Dynamic changing of soil water in artificial ryegrass land in the hilly regions of Sichuan Basin area

To understand the impacts of fertilizer treatment and ryegrass growth on the dynamic changes of soil water is essential to use available soil water and rainfall sagaciously and develop a sustainable artificial ryegrass land in Sichuan Basin area and the similar areas in the world. In the current research, the dynamic changes of soil water were measured under different nitrogen fertilizer treatments by field experiment and EPIC model (Environment Policy Integrated Climate) simulation in the hilly region of Sichuan Basin area from 2011 to 2015. Results revealed that the EPIC model simulated the dynamic changes of soil water well, as the simulated and observed values of forage yield, leaf area index and ryegrass height exhibited a good correlation. When the nitrogen fertilizer was 150 kg/hm2 the soil water consumed by ryegrass during January to May period recovered well during June to September, it is more sustainable treatment than other experimental treatments, considering in a long period. Furthermore, our simulation demonstrated that the roots especially distributed in 0–50 cm soil has a significant effect on available soil water in 0–1 m soil. Root distributed in 0–20 cm and 60–100 cm soil affected the available soil water in 0–50 cm and 60–100 cm soil respectively.