Effect of tillage practice on carbon footprint of rainfed winter wheat

It is crucial to mitigate greenhouse gas emissions from soil and to abate carbon emissions from the production of goods (e.g., fertilizers, seeds, etc.) and production processes (e.g., diesel consumption by machines) for sustainable agricultural production. In order to evaluate carbon footprint and carbon emission intensity of different tillage practices in rainfed field, a 15-year long-term experiment with three different tillage practices was conducted in Linfen, Shanxi Province, a typical semi-arid area in North China. The investigated tillage management practices were rotary tillage without straw incorporation (RT), straw incorporation and rotary tillage (SRT) and straw-mulch and no-tillage (SNT). Carbon footprint in the production life-cycle of different tillage practice of rainfed winter wheat was explored, in which N₂O emissions from field were measured using the static chamber-gas chromatography method and the other emissions calculated by analyzing emissions from the production of main goods and the associated processes during life-cycle period of winter wheat. The results showed that N₂O emissions under SNT and RT management practices were 19.2% and 18.9% lower than that under SRT practice, respectively. N₂O emissions mainly occurred during the period from booting to maturity and then the period of summer fallow when soil temperature and moisture were most appropriate. N₂O emissions derived directly from nitrogen fertilizer and carbon emissions from the processes of chemical fertilizer production explained the most share of carbon footprint in the life-cycle of rainfed winter wheat, accounting for 21.6% and 46.4% of the total carbon footprints, respectively. N₂O emissions and carbon emissions derived from nitrogen fertilizer production and diesel consumption, and direct emission for field accounted for over 90% of the carbon footprint of rainfed winter wheat system. Carbon footprint under SNT practice was the lowest among three treatments, it was respectively 7.9%-11.0% and 6.9%-8.3% lower than those under SRT and RT. SNT management practice had the lowest carbon footprint among three tillage practices. Thus, straw incorporation with no-tillage was the most appropriate practice for sustainable agricultural production aimed at low greenhouse gas emissions and low carbon consumption in the semi-arid area of North China.