Subsoiling increases grain yield, water use efficiency, and economic return of maize under a fully mulched ridge-furrow system in a semiarid environment in China

After widespread application of the fully mulched ridge-furrow system, maize (Zea mays L.) has become a newly dominant crop in the semiarid Loess Plateau of China. Maximization of water use efficiency (WUE) through optimal farming practice are of great importance for sustainable intensification of maize production in this region. In this study, the impact of different tillage practices on soil quality, soil water, grain yield, WUE, and net economic return in a fully mulched ridge-furrow system were examined in a five-year field experiment, to optimize tillage practice for maize production in the area. Four tillage practices (CT, conventional tillage; NT, no-tillage; RT, rotary tillage; SS, subsoiling) were assessed. Compared to CT, SS reduced soil bulk density and penetration resistance, and increased saturated hydraulic conductivity and the percentage of macro-aggregates (≥ 0.25 mm) in the 0–30 cm soil layers, but NT and RT had the opposite effects to above soil physical properties except for macro-aggregates. Tillage practice did not significantly affect soil water storage, evapotranspiration, but annual soil water balance was lowest under SS, followed by CT, NT, and RT. SS increased soil organic C, mineral N and available P at 0−30 cm soil layer compared to CT. Grain yield and WUE under SS were increased by 12 and 15 % compared to CT, NT and RT had no significant effect on grain yield and WUE. Net economic return under NT and SS were increased by 42 and 23 % respectively compare to CT. These results demonstrated that subsoiling could improve grain yield, WUE, and net economic return of dryland maize by improving soil quality and mitigating soil water depletion. In the long-run, although no-tillage increased net economic return, it may not be sufficient to maintain yield and WUE due to deteriorated soil properties and accelerated soil water depletion. Thereby, subsoiling is optimal tillage practice for sustainable intensification of maize production in the semiarid Loess Plateau of China.