Water footprint-based evaluation of ecological efficiency in China’s grain production and its driving factors

Water scarcity has increasingly become a critical challenge for the sustainable development of Chinese agriculture. Investigating the eco-efficiency of China’s grain production (ECGP) through the water footprint (WF) lens is essential for gaining deeper insights into the current state of grain production and promoting sustainable agricultural practices. In this paper, the CROPWAT model was used to measure the water footprint (WF) of China’s provinces, to evaluate the ECGP with the food production function based on the WF, and to explore the main influencing factors of the ECGP. The study found that (1) the green water footprint of grain production (WFGPgreen) dominates the WFGP in China, and the WFGP shows an overall fluctuating growth trend. In contrast, the gray water footprint of grain production (WFGPgrey) begins to decline after reaching the peak, especially after the implementation of the “Zero Growth Action Plan for Fertilizers and Pesticides,” significantly reducing the WFGP. The three phases of change in the ECGP, namely, “high-level decline period, adjustment period in the trough, and rebound and stabilization period,” show that China has gradually shifted from an initial model of high inputs and low efficiencies to a sustainable development model oriented toward green agriculture. ECGP varies significantly among the seven major regions of China, with the northeastern region being an area of high eco-efficiency in food production, probably mainly due to its more centralized pattern of food production. (3) The level of economic development, urban–rural income disparity, scale-up level, irrigation rate of grain fields, and grain yield per unit area significantly affect ECGP.