The behavior of clomazone in the soil environment

BACKGROUND: Clomazone is a herbicide used to control broadleaf weeds and grasses. Clomazone use in agriculturally important crops and forests for weed control has increased and is a potential water contaminant given its high water solubility (1100 µg mL−1). Soil sorption is an environmental fate par...

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Bibliographic Details
Published in:Pest management science 2009-06, Vol.65 (6), p.711-716
Main Authors: Gunasekara, Amrith S, dela Cruz, Imma Donna P, Curtis, Matthew J, Claassen, Victor P, Tjeerdema, Ronald S
Format: Article
Language:English
Subjects:
Adsorption
Biological and medical sciences
black carbon
clomazone
Forest soils
Fundamental and applied biological sciences. Psychology
Grasses
Herbicides
Herbicides - chemistry
humic acid
Humic Substances - analysis
Isoxazoles - chemistry
NMR
Oryza sativa
Oxazolidinones - chemistry
Parasitic plants. Weeds
Phytopathology. Animal pests. Plant and forest protection
soil
Soil - analysis
Sorption
Weeds
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Summary:BACKGROUND: Clomazone is a herbicide used to control broadleaf weeds and grasses. Clomazone use in agriculturally important crops and forests for weed control has increased and is a potential water contaminant given its high water solubility (1100 µg mL−1). Soil sorption is an environmental fate parameter that may limit its movement to water systems. The authors used model rice and forest soils of California to test clomazone sorption affinity, capacity, desorption, interaction with soil organic matter and behavior with black carbon. RESULTS: Sorption of clomazone to the major organic matter fraction of soil, humic acid (HA) (Kd = 29–87 L kg−1), was greater than to whole soils (Kd = 2.3–11 L kg−1). Increased isotherm non‐linearity was observed for the whole soils (N = 0.831–0.893) when compared with the humic acids (N = 0.954–0.999). Desorption isotherm results showed hysteresis, which was greatest at the lowest solution concentration of 0.067 µg mL−1 for all whole soils and HA extracts. Aliphatic carbon content appeared to contribute to increased isotherm linearity. CONCLUSION: The results indicate that clomazone does not sorb appreciably to sandy or clay soils. Its sorption affinity and capacity is greater in humic acid, and consequently clomazone has difficulty desorbing from soil organic matter. Sorption appears to follow processes explained by the dual‐mode model, the presence of fire residues (black carbon) and a recently proposed sorption mechanism. Copyright © 2009 Society of Chemical Industry
ISSN:1526-498X
1526-4998
DOI:10.1002/ps.1733