Characteristics of carbon emission and approaches of carbon mitigation and sequestration for carbon neutrality in China's crop production

Crop production not only ensures national food security, but also is the main source of agricultural carbon emissions and an important pool of carbon sequestration. To clarify the characteristics of carbon emissions from crop production and discuss the approaches to reach the peak and neutrality in major agricultural areas can provide important scientific basis to the decision making of green and high-quality agricultural development and "dual-carbon" goal. Based on the national statistical data, this study compared and analyzed the characteristics of carbon emissions in crop planting regions in China, and presented the recommendations for carbon sequestration and greenhouse gas emission mitigation. The carbon emissions of crop production accounted for 45.5% of the national agricultural total carbon emissions in 2018, and the emissions of farmland methane (CH), nitrous oxide (NO), and carbon dioxide (CO) of diesel consumption accounted for 22.9%, 14.7%, and 7.9% of the total carbon emissions of agricultural production, respectively. In terms of the regional emissions, both the total carbon emission of crop production and the carbon emission per sowing area are higher in South than North China, with the highest emissions in East and central China and the greatest potential for emission mitigation. In the carbon emission from crop production, CH emission from rice fields accounts for the main part (50.3%) and is the focus of emission reduction. The annual carbon emission of crop production in China peaked in 2015, and then dropped down. It was mainly attributed to the decrease trend of rice sown area, agricultural nitrogen application rate, and diesel oil consumption. If the existing agricultural imports are not significantly affected, the carbon emissions in crop production have basically reached the peak. However, it is very difficult to achieve carbon neutrality in crop production if only by soil carbon sequestration of farmland, and it is necessary to consider both farmland emission reduction and carbon sequestration. On the premise of high and stable grain yield, the carbon neutrality of modern crop production should prioritize CH and NO reduction, and fully exploit the integrated carbon sequestration potential of farmland ecosystems, such as straw utilization, combination of the use and protection of farmland, and construction of farmland forest network.