Dynamic changes and sustainable usage of soil water in the wheat- maize and rape-maize rotation in terrace fields of Southwest China

Abstract The terraced agriculture has great significance for the utilization of soil water and crop carbon fixation in hilly areas, which is beneficial to the sustainable development of soil water. In this study, we focused on two main rotation modes (WM, winter wheat-summer maize rotation; RM, winter rape-summer maize rotation) as the research objective of this experiment. By reducing nitrogen fertilizer (N1 is normal fertilization, N2 is reduced by 15%), exploring the change in soil water and crop carbon under two rotation systems, as well as crop water use efficiency and carbon fixation under nitrogen fertilizer application. The results showed that compared with WM, the RM yield increased significantly by 7.52%, crop carbon fixation was significantly increased by 14.4%, while soil water consumption decreased significantly by 3.45% in the respective treatment. The crop water use efficiency increased significantly by 11.48% in RM as compared to WM, which indicates RM had stronger crop water utilization and crop carbon fixation capabilities. We also found no significant difference in WM soil water consumption, yield, crop carbon fixation and crop water use efficiency under N2 treatment. The environmental load rate of RM soil water was significantly lower than that of WM in the same treatment. Therefore, RM faced less soil water deficit and was more sustainable. In conclusion, the RM in hilly regions had better soil water utilization, economic benefit, carbon fixation and more conducive to the sustainable development of soil water storage than the WM.