Multi-objective optimization of subsurface drip fertigation for winter wheat in the North China Plain: balancing grain yield, resource use efficiency, and soil quality

Drip fertigation has been adopted to conserve water resources and improve water-nitrogen use efficiency. However, the optimal irrigation level and nitrogen application rate for drip-fertigated winter wheat in the North China Plain (NCP) are still unclear. To promote synergies among grain yield, soil quality (SQI), and resource use efficiency in drip-fertigated winter wheat in the North China Plain, this study investigated the optimal combination of irrigation level and nitrogen application rate. A split-plot field experiment was conducted from 2021 to 2024, involving three drip irrigation levels (D1, 65% FC, FC is field capacity; D2, 75% FC; D3, 85% FC) coupled with three nitrogen application rates (N1, 150; N2, 210; N3, 270 kg ha −1 ). Results showed that D2N2 increased grain yield and water use efficiency by 1.88%–17.9% and 7.65%–14.5% compared with other treatments, but reduced nitrogen partial factor productivity. In addition, D2N2, D3N2 and D3N3 promoted higher yield stability and sustainability. D2N2 improved soil physical quality and soil biological quality by 3.23%–18.7% and 4.53%–36.6% compared with other eight treatments. Comprehensively, D2N2 enhanced SQI by 3.98%–28.9% by improving soil physical structure, nutrient availability, and microbial activity. Based on response surface methodology analysis, the optimal ranges were determined as 77%–85% of FC for irrigation level and 181–194 kg ha⁻ 1 for nitrogen application rate, which could achieve a multi-objective scenario encompassing higher yield, greater resource use efficiency, and improved soil quality in the NCP. This study helps address a knowledge gap in winter wheat production in the NCP by incorporating the SQI into the multi-objective optimization under a drip fertigation system. These results may provide scientific basis for sustainable water and nitrogen management in drip-irrigated winter wheat systems in the NCP.