不同氮源及秸秆添加对菜地土壤N_2O排放影响

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。

Effect of Different Nitrogen Sources and Straw Adding on N2O Emission from Vegetable Soil

A laboratory incubation with soil water content of 75%(water-filled pore space)and 25℃ was conducted to study whether the straw adding or not nitrous oxide(N2O) emission under different nitrogen fertilizers(Calcium nitrate,CN;Ammonium bicarbonate,AB;Ammonium sulfate,AS;Urea,U) from facilities vegetable soils.The results showed that in all kinds of fertilizers,adding straw or not,the blank(CK) and nitrate fertilizer emission peak first appeared,ammonium nitrogen fertilizer appeared later.In the case of whether adding the straw or not,ammonium bicarbonate(AB) had the highest cumulative emissions(4.206±0.899 and 2.159±0.256 μg g-1 dry soil).The emission of N2O from ammonium nitrate fertilizer was significantly higher than nitrate fertilizer.In addition,the N2O emissions were increased about 1 time after adding the straw compared with no straw(CN treatment excluded).Each treatment(CK excluded) was observed that cumulative N2O emissions with time could described by y=aLn(x) +b(P < 0.001).It was also found that no matter what kind of fertilizer could lead to soil acidification,but straw can improve soil acidification phenomenon.