绿黄隆在三种土壤中的降解

Degradation of Chlorsulfuron in Three Types of Soil

在实验室内，采用改进的玉米根长生测方法，定期测定一定温、湿度条件下绿黄隆在３种土壤中的残留动态。对降解时间和残留剂量进行回归分析，符合一级反应动力学指数方程Ｃ＝Ｃ０ｅ－ｋｔ，相关系数达极显著水平，半衰期ｔ１／２＝ｌｎ２／ｋ。实验结果表明，在２５℃、２５％温、湿度条件下，绿黄隆在太湖水稻土中降解最快，半衰期为１．６周；其次是砂姜黑土，半衰期为２．５周；高砂土中降解最慢，半衰期为１３．３周。分析认为，土壤ｐＨ值和微生物量是影响绿黄隆降解的主要因素。高温灭菌土壤测得绿黄隆在砂姜黑土的灭菌土和未灭菌土中，半衰期分别为２６．５周和２．１周；太湖水稻土的灭菌和未灭菌土中，半衰期分别为５．０周和０．９周。从而进一步证实，绿黄隆在太湖水稻土中以非酶水解和微生物活动共同降解，在碱性砂姜黑土中主要以微生物降解。探讨了绿黄隆在３种土壤中的残留动态对农业生产的重要性，建议长江流域碱性沙质土壤农区慎用或禁用绿黄隆。

A newly developed corn root bioassay method was used to determine the degradation of chlorsulfuron in three types of soils,i.e. A: Gleyed sandy loam paddy soil(pH 5 46) ; B:Sajiang black clay loam soil(pH7 31) ; C:Fluvo aquic sandy loam soil(pH7 64).Regression analysis of degradation time and residual dose accorded with the exponent equation C=c 0e -kt ,t 1/2 (half life of chlorsulfuron)=ln2/k.The results showed half lives were 1 6 weeks in A,2 5 weeks in B and 13 3 weeks in C(25℃,25% soil water contents),respectively.The differences of half lives resulted from soil pH value and microbial biomass.The half life of chlorsulfuron in the sterilized and nonsterilized soil of B were 26 5 weeks and 2 1 weeks,respectively,while those of A were 5 weeks and 0 9 week,which demonstrated that chlorsulfuron degradation was conducted by chemical hydrolysis and microbes activities in A while chlorsulfuron degradation was conducted mostly by microbes activities in B.Importance of residual state of chlorsulfuron on agricultural production was discussed,and chlorsulfuron should be used cautiously in sandy soil (pH>7).