We evaluated the efficiency of the RothC model to simulate Soil Organic Carbon (SOC) dynamics after 12 years of organic and mineral fertilization practices in a study area located in northern Italy, on a silty-loam Inceptisol with a rotation including tomato, maize and alfalfa. The model performance was assessed by RMSE and EF coefficients. RothC simulated well observed SOC decreases in 71 samples (RMSE=7.42; EF=0.79), while performed with less accuracy when considering all samples (96 samples; RMSE=12.37; EF=0.58), due to the fact that the model failed in case of measured SOC increases (25 samples; RMSE=20.77; EF=-0.038). The model was used to forecast the SOC dynamics over a 50 year period under the same pedoclimatic conditions. Only clay contents >15% allowed to predict increasing levels of SOC respect to the starting values.