Carbon effect of modern tobacco agriculture: Based on tobacco cooperatives in Shaanxi Province

Greenhouse gas emission from agriculture activities have an important impact on global warming. As the part of the agriculture system, tobacco agriculture has the obligation to address the climate change in the background of Ecological Civilization Construction and Rural Revitalization. To Explore the carbon effect of tobacco agriculture in Shaanxi Province and formulate effectively emission reduction policies to promote the low-carbon tobacco agriculture development, this paper constructed the comprehensive carbon effect accounting system of the tobacco agricultural, calculated the carbon emission, carbon sink, net carbon sink, and analyzed the carbon efficiency, carbon intensity and other comprehensive carbon effect indexes through all production processes of the 393 farmers who engaged in tobacco agriculture from tobacco professional cooperative in Shaanxi Province. The results showed that:for the total 641.17 hectare tobacco fields in the survey area, the total carbon emission was 3 276.27 t C, and the average carbon emission per hectare 5.11 t C, among which the agricultural energy consumption was the largest emission, and the percentage of total carbon emission was 68.21%. Next was the agricultural material inputs which accounted for 24.88% of the total carbon emissions. The agricultural waste disposal, the farmland management, and the farmland soil's nitrous oxide emission accounted for low proportion of carbon emission. The order of average carbon emission per hectare for each region from large to small was Baoji, Shangluo, Ankang and Hanzhong. The total carbon sink was 1 361.86 t C, the average per hectare of the carbon sink was 2.12 t C. Soil carbon sequestration caused by straw returning, no-tillage, and rational applying the chemical fertilizer and organic fertilization accounted for 81.12% of the total carbon sequestration. The average carbon sequestration per hectare in each region was ranked as Shangluo > Baoji > Hanzhong > Ankang. The total net carbon sink was -1 914.41 t C, and the net carbon sink per hectare was -2.99 t C. The total carbon emission of tobacco agriculture was greater than that of carbon sink, showing negative net carbon sink effect. Therefore, it is important to develop the low-carbon modern tobacco agriculture to promote low-carbon technological progress and explore the clean energy instead of coal in the bulk curing barn for flue-cured tobacco. In addition, by adopting measures such as adjusting management and operation mode, optimizing the input structure of farmers, improving the utilization efficiency of agricultural resources, improving tobacco agricultural technology and changing farming methods, Hanzhong Tobacco Professional Cooperative presented the optimal comprehensive carbon effects such as carbon efficiency, carbon intensity, carbon density, and maximize the net carbon sink per hectare.