Degradation of Dimethoate Pesticide in Soil: Impact of Soil Moisture and Enhanced Sunlight Intensity

In today’s agriculture, the use of pesticides has become a necessity for higher yield of crops. Out of the total pesticides applied, only a small fraction reaches the target pest and the rest pollute different environmental segments. The present study signifies the effect of soil moisture and enhanced sunlight intensity on the degradation of dimethoate, a commonly used organophosphate pesticide in soil. The study was conducted in dry, field capacity, and submerged soils under enhanced sunlight conditions (3 intensity levels) obtained by using a solar collector. Higher degradation was observed in submerged soil followed by dry and field capacity soils under all the light conditions and might have occurred through radical mediated mechanism. When sunlight intensity was almost doubled, the pesticide residue was 17.2% less but 9% higher as compared to UV light in submerged soil after 30 days of experimentation, mainly due to the increase in UV component of enhanced sunlight intensity. Therefore, although artificial UV light is still most effective in pesticide degradation, enhanced sunlight can also play an important role and be used as a viable, economical, and greener technique. Statistically, sunlight intensity and the degradation rate were correlated positively. Moreover, the degradation of the pesticide in soil followed first order kinetic model. The half-life of the pesticide varied widely from 7.96 to 41.11 days under different soil moisture and sunlight conditions. This study can help in understanding and modeling the degradation behavior of dimethoate under varying soil and environmental conditions.