Application of Roth Carbon model over 50 years under a rotation tomato-maize on a silty loam soil

Starting from the management data from 10 ten years of fertilization practices on a silty-loam soil where RothC model proved to be suitable to simulate SOC dynamics (see Symposium 7.8), the model was applied to simulate the SOC trend over 50 years, on the same soil type under a baseline climate generated with LarsWG5, assuming a biennial rotation tomato-maize with additions of 50 t ha-1 and 40 t ha-1 of FYM respectively. Since the behaviour of SOC in RothC is affected mainly by the clay content, four clay classes were identified to verify the effectiveness of the proposed rotation for SOC increase: clay10 (<10%clay); clay15 (10-15% clay); clay 20 (15-20% clay); clay 25 (20-25% clay). For clay 10 a significant decrease of SOC was observed (-6.0 ± 2.2 t ha-1); for clay 15 a nearly steady-state (-1.1 ± 0.9 t ha-1); for clay 20 (+5.2 ± 2.2 t ha-1) and clay 25 (+10.8 ± 4.7 t ha-1) a significant increase of total C. Results have shown that under these specific pedoclimatic conditions, the proposed rotation has increased the SOC levels only at higher clay contents in comparison with the traditional rotation (including maize, tomato and alfalfa with and without organic inputs).