Study of Microbial Diversity and the Soil Enzyme Activity in Different Salinized Soil in Ningxia Yellow River Irrigation Region

In order to know the effects of different degradation degree of salinized soil on microbial diversity and soil enzyme activity in Ningxia irrigation area of Yellow River,soil microbial diversity and soil enzyme activity were studied in different degree of salinized using biolog microbial identification system,colorimetry and titration in Ningxia Yellow River Irrigation.The results showed that soil microbial community diversity decreased with the saline degree in ecreased.Soil catalase,invertase,alkaline phosphatase and urease activity tend to decrease with the increase of salt degree.The seasonal variation of soil enzyme activity was not exactly the same,and fluctuateed in different layers of soil.Converting enzyme and alkaline phosphatase activities in 0—20 cm soil performanced in the order of September>August>June,catalase and alkaline phosphatase activities in 20—40 cm soil presented as the sequence of June>August>September.There was a significant positive correlation（p<0.05） between different salinization degree soil and converting enzyme,alkaline phosphatase activity,there was a very significant positive correlation（p<0.01） between soil microbial diversity and converting enzyme,alkaline phosphatase,catalase activity,and was a significant positive correlation（p<0.05） between soil microbial diversity and different soil salinization degree,soil urease activity.These results suggested that the relationships between soil enzyme activity and soil salinization degree were closely related,and the soil converting enzyme,alkaline phosphatase and microbial diversity can be used as biological indicators for the evaluation of saline-alkali soil degradation degree and soil fertility.