氮肥施用对紫色土-玉米根系系统N2O排放的影响

通过不同施氮水平与不同氮肥品种2个田间试验,结合静态箱-气相色谱法研究了川中丘陵区2005年5～9月石灰性紫色土-玉米根系系统的N2O排放变化.结果表明:1)施用氮肥显著地增加了N2O排放,在3个施氮水平下(0、150和250 kg·hm-2),N2O排放总量分别为0.88、2.19和2.52 kg·hm-2;施氮量越高,N2O排放量也越高.当施氮量超过一定水平后,施肥量高低对N2O排放总量的影响并不显著.由氮肥施用引起的N2O排放量占施氮量的0.87%(150 kg·hm-2)和0.66%(250 kg·hm-2).2)氮肥品种显著影响N2O排放,尿素(酰胺态氮肥)和硫酸铵(铵态氮肥)处理的N2O排放量分别为2.09和1.80 kg·hm-2,显著高于硝酸钾(硝态氮肥)处理(1.27 kg·hm-2),三者排放量分别占施氮量的0·80%、0.60%和0.27%.3)降雨是玉米生长季N2O排放的主要影响因子,而无机氮则是影响N2O排放的主要限制因子.

Effects of nitrogen fertilizer application on N2O emission in a purple soil and maize root system

The static chamber-gas chromatograph method was used to measure the N₂O flux under the calcareous purple soil and maize root system treated with different nitrogen fertilizer rates and types in the hilly land of central Sichuan Basin from March to September in 2005. The results showed,1) Nitrogen fertilizer application enhanced the N₂O emission significantly. The total N₂O emission was 0.80, 2.19 and 2.52 kg·hm^-2 from the three application rates (0,150 and 250 kg·hm^-2),respectively. The higher the fertilizer applied, the more the N₂O emitted. But when it exceeded to a critical rate, fertilizer application rate had no significant effects on the N₂O emission. The total Nlosses derived from Napplied accounted for 0.87% and 0.66% when application rate were 150 kg·hm^-2 and 250 kg·hm^-2, respectively. 2) Nitrogen fertilizer types influenced N₂O emissions significantly. The higher N₂O emission occurred in CO(NH₂)₂ and(NH₄)₂SO₄,which amounted to 2.09 kg·hm^-2 and 1.80 kg·hm^-2, respectively. Both were markedly higher than that of KNO₃ (1.27 kg·hm^-2). The total Nlosses derived from Napplied accounted for 0.80%, 0.60% and 0.27% from the CO(NH₂)₂,(NH₄)₂SO₄, KNO₃, respectively. 3) Precipitation was the main influencing factor while inorganic nitrogen was main limited factor on N₂O emission.