Location: Crop Production Systems Research Unit
Project Number: 6066-12220-004-00
Start Date: May 09, 2011
End Date: Dec 21, 2015
Pesticide persistence in soil and soil sorption estimates are integral components of fate, transport and risk assessment models, which are utilized by Environmental Protection Agency (EPA), industry, National Resource Conservation Service (NRCS), and others to make pesticide use decisions. Sensitivity analysis, that is, investigations into how model performance varies along with changes in the key assumptions on which the model projections are based, indicates that inaccurate persistence and sorption estimates adversely affect model predictions; thus, pesticides may act differently than expected depending on many factors. Accurately predicting pesticide behavior increases the probability for successful pest control while simultaneously protecting the environment. Currently, modelers use default input persistence and sorption estimates to predict pesticide transport, and these default input estimates are based on scant data from a few locations scattered across the United States. For example, data for glyphosate, the most widely used herbicide in the United States, is negligible, with dissipation kinetics available for only six soils within our borders. Dissipation and sorption data for herbicides that will augment and/or supplant the Roundup Ready™ system, e.g., glufosinate, dicamba, 2,4-D and mesotrione, are equally scarce, particularly for the Mid-South. Thus, the objective of this project is to determine glyphosate, glufosinate and perhaps dicamba, 2,4-D and mesotrione fate, i.e., sorption, mineralization, dissipation, and bound residue formation, in Mid-South soils under various crop production systems that vary widely in physiochemical properties. Regression analysis will be used to construct regional sorption, mineralization, dissipation and bound residue formation models that more accurately predict the behavior of these pesticides in the environment. In addition, weed managers will utilize our fate and transport expertise to begin addressing resistant weed seed transport in Mid-South soils.