Emergy analysis of grain production systems on large-scale farms in the North China Plain based on LCA

Traditionally, primary grain production systems in China have been on a small scale and are associated with high costs and low labor productivity. Therefore, the substitution of small‐scale farming with large‐scale farming has been discussed in recent years. The North China Plain (NCP) is one of the primary grain production areas in China, and the winter wheat–summer maize double‐cropping system dominates the region. Emergy evaluation based on life cycle assessment (LCA) was introduced in a farm case study to explore the ecological and economic effects of the wheat–maize double‐cropping system on large‐scale grain production compared with small‐scale production. The results indicated that the emergy efficiency of maize production on the large‐scale farm was 67.4–88.5% higher than that of common maize production systems, and the emergy efficiency of wheat production in the same farm decreased by 23.5–43.0% compared to other wheat production systems. The emergy sustainability index (ESI) of the double‐cropping system was 64.0–84.5% lower than that reported by household farms. This is caused by large‐scale farming requiring enormous emergy inputs from irrigation, fertilizers, and labor at the pre‐sowing and growth stages of wheat production. Nevertheless, the scenario analysis results showed that the emergy efficiency and ESI of wheat production could be improved by 14.7–59.1% and 18.2–123.3%, respectively, using appropriate water, nutrient, and agronomic management measures. We found that the emergy efficiency of wheat production in this large‐scale farm was 41.5% higher than in household farms in the same area if comprehensive improvement measures were applied. In conclusion, the ESI value of the double‐cropping system in the NCP needs to be modified to increase the emergy efficiency of large‐scale grain production farms. If this is accomplished, the large‐scale farming pattern may be applicable for grain production in the NCP.