Optimization of crop planting structure based on agricultural water-energy-food-carbon nexus index: A case study of the Tuojiang river basin

Addressing the escalating tensions between low-carbon transition, food security, energy provision, and resource limitations presents a pivotal challenge for achieving sustainable agricultural modernization. This research advances a novel Water-Energy-Food-Carbon Nexus Index (WEFCNI) framework that systematically incorporates carbon emission into traditional agricultural nexus analysis, enabling quantitative assessment of synergistic relationships among these four critical subsystems. Building upon this foundation, we develop an innovative multi-objective optimization model that simultaneously considers bioenergy potential and nexus system coordination, designed to optimize resource allocation. The proposed methodology undergoes rigorous empirical validation through application in China's Tuojiang River Basin, demonstrating its effectiveness in guiding sustainable agricultural planning. Results indicate that the average WEFCNI values for crops in the basin ranged between 0.2 and 0.7 from 2011 to 2022, suggesting substantial potential for enhancing coupled coordination. The total bioenergy production from crop residues reached 16379.62 $\left({10}^{8}MJ\right)$ during this period, with rice straw contributing 41.34 % of the total yield. The optimization model effectively increased crop yields and bioenergy production. At the same time, it achieved remarkable effects in energy conservation and carbon reduction. The carbon emissions decreased by 275.98 $\left({10}^{8}kgC{O}_{2}eq\right)$, and energy consumption decreased by 411.41 $\left({10}^{8}MJ\right)$. This study's model provides a useful reference for managing agricultural resources sustainably.