[Effects of different fertilization modes on soil ammonia volatilization and nitrous oxide emission]

With enclosed and static chambers, this paper studied the effects of different fertilization modes, i.e., top-dressing nitrogen (N) fertilizer followed by tillage (SF), drilling N fertilizer followed by covering soil (TF), and top-dressing N fertilizer followed by irrigation (SS), on soil ammonia (NH3) volatilization and nitrous oxide (N2O) emission. The results showed that fertilization mode had significant effects on the NH3 volatilization and N2O emission. SS promoted NH3 volatilization obviously, with the maximum NH3 volatilization rate higher than other treatments and the total amount of cumulative NH3 volatilization up to 2.465 kg N x hm(-2). There were significant differences (P < 0.05) in the N2O flux among different treatments, and the peak appeared at different time. The N2O flux in SS got to its peak (193.66 miccrog x m(-2) x h(-1)) after two days of fertilization, while that in TF got to the peak (51.13 microg x m(-2) x h(-1), the lowest among different treatments) after five days of fertilization. The net cumulative N2O emission in SS was 121.55 g N x hm(-2), much higher than that of SF and TF. SF and TF reduced NH3 volatilization and N2O emission markedly, suggesting that both of them could be the rational and practicable N fertilization modes.