Author
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SIMS, GERALD |
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Submitted to: Soil Biology and Biochemistry
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 1/12/2006 Publication Date: 3/2/2006 Citation: Sims, G.K. 2006. Nitrogen starvation promotes biodegradation of n-heterocyclic compounds in soil. Soil Biology and Biochemistry, Vol 38. Available: http//www.sciencedirect.com. Interpretive Summary: Recent research has shown that the herbicide, atrazine, is used by microorganisms as a source of nitrogen. Studies were performed to examine the impact on degradation of the herbicides, atrazine and cloransulam-methyl, caused by depriving soil microbial communities of nitrogen. Soil depleted by 125 years of cropping to corn without fertilization was contrasted to soil from the same site regularly receiving fertilizers. Long-term nitrogen deprivation promoted rapid degradation of atrazine and the nitrogen-containing portion of the cloransulam-methyl molecule, whereas no significant effect was observed on degradation of remainder of the cloransulam-methyl molecule. Using a sandy soil naturally low in N, we observed that degradation of the nitrogen-containing portion of the cloransulam-methyl molecule was inhibited by the addition of as little as one microgram of ammonium-nitrogen per gram of soil. These findings suggest broader implications for the role of soil nitrogen in degradation of nitrogen-containing herbicides. The impact of this work will be realized in the development of management strategies that integrate fertility and weed management approaches to enhance productivity while minimizing environmental costs. Technical Abstract: Mineralization studies were performed to examine the impact of N deprivation on microbial utilization of the herbicides, atrazine and cloransulam-methyl (C-M). Soil depleted by 125 years of cropping to Zea mays without fertilization was contrasted to soil from the same site regularly receiving fertilizers. Long-term N deprivation promoted rapid degradation of atrazine and the C-M pyrimidine ring, whereas no significant effect was observed on degradation of the C-M phenyl ring. Using a sandy soil naturally low in N, we observed that mineralization of the C-M pyrimidine ring was inhibited by the addition of as little as 1 µg NH4-N/g soil. These findings suggest broader implications for the role of exogenous N in degradation of heterocyclic herbicides. |
