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在饱和田间持水量WFPS(water-filled pore space)为75%、温度为25℃的条件下,用室内培养研究设施菜地土壤在不同氮肥种类(硝酸钙CN,碳酸氢铵AB,硫酸铵AS,尿素U,对照CK)和有无秸秆添加情况下N2O的排放特征。培养17天的结果表明,各种肥料类型中,对照和硝态氮肥处理最先出现N2O排放高峰,铵态氮肥处理出现较晚。无论有无秸秆,碳酸氢铵(AB)处理的累积排放量都最高,分别为4.206±0.899和2.159±0.256μg g-1干土,铵态氮肥处理N2O排放量明显高于硝态氮肥。添加秸秆后各处理N2O排放明显增加,比未施秸秆增加1倍多(CN处理除外)。不同处理(CK除外)的N2O累积排放量与时间的关系都可用y=aLn(x)+b表示(P<0.001)。实验还发现,施用氮肥会导致土壤酸化,添加秸秆可改善土壤酸化现象。
Under the conditions of saturated field water-filled pore space (WFPS) of 75% and temperature of 25 ℃, the soil samples of vegetable garden under different cultivation conditions (calcium nitrate CN, ammonium bicarbonate AB, ammonium sulfate AS , Urea U, control CK) and N2O emission with or without straw addition. The result of cultivating for 17 days showed that the highest N2O emission occurred in the control and nitrate nitrogen treatments and the ammonium nitrogen treatment appeared later in various fertilizer types. The cumulative emissions of ammonium bicarbonate (AB) with or without straw were the highest, which were 4.206 ± 0.899 and 2.159 ± 0.256μg g-1 respectively. The N2O emission of ammonium nitrogen fertilizer was significantly higher than that of nitrate nitrogen fertilizer. After adding straw, the N2O emission of each treatment increased obviously, more than double than that of no straw (except CN treatment). The relationship between cumulative N2O emissions and time for different treatment (except CK) can be expressed as y = aLn (x) + b (P <0.001). The experiment also found that the application of nitrogen fertilizer will lead to soil acidification, adding straw can improve soil acidification.