|Moorman, Thomas - Tom|
Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: 5/8/1998
Publication Date: N/A
Technical Abstract: Contamination of surface soil and groundwater due to spills and careless mixing, storage, and disposal of herbicides at agricultural chemical dealerships is a major concern in the U.S. The herbicide atrazine is frequently found at Midwest dealership sites. An atrazine-mineralizing bacterium, Agrobacterium radiobacter strain J14a, was added (10**5 cells g**-1 soil) into two Iowa dealership soils, code-named Alpha and atrazine Bravo, containing 5 or 200 ppm atrazine. Strain J14a increased mineralization 10X in the 50 ppm-treated soil and 3X more in the 200 ppm-treated soil than the indigenous microorganisms. J14a inoculated into Bravo soil did not enhance atrazine mineralization, but the indigenous atrazine-degrading population was substantially larger than the Alpha soil population. The effect of organic amendments on degradation was examined in Bravo soil. In Bravo soil treated with 200 ppm, sawdust addition decreased degradation, while manure addition resulted in similar amounts of atrazine degradation compared to the unamended soil. Degradation in soil treated with 200 ppm atrazine was also compared to soil treated with a combination of atrazine, metolachlor, and trifluralin at 200 ppm each. Atrazine degradation in the Bravo soil treated with the three-herbicide mixture was increased significantly over the unamended soil by the 0.5 and 5% manure, 5% peat, 0.5% corn fermentation by-product, and 5% cornstalk treatments. Metolachlor at 200 ppm caused a decrease in atrazine degradation.