Impacts of three soil applied pesticides on soil enzymes activity and soil respiration under controlled conditions

The experiment was conducted in a laboratory to investigate the impact of soil applied pesticides belonging to three different types; herbicides (Metribuzin), fungicide (Carbendazim) and insecticide (imidacloprid) on the activity of enzymes in soil, alkaline phosphatase, Urease, dehydrogenase and Rhodanese as well as soil respiration in two types of soil, silty and silty loam. The pesticides were applied in 0, 0.1, 10, and 100 mg kg-1 dry soil. The measurable microbiological processes in soil were estimated after 0, 1, 2, 7.14, 21, 45.60 and 120 days from the application of pesticides. The study showed that based on the enzyme activity and soil respiration in the estimated time after treatment with pesticides. It was clear that after the application of pesticides to increase the rate of activity for 24 hours and then drop to the lowest level after 48 hours. Highest values of the activity of processes studied were recorded in 14 days of soil treatment with pesticides. Curb these operations again after 45 days and return to normal activity with the passage of time after 120 days. Herbicides, metribuzin was an highest inhibitor for enzymes activity and soil respiration, followed by insecticide, Imidacloprid and less impact by Fungicide, carbendazim was noticed depending on the concentration of pesticides. Phosphatase was more sensitive to pesticides, and the less sensitive in the two types of soil was urease. Biological processes studied were more sensitive to pesticides in the silty soil than the silty loam one.