Interaction Effects of Insecticides on Enzyme Activities in Black Clay Soil from Groundnut (Arachis hypogaea L.) Fields
In practice pesticides are extensively used in agriculture as a part of pest control strategies. Two insecticides, endosulfan (organochlorine) and profenophos (organophosphate), were assessed for their effects on the activities of protease (in terms of tyrosine formed from casein) and urease (as ammonia released from urea) in soil, collected from a fallow groundnut field by applications of insecticides at normal field rates and at higher concentrations (1.0, 2.5, 5.0, 7.5, 10.0 kg ha-1), in a laboratory study. The results showed a strong positive influence on protease and urease enzyme activities in soil treated with 2.5 and 5.0 kg ha-1 dry soil and they were significantly (P ≤ 0.05) higher than the control over the course of incubation. In soil treatment, there was a significant increase in protease and decrease in urease activities after 24h of incubation which continued up to 20 days. However, a significant decrease in both protease and urease enzyme activities was observed in 30 and 40 days of incubation.