Abstract: Agriculture is not only the dominant source of human food and clothing, but also the potential sector of global anthropogenic greenhouse gas (GHG) emissions mitigation, especially methane (CH₄) and nitrous oxide (N₂O). To standardize GHG accounting is an urgent need for agricultural carbon emission inventory compilation, carbon trading of emission reduction verification and low-carbon agricultural product certification, as well as the basis for the policy making and technology selection of agricultural carbon reduction and sequestration. This is of great significance for the green-low-carbon and high-quality development of agriculture. Based on a systematic review of the relevant global specifications, guidelines, methodologies and standards of agricultural GHG accounting, this paper aims to address the problems of imperfect monitoring and reporting systems, unsystematic accounting and calculating methods, and uncertain accounting results, by providing the following four suggestions for the establishment and improvement of agricultural GHG accounting systems. Firstly, we should further establish and improve the institutional system of the accounting system, to better clarify the subject of the main responsibility. On the existing basis of China's agricultural statistics and non-point source pollution monitoring and reporting systems, we should strengthen the construction of agricultural GHG emission monitoring (M), reporting (R) and verifying (V) system (i.e. MRV system); and supplement and improve the policy making and institutional setting, so as to clarify the main responsibilities of agricultural GHG statistical accounting and carbon reduction and sequestration. Secondly, we should further supplement and improve the accounting standards and methodologies. According to the newly issued international standards and methodologies, and the actual situation of China’s agricultural production and future development, we need to revise the agricultural components of China's Guidelines of Provincial GHG Emission Inventories. For example, the farmland carbon sequestrations of biochar application, ecological farm and well-facilitated farmland construction, and crop straw comprehensive utilization, as well as the carbon emissions of lime and urea application, ruminant livestock feeding and freshwater aquaculture need to be supplemented into the guidelines; the accounting standards and methods of agricultural indirect GHG emissions need to be revised, and some new CCER (Chinese certified emission reduction) methodologies need to be developed for agricultural carbon trading. Thirdly, the database needs to be further renewed and upgraded. We need to strengthen scientific and technological innovations and accounting data accumulation of agricultural carbon reduction and sequestration, to renew and upgrade the basic data, action data and emission factor data of the existing accounting systems in combination with field monitoring, model estimation and literature synthesis. The fourthly, at last, it is also necessary to develop the application software supporting the accounting standards and methodologies, and carry out science popularization, technical training and application demonstration. Our suggestions can provide references for the guideline revision of agricultural greenhouse gas emission inventories, and supports to the methodology development for trading verification of agricultural voluntary emission reduction and carbon footprint assessment of low-carbon agricultural product certification.

Key words: food security, climate change, green and low-carbon development, carbon emission inventory, carbon trading for emission reduction, MRV methodologies