Effects of pre-sowing irrigation and straw mulching on the grain yield and water use efficiency of summer maize in the North China Plain

To develop water-saving agriculture in the North China plain, we conducted field experiments using three pre-sowing irrigation applications (30, 70, and 110 mm) on summer maize, with and without straw mulching, during the 2014 and 2015 growing seasons. We studied the effects of pre-sowing irrigation and straw mulching on soil moisture before sowing (SMBS) consumption, evapotranspiration (ET), grain yield, and water use efficiency (WUE). The results indicated that straw mulching and increased pre-sowing irrigation significantly improved grain yield. Increasing amounts of pre-sowing irrigation increased ET, whereas straw mulching had no significant effect on ET. Conversely, while pre-sowing irrigation showed no linear correlation with WUE, straw mulching increased it significantly. The combination of straw mulching and the 70-mm pre-sowing irrigation treatment (70M) improved grain yield at a significantly higher rate than with the combination of 110-mm and the non-straw mulching treatment (110N); moreover, significantly more deep soil water was absorbed with 70M than with the other pre-sowing irrigation treatments. These results indicate that the combination of straw mulching and 70-mm pre-sowing irrigation is the ideal water-saving agricultural technique for growing summer maize in the North China Plain.