Responses of greenhouse gas fluxes to experimental warming in wheat season under conventional tillage and no-tillage fields

Understanding the effects of warming on greenhouse gas (GHG, such as N₂O, CH₄ and CO₂) feedbacks to climate change represents the major environmental issue. However, little information is available on how warming effects on GHG fluxes in farmland of North China Plain (NCP). An infrared warming simulation experiment was used to assess the responses of N₂O, CH₄ and CO₂ to warming in wheat season of 2012–2014 from conventional tillage (CT) and no-tillage (NT) systems. The results showed that warming increased cumulative N₂O emission by 7.7% in CT but decreased it by 9.7% in NT fields (p < 0.05). Cumulative CH₄ uptake and CO₂ emission were increased by 28.7%–51.7% and 6.3%–15.9% in both two tillage systems, respectively (p < 0.05). The stepwise regressions relationship between GHG fluxes and soil temperature and soil moisture indicated that the supply soil moisture due to irrigation and precipitation would enhance the positive warming effects on GHG fluxes in two wheat seasons. However, in 2013, the long-term drought stress due to infrared warming and less precipitation decreased N₂O and CO₂ emission in warmed treatments. In contrast, warming during this time increased CH₄ emission from deep soil depth. Across two years wheat seasons, warming significantly decreased by 30.3% and 63.9% sustained-flux global warming potential (SGWP) of N₂O and CH₄ expressed as CO₂ equivalent in CT and NT fields, respectively. However, increase in soil CO₂ emission indicated that future warming projection might provide positive feedback between soil C release and global warming in NCP.