Effects of Three Kinds of Fungicides on Enzyme Activities in Greenhouse Soil

In this paper, we studied the effects of three fungicides (ehlorothalonil, mancozed and propamocarb hydrochloride), which were commonly used in north of China, on the activity of greenhouse soil enzyme. It was shown that ehlorothalonil, mancozed and propamocarb hydrochloride had insignificant effects on sucrase and urease activities at concentration of 10 mg·kg^-1 and 50 mg·kg^-1, while they had significant effects on the soil enzyme activities at concentration of 100 mg·k^g-1. The sucrase activity was stimulated significantly by ehlorothalonil, mancozed and propamocarb hydrochloride at 100 mg·kg^-1 concentration with the maximum activation rate of 88.89%, 79.53% and 77.67%, respectively. On the contrary, the urease activity was inhibited significantly by these fungicides at 100 mg·kg^-1 concentration with the maximum inhibition rate of 38.06%, 42.86% and 14.76%, respectively. It suggested that in the range of 10~50 mg·kg^-1 dose (equivalent to 2~10 times recommended spraying dose), there was no significant effect on the greenhouse soil environment. However, when the concentration increased to 100 mg·kg^-1, fungicides would have significant influence on soil sucrase and urease. This would cause soil enzyme activity in large fluctuation. Then it will produce disadvantageous effects on agricultural production since both too high and too low activities of enzyme would have unfavorable effect on the nutrition cycle in the soil.