Simulation of SOC content and storage under different irrigation, fertilization and tillage conditions using EPIC model in the North China Plain

The objectives of the study were to use the EPIC model in simulation of soil organic carbon (SOC) content and storage under different irrigation, fertilization and tillage conditions in the North China Plain and identify the relationship of SOC change with the different field managements. There are optimal and conventional irrigation and fertilization treatments at Dongbeiwang, Quzhou and Wuqiao sites and different tillage treatments at Luancheng site. The results indicated that the simulated SOC content in Dongbeiwang, Quzhou and Wuqiao showed an increasing trend in optimal irrigation and fertilization treatments, which had the same trend with the measured data. Under different tillage conditions, the simulated SOC content in no tillage treatment reached the highest point, which was followed by rotary tillage and conventional tillage. The measured SOC content changed much compared to the simulated result in different tillage treatments. In SOC storage modeling, the optimal irrigation and fertilization treatment, no tillage treatment can sequestrate more carbon than the other treatments, which had the same trend with the measured data. The simulated highest annual change rate of SOC storage was 1.39 t ha−1 a−1 in optimal irrigation and fertilization treatment at Wuqiao site and the lowest one was −0.18 t ha−1 a−1 in conventional tillage treatment at Luancheng site. The SOC simulation and measurement showed optimal irrigation and fertilization, reduced tillage, and residue return were all effective strategies for improving on SOC content and storage in the North China Plain. The SOC modeling showed a good match between simulation and measurement in optimal and conventional irrigation and fertilization treatments in different sites and showed reliable trend in simulation of SOC content and storage under different irrigation, fertilization and tillage managements at different sites.

► The EPIC model was used to simulate SOC content and storage in agricultural topsoil.
► Optimal irrigation and fertilization, and reduced tillage improved SOC storage.
► SOC simulation in different irrigation and fertilization treatments showed a good performance.
► Simulated results showed a reliable SOC change trend.