Abstract: To understand the impact of chemical control over Mikania micrantha on soil ecological environment, we assessed the control effects of 25% 2,4-D picloram, 24% 2,4-D clopyralid and 70% sulfometuron-methyl on Mikania micrantha and evaluated their effects on soil enzyme activity. The results showed that the killing rate of 25% 2,4-D- picloram and 24% 2,4-D clopyralid on Mikania micrantha was 100%, and the control effects were significantly higher than that of 70% sulfometuron-methyl. Additionally, 25% 2,4-D picloram significantly promoted soil catalase activity, while 24% 2,4-D clopyralid did not affect soil catalase activity. On the 14th, 21st, and 49th day after spraying, the activity of soil catalase under 25% 2,4-D picloram was significantly higher than that under 70% sulfometuron-methyl. The effects of 25% 2,4-D picloram and 24% 2,4-D clopyralid on soil phosphatase activity exhibited a “promotion-inhibition” pattern, while 70% sulfometuron-methyl did not affect soil phosphatase activity. On the 14th day after spraying, the activity of soil phosphatase under 25% 2,4-D picloram was significantly higher than that under 24% 2,4-D clopyralid and 70% sulfometuron-methyl. The effect of 24% 2,4-D clopyralid on soil urease activity exhibited a “promotion-inhibition” pattern, while 25% 2,4-D picloram and 70% sulfometuron-methyl did not affect soil urease activity. On the 14th day after spraying, the activity of soil urease under 25% 2,4-D picloram was significantly lower than that under 24% 2,4-D clopyralid. Overall, soil enzyme activity can be used as an indicator to characterize soil pollution after chemical control of Mikania micrantha.

Key words: chemical contro, Mikania micrantha, soil enzyme activity, control effect