Abstract: Nitrous oxide (N₂O) is a greenhouse gas in the troposphere and contributes to ozone depletion in the stratosphere. Soil N₂O production involves biotic (autotrophic nitrification, heterotrophic nitrification, nitrifier denitrification, nitrification-coupled denitrification, heterotrophic denitrification, codenitrification, dissimilatory nitrate reduction to ammonium) and abiotic pathways. A couple of N₂O production pathways may occur simultaneously, it is thus difficult to quantify the contribution of a single pathway to N₂O production. However, quantifying the contribution of individual pathways to total N₂O production is necessary to mitigate soil N₂O emission, or to simulate soil N₂O production and its responses to global change using Earth system models. Some methods have been developed to decipher N₂O production pathways, including molecular methods, inhibition techniques, and stable isotope methods. Here, we review current status of soil N₂O production pathways and their research methods. We pointed out the advantages and disadvantages of each method and the knowledge gaps. The information is useful for researchers to carry out relevant researches, or can help understand the major sources of soil N₂O emission and thus make effective measures to mitigate soil N₂O emission.

Key words: nitrous oxide source, biotic pathway, abiotic pathway, molecular technique, inhibition method, stable isotope technique.