Effect of Rate of Application and Moisture Regimes on Persistence of Bifenthrin in Soil under Laboratory Conditions

Persistence of bifenthrin as affected by rate of application and moisture regimes was studied in alluvial soil under laboratory conditions. The fortified soil (1.0 and 10.0 mg kg⁻¹) with air-dry, field capacity and submerged moisture content was incubated at 25°C and 90% relative humidity. The initial deposits of 0.92–0.95 mg kg⁻¹ and 8.71–8.86 mg kg⁻¹ dissipated with time and 42.3–77.1% loss was recorded at 60 days. Residues persisted in soil for more than 60 days in all treatments indicating moderately longer persistence of bifenthrin. Dissipation of bifenthrin followed first order kinetics with half-life values varying from 29.5–73.4 days. At higher dose the rate of dissipation was slower. Persistence of bifenthrin under different moisture regimes followed the trend: air-dry > field capacity > submerged. The trend could be attributed to the effect of moisture on number and type of microbes. It seems that un-aerobic microbes are efficient in degradation of bifenthrin.