Long-term effect of fertilizer and manure application on the balance of soil organic carbon and yield sustainability in fluvo-aquic soil

Investigating soil organic carbon balance characteristics is important for a better understanding of the stabilization and fertility mechanism of soil organic carbon. We analyzed the dynamics of soil organic carbon (SOC) and crop yield in a long-term fertilization experiment initiated in 1980. We observed that balanced fertilization treatments regardless of manure application increased the carbon input in 36 years. Higher SOC sequestration rates were observed after manure application. A significantly positive correlation was observed between the annual SOC sequestration rate and annual carbon input (R-2 = 0.94); while the minimum amount of annual carbon input to maintain the SOC equilibrium amount was 0.24 t C ha(-1). In particular, balanced fertilization had positive effects on the crop yields regardless of manure application. Meanwhile, a significant positive correlation was observed between SOC content and crop yields in wheat (R-2 = 0.29), maize (R-2 = 0.38), and sweet potato (R-2 = 0.13). These results indicated that a balanced application of manure was beneficial for crop yield and SOC sequestration.