Studies of Soil Microorganisms and Enzyme Activities on Artificial Grassland with Different Cultivation Years in Headwater Area of Yangtze and Yellow Rivers

The soil nutrients,microorganism quantity and enzyme activity are studied and analyzed in artificial grassland with different cultivation years in the headwater area of Yangtze and yellow rivers.The results are as follows: soil nutrients of artificial grassland decreased and then increased regularly with change of the cultivation years.The soil nutrient content of two aged artificial grassland was highest,and the six aged grassland lower than two aged,and both of them were significantly higher than the four aged.The changes of soil bacterium and actinomycetes were consistent with the soil nutrients.Similarly,the soil urease,catalase and neutral phosphatase activities have equal regularities. The quantities of fungi descended with the increase of cultivation years.Meanwhile,the soil nutrients,microbial quantities and enzyme activities decreased with the increase of soil depth.The canonical correlation analysis showed that soil bacterium had the best correlation with soil organic matter,total nitrogen, effective K and pH value;soil urease and catalase activities had the best correlation with soil organic matter,total nitrogen,effective nitrogen,effective K and pH value.So the soil microorganism and enzymes can be used as evaluation index of soil fertility.