Jiang Zhide

　　(College of economics and management, Northwest Agriculture and Forestry University, Yangling, Shaanxi, China)

　　Calculating carbon effects at the farmer level is fundamental to agriculture's response to climate change. What are the combined effects of carbon source and carbon sequestration? What are their future trends? This study attempts to build an analysis framework of carbon effects for farmers' production projects and choose accounting methods. On this basis, we use the typical farmer cases survey data obtained from Loess Plateau of China to analyze and validate. The results show that farmers' production items can be classified to four types of crops, fruit trees, grasses and aquaculture, and the carbon emission level in the production process can be estimated according to the quantity of energy input under different technical conditions. The carbon sink level can be determined by the net absorption of carbon dioxide by green plant photosynthesis. We select the appropriate conversion coefficient to calculate the comprehensive carbon effect according to the field survey and literature demonstration. Case analysis found that the input of chemical fertilizer, plastic film and energy for machinery operation was the main source of soil carbon emissions; additional carbon emissions from planting may be derived from the farmer's inappropriate soil tillage practices, or from the habit of burning crop stalks; carbon emissions in aquaculture mainly come from enteric fermentation and manure management, feeding the artificial diet and facilities is an important factor leading to increased carbon emissions. The increase of crop planting density was beneficial to the increase of plant biomass, and the conversion of cropland to forest or grassland promoted the restoration of perennial vegetation, which together led to the increase of carbon sink. In the long run, the pressure for increased carbon emissions and the potential to increase carbon sinks and reduce carbon emissions coexist, the overall carbon effect of farmers’ production is uncertain, it depends largely on the key low-carbon technology promotion and whether the relevant policy incentives are in place.