Carbon sequestration and greenhouse gas mitigation paths and modes in a typical agroecosystem in northern China

“Carbon peak and carbon neutrality” is a commitment of the country to achieve sustainable development in “response and mitigate climate change”, and agroecosystems should bear the corresponding share of non-CO₂ greenhouse gas emission mitigation and farmland soil carbon sequestration. Northern agroecosystems play a pivotal role in ensuring food and ecological security in China, and many previous studies have shown that northern agroecosystems have great potential in N₂O emission mitigation and soil carbon sequestration. However, to ensure food security during the implementation of “carbon peak and carbon neutrality”, how do we choose the path of soil carbon sequestration and non-CO₂ emission mitigation in farmland soil? What are the carbon sequestration and emission mitigation modes of typical agroecosystems in different regions? What problems should be addressed in the implementation of carbon sequestration and emission mitigation? Other issues remain inconclusive or lack systematic research. Therefore, according to the method of agricultural division, the north of China is divided into three agricultural regions, i. e. Northeast China, North China and Northwest China. Based on the systematic analysis of the characteristics of agricultural production in different regions of northern China, this study proposed that the greenhouse gas emission reduction of the northern agroecosystems follows the path of “optimizing production capacity and mitigating emissions (stabilization of productivity of farming and breeding; and mitigation of N₂O emission from farmland, carbon emission from agricultural energy consumption and breeding and its’ wastes)”, and carbon sequestration follows the path of “slow-down and double increase (slow down of the decrease of soil organic carbon of black soil in the Northeast China and increase soil carbon storage of medium and low-yield field and grazing grassland)”. The study puts forward the key contents of carbon sequestration and emission mitigation in different regions. This paper summarizes the technical composition, carbon sequestration and emission mitigation effects, and adaptation area of four modes, namely low carbon cycle mode, capacity expansion and carbon increase mode, carbon optimized breeding mode, and nitrogen saving and carbon conservation mode. Furthermore, this study illustrates that the process of “carbon peak and carbon neutrality” assisted by agricultural production in northern China needs to focus on “coordination of carbon sequestration and emission mitigation, efficiency of carbon sequestration and emission mitigation, large-scale implementation of technology and mode” to provide ideas and support for the development of “low-carbon” green agroecosystems in northern China.