Abstract:

Based on the “Provincial Greenhouse Gas Preparation Guidelines (Trial)”, the characteristics of carbon emission equivalents, carbon sinks and carbon footprints of farmland ecosystems in Yunnan Province in 2008 to 2020 were studied, and the main measures for reducing carbon sequestration in future agricultural development were proposed. Based on the data related to production inputs and crop yields in Yunnan Province from 2008 to 2020, the carbon footprint analysis method was applied to systematically analyze the carbon emissions and carbon sequestration of farmland ecosystems in Yunnan Province. The results showed that the small amount of greenhouse gas emissions such as CH₄ and N₂O from farmland ecosystems should not be ignored, and the direct carbon emissions, carbon equivalent emissions of nitrous oxide and carbon equivalent emissions of methane from farmland ecosystems became the three most important factors of greenhouse gas emissions from farmland. On the other hand, the carbon equivalent emissions of greenhouse gases in Yunnan Province increased year by year from 2008 to 2017, and then showed a decreasing trend year by year. The carbon equivalent emission intensity showed fluctuating changes, among which straw burning, fertilizer degradation and diesel combustion were the main direct carbon emission sources, and N₂O and CH₄ were the main carbon equivalent emission sources; the carbon absorption intensity showed fluctuating changes, and the carbon absorption of maize and sugarcane were much higher than that of other crops, which was the main source of carbon sequestration; vegetables and melons had certain potential to increase sinks, and crops had a tendency to change from food crops to cash crops; the carbon footprint showed a trend of increasing and then decreasing, and was basically positively correlated with the trend of carbon emission equivalent. The average annual growth rate of carbon emission equivalent and carbon sequestration of agricultural ecosystem in Yunnan Province from 2008 to 2020 was 0.98% and 1.78%, respectively. The carbon footprint had not yet reached the limit of regional ecological carrying capacity, and the ecological carbon surplus had improved from 2017 to 2020, but the current ecological carbon surplus situation was still more severe. Finally, it is concluded that straw recycling, precise fertilization and the development of low carbon and high yield seed industry will be the main measures to control agricultural carbon emissions in Yunnan Province in the future.

Key words: farmland ecosystem, carbon footprint, crop straw recycling, precision fertilization