Effects of long-term of 2,4-D and MCPA field applications on the soil breakdown of 2,4-D, MCPA, mecoprop, and 2,4,5-T
- Agriculture Canada, Regina, Saskatchawan (Canada)
Under laboratory conditions, the rates of breakdown of ({sup 14}C)2,4-D (2,4-dichlorophenoxyacetic acid), ({sup 14}C)MCPA (4-chloro-2-methyl-phenoxyacetic acid), ({sup 14}C)mecoprop (2-(4-chloro-2-methylphenoxy)propionic acid), and 2,4,5-T (2,4-5-trichlorophenoxyacetic acid) in soils from Canadian prairie field plots, 6 wk after receiving the 43rd annual application of 2,4-D formulations or the 37th annual treatment with MCPA, were compared with those in soils from untreated plots. Loss of 2,4-D and MCPA was faster in soils that had received continuous applications with the apopropriate herbicide than in soil from the control plots. There was some indication that ({sup 14}C)2,4-D was dissipated more rapidly from soils treated annually with MCPA than from the control soils, though breakdown was slower than in soil from the 2,4-D treated plots. In contrast, ({sup 14}C)MCPA breakdown in the 2,4-D treated plots was similar to that in untreated soils. Breakdown of ({sup 14}C)mecoprop and 2,4,5-T in the 2,4-D and MCPA-treated soils was very similar to that in the control soils. Thus, there was no support for the phenomenon of cross-enhancement. Forty-eight weeks after the last herbicide applications, the field soils still maintained their ability to degrade 2,4-D or MCPA more rapidly than soil from untreated control plots.
- OSTI ID:
- 5269124
- Journal Information:
- Journal of Environmental Quality; (United States), Journal Name: Journal of Environmental Quality; (United States) Vol. 20:2; ISSN JEVQA; ISSN 0047-2425
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
540211* -- Environment
Terrestrial-- Basic Studies-- Radiometric Techniques-- (1990-)
BIODEGRADATION
CANADA
CARBON 14 COMPOUNDS
CARBON COMPOUNDS
CHEMICAL REACTIONS
DECOMPOSITION
DEVELOPED COUNTRIES
ENVIRONMENTAL EFFECTS
HERBICIDES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
NORTH AMERICA
PESTICIDES
SOILS
TRACER TECHNIQUES