Effects of deficit irrigation combined with rainwater harvesting planting system on the water use efficiency and maize (Zea mays L.) yield in a semiarid area

The ridge and furrow rainfall harvesting planting system (RFRHP) where runoff is collected by plastic mulched ridges can improve the crop productivity in the semiarid areas of northwest China. During 2012–2014, we performed a field evaluation of the influence of RFRHP with supplementary irrigation (RI) on the water irrigation use and water use efficiency by maize in a semiarid climate using the following treatments: (1) no supplementary irrigation (RN); (2) irrigation during the trumpeting stage (RB); (3) irrigation during the blooming stage (RF); (4) irrigation during the trumpeting and blooming stages (RBF); and (4) traditional flat planting with border irrigation (CK). We found that although the irrigation volume was double under CK, the soil water content in the 0–120 cm soil layer did not differ significantly between the RFRHP with supplementary irrigation treatments and CK. The RFRHP with supplementary irrigation treatments reduced the irrigation water volume required (750–1125 m3 hm−2) and alleviated drought stress during key maize growth periods. The biomass, grain yield, and water use efficiency were significantly higher under RFRHP with supplementary irrigation, i.e., 6.0–8.7%, 15.4–25.8%, and 34.9–39.2% higher compared with CK, respectively, and 3.8–6.4%, 4.8–14.2%, and 9.2–12.7% higher compared with RFRHP with no supplementary irrigation. Under RFRHP with supplementary irrigation treatments, the irrigation water use efficiency was 1.5–3.9 times higher than that under CK. The irrigation water productivity levels under the RFRHP with supplementary irrigation treatments were ranked as follows: trumpeting stage > trumpeting and blooming stages > blooming stage. Compared with CK, RFRHP with supplementary irrigation significantly increased the out/input ratio and net income by 13.1–26.9% and 2600–3762 Chinese Yuan hm−2, respectively.