湛水土壤에 IBP 粒劑를 反復處理하고 後處理한 藥劑의 分解에 미치는 影響을 試驗한 結果 1) IBP의 反復處理로 後處理한 IBP의 分解가 促進되었으며 그 效果는 약 53日間 持續되었으나 diazinon의 分解에는 影響이 없었다. 2) 土壤殺菌으로 IBP의 分解가 크게 抑制되어 分解速度는 無殺菌土壤에 비해 3倍이상 遲延되었으며 反復處理에 의해 生成된 IBP 分解促進能力도 消失되었다. 3) IBP 反復處理로 因한 土壤微生物의 전체 colony數는 변하지 않았다.

This experiment was conducted to see the effect of repeated application of IBP granular formulation(17%, 0,0-diisopropyl-S-benzyl thiophosphate) on the biodegradation of IBP and diazinon〔0,0-diethyl 0-(2-isopropyl-4-methyl-5-pyrimidinyl) phosphorothioate〕 in silt loam soil with 2.1% organic matter under flooded condition. The persistence of IBP in the soil was shortened by increasing the frequencies of application of the chemical. Enhanced degradation ability in the soil caused by repeated application of IBP was prolonged about 53 days, while the ability did not influence diazinon persistence in the soil. The half-lives of IBP in sterilized soil autoclaved at 121℃ for 30 minutes were about 3 times longer than those in viable soil, suggesting that microbial process was a major factor for IBP degradation in the soil. The total colony number of soil microbes showed little difference between the soils with and without repeated application of IBP. A possible concern of specific soil microorganisms on the pesticide degradation in soil was discussed.