Resources Integration Theory and Gray Correlation Analysis: A Study for Evaluating China's Agri-food Systems Supply Capacity

China's agri-food systems face the challenge of ensuring food and grain security for a large population with limited resources. This paper constructs a resources integration theory, which classifies agricultural resources into six types and measures their correlation with food and grain supply capacity using grey correlation analysis. The results show that, during 2002-2020, among the factor resources, the highest correlation with food and grain was technology; among the related industry resources, the highest correlation with food was rural roads, and with grain was agricultural machinery; among the demand resources, the highest correlation was domestic market; among the six types of resources, the highest correlation was government resources; and the static correlation evaluation indices of agricultural resources with food and grain supply capacity were 0.8312 and 0.8090, respectively, indicating a compare match. Based on the results, this paper argues that the Chinese agri-food system is matched with agricultural resources, but still needs to be improved to achieve a high match. Opportunity resources, foreign investment, and international markets are disadvantageous resources because China has insufficient ability to stably utilize foreign resources. China’s proposal of a "big food view" is conducive to reducing dependence on factor resources, especially cultivated land and water resources.