AbstractIncreasing adsorption of 14C‐labelled carbendazim in soil took place within a few weeks of incubation and was greatest in soil with a high organic matter content. Carbendazim was slowly decomposed in soil, mainly by soil microorganisms. After 250 days of incubation in two unsterilised soils, 13 and 5 respectively of added 14C‐carbendazim was recovered compared with 70 and 50 respectively from sterile soils; 4–8 of added carbendazim was recovered as 2‐aminobenzimidazole (2‐AB) from both unsterilised and sterile soil. After 270 days' incubation, 33 and 9 of14C was recovered as14CO2from soil supplied with 14C‐carbendazim (20 and 100 mg/kg) respectively. Degradation started more rapidly when carbendazim was added to soil preincubated with the fungicide but the degradation rate was very low in all cases, indicating that the compound is a poor microbial energy source and that the degradation is a co‐metabolic process. 2‐AB was found as a degradation product although it appeared to be unstable in soil, decomposing rapidly after a lag period of about 3 weeks; small amounts remained in the soil for several months, however, presumably adsorbed on
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