Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: 4/30/2003
Publication Date: 11/4/2003
Citation: McKee, L.G., Gish, T.J., Prueger, J.H. 2003. Impact of climate on watershed scale volatization fluxes of metolachlor and atrazine [CD-ROM]. Crop Science Society, Soil Science Society of America. Denver, Colorado: Agronomy Society of America.
Technical Abstract: Agricultural chemicals can enter environments where they were not intended by one or more of three major processes, volatilization, surface runoff, and/or subsurface leaching. Although soil moisture and temperature have been cited as influencing pesticide volatilization, the relevance of climatic conditions on watershed scale pesticide volatilization is poorly understood. In this study, the impact of climate on watershed scale pesticide volatilization fluxes is studied by evaluating metolachlor and atrazine volatilization fluxes over 5 years at the USDA-ARS Optimizing Production Inputs for Economic and Environmental Enhancement program in Beltsville, Maryland. Throughout the 5-year study, tillage, management practice and pesticide formulation where held constant. Volatilization rates of pre-emergent herbicides metolachlor and atrazine, applied as a broadcast spray, were calculated with a flux-gradient technique using data from eddy correlation measurements. Regardless of weather conditions, pesticide flux profile concentrations of metolachlor and atrazine were large during the first 24 hours and quickly declined for the duration of the study. However, climatic conditions had a dramatic impact on the total pesticide loss to the atmosphere, with metolachlor vapor losses ranging from 3 to 20% of that applied. As a result, temperature and timing of precipitation events relative to chemical application will have a critical impact on pesticide volatilization losses.