Soil metabolism seems to be one of the major tools to study the effect of agrochemicals (pesticides and fertilizers) on soil health. It is an appropriate indicator for highlighting the impact of land use management, soil quality monitoring and pollution. Several experiments were conducted to find out the effect of pesticides on soil metabolism. However few studies were conducted on Imidacloprid (neonicotinoid) and Dimethoate (organophosphate) which showed no concrete conclusion. So an attempt was undertaken to find out the toxicity of Imidacloprid and Dimethoate which are being used mostly in the Indian crop fields today due to its less toxicity. The study found an increase of dehydrogenase activity by 15.36% in recommended agricultural dose of imidacloprid treated soil and decreased by 36.25% in dimethoate treated soil after 15 days. The acid phosphatase activity was also increased by 24.37% in imidacloprid treated soil and decreased by 23.65% in dimethoate treated soil till 15 days. Similar trend was also found in alkaline phosphatase activity where there is an increase of 22.87% in imidacloprid treated soil and decreased by 31.77% in dimethoate treated soil. But the urease activity was less in soil treated with recommended agricultural doses of imidacloprid and dimethoate as compared to control soil. The present study indicates greater toxicity of dimethoate in comparison to Imidacloprid. So it is suggested to avoid dimethoate even at the recommended doses.
