As a key staple for China's food security, winter wheat dominates grain production in the Huang-Huai-Hai Plain, where the dominant winter wheat-summer maize (M-W) system faces severe challenges of high-water demand, inefficient water-nitrogen use, and groundwater overexploitation. To address these issues, a three-year field experiment was conducted to evaluate the potential of replacing the M-W system with a summer soybean-winter wheat (S-W) system under three irrigation regimes (only applied in winter wheat season): I0 (rainfed), I4 (irrigation maintaining 60% field capacity in 0–40 cm soil layer), and I6 (irrigation maintaining 80% field capacity in 0–60 cm soil layer). We examined the impacts of different treatments on winter wheat yield, nitrogen accumulation, reactive nitrogen losses, water-nitrogen productivity, and net ecological economic benefits (NEEB). Results showed that the S-W system combined with I4 significantly increased winter wheat yield by 10.4%, plant nitrogen accumulation by 45.7%, and system yield by 44.6%, while reducing reactive nitrogen losses by 11.7%-14.5% relative to the M-W system. This treatment also increased water productivity by 6.9%, nitrogen partial factor productivity by 46.7%, and NEEB by 48.6%-67.2% compared with the M-W system. Structural equation modeling and path analysis confirmed the S-W system had lower irrigation dependence and higher nitrogen uptake efficiency. These findings demonstrate that the S-W system with moderate I4 irrigation provides a sustainable pathway for balancing high productivity and environmental protection in the region. • Soybean-wheat with optimized irrigation balances productivity and sustainability. • Soybean-wheat system reduces irrigation dependency, enhances nitrogen use efficiency. • Synergistic management cuts environmental costs and boosts ecological benefits. • Improved water-nitrogen efficiency strengthens the system's resilience.
Wang et al. (Thu,) studied this question.