Geopolitical competition between China and the United States has been intensifying, and uncertain events such as COVID-19 and extreme weather and climate occur frequently. The national strategy, which relies on two types of resources and two markets to ensure national food security, is facing challenges. Based on statistical data and literature viewpoints, this paper focuses on the main problems facing China's food security in the context of opening-up and how to ensure China's food security. The results show that: (1) China has made remarkable achievements in improving domestic food security, but with huge economic and resource environmental costs of food supply, and the increasing risks of stable food supply and access. The government is exploring practical ways for the achievement of food security in the era of globalization. (2) Agricultural opening-up can affect food supply, access, utilization and stability. The current opening-up has promoted the country's food supply, but it has not yet achieved stable and competitive food security. Agricultural opening-up still has a broad foundation for mutual benefit and win-win effect, while it is also facing greater uncertainty, which tests China's ability to deal with the challenges of globalization in food sector. (3) National food security governance is very important to food security. This paper recommends that we should adopt a self-sufficiency strategy with production capacity highlighted, a food security strategy for the entire industry chain to enrich the content of food, and a higher level of agricultural opening-up strategy, which will help to achieve the goal of national food security.

In the context of deteriorating global food security as well as the large population and scarce land resources in China, it is of great significance to explore grain industrialization. From the perspective of network organization, this study analyzes the models and optimal path of grain industrialization in China. Results show that the development of grain industrialization is a networked growth process and presents different forms of network organization. This study identifies grain industrialization into four modes, namely, state-regulated multinational company organization mode, locally-driven leading enterprise driving mode, government-led social multi-subject participation mode and market-oriented private enterprise driving mode, based on the ability of different network subjects to control and participate in the network, combined with the financing form of industrialization process and the spatial scale of its foothold or service, which correspond to the global-regional-local network organizations between market organizations and hierarchical organizations in the form of industrial organizations such as multinational corporations, local leading enterprises, industrial complexes, industrial parks and industrial clusters. Furthermore, it is suggested that we should improve the network subjects, upgrade the network structure, optimize the network carriers and strengthen the network governance to guide the high-quality development of grain industrialization.

During the transformation period of China, the unreasonable use of rural space has become a major hidden threat to food security. Therefore, the comprehensive governance of rural space has become an important driving force to promote the orderly transformation of grain production. A systematic analysis of the transformation mechanism of grain production guided by rural spatial governance and its security effects is beneficial for the improvement of the theoretical analysis of food security. Taking the internal mechanism of the transformation of grain production guided by rural spatial governance as a breakthrough, this paper conducts an empirical study in combination with typical cases of traditional farming area, and discusses the interactive relationship between rural spatial governance and food security. The main conclusions are as follows: (1) Unreasonable use of rural space is a factor that restricts the efficient operation of grain production. (2) Rural space "matter-ownership-organization" governance, through changing the software and hardware foundation needed for grain production, can achieve the purpose of optimizing the transformation of grain production, and promote the grain production towards a large-scale, high efficiency, green and fair transformation. (3) The spatial governance of Xiangbu village has significantly improved the conditions of grain production and effectively promoted the coordination and interaction between food security and rural transformation. (4) The modernization of rural spatial governance capacity is an important means to promote the modernization of the ability to ensure food security. The comprehensive governance of "matter-ownership-organization" in traditional agricultural areas can ensure food security during the transformation period, and is favourable to the implementation of the strategy of "storing food in land", which is of practical significance.

Food security is crucial to China's stability, development and international trade order. In this study, provincial-level administrative regions were taken as the basic unit to calculate the soil and water resources demand that can ensure the food self-sufficiency of each province continuously and to evaluate the carrying capacity of water and soil resources in each province. This study calculated the agricultural products for eating and reproducing and unavoidable food loss, without considering the difference of farmland quality in different regions of China. The required data referred to the provincial permanent population, food consumption per capita, data on agricultural products per unit area, and arable land and water resources from statistical yearbooks of China from 2017 to 2019; the arable land and water consumption parameters were obtained from relevant literature. Using ecological footprint and water footprint method, this study results are as follows: The total arable land resource in China is 1.81 times as much as the total demand for arable land, which means that the current arable land resource can fully meet the food production demand of Chinese people. However, there are large differences between provinces. The arable land in provinces or municipalities with a developed economy in coastal China is insufficient. The total available water resources for agriculture are 7.15 times as much as the general agricultural water demand and 1.78 times as much as the agricultural water demand to keep environmental sustainability, respectively. Thus, the available water resources for agriculture can fully meet the agricultural products demand of Chinese people. But the water resource of the North China Plain and Ningxia Hui Autonomous Region, as the important regions producing agricultural products, is deficit; the provinces on the Qinghai-Tibet Plateau and south of the Yangtze River have more available water resources. The spatial mismatch of water and soil resources restricts the crops production potential. If we do not consider the water demand for environmental pollution purification, the matching state of soil and water resources can meet the need of agricultural products nationwide; however, if we consider that, it is difficult to achieve self-sufficiency in agricultural products. There is a huge food deficit in food demand of 337155 thousand persons. Guided by the theory of sustainable development of resources and environment, China should take the following measures to ensure food security: (1) optimizing the distribution of agricultural production; (2) adjusting agricultural structure; (3) moving industries with highly consumed water and labor-intensity to the regions with rich water resources; (4) promoting technological progress, products import, and international cooperation in agriculture in the future.