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Bromoxynil degradation in a Mississippi silt loam soil

Permanent URL:
http://handle.nal.usda.gov/10113/30359
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Abstract:
BACKGROUND: The objectives of these laboratory experiments were: (1) to assess bromoxynil sorption, mineralization, bound residue formation and extractable residue persistence in a Dundee silt loam collected from 0-2 cm and 2-10 cm depths under continuous conventional tillage and no-tillage; (2) to assess the effects of autoclaving on bromoxynil mineralization and bound residue formation; (3) to determine the partitioning of non-extractable residues; and (4) to ascertain the effects of bromoxynil concentration on extractable and bound residues and metabolite formation.RESULTS: Bromoxynil Kd values ranged from 0.7 to 1.4 L kg⁻¹ and were positively correlated with soil organic carbon. Cumulative mineralization (38.5% ± 1.5), bound residue formation (46.5% ± 0.5) and persistence of extractable residues (T₁/₂ < 1 day) in non-autoclaved soils were independent of tillage and depth. Autoclaving decreased mineralization and bound residue formation 257-fold and 6.0-fold respectively. Bromoxynil persistence in soil was rate independent (T₁/₂ < 1 day), and the majority of non-extractable residues (87%) were associated with the humic acid fraction of soil organic matter.CONCLUSIONS: Irrespective of tillage or depth, bromoxynil half-life in native soil is less than 1 day owing to rapid incorporation of the herbicide into non-extractable residues. Bound residue formation is governed principally by biochemical metabolite formation and primarily associated with soil humic acids that are moderately bioavailable for mineralization. These data indicate that the risk of off-site transport of bromoxynil residues is low owing to rapid incorporation into non-extractable residues.
Author(s):
Zablotowicz, Robert M. , Krutz, L. Jason , Accinelli, Cesare , Reddy, Krishna N.
Subject(s):
bromoxynil , silt loam soils , biodegradation , pesticide residues , sorption , mineralization , half life , soil depth , conventional tillage , no-tillage , autoclaving , soil organic matter , metabolites , humic acids , leaching , Mississippi
Format:
p. 658-664.
Note:
Includes references
Source:
Pest management science 2009 June, v. 65, no. 6
Language:
English
Publisher:
John Wiley & Sons, Ltd.
Year:
2009
Collection:
Journal Articles, USDA Authors, Peer-Reviewed
Rights:
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.