Effects of Sulfonyl Urea Herbicides on Soil Microbial Community.

磺酰脲类除草剂于1975年被发现，并立即为化学杂草控制设定了新的标准。这些除草剂的特点包括其极低的施用量（通常比传统除草剂低10-100倍），良好的环境和毒理学特性，以及与出现后杂草控制的趋势相适应。甲基苯磺隆是第一个用于水稻的商业化磺酰脲除草剂。在本研究中，根据上述建议评估了该化学品对微生物群的副作用。在20世纪70年代初，欧洲的管理当局正在考虑引入测试农药对土壤微生物群影响的要求。欧洲的几个研讨会发表了关于测试的建议。同样在日本，Yamamoto等人于1993年提出了一项关于农药对土壤微生物群副作用测试的建议草案。作为评估方法的一部分，我们使用该测试方法研究了甲基苯磺隆对“氨化”、“硝化”和“微生物生物量”的影响。在推荐用量下施用该除草剂对稻田土壤的“氨化作用”和“微生物生物量”无显著影响。然而，这种化学物质似乎对“硝化”有暂时的不利影响，并且在28天内完全恢复。为了对这些方法得到的数据进行评价，研究了野外条件下微生物活动的年波动情况。其波动幅度明显大于农药处理。

The sulfonylurea herbicides were discovered in 1975 and immediately set a new standard for chemical weed control. The herbicides include their exceptionally low application rates (often a factor of 10-100 times lower than conventional herbicides), favorable environmental and toxicological properties, and compatibility with the trend towards post emergence weed control. Bensulfuron methyl was the first sulfonylurea herbicide commercialized for use in rice. In this study, side-effects of the chemical on microflora were assessed according to the recommendations stated above.In the early 1970's regulatory authorities in Europe were considering the introduction of the requirement for tests of pesticides effects on soil microflora. Several workshops in Europe published recommendations for the testing. Also in Japan, a draft recommendation for the testing of side-effects of pesticides on soil microflora was proposed by Yamamoto et al.in 1993.As part of our evaluation of the proposed method, we studied the effects of bensulfuron methyl on 'ammonification', 'nitrification' and 'microbial biomass' using the proposed test method. The herbicide, applied at the recommended rate to paddy field soil, has no significant effect on 'ammonification and 'microbialbiomass'. The chemical, however, appears to have a temporary adverse effect on 'nitrification', and a complete recovery was evident at 28 days.For the evaluation of the data derived by those method, annual fluctuation of the microbial activities under field condition were investigated. The fluctuation were much more than those by the pesticide treatment.