Limited irrigation and fertilization in sand-layered soil increases nitrogen use efficiency and economic benefits under film mulched ridge-furrow irrigation in arid areas

Hetao Irrigation District (HID) in the upper Yellow River Basin of China is vulnerable due to the scarcity of water resources and environmental pollution caused by nutrient leaching. Appropriate irrigation and fertilization management are essential for improving crop productivity and developing sustainable agriculture in the HID. A two-year field experiment investigated the effects of irrigation and fertilization regimes on soil water, nitrogen accumulation and distribution in the soil profile and plant organs, nitrogen use efficiency, and economic benefits of spring maize (Zea mays L.) under film mulched ridge–furrow system. Three irrigation levels—I1 (high, 400 mm), I2 (medium, 300 mm), and I3 (low, 200 mm)—and two fertilization levels—F1 (high, 300 kg N ha−1) and F2 (low, 150 kg N ha−1) were designed. Mean soil NO3−-N contents did not significantly differ between I2 and I3 and were significantly higher than I1. I1F1 and I1F2 remarkably increased soil NO3−-N accumulation in the 80 − 100 cm soil layer at harvest. High irrigation increased the risk of N leaching into the deep soil layer. I2F2 increased plant nitrogen accumulation and promoted nitrogen transport to grains, improved nitrogen harvest index, and internal use efficiency. Under 400 or 300 mm irrigation amount, soil moisture and plant growth had little difference. Grain yields among I1F1, I1F2, I2F1, and I2F2 did not significantly differ in 2017 and 2018. In the relatively poor rainfall year (2017), I2F2 had 13.1%, 211.8%, and 294.1% higher net income than I2F1, I3F1, and I3F2, respectively, but 24.5% and 33.0% lower net income than I1F1 and I1F2, respectively. In 2018 with normal rainfall, I2F2 had 38.5%, 4.8%, 29.5%, 114.3%, and 96.2% higher net income than I1F1, I1F2, I2F1, I3F1, and I3F2, respectively. Therefore, the film mulched ridge–furrow irrigation system with 300 mm irrigation and 150 kg N ha−1 fertilization is a promising approach for reducing water supply and nitrogen leaching, and obtaining acceptable grain yield and economic benefits for spring maize production in the upper Yellow River Basin of China.