Abstract: Century model is one of the main models in predicting the changing trend of soil organic carbon (SOC), and has been used extensively for agricultural and forest ecosystems in recent two decades. In this paper, this model was used to predict the changing trend of organic carbon in black soil under different farming systems. The results showed that Century model was available in predicting the changing trend of organic carbon in farmland black soil. According to the prediction, the annual decrement of SOC content in 2006-2015 would be 0.063 g·kg^-1 under shift farming, 0.027 g·kg^-1 under organic farming, and 0.045 g·kg^-1 under ‘petroleum’ farming. The decreasing trend of the SOC content could be controlled when a combined ‘petroleum’organic farming system was implemented, under which, the SOC content could be maintained at a level of around 34.00 g·kg^-1, being in a balance status.

Key words: Biomass, Nodule number, Infection rate, ALP, SDH