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Kinetic Distribution of 14 C‐Metsulfuron‐methyl Residues in Paddy Soils under Different Moisture Conditions
Author(s) -
Wang H. Z.,
Gan J.,
Zhang J. B.,
Xu J. M.,
Yates S. R.,
Wu J. J.,
Ye Q. F.
Publication year - 2009
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2007.0607
Subject(s) - soil water , chemistry , water content , leaching (pedology) , agronomy , moisture , incubation , residue (chemistry) , environmental chemistry , environmental science , soil science , biology , biochemistry , geotechnical engineering , organic chemistry , engineering
Rice paddy soils undergo several cycles of drying and wetting during a growing season. A laboratory study was conducted to determine the effect of soil moisture conditions on the distribution and kinetics of extractable and bound residues of 14 C‐metsulfuron‐methyl in six Chinese paddy soils during 84 d of incubation at 15°C with moisture contents varying from 20 to 50% of the field water‐holding capacity. The amount of extractable residues consistently increased and bound residues decreased with increasing soil moisture content. At the end of the incubation experiments, extractable residues and bound residues accounted for 34.5 to 84.4% and 11.6 to 53.3% of applied radioactivity in soils, respectively. Soil pH and soil microbial biomass carbon were the most predominant factors affecting the formation and relative distribution of herbicide residues between extractable and bound residue forms. In high‐pH soils, bound residues decreased and extractable residues increased, suggesting an increased leaching risk for metsulfuron‐methyl in alkaline soils. High precipitation rates, along with the common practice of liming in southeastern China, may lead to enhanced herbicide leaching as well as phytotoxicity to rotation plants and should be considered in overall pest management practices.