Ridge–furrow rainwater harvesting combined with supplementary irrigation: Water-saving and yield-maintaining mode for winter wheat in a semiarid region based on 8-year in-situ experiment

The ridge and furrow rainwater harvesting (RFRH) system has been adopted widely to improve and stabilize the productivity of dryland crops. In order to significantly reduce irrigation rate applied to fields, an 8-year (2012–2020) in-situ field experiment that RFRH combined with supplemental irrigation (RI) of winter wheat was conducted in the semiarid region of Northwest China. Border irrigation (BI) was used as the control. Under RI and BI, irrigation was applied only once (jointing–heading stage) or twice (jointing–heading and heading–flowering stage) in separate trials. Irrigation rates applied each time under RI and BI were 37.5 mm (50% of that under BI) and 75.0 mm, respectively. The results indicated that compared with BI, RI significantly increased the soil water storage in the early growth stage, net photosynthetic rate, water use efficiency (WUE), and irrigation water use efficiency, and decreased the evapotranspiration in years with different precipitation distributions. When irrigation was applied once, RI increased WUE by 13.4%, 9.1%, and 8.7% compared with BI in dry, normal, and wet years, respectively. When irrigation was applied twice, RI increased WUE by 12.6%, 8.9%, and 5.1% compared with BI in dry, normal, and wet years, respectively. Compared with BI, RI required 50% less irrigation water but it increased the grain yield by 3.3%, 2.4%, and 2.8% with once application in dry, normal, and wet years, respectively, and decreased it by 6.3%, 4.1%, and 3.2% when applied twice (P > 0.05). RI effectively maintained the yield and there was no significant difference compared with the yield under BI. Therefore, RI could be applied as a technique for significantly reducing irrigation rate consumed in semiarid and semi-humid areas.