area in north-central Missouri, were simulated with the farm field-scale watershed model Agricultural Policy/Environmental eXtender (APEX). Plots were under three different tillage and herbicide management systems for three grain crop production systems. Runoff was measured and samples were collected from 1997 to 2002 during the corn year of the crop rotations. Runoff samples were analyzed for dissolved herbicide (atrazine and metolachlor) and nutrient (NO3-N, NH4-N and PO4-P) concentrations. Each plot contained three landscape positions: summit, backslope, and footslope along with two transition zones. The APEX model was calibrated with data from each plot. The calibrated model was used to simulate variable sequencing of landscape positions and associated soil properties as well as variable lengths of landscape positions. Results indicated that as the length of the backslope increased, so did the volume of runoff discharged at the plot outlet. In addition, the backslope position with its associated soil properties being at the outlet created the most significant runoff. Variations of pollutant loads and concentrations will also be presented. Results from this study will be helpful in placement of conservation practices on sensitive landscapes for improvement in water quality.

Last Modified: 06/25/2017
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