|Lerch, Robert - Bob|
Submitted to: Symposium on the Fate and Chemistry of Modern Pesticides Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/30/2001
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Grass riparian buffer strips are recognized as one of the most effective bioremediation approaches to alleviating transport of agricultural chemicals from crop lands. A lysimeter study with 6 different ground covers (bare ground, tall fescue, smooth bromegrass, orchardgrass, timothy, and switchgrass) was established to evaluate the effect of forages on the fate of Balance (isoxaflutole, IXF) and atrazine. Herbicides were uniformly applied to each lysimeter and the effluent was sampled as a function of time. Balance reportedly has a very short half-life (<3 d)in soils degrading to the biologically active diketonitrile (DKN) metabolite which further degrades to a benzoic acid (BA) derivative. Our results showed no detections of IXF in lysimeter leachate at any sample date. The DKN metabolite was the primary IXF metabolite in leachate with detections at all sample dates. Grass treatments did not promote the hydrolysis of DKN to oBA, but they did significantly reduce the total quantity of IXF metabolite in leachate. Although the grass treatments were not able to reduce the total atrazine (atrazine plus metabolites) present in the leachate, they did significantly enhance atrazine degradation, particularly dealkylation reactions. For atrazine treated lysimeters, the microbial population strongly correlated (p<0.05) with the amount of degradation products in the leachate. In contrast, the correlation between microbial population and amount of DKN degradation products in leachate was insignificant (p>0.05).