2007 Annual Report 1a.Objectives (from AD-416) 1)Develop optimized novel clay-based CRFs of herbicides that reduce leaching;. 2)Compare CRF efficacy and field and laboratory leaching and dissipation rates to conventional formulations in cotton and peanuts under conventional and reduced tillage management; and 3)Conduct simulations of the environmental fate of CRF and conventional formulations using models widely used to assess water quality risks of pesticide use. 1b.Approach (from AD-416) Optimized CRFs of metolachlor, and sulfentrazone will be prepared. These compounds provide effective control of many problematic weeds; however, conventional formulations present leaching risks. The CRFs will be tested for herbicidal activity in greenhouse studies and leaching, adsorption-desoption and bio-degradation coupled with cyclic soil wetting and drying will be studied in laboratory. Weed control efficacy and runoff, leaching and dissipation rates of CRFs and conventional formulations will be compared during cotton and peanut production under reduced-tillage management in large scale field studies. Finally, environmental fate data will be evaluated using simulation models so that water quality risks of the CRF and conventional forms of the herbicides can be quantitatively compared. 3.Progress Report This report documents 3-year study of research conducted under a foreign reimbursable agreement between the USDA-ARS Southeast Watershed Research Laboratory, the Volcani Institute and Hebrew University of Jerusalem and is funded by the United States - Israel Bi-national Agricultural Research and Development Fund (BARD). The project start date was Septemer 1, 2005. Additional details of research can be found in the report for the in-house associated project 6602-12130-001-00D, Soil Response to Conservation Tillage in a Cotton-Peanut Rotation. Quantified combined effect of herbicide incorporation by irrigation and tillage impact on runoff loss. To reduce herbicide runoff risk, cotton and peanut farmers in the Atlantic Coastal Plain are encouraged to irrigate soon after application the herbicides are applied. In theory the practice should effectively reduce runoff losses. To quantify impacts, we conducted rainfall simulations in a field in a cotton-peanut rotation in south central Georgia (USA). We found that herbicide runoff was up to two times less from plots that were irrigated prior to a rainfall event compared to those that were not. Studies also showed that the practice’s efficacy was strongly impacted by tillage management and herbicide properties. When a commonly used conservation-tillage practice, strip-tillage, was used, whether plots were irrigated or not had little impact on runoff of an herbicide that has low water solubility and high capacity for adsorption by soil. These findings will be useful to growers, since it will help them determine when irrigation will be most useful to reduce herbicide runoff losses. 5.Significant Activities that Support Special Target Populations None 6.Technology Transfer