USE OF THE "RothC" MODEL TO SIMULATE SOIL ORGANIC CARBON DYNAMICS ON A SILTY-LOAM INCEPTISOL IN NORTHERN ITALY UNDER DIFFERENT FERTILIZATION PRACTICES

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.