It is known as "laughing gas", it is used as an oxidizer in rocket propellants, it is adopted in motor racing to increase the power output of engines. Yet, it is also a major greenhouse gas and air pollutant. 

Nitrous oxide or N₂O, is produced naturally in the soil during the microbial processes of nitrification and denitrification. It is a greenhouse gas with a large global warming potential (GWP). When compared to carbon dioxide (CO₂), N₂O has 298 times the ability per molecule of gas to trap heat in the atmosphere. 

Scientists have been working for decades to find solutions to reduce N₂O emissions, including adding biochar. However, the effect of biochar amendment on soil N₂O emissions during freeze-thaw cycle (FTC) is still rarely known by people. 

Soil FTC is a process caused by phase transition of soil water. It is a common process during the non-growing season in mid-high latitude regions. China is a country with large areas at mid and high latitude and high altitude where FTC occurs frequently. Thus it means a lot for researches on finding ways to reduce N₂O emissions especially in these areas.  

Scientists at the Xinjiang Institute of Ecology and Geography (XIEG) may have recently found an answer to this question. They created a man-made soil FTC through laboratory simulation, and used it in their research on the effect of biochar amendments on N₂O emissions. 

Analysis showed that soil N₂O emissions could be reduced by adding biochar during FTC. Biochar amendments also had a positive effect on retaining soil urease and protease activities.  

Their study indicates that biochar amendment can be a potential method to reduce soil N₂O emissions during freeze-thaw periods.  

“The loss of N from soils will also decrease N availability to crops and affect crop productivity negatively. Hence, new agricultural management practices are needed to reduce N₂O emission as well as maintain N availability of soils,” said LIU Xiang, a researcher from the team. 

Their research was published on Scientific Reports, entitled “Response of N₂O emissions to biochar amendment in a cultivated sandy loam soil during freeze-thaw cycles”.