Field Residue Decline Study of Acephate andMethamidophos in Crop and Soil

In order to evaluate the safety application of acephate,field residue decline study of acephate in different climatic conditions of crop and soil were studied using gas chromatography(GC) determination method.The results showed that acephate could metabolize to methamidophos rapidly in tested crop and soil.Metabolic rate of methamidophos in 2 hours was significantly affected by crop species.The half-life of acephate was 3.1~13.5 days in crop,while that of its metabolite methamidophos was 2.7~12.8 days in crop.The half-life of acephate was 1.4~6.4 days in soil,and that of methamidophos was 4.5~10.7 days in soil.The degradation of acephate and methamidophos in soil was affected significantly by soil pH,the alkaline soil caused faster degradation.The climate condition of higher net radiation may accelerate the degradation of acephate and methamidophos in crop,so the crop applied acephate had higher methamidophos residue risk in the warm climate condition than in the subtropical climate condition.Leafy vegetables applied acephate have higher methamidophos residue risk than other crops,it's suggested that leafy vegetables needed to use acephate carefully.