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.
Highlights
There is a serious shortage of water resources in arid areas of northwest China, where annual potential evaporation is more than 1500 mm with less than 200 mm precipitation [1]
The available water content (AWC) at intervals of 0−40, 40−70, 70−100 cm depths were measured in both seasons (Figure 2)
Similar Available Water Content (AWC) were observed in 0–40 cm layer in either season
Summary
There is a serious shortage of water resources in arid areas of northwest China, where annual potential evaporation is more than 1500 mm with less than 200 mm precipitation [1]. As the main source of irrigation water, groundwater has a rapid decrease in recent years and it is difficult to guarantee irrigation in the region [2,3]. This is exacerbated by the inappropriate irrigation strategy applied in local area. Pre-sowing irrigation is adopted generally before sowing due to less precipitation during the sowing period of spring maize in northwest. The pre-sowing irrigation is sufficient to replenish soil water content (SWC) in soil profile of 0–1 m to field capacity
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