Effects of rainwater harvesting planting combined with deficiency irrigation on soil water use efficiency and winter wheat (Triticum aestivum L.) yield in a semiarid area

The plastic-covered ridge and furrow rainwater harvesting planting system (RFRHP) has been widely used for increasing and stabilizing the crop productivity in the semiarid areas of northwest China. During 2012-2015, we performed a consecutive field experiment to evaluated the influence of rainwater harvesting planting with supplementary irrigation (RI) on the water irrigation use and water use efficiency by winter wheat in a semiarid climate using the following 8 treatments: the rainwater harvesting planting system supplemented with 375 m3 ha−1 irrigation during the early growth stage (R1), both the early and late stages (R2), late growth stage (R3), and no irrigation during whole winter wheat growth stage (R0); the traditional flat planting supplemented with 750 m3 ha−1 irrigation during the early growth stage (B1), both the early and late stages (B2), late growth stage (B3), and no irrigation during whole winter wheat growth stage (B0). We found that although the irrigation amount was double under traditional flat planting, but the soil water content in the 0-120 cm soil layer did not differ significantly between the rainwater harvesting planting with supplementary irrigation treatments (RI) and border irrigation treatments (BI). The rainwater harvesting irrigation (R1, R2, and R3) treatments reduced the irrigation water amounts required (750-1125 m3 ha−1) and alleviated drought stress during key winter wheat growth periods, it also could maintain higher grain yield (1.9%) without irrigation or with irrigation amount reduction by 50%. The irrigation water utilization efficiency of rainwater harvesting irrigation (RI) treatments under the condition of irrigation amounts reduction by 50% was improved significantly, i.e. compared with border irrigation (BI) treatments, the irrigation water use efficiency (IWUE) and water productivity (IWP) increased by 0.9-1.1 and 0.2-0.6 times, respectively, and the net incomes of farmers could increase by 718 Chinese Yuan ha−1.