Topography modulates effects of nitrogen deposition on soil nitrous oxide sources in a subtropical forest

Nevertheless, it is still unclear whether topography modulates the magnitude and source partitioning of soil N2O emission under elevated N deposition. Here, an N addition experiment was conducted in the valley and on the slope of a subtropical secondary forest, respectively, with three treatments, i.e., 0, 50 and 100 kg N ha-1 year-1.

A combination of the 15N–18O labelling technique, 15N pool mixing model and transcriptome analysis were used to identify contribution of seven pathways to soil N2O production. Autotrophic nitrification pathways (ammonia oxidization, nitrifier denitrification and nitrification coupled denitrification) accounted for > 70% of total N2O production, but denitrification pathways (heterotrophic denitrification and co–denitrification) were the minor sources of N2O at both topographic positions.