Enzymatic sctivity of different salt affected soils in Tumochuan plain

In order to understand the seasonal dynamics of soil enzyme activities in different salt affected in Tumochuan plain, we collected light, moderate and high salt affected soil and measured the activities of invertase, catalase, urease and alkaline phosphatase at 0-40 cm soil layer in different seasons. The results showed that soil invertase、catalase、urease and alkaline phosphatase activities decreased with the increase of total salt content. The content of invertase, catalase, urease and alkaline phosphatase ranged from 0.65to 36.55 mg·g-1, from 2.76 to 3.35 mL·g-1, from 0.003 to 0.018 mg·g-1and from 0.10 to 0.98 mg·g-1, respectively. Soil invertase,urease and alkaline phosphatase activities decreased with a increase of soil depth. Catalase activity in 20 40 cm soil layer is much higher than 0 20 cm soil layer. There is a different seasonal variation trend in soil enzyme activity with different degree of salinization. The seasonal variation of catalase and sucrase activities were observed significantly increased and then decreased. The seasonal variation of urease and alkaline phosphatase activity increased at first, decreased subsequently and decreased finally.Alkaline phosphatase enzyme activity increased gradually with the advance of time. The maximum value of sucrase and urease appeared in August while catalase and alkaline phosphatase was in July and September, respectively. The ranking of soil enzyme activities is characterized by light moderate high salt affected soil. Alkaline phosphatase significantly correlated to urease and invertase, whereas negatively correlated to catalase. A significantly positive correlation is observed between invertase and urease. In conclusion, soil enzyme activities have a significant different in different salt affected soil and seasons. Soil salt content affected enzymatic activity of soil in this area.