SIMULATION OF HERBICIDE CONCENTRATIONS IN STORMFLOW FROM FORESTED WATERSHEDS1 |
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Authors: | W L Nutter T Tkacs P B Bush D G Neary |
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Institution: | 1. Associate Professor of Forest Hydrology, former Graduate Student, School of Forest Resources, University of Georgia, Athens, Georgia 30602;2. Residue Chemist, Extension Poultry Science Department, University of Georgia, Athens, Georgia 30602;3. Soil Scientist, Southeastern Forest Experiment Station, USDA Forest Service, University of Florida, Gainesville, Florida 32611.;4. Soil Science Department, University of Florida, Gainesville, Florida 32611. |
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Abstract: | The breakpoint rainfall hydrology and pesticide options of the field scale model CREAMS (Chemicals, Runoff, and Erosion from Agricultural Management Systems) were used to predict average concentrations of hexazinone 3 cyclohexyl-6-(dimethyl-amino)-1-methyl-1,3,5-triazine-2,4(1H,3H)-dione] in stormflow from four forested watersheds in the upper Piedmont region of Georgia. Predicted concentrations were compared with measured concentrations recorded over a 13-month period. CREAMS accurately predicted hexazinone concetrations in the initial stormflow events which also contained the highest concentrations. The model underestimated the hexazinone concentrations in stormflow two months and greater following pesticide application. In a companion study, the daily rainfall option of the CREAMS model was used to evaluate the reltive risk associated with the maximum expected concentration of hexazinone, bromacil (5-bromo-3 sec-butyl-6 methyuracil), picloram (4-amino-3,5,6 trichloropicolinic acid), dicamba (3,6-dichloro-0-anisic acid), and triclopyr {(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid} in stormflow from small forested watersheds. The model predicted the following order of potential residue appearance in stormflow: bromacil>triclopyr>hexazinone>picloram>dicamba. Subsurface movement of residues via interflow and deep leaching losses are not simulated by the version of CREAMS used in these studies. |
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Keywords: | CREAMS field scale model herbicide residue storm-flow forests |
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