Wang Haizhen, Wu Jianjun, Yates Scott, Gan Jay
Institute of Soil and Water Resources and Environmental Science, Zhejiang University, Hangzhou 310029, China.
Pest Manag Sci. 2008 Oct;64(10):1074-9. doi: 10.1002/ps.1607.
Metsulfuron-methyl is widely used for controlling many annual grasses and broadleaf weeds in cereal crops. Nonetheless, increasing evidence has demonstrated that even extremely low levels of metsulfuron-methyl residues in soil can be toxic to subsequent crops or non-target organisms. The behavior of herbicides in soils is mostly related to their residual forms. The intent of the present study was to investigate the dynamics of extractable residues (ERs) and non-extractable residues (NERs) of (14)C-metsulfuron-methyl in twelve Chinese paddy soils and their relationships to soil properties.
ERs decreased gradually after application, whereas NERs increased rapidly during the initial 28 days, and gradually decreased thereafter. ERs and NERs were respectively 10.1-67.9% and 5.6-28.7% of applied radioactivity in soils at 224 days after application. ERs correlated positively with soil pH and silt fractions, and negatively with microbial biomass carbon (MBC) and clay fractions, but the opposite was observed for NERs.
Both ERs and NERs may be present in the soil at the time of planting following rice crops, and the risk of phytotoxic effects needs to be considered. Soil pH, MBC and clay/silt fractions were the main factors in affecting the amounts of both ERs and NERs of metsulfuron-methyl in the tested soils.
甲基磺草酮被广泛用于防治谷类作物中的多种一年生禾本科杂草和阔叶杂草。然而，越来越多的证据表明，即使土壤中甲基磺草酮残留量极低，也可能对后续作物或非靶标生物产生毒性。除草剂在土壤中的行为主要与其残留形态有关。本研究旨在调查14C-甲基磺草酮在12种中国水稻土中的可提取残留（ERs）和不可提取残留（NERs）的动态变化及其与土壤性质的关系。
施药后ERs逐渐降低，而NERs在最初28天内迅速增加，此后逐渐降低。施药224天后，土壤中ERs和NERs分别占施入放射性的10.1-67.9%和5.6-28.7%。ERs与土壤pH值和粉粒组分呈正相关，与微生物生物量碳（MBC）和黏粒组分呈负相关，而NERs则相反。
水稻作物种植时，土壤中可能同时存在ERs和NERs，需要考虑植物毒性效应的风险。土壤pH值、MBC以及黏粒/粉粒组分是影响供试土壤中甲基磺草酮ERs和NERs含量的主要因素。
