Effects of phase change material inclusion on reducing greenhouse gas emissions from soil in cold region

Increased gas emissions from soil into the atmosphere are one form of ecosystem feedback in response to climate change. Soil temperature plays a critical role in the soil emission of carbon dioxide (CO₂) and nitrous oxide (N₂O) suggesting that the release of gases can be reduced by regulating soil temperature. This study proposes a green microencapsulated phase-change material (mPCM) as a soil temperature regulator due to its ability to absorb and release heat during temperature phase transition. The objective is to test how mPCM in soil mixtures influences CO₂ and N₂O fluxes under laboratory-controlled conditions. For this purpose, a series of soil incubations were carried out with different temperature regimes and soil moisture. The test results revealed that at 20% soil moisture mPCM reduced cumulative CO₂ emissions from the soil by 16.4% during the thawing stage and by 20.5% during the freezing stage. At 25% soil moisture, mPCM showed a greater effect reducing cumulative CO₂ emissions by 23.9% during the thawing stage and by 24.2% during the freezing stage. At below-zero temperatures, mPCM reduced the total N₂O flux by 11.6% at 20% soil moisture and by 26.0% at 25% soil moisture, compared to soil without mPCM. As soil moisture increased, the effects of mPCM on CO₂ and N₂O fluxes became more pronounced. Cyclic freezing and thawing of soil led to an increase in gas flux. This variation was reduced by the mPCM due to its ability to mitigate the change of soil temperature. Inhibition of the rise in soil temperature due to the inclusion of mPCM reduced the rate of activation of soil mineralization, which reduced gas fluxes. This study demonstrates the potential of mPCM application to reduce greenhouse gas emissions from soil through thermoregulation.