Effect of cornstalk addition on soil organic matter dynamics and microorganism under different land use patterns

85 soil samples under different land use pattern were collected from 17 provinces in China.Then each soil sample was added with cornstalk and cultivated under natural condition for 90 d in order to understand the dynamics and motivation of soil organic matter (SOM) after the cornstalk addition.The results showed that the original land use pattern significantly affected SOM of soil samples with stalk.63.5% soil samples had shown an increase of SOM,while SOM of 36.5% soil samples decreased,which indicates that cornstalk addition did not necessarily lead to SOM increasing within a short period of time. SOM of 88% soil samples from crop dry land had increased while it decreased all samples from paddy soils, and SOM in soils from forest lands and vegetable fields did not have obvious trend. After cornstalk addition, the number of cultivable bacteria, fungi and actinomycetes of all soil samples increased in the following orders:paddy field> forest> vegetable>crop dry land, and fungi>actinomycetes>bacteria. According to phospholipid fatty acids (PLFA), the smaller bacteria/fungi and G+/G-, the more stable soil micro-ecosystem is; the smaller A/B,ios/anteiso and C/A are, the more unstabilitythe environment in soilis. PLFA analysis shows that soil micro-ecosystem stability increases in the following series:paddy field,crop dry land, forest land and vegetable land; the environmental and soil nutrient stress increases in the following series:vegetable land,crop dry land, forest land and paddy field. Therefore, paddy field had the worst soil micro-ecosystem stability and suffered the most nutrient and environment stress than all the other soils in this study.