Effects of EDTA, EDDS and Oxalic Acid on Catalase and Peroxydase Activities of Soil

EDTA, EDDS and oxalic acid were added to soil to control the concentrations of the three chelators in soil at 2, 5, 10, 15, 20, 30 mmol/kg, then catalase and peroxydase activities of the soil were determined after 24h to identify the effects of three chelators on enzyme activity of soil. The results showed that the catalase activities of soil treated with oxalic acid and EDTA decreased with the increase of the concentrations (p＜0.01, p＜0.05 respectively), while it rised with the increase of the concentration of EDDS (p＜0.01). EDTA, EDDS and oxalic acid all showed significant stimulation on peroxidase activity of soil, especially at low concentration (2 mmol/kg).