Optimized single irrigation can achieve high corn yield and water use efficiency in the Corn Belt of Northeast China

Decreasing the corn (Zea mays L.) gap between the potential yield and farm yield and reducing the risk of grain yield of drought are very important for corn production in the Corn Belt of Northeast China (CBNC). To achieve a high and stable corn yield, the effects of supplementary irrigation on yield, water use efficiency (WUE) and irrigation water use efficiency (IWUE) were studied using a modelling approach. The Root Zone Water Quality Model 2 was parameterized and evaluated using two years of experimental data in aeolian sandy soil and black soil. The evaluated model was then used to investigate responses to various irrigation strategies (rainfed, full irrigation and 12 single irrigation scenarios) using long-term weather data from 1980 to 2012. Full irrigation guarantees a high and stable corn grain yield (12.92Mgha−1 and has a coefficient of variation (CV) of 14.8% in aeolian sandy soil; 12.30kgMa−1 and CV of 11.1% in black soil), but has a low water use efficiency (19.92 and 21.81kgha−1mm−1) and a low irrigation water use efficiency (10.01 and 11.03kgha−1mm−1). A single irrigation can increase corn yields by 3–35% for aeolian sandy soil and 5–35% for black soil over different irrigation dates compared with no irrigation. The most suitable single irrigation date was during late June to early July for aeolian sandy soil (yield=10.73Mgha−1 and WUE=27.94kgha−1mm−1) and early to mid-July for black soil (yield=11.20Mgha−1 and WUE=27.70kgha−1mm−1). The lowest yield risk of falling short of the yield goal of 8, 9, and 10Mgha−1 were 9.1%, 18.2%, and 33.33% in aeolian sandy soil and 3.0%, 15.25, and 21.2% in black soil when an optimized single irrigation was applied in late June or early July, respectively. Therefore, an optimized single irrigation should be applied in late June to early July with the irrigation amount to refill soil water storage of root zone to field capacity in CBNC.