Abstract:

Nitrification，denitrification and nitrifier denitrification are the main microbial producing processes of Nitrous oxide（N₂O）in soil. The Nitrous Oxide emission processes of soil and its response to N application were studied by different gas（air，oxygen or acetylene）inhibition methods in Poa pratensis L. The results indicated that the N₂O emissions of 10 g · m^-2 N applying treatments didn’t increase compared with the control treatment（7.2–8.2 g · m^-2 · d^-1）；but N₂O emissions increased significantly with N applying dose increased to 25 and 35 g · m^-2，the N₂O emissions were 1.52 and 1.88 times higher than that of the control treatment respectively，and there was no difference between them. The contribution rate of heterotrophic nitrification and denitrification of control treatment reached 65.7% and 34% respectively，and the contribution rate of autotrophic nitrification and nitrifier denitrification were nearly zero. Therefore，heterotrophic nitrification was the dominant process in the control treatment. The contribution rate of nitrifier denitrification，heterotrophic nitrification and denitrification under 25 g · m^-2 N applying treatment reached 35%，35% and 29%. Under 35 g · m^-2 N applying treatment，N₂O emissi on could happen with nitrifier denitrification，heterotrophic nitrification，denitrification and autotrophic nitrification， the contribution rate of autotrophic nitrification and denitrification reached 20% and 41%，respectively.

Key words: turfgrass, N fertilizer, nitrous oxide, nitrification, denitrification, nitrifier denitrification