Effects of four pesticides on catalase activity in soil and soil respiration

The effects of thiophanate-methyl,mancozeb,fenvalerate and abamectin on soil catalase activity and soil respiration were studied.The safety of four pesticides was also evaluated.The results showed that catalase activity was inhibited first,then stimulated and recovered finally with the treatments of four pesticides.The inhibition and the stimulation was stronger with higher concentration.Soil respiration was slightly stimulated during initial period,inhibited after 5 days,and then recovered to control level after 12 days.Safety evaluation showed that the four pesticides had little harm to soil microorganisms because their toxicities were low.