Effects of Soil Environmental Conditions on the Decomposition Rate of Insecticide Fenitrothion in Flooded Soils

담수토양중(湛水土壤中)에 있어서 살충제(殺蟲劑) fenitrothion의 분해속도(分解速度)에 미치는 각종(各種) 토양환경조건(土壤環境條件)의 영향

The effects of soil environmental conditions on the degradation rates of fenitrothion(O-O-dimethyl O-4-nitro-m-tolyl phosphorothioate) in soils under flooded conditions were examined in the laboratory. Fenitrothion was degraded rapidly and the half life period was within 4 days. Furthermore the degradation was mere rapid under flooded conditions than under upland conditions. The decomposition rate was varied with soils and soil temperatures. Fenitrothion degraded more slowly at 30ppm than at l0ppm. Repeated applications of fenitrothion in soils accelerated the degradation rates. The degradation remarkably increased with amendment of rice straw. However, degradation rates ,were virtually unaffected by the addition of the mixed-fertilizer, the fungicide IBP and the herbicide butachlor. The population of fenitrothion-degrading microbes, which were counted by MPN method, always corresponded with the degradation rates in the soils.

담수토양중(湛水土壤中) fenitrothion의 분해(分解)에 미치는 각종환경조건(各種條件條件)에 영향(影響)에 대하여 연구(硏究) 검토(檢討)하였다. Fenitrothion은 습윤조건(濕潤條件)에서보다 담수조건(湛水條件0에서 월등(越等)히 빨리 분해(分解)되었으며, 토양중(土壤中) 분해반감기(分解半減期)는 4일이하(日以內)였다. 분해속도(分解速度)는 토양종류(土壤種類)에 따라 차이(差異)를 보였으며, 저온(低溫)($15^{\circ}C$)에서보다 고온(高溫)($35^{\circ}C$)에서 현저히 빨리 분해(分解)되었다. Fenitrothion은 저농도처리(低濃度處理)(10ppm)에서보다 고농도처리(高濃度處理)(30ppm)에서 분해(分解)가 느렸다. Fenitrothion의 반부처리(反復處理)는 분해속도(分解速度)를 크게 촉진(促進)시켰다. 토양중(土壤中) fenitrothion의 분해(分解)는 볏짚 첨가(添加)에 의하여 현저히 촉진(促進)되었으나, 복합비료첨가(複合肥料添加)나 살균제(殺菌劑) IBP와 제초제(除草劑) butachlor의 혼합처리(混合處理)에 의하여는 거의 영향(影響)을 받지 않았다. 토양(土壤)중에 있어서 fenitrothion분해균(分解菌)의 증식(增殖)과 fenitrothion분해정도(分解程度)는 비례(比例)하였다.