Effect of Pesticide on Soil Microbial Properties

Biotic-abiotic degradation of two pesticides and their effect on the microbial properties in tropical soils were investigated considering different experimental variables (e.g., application rates, moisture regime, soil conditions, and organic amendment). Experiments were conducted both under controlled laboratory incubation (60% of maximum water holding capacity of soil and waterlogged condition) and actual field conditions (with rice under waterlogged condition). The degradation patterns of pesticides showed a wide variation according to the treatment combinations employed in this study. A short-lived and transitory toxic effect on the soil microbial parameters was discernible during laboratory incubation at the 60% of maximum water holding capacity of both the soils. However, under waterlogged condition microbial properties showed continued declining trends for all the treatments including the control. In the field, the microbial properties declined till the field was waterlogged. Interestingly, after crop harvest, when the experimental plots became aerobic, the all the microbial parameters increased remarkably irrespective of the treatment combinations.