Effects of Hexaconazole, Propiconazole, Profenofos and Pretilachlor on Soil Phosphatase and Dehydrogenase Activities

The effects of hexaconazole (fungicide), propiconazole (fungicide), pretilachlor (herbicide), and profenophos (insecticide) on acid phosphatase and dehydrogenase activities of the soil were investigated. All pesticides had moderate to high inhibitory effect on acid phosphatase, while the effect of pretilachlor was most persistent. More than 50% activity was inhibited even after 35 d at 1000-ppm level. Profenofos was highly toxic at the initial stage and the toxicity gradually declined. It was found to be the most toxic for phosphatase inhibiting 65 percent activity at 1000-ppm level and 28% toxicity persisted even after 35 d of incubation. Dehydrogenase activity was highly affected in presence of all the pesticides and initially toxicity reached around 90% in all the cases except in hexaconazole. Propiconazole was the most toxic one and inhibited 95% activity after 21 d and 84% toxicity persisted after 35 d of incubation at 1000 ppm level. Profenofos was the least toxic to dehydrogenase activity and after 21 to 28 d it had stimulating effect on dehydrogenase activity.