Abstract:In order to investigate the effects of acetochlor deposition on soil microorganism in black soil of corn field, and the effect of acetochlor on microbial activity in black soil environment was revealed. The dosage of acetochlor was 1 012.5, 1 350 and 2 025 g/hm 2. At 7, 14, 30, 45 and 60 days after application, the amount of acetochlor deposit in soil was measured, the amount of microorganism in black soil was investigated and the enzyme activity of soil was determined. The results showed that the deposition amount of acetochlor in soil was 1.129-1.879 mg/kg in 7 days, 1.108-1.680 mg/kg in 14 days, 0.378-0.554 mg/kg in 30 days, 0.164-0.202 mg/kg in 45 days, and 0.07-0.115 mg/kg in 60 days, respectively, and the digestibility of acetochlor in 45 days was more than 90%. Acetochlor showed inhibitory effect on soil bacteria from 7 days to 14 days after soil treatment, but at 30 days,only the highest dose (2 025 g/hm2) inhibited bacteria. After 45 days, the inhibition was alleviated and gradually approached to the control level. Seven days after application, the inhibition increased with the increase of the concentration of fungi, and the number of fungi returned to the normal level
30 days later. Actinomycetes showed strong adaptability to acetochlor. Seven days after application,the promoting effect was enhanced with the increase of dosage, and then gradually returned to the normal level. At the same time, the effect of acetochlor on soil enzyme activity was studied, and there was no significant effect on catalase activity at each treatment concentration, but the inhibitory effect on soil urease with high concentration and low concentration was not obvious. The effect of soil dehy‐drogenase on soil dehydrogenase increased with the increase of application concentration.