Effects of Pesticide-Contamination on Population and Activity of Bacteria in Purple Paddy Soil

The effect of pesticides on microbial in soil is susally used as an important guide line for estimating the ecological safty of soil. Effects of pesticide-contamination on population and activity of bacteria were investigated in purple paddy soil by in door culture method. The results showed that the population and activity of methanogens was stimulated slightly by adding carbofuran or butachlor in paddy soil, but significantly inhibited by adding of butachlor (10 mg kg-1), carbofuran (0.5 mg kg-1) and carbendazim (10 mg kg-1) in paddy soil. At 7th day the inhibition reached the maximum and then gradually reduced down to the level in control. 1 mg kg-1 carbufuran and butachlor markedly stimulate the populations and activity of soil methane-producing bacteria, soil anti-nitrifying bacteria, soil nitrogen-fixing bacteria, and soil sulfate-reducing bacteria in purple paddy rice soils. Higher concentration carbufuran and butachlor significantly inhibite the populations and activity of above bacteria. Then the inhibition effects of the contaminants were gradually attenuating. The population and activity of above bacteria were inhibited by different level carbendazim.