Multi-Objective Optimization of Integrated Crop–Livestock Systems: Exploring Resource Allocation Based on Emergy Evaluation

Integrated crop–livestock systems (ICLSs) can improve the sustainability of agriculture. The configuration of an ICLS to achieve sustainable development while maintaining the effectiveness of resource utilization is complicated due to conflicts between economic performance and environmental protection. In this paper, a novel optimization model-based emergy evaluation (OMEE) method is proposed for ICLS configuration. OMEE encompasses an emergy analysis and an improved non-dominated sorting genetic algorithm II (NSGA-II) programming model. Based on the emergy analysis, the emergy economic efficiency index (EYR), emergy environmental efficiency index (ELR) and emergy sustainability index (ESI) are used for the sustainable development evaluation, and the results provided the basis for the objective function for economic and environmental equilibrium. Considering programming issues, the configured initial data and hierarchical evaluation results are integrated into the improved NSGA-II (CIHE-NSGA-II) model. This model is capable of (1) configuring the initial solution based on original farming data and (2) performing hierarchical evaluations of EYR, ELR and ESI based on bilevel programming. This exploratory approach was verified based on a real case study in northern China. The results showed that the ESI increased by 16.8% when the proposed approach was applied. This simulation research demonstrates the usefulness of CIHE-NSGA II in optimizing the allocation of resources in ICLSs, and OMEE can provide evaluation results that aid in meeting decision-making goals and configuring crop and livestock resources.