Fallow priority areas for spatial trade-offs between cost and efficiency in China

Fallow pilot policies exist in China but fallow priority areas have yet to be identified based on eco-environmental stressors and spatial cost-benefit analyses. Here we use a multi-criteria optimization algorithm to determine fallow priority areas based on soil pollution, groundwater overexploitation, land quality, and ecological protection redlines delineation data and with high-cost effectiveness. By considering five spatial scenarios on three objective functions, we find most notably that fallowing the top 20% of priority areas, the benefit of pollution control and environmental protection can be achieved by up to 98.7% and 64.7%, respectively. Our results show that effective fallow prioritization on cultivated land may reduce implementation costs by up to 509.3 billion USD, corresponding to 13.6% of China's budget in 2021. Thus, effective fallow prioritization will promote sustainable land use by pursuing goals between benefits and cost synergistically and allow budget allocation to other sustainable agricultural targets based on agricultural diversification. Leaving as fallow 20% of the cultivated land in China, chosen to optimise environmental protection for factors such as soil pollution and land quality, for example, can produce substantial environmental benefits, according to an analysis of multiple data sources to optimize spatial trade-offs.