Can organic agriculture feed China? Implications from the nitrogen supply

In recent years, organic agriculture has been rapidly developed in China and throughout the world. However, the position and role of organic agriculture in overall agriculture and the corresponding development strategy of organic agriculture are still debated. From the perspective of nitrogen (N) supply, this study attempted to evaluate the effects of not using synthetic fertilizer N on foodstuff production and consumption and to provide technical support for N management in China. The study selected the whole agroecosystem in China and quantified the symbiotic N fixation, the impact of agricultural product on N supply and grain production, and the population fed under different levels of foodstuff consumption. The annual N fixation capacity of leguminous crops in China was 15.41×10⁶ t·a^-1 if organic agriculture was adopted for all agricultural land. If no chemical N fertilizer was applied, the total agricultural product output in 1979 and 2018 was 381.96×10⁶ and 420.72×10⁶ t, respectively. These agricultural products (excluding vegetables and fruits) could feed a population of 0.81×10⁹-1.24×10⁹ and 0.50×10⁹-0.77×10⁹, respectively. Thus, if all agricultural lands were completely operated with organic agriculture principles and under the current acreage of agricultural land and science and technology levels, it would be difficult to feed the entire population of China. With consideration of the imported agricultural products, the actual per capita grain consumption (converted to standard grain, excluding vegetables and fruits) was 689.35 kg·a^-1 in 2018. Reductions in food waste, adjusting the food consumption structure, and increasing grain imports are key measures for resolving the food security issues in China. The importation of soybeans and other agricultural products has played an important role in reducing fertilizer usage in recent years in China. Chemical N fertilizer has made a great contribution to grain production in China, but there is still room for improvement in N fertilizer efficiency. Organic and ecological agriculture emphasizes the principles of holistic, coordination, circulation, and regeneration, which is the theoretical basis and technical guarantee to promote sustainable agriculture that will play a dominating role in agricultural development. The integration of cropping with livestock production should be disseminated and implemented throughout China to reduce resource waste and environmental pollution. At the policy and legislative levels, ecological compensation, and crop integration with livestock production may increase N utilization efficiency and achieve multiple goals of agricultural development, including food security, food safety, and ecological soundness.