담수토양중(湛水土壤中)에 있어서 살균제(殺菌劑) IBP의 분해속도(分解速度)에 미치는 각종(各種) 토양환경조건(土壤環境條件)의 영향(影響)

Effect of soil environmental conditions on the degradation rate of the fungicide IBP in flooded soils

담수토양중(湛水土壤中)에 있어서 IBP의 분해(分解)에 미치는 각종(各種) 토양환경조건(土壤環境條件)의 영향(影響)에 대하여 연구검토(硏究檢討)하였다. IBP는 비담수조건(非湛水條件)에서 보다 담수조건(湛水條件)에서 느리게 분해(分解)되었다. 분해속도(分解速度)는 토양종류(土壤種類)에 따라 크게 변화(變化)되었으며, 유기물함양(有機物含量)이 높은 토양(土壤)에서보다 낮은 토양(土壤)에서 빨랐다. IBP는 저온(低溫)에서보다 고온(高溫)의 토양(土壤)에서, 고농도(高濃度)에서보다 저농도(低濃度) 첨가(添加)에서 빨리 분해(分解)되었다. 토양중(土壤中) 분해속도(分解速度)는 볏짚첨가에 의하여 현저히 저하(低下)되었으나, 복합비료(複合肥料)나 타농약(他農藥) fenitrothion과 butachlor의 첨가(添加)에 의하여는 영향(影響)을 받지 않았다. 토양중(土壤中) IBP는 호기적(好氣的) 미생물(微生物)에 의하여 분해(分解)되는 것으로 추정(推定)되었다.

The effects of soil environmental conditions on the rate of degradation of fungicide IBP (Iprobenfos, S-benzyl O, O-diisopropyl phosphorothioate) in the soils under flooded condintions were examined in the laboratory. IBP in soil was degraded more slowly under flooded conditions than under upland conditions. The degradation greatly varied among soils, and the degradation rate was negatively correlated with the content of soil organic matter. Degradation of IBP was influenced by the soil temperature and the amount of IBP applied. The rate of degradation in soil was remarkably inhibited by the amendment of rice straw but not affected by the treatment of mixed-fertilizer, and insecticide fenitrothion and herbicide butachlor. The degradation of IBP was assumed to be due to microorganisms, especially aerobic microbes, as no degradation was observed in sterilized soil.