Soil enzymes play essential roles in catalyzing reactions necessary for nutrient cycling in the biosphere. They are also sensitive indicators of ecosystem stress, therefore their evaluation is very important in assessing soil health and quality. By keeping this point in view in the present study, we investigated the soil urease activity at low and higher doses (1.0, 2.5, 5.0, 7.5, 10.0 kg ha-1) and then incubated under laboratory conditions for different time intervals (10, 20, 30 and 40 d). Initially samples were analyzed for physicochemical characteristics, and then soil enzyme activities were determined after respective incubations. The enzyme activities were affected significantly (P ≤ 0.05) when pesticide concentration was 10 kg per ha-1 soil. In contrast, insecticides application at low concentrations (1.0-2.5 kg ha-1) caused stimulated effects. Especially, carbofuran was more effective than acetamiprid in the stimulation of enzyme activities at lower concentrations. Based on the results obtained in the present study, it is concluded that, although pesticide concentration had a somewhat inconsistent and erratic effects on activities of the soil enzymes, but it is true. Insecticides application at more than 7.5 kg ha-1 soils and prolonged incubations did have a negative impact on the investigated soil enzyme activities.
