Abstract:The effects of 1,3-dichloropropene on the number of microbial population and activities of the urease, invertase and hydrogen peroxidase in the soil were studied in this study. The results indicated that, upon application as soil fumigation, 1,3-dichloropropene at each concentration tested had significant inhibitory effect on soil fungal population; however, their effects on soil bacteria and actinomyces were significantly inhibitory at the beginning, then decreased later on and finally became stimulating effect. The effects of 1,3-dichloropropene on soil urease were dosage-dependent. When soil was fumigated with high concentrations of 1,3-dichloropropene, the effects were firstly inhibition and then stimulation, while those treated with low concentrations of 1,3-dichloropropene showed stimulation-inhibition-stimulation effect. The levels and sustained time of inhibition and stimulation were proportional to the concentrations of 1,3-dichloropropene. The effects of 1,3-dichloropropene on the activities of soil invertase were stimulatory at first, and then it become inhibitory, which was increasing with time. The effects of 1,3-dichloropropene on soil hydrogen peroxidase activities were inhibition-stimulation. The activities of soil hydrogen peroxidase in both soils treated with 1,3-dichloropropene and those of CK tended to be similar 50 days after treatment.