噁草酮在棉花和土壤中的残留和降解行为研究

Study on Residue and Degradation of Oxadiazon in Cotton and Soil

为了评价噁草酮在棉花上使用的安全性，在济南、杭州两地采用田间试验和气相分析方法研究了噁草酮在棉叶、棉籽及土壤中的消解动态和最终残留。噁草酮在棉叶和土壤中的降解行为均符合一级降解动力学方程，其降解半衰期分别为4．6～5．5 d、54．6～71．5 d。噁草酮在棉籽中的最终残留质量分数均小于最低检出限0．01 mg/kg，低于噁草酮在棉花上的最高残留限量（MRL）0．1 mg/kg。建议噁草酮防治杂草用药次数1次，使用剂量是180 g/hm2。

To evaluate the use security of oxadiazon on cotton , its degradation dynamics and final resi-dues in cotton leaves , seeds and soil were studied by field experiment and gas chromatography （ GC） in Jinan and Hangzhou .The degradation behaviors of oxadiazon in cotton leaves and soil both conformed to the first -degree degradation dynamics equation .Their degradation half -life periods were 4.6~5.5 days and 54.6~71 .5 days respectively .The final residual mass fraction of oxadiazon in cotton seeds was lower than the limit of detection （ LOD） of 0.01 mg/kg and the maximum residue limit （ MRL） of 0.1 mg/kg.It was suggested to spray oxadiazon 1 time with the dosage of 180 g/hm2 in contton field.