Water scarcity is the most significant constraint for grain production in the North China Plain (NCP). Water-saving irrigation technology is a valuable tool for addressing the NCP’s water scarcity. Drip irrigation is considered as one of the most water-saving irrigation technologies. However, drip irrigation is not now commonly used in NCP field grain crops (particularly maize). Fertilizers are accurately administered to summer-maize root soil by recycling the drip-irrigation system of winter wheat. To increase the water and fertilizer-use efficiency of summer-maize fields, the coupling body of root-zone soil water and fertilizer for summer maize was thoroughly adjusted using a combination of emitter flow rate, irrigation quota, and fertilizer frequency. In this experiment, a split plot design with randomized blocks was employed. The primary plot was emitter flow rate (0.8 and 2.7 L/h), the subplot was irrigation water quota (120 and 150 m³/hm², 1 hm² = 10,000 m²), and the final plot was fertigation frequency (7, 14, and 28 days). The grain yield, water-use efficiency and fertilizer-use efficiency of summer maize were measured in this study. The results showed that grain yield and water-use efficiency (WUE) of the small-flow drip-irrigation treatment (emitter flow rate < 1 L/h) were significantly higher than the large-flow treatment (emitter flow rate > 1 L/h); the rates of grain yield increase were 8.2% and 13.3% and WUE were 3.5% and 8.0%, respectively. A higher irrigation quota can increase the yield of summer maize. The maximum yield and WUE were observed at the fertigation frequency of 7 days under small-flow drip-irrigation conditions. All comparisons and analyses showed that small-flow drip irrigation combined with high fertigation frequency could obtain higher yield and WUE in the NCP. This study proposes a new way to improve water and fertilizer utilization efficiency to achieve the goal of “increasing grain yield by fertilizing” and “adjusting the quality by fertilizing”, from the perspective of winter wheat–summer maize no-tillage annual rotation planting.

Choosing the proper fertilizer regime for a crop in a given location remains challenging to increase yield, profitability, environmental growth protection, and sustainability. However, the nutrient demand characteristics of cotton in the North China Plain are different at various growth stages. Therefore, we choose the local superior cotton variety (Lumian 532) with high yield as the material, in the present study, we assessed the cotton yield, biomass accumulation and distribution, nitrogen absorption and utilization efficiency, and other parameters by setting four nitrogen allocation ratios (3:5:2, 0:10:0, 3:7:0, and 0:7:3) when the nitrogen application rates were 0, 150, 220, and 300 kg hm⁻². The results showed that when the nitrogen application rate was 300 kg hm⁻², the growth index, biomass, nitrogen content, and yield of Lumian 532 were the highest, while the nitrogen partial productivity (12.2 and 12.8) was the lowest. When the nitrogen application rate was 220 kg hm⁻² and the nitrogen allocation ratio was 3:5:2, the agronomic nitrogen use efficiency (3.2 and 3.5) and nitrogen physiological (24.8 and 25.0) was achieved. When the nitrogen application rate was 150 kg hm⁻², the nitrogen partial productivity (20.6 and 20.9) was the highest. In conclusion, the biomass accumulation and distribution, nitrogen use efficiency, yield, and yield composition of Lumian 532 could be effectively regulated by appropriate nitrogen application rate and nitrogen allocation ratio. Therefore, to optimize the yield and improve the nitrogen use efficiency, the optimal nitrogen application rate of Lumian 532 was 220 kg hm⁻², and the optimal nitrogen allocation ratio was 3:5:2 in the North China Plain. The results provided practical basis for nutrient demand, cotton yield and ecological protection in different growth stages of cotton in North China Plain.