Coordinated relationship between urbanization and grain production in China: Degree measurement, spatial differentiation and its factors detection

The entropy method was used to measure urbanization, and applied the coupled coordination degree model (CCDM) to calculate the coupled coordination degree of urbanization and grain production (CCDUG) of 330 cities at the prefecture-level and above from 2000 to 2018 in China, the exploratory spatial data analysis method (ESDA) is used to reveal their spatial-temporal differentiation, and the geographical detector (GeoDetector) is used to identify the dominant factors and their interaction affecting this spatial differentiation. Although the CCDUG has entered a high coordination interval, there is still much room for improvement. The spatial differentiation and agglomeration characteristics of CCDUG are significant, showing a "center-periphery" distribution pattern with the east as the center gradually decreases towards the west. The CCDUG with high-high cluster is mainly distributed in the main grain-producing areas of Northeast Plain and North China Plain. Low-low cluster is primarily distributed in the grain balance and main marketing areas of Northwest, Southwest, and South China coast. Elevation, urban-rural income gap, opening to the outside world, economic growth, and cropland resources per capita are the dominant factors affecting the spatial differentiation of CCDUG. The interaction between factors will enhance this spatial differentiation, among which the interaction between basic endowment conditions and socio-economic factors is the strongest. Understanding and portraying the interactive relationship between urbanization and grain production and its spatial laws have important theoretical references for achieving balanced coordination between high-quality economic-social transformation and food security.