Improving Water Use Efficiency of Spring Maize by Adopting Limited Supplemental Irrigation Following Sufficient Pre-Sowing Irrigation in Northwest China

Abstract

In order to improve the water use efficiency (WUE) of spring maize in northwest China, the irrigation strategy of adopting limited supplemental irrigation following a high quota pre-sowing irrigation was evaluated under field conditions in 2016 and 2018. There were three treatments (W1, W2 and W3) differing in designed wetting depth (Dh) where soil water was replenished. Dh in W1, W2 and W3 were 0–40, 0–50 and 0–60 cm, respectively. The limited supplemental irrigation was adopted to improve soil water content (SWC) within Dh to field capacity (θFC) when SWC within 0–40 cm layer decreased to 60%θFC following a high rate of pre-sowing irrigation. Results showed that the smaller Dh was beneficial for improving root length density and enhance the utilization of water in subsoil. In both seasons, different Dh led to similar grain yields, which were comparable to the typical regional yield (14.3 t ha−1). The highest WUE (2.79 kg m−3) was achieved in W1 and was 13% more than the typical regional level of 2.46 kg m−3, implying it was adequate for achieving high yield and WUE to maintain SWC in 0–40 cm above 60% θFC with not replenishing soil water in 40–100 cm during the growth season after pre-sowing irrigation.