Abstract: With intact soil core and by using acetylene inhibition method, this paper measured the N₂O emission and denitrification rates of typical Calamagrostis angustifolia wetland soils in Sanjiang Plain, analyzed their relationships with environmental factors, and estimated the total amounts of N₂O emission and denitrification loss. The results showed that meadow marsh soil and humus marsh soil had a similar change range of N₂O emission rate (0.020-0.089 kg N·hm²·d^-1 and 0.012-0.033 kg N·hm²·d^-1, respectively), but the former had a much higher N₂O emission rate than the latter, and the difference was significant (P＜0.05). As for denitrification rate, its change range was 0.024-0.127 kg N·hm²·d^-1 for meadow marsh soil and 0.021-0.043 kg N·hm²·d^-1 for humus marsh soil. Meadow marsh soil also had a higher denitrification rate than humus marsh soil, but the difference was not significant (P＞0.05). In meadow marsh soil, nitrification played an important role in N₂O emission and nitrogen loss; while in humus marsh soil, denitrification was the main process inducing N₂O emission and nitrogen loss. For these two soils, nitrogenous compounds were not the important factor affecting nitrification-denitrification. In meadow marsh soil, temperature had more evident effect, where nitrification-denitrification had a significant positive correlation with the soil temperature at the depths of 5 cm, 10 cm and 15 cm (P＜0.05). Soil moisture condition was another important factor inducing the difference of N₂O emission and denitrification rates. In growth season, the amount of N₂O emission and denitrification loss was 5.216 kg N·hm^-2 and 6.166 kg N·hm^-2 for meadow marsh soil, and 3.196 kg N·hm^-2 and 4.407 kg N·hm^-2 for humus marsh soil, respectively. In the denitrification productions of meadow marsh soil and humus marsh soil, the maximum value of N₂O/N₂ ratio was 5.49 and 3.76, respectively, indicating that the proportion of N₂ in denitrification productions was higher in humus marsh soil than in meadow marsh soil, and the seasonal waterlogged condition could induce the decrease of N₂O/N₂ ratio.

Key words: Dryland wheat, Long-term fertilization, Yields effect