Food provided a material foundation for the development of human society and was an important cornerstone for ensuring national security. The Chinese government has always attached great importance to food security, which is not only related to economic development and social stability but also to national security and self-reliance. As the core region for grain production and the supply of staple food in China, the major grain-producing areas account for 78.25% of the total national grain output, truly earning the title of China’s “granary”. Considering the establishment of 13 major grain-producing regions across the country in 2004 as a quasi-natural experiment, the impact of policies in major grain-producing regions on ensuring national food security is examined using a difference-in-differences method based on inter-provincial panel data for 30 provinces across the country from 1997 to 2020, and the mechanisms of their effects are further analyzed. The findings show that (1) the main producing-areas policy has a significant driving effect on China’s food security, with an average annual increase of 0.0351 units in the food-security index, and the impact is expanding year by year. (2) The policy of the main grain-producing provinces mainly plays a role in guaranteeing food security by expanding the scale of grain cultivation and the scale of family land management in the main grain-producing provinces, and the scale effect of grain cultivation has a more significant impact. Further adjusting and improving the policy of the main grain-producing areas and expanding the scale-driven effect of this policy are of great significance for transforming agricultural production methods and realizing a strong agricultural country.

Straw returning technology has the potential to not only enhance the crop’s nitrogen yield but also protect the ecological environment and enhance crop yield. This paper explores the impact of uncertainty on rural households’ adoption of straw returning technology using an experimental method based on 703 wheat planting households in the Loess Plateau, China. The results show that 1) most farmers are inclined to risk aversion, and farmers generally have the characteristics of ambiguity aversion. 2) Risk preference and ambiguity preference obviously and negatively impact the possibility of adopting straw returning technology, and when the farmer’s risk preference and ambiguity preference increase by 0.1 units, the probability of adopting straw returning technology will decrease by 19.4% and 17.1%, respectively. 3) When we take the risk preference and ambiguity preference together into account, risk preference has sufficiently large effects on farmers’ decision on adopting straw returning technology relative to ambiguity preference. Overall, this research provides a micro-foundation and policy recommendations for farmers’ straw returning technology promotion in rural China and sheds light upon how the government can formulate relevant policies to promote green environmental development.