EFFECTS OF BUTACHLOR ON MICROBIAL POPULATIONS AND ENZYME ACTIVITIES IN PADDY SOIL

This paper reports the influences of the herbicide butachlor (n-butoxymethl-chloro -2′,6′ -diethylacetnilide) on microbial populations, respiration, nitrogen fixation andnitrification, and on the activities of dehydrogenase and hydrogen peroxidase in paddy soil. The results showed that the number of actinomycetes declined significantly after the application of butachlor at different concentrations ranging from 5.5μg g−1 to 22.0μg g−1 dried soil, while that of bacteria and fungi increased. Fungi were easily affected by butachlor compared to the bacteria. The growth of fungi was retarded by butachlor at higher concentrations. Butachlor however, stimulated the growth of anaerobic hydrolytic fermentative bacteria, sulfate-reducing bacteria (SRB) and denitrifying bacteria. The increased concentration of butachlor applied resulted in the higher number of SRB. Butachlor inhibited the growth of hydrogen-producing acetogenic bacteria. The effect of butachlor varied on methane-producing bacteria (MPB) at different ...