| Abstract: | Prediction of the fate of pesticides in soil is of interest from an environmental (pollution) as well as an agricultural (efficacy, carryover) viewpoint. Two environmental parameters that control microbial degradation of pesticides in soil are moisture and temperature. This study was designed to quantify the impact of soil water content and temperature on microbial degradation rates of the insecticide carbofuran (2, 3-dihydro-2, 2-dimethylbenzofuran-7-yl methyl-carbamate). Carbofuran degradation was determined by monitoring the 14 C] carbondioxide production from soils amended with carbonyl- 14 C]carbofuran. Soils were incubated at seven soil-water tensions over the range of 0–03 to 1–5 MPa, and at five temperatures (10°C to 30°C). The sigmoidal degradation kinetics observed from these incubations were modeled using a general saturation model. For the moisture experiments, maximum rate of hydrolysis and half-life (DT50) were accurately modeled by an exponential relationship. The response of carbofuran degradation to temperature was also well described by an exponential relationship, from which it was estimated that the Q10 associated with the maximum rate was 1.68, and the Q10 for DT50 was 1–89. |
