The Loess Plateau region is one of the friable regions in China and there are many factors limiting the accumulation of soil organic carbon (SOC), such as aridity, erosion and vegetation degradation, and so on. The agricultural productivity of subtropical hilly region is superior to the Loess Plateau distinctly. Therefore, study of the SOC contents differences of two regions and its key controlling factors is of great important for the soil fertility regulation and controlling of the farmland in...