外源氮添加对湿地土壤N2O排放量的影响

为搞清湿地土壤驱动N2O排放的关键氮源类型,有效减少湿地N₂O的排放,本文通过室内控制温湿度,用气相色谱法分析不同外源氮素对湿地N₂O排放的影响。结果表明:外加氮源组总是高于对照组N₂O排放量(4.4 mg·m^-3)。在设定的剂量范围内,单独添加尿素或尿素与硝酸铵1∶1配合时N2O排放量呈现先增后减的单峰分布趋势,峰值分别为10.6 mg·m^-3和229.0 mg·m^-3;单独添加硝酸铵时N₂O排放量(32.6-111.0 mg·m^-3)随着氮素添加量增加呈现持续上升趋势。单独添加尿素或硝酸铵、尿素与硝酸铵1∶1配合均促进N₂O的排放,但硝酸铵尿素混合添加对N₂O排放量的贡献>单独添加硝酸铵>单独添加尿素。这为预测内蒙古高原区农牧交错带湿地氮素输入可能带来的温室效应和有效减排提供科学依据。

Effect of Exogenous Nitrogen Addition on Nitrous Oxide N 2 O Emissions from Wetland Soil

It is important to make sure key nitrogen driving N₂O emission source from wetland soil for efficient N₂O emission reduction. In lab-oratory, the temperature and humidity were kept constant to study effect from different forms of exogenous N on N₂O emissions from wetland soil by gas chromatography. The results showed that all groups of exogenous N inputs increased N₂O emissions from wetland soil in contrast to CK group(4.4 mg·m ^-3). Under the group urea(U)alone and the combination of urea with ammonium nitrate(UAN)in a 1:1 concentration ra-tio, the change of N₂O emissions showed a unimodal trend, first increased and then decreased, the peak value 10.6 mg· m ^-3 and 229.0 mg·m ^-3 of N₂ O emissions corresponded to U and of UAN, respectively. While N₂O emissions showed an upward trend for ammonium nitrate(AN)alone, within the range from 32.6 mg·m ^-3 to 111.0 mg·m ^-3 N₂O emissions. All exogenous N treatments increased N₂O emissions more than CK,UAN combination>AN alone>U alone. This provided a scientific basis for predicting greenhouse effect caused by N fertilizer in wetland soil from farming-pastoral transition zone, as well as a reference for effective reducing N₂ O emissions from wetlands in Inner Mongolia Plateau.