Impacts of 2,4-D on Soil Enzymatic Activity

As organic chlorine herbicides, 2,4-D was used earlier on agriculture, therefore, it's environmental influence has been receiving an important topic to be studied. By simulation, the present investigation studied the relationship between 2,4-D and enzymatic activity in a selected soil. The results showed as follows: 2,4-D remarkably decreased soil urease activity. Soil urease activity varied less at low 2,4-D concentrations, then was more severely inhibited as its contents increased. The three equations had significant or remarkable significant correlation between soil urease activity and 2,4-D concentration. It may be suggested that soil urease activity be an index of soil polluted by 2,4-D, and their reaction mechanism was full inhibition. The critical concentrations was in a range of 5.88～15.15 mg·L-1 when soil samples were severely polluted by 2,4-D. In addition, soil invertase activity had not a regular change, reflecting the enzyme was not sensitive to 2,4-D. It was also discovered that soil alkaline phosphatase activity was activated at lower concentrations, but inhibited at higher concentrations and activated at the highest concentrations. The regression equation was significant or remarkable significant correlation except No.4 sample, i.e. alkaline phosphatase activity had a closer relationship with soil fertility. Further, soil fertility exhibited more important effect on the ecological toxicity of pesticides.