Effects of micro-sprinkling limited irrigation on winter wheat yield, water and nitrogen use efficiency

To clarify the influence of micro-sprinkling limited irrigation on winter wheat yield, water, and nitrogen use efficiency, we conducted an experiment with four treatments in irrigated wheat fields in southern Shanxi: normal micro-sprinkling irrigation (S0), micro-sprinkling limited irrigation (S1), excessive micro-sprinkling irrigation (S2), and flood irrigation (F0). We analyzed the different performance rules in farmland soil water storage and consumption, yield component factors, plant nitrogen distribution, and water and nitrogen utilization under these different irrigation levels. The results showed that soil pondage in the 0-200 cm layer under excessive irrigation (F0 and S2) was significantly higher than under normal micro-sprinkling irrigation (S0) and micro-sprinkling limited irrigation (S1), with no significant difference between S0 and S1. Soil pondage increased with increasing irrigation amounts in all treatments, with the 0-100 cm soil pondage being lower than the 100-200 cm pondage. The percentage of 0-200 cm soil water consumption relative to total water consumption during the winter wheat growth period ranged from 8.95% to 48.48% under the four irrigation treatments, decreasing with increasing irrigation amounts. The peak of 0-200 cm soil water consumption was observed in the S1 treatment, while the peak of irrigation water consumption was in the F0 treatment. The deeper 100-200 cm soil water consumption in the F0 and S2 treatments was significantly lower than in S0 and S1. The spike number of the yield components under excessive irrigation treatments (F0 and S2) were significantly lower than those in S0 and S1, while the 1000-grain weight was higher in F0 and S2. The ranks of winter wheat grain yield in different irrigation treatments were S0, S1, S2, and F0. There was no significant difference between S0 and S1; however, the yields of both treatments were significantly higher than those of F0 and S2. Water use efficiency (WUE) in winter wheat decreased with increasing irrigation amounts, with the WUE in the micro-sprinkling limited irrigation (S1) treatment being 1.39 to 7.36 kg hm-2 mm-1 higher than in the other treatments. The nitrogen uptake efficiency and nitrogen harvest index of the S1 treatment were 1.64% and 1.91% higher than those of the normal micro-sprinkling irrigation (S0) treatment, while nitrogen fertilizer partial productivity was slightly lower. The nitrogen fertilizer partial productivity in the S0 and S1 treatments was significantly higher than in F0 and S2. The nitrogen apparent surplus amount in the S1 treatment was 2.46% to 21.01% lower than in the other treatments, while the nitrogen accumulation in the seeds of the S1 treatment was 3.64% to 31.39% higher. In summary, micro-sprinkling limited irrigation can promote water uptake in deeper soil layers and grain nitrogen accumulation in winter wheat, optimize irrigation patterns, and improve water use and nitrogen uptake efficiency. This irrigation pattern is characterized by stable production and high efficiency, significantly reducing soil nitrogen surplus and the risk of inorganic nitrogen downward leaching. Thus, it promotes the sustainable and healthy development of water-saving agriculture.