Stable mechanisms of soil aggregate and effects of human activities

Soil aggregate is the basic unit of soil structure. Its formation is a natural process but influenced severely by human activities,including land utilization ,tillage disturbance, manure application, and cropping system. The improvement of soil structure is decided not only by total amount of organic C inputted into soil, but also by the composition and characteristic of organic matter. Owing to the different composition and characteristic of organic matter, there are different mechanisms for the stability of micro and macro aggregates.