Whether Cities are in Sustainable Grain Security

This study focuses on grain security trend of cities in China rather than their traditional grain condition, aiming to illuminate potential problems hiding behind perfect balance . We newly characterize grain security of 357 cities as enhanced and slack trend integrating temporal and spatial heterogeneity, and then summarize cities by comparing the variations of population, grain output and the distribution of cultivated land. Here, we find regional grain security is generally sustainable in the sense that about 54% of cities see enhanced grain security in comparison with ten years ago. Most cities see grain security trend keep in step with the variation of grain output. The variation of population contributes little to grain security enhancement but mostly induces slack grain security. It shows cities presenting enhanced grain security occupy about 62.42% of cultivated land but are heavily subject to cultivated land quality. By contrast, there are nearly half of top-grade land and merely 16% of low-grade land distributing in grain security slack regions. We conclude regional disparities of grain security are diffusing. And the increased population and decreased grain output seemingly interact to weaken grain security . Given the regional disparities and uneven cultivated land, we suggest current intensive management