Optimizing spatial food crops planting structure under water-energy-food-carbon emissions nexus constraints

The interrelationship among water, energy, food, and carbon emissions has emerged as a critical factor influencing agricultural sustainability. However, existing studies on food crop planting structure (FCPS) optimization primarily focus on the water–food relationship, overlooking the complex and dynamic interactions within the water–energy–food–carbon emissions nexus (WEFCN). Additionally, the concept of harmony provides a quantitative framework for assessing system stability and coordination. Previous research has largely overlooked the influence of the WEFCN harmony degree on optimizing food crop planting structure. In response, this study proposes a novel FCPS optimization method that integrates the WEFCN and incorporates harmony degree constraints, aiming to address two key scientific challenges: (1) integrating the WEFCN into FCPS optimization research, and (2) quantitatively evaluating and constraining system harmony degree to enhance overall system stability and coordination. The results indicate that, compared to approaches focusing solely on single or localized relationships, the proposed method effectively reduces water and energy consumption, mitigates water pollution, and significantly decreases agricultural carbon emissions. Relative to methods without harmony degree constraints, it achieves reductions of 4.591 × 10⁸ m³ in blue water, 3.325 × 10⁸ m³ in grey water, 8.527 × 10⁸ m³ in total water footprint, 6.04 × 107 kgce in energy consumption, and 1.09 × 106 tCO₂eq in carbon emissions, while improving the system harmony degree from 3.411 to 3.434. This study addresses the limitations of conventional research that focuses primarily on the water–food relationship, which often results in suboptimal outcomes insufficient for advancing green agricultural development. It enhances the stability, balance, and coordination of the WEFCN, offers a reference for addressing its internal imbalances, and contributes to the promotion of sustainable agricultural development.