Effects of temperature, soil moisture content and soil type on the degradation of cypermethrin in two types of Malaysian agricultural soils

The effects of temperature, soil moisture content and soil type on the degradation of cypermethrin was studied using two agricultural soil types namely peat and silty clay. The cypermethrin residue in the soil was extracted using a mixture of water and acetonitril (ratio 1:2). The final extract was redisolved in hexane prior to GC-ECD analysis. The half-life of cypermethrin decreased from 5.93 to 3.24 weeks when the temperature was increased from 25 to 35°C. Results also showed that the half-life decreased from 6.59 to 2.54 weeks as soil moisture content increased from 40 to 60%. The half-life of cypermethrin in non-autoclaved peat and silty clay soil was lower compared to that in the autoclaved soils. In conclusion, temperature, moisture content and soil type greatly influenced the dissipation of cypermethrin.