Project Number: 6402-12220-003-00
Project Type: Appropriated

Start Date: May 09, 2006
End Date: May 08, 2011

Objective:
This research project objective is to assess the effects of weed management and conservation practices on soil biological, chemical, and physical properties under Mississippi Delta conditions. This will provide an understanding of the interactions between alteration of soil properties by crop and weed management practices and their influence on herbicide fate. This information will be used to develop strategies to both improve herbicide efficacy and reduce the environmental impact of herbicide use.

Approach:
Assessment of weed and conservation practices on the environmental fate of herbicides in soil and plant residues will be assessed in laboratory, greenhouse and field conditions. Most field investigations will study long-term changes in soil properties associated with reduced tillage, cover crops, and residue management to determine how suites of best management practices can be developed to facilitate herbicide effectiveness with minimal potential for adverse effects on the environment. Edge-of-field practices such as filter strips will be assessed to make recommendations on the most effective materials for removal and processing of herbicide contaminants. Field and laboratory research on the environmental fate of the herbicide s-metolachlor will be part of a national effort to examine the role of edaphic factors in degradation kinetics of this herbicide to develop into a predictive model for ascertaining herbicide efficacy and minimize environmental risks. Factors associated with herbicide dissipation, e.g., herbicide degradation, sorption and movement, and specific microbial degradation pathways, will be studied to determine interactions among weed management practices and the environmental fate of herbicides. The effects of using transgenic crops resistant to the herbicides glyphosate and glufosinate on soil microflora and plant-microbial interactions will be evaluated, specifically nitrogen fixation and nitrogen assimilation. The ecology of soil microflora and associated microbial processes will be studied in legume cover crop systems for cotton and flooding systems for a rice soybean rotation.