Organic matter and parathion degradation in flooded soil

Abstract

The effect of rice straw on parathion degradation in a flooded alluvial soil was investigated. In soils inoculated with an enrichment culture which exhibited an exceptionally high ability to hydrolyze parathion, rice straw amendments inhibited parathion hydrolysis to p-nitrophenol and diethyl thiophosphoric acid. On the other hand, in uninoculated soils, rice straw enhanced the degradation of parathion via nitro reduction. During the enhanced breakdown of parathion in uninoculated soils amended with rice straw, aminoparathion and an unidentified metabolite evidently possessing a P=S bond were detected. Thus, the influence of organic matter on the persistence of parathion in flooded soil is governed by the metabolic pathway involved in the degradation.