【摘要】 【目的】明确土壤水含量与氮肥类型对碱性水稻土N₂O释放总量及释放途径的影响,为制定合理的农田氮素管理措施及减少土壤N₂O排放提供理论依据。【方法】以潮土性水稻土（pH 7.9）为供试土壤,通过室内培养调整不同的土壤水含量,即调节土壤最大持水量（WHC）分别为50%、80%、100%、120%和160%,施用尿素与硫酸铵（N 100 mg/kg）两种氮肥,使用乙炔（C2H2,10 Pa）与氧气（O2,100 k Pa）抑制100%WHC时不同氮肥处理的自养硝化与反硝化过程,利用气相色谱及流动分析仪测定不同处理下土壤的N₂O排放量、硝态氮与铵态氮含量。【结果】对比不施肥处理（CK）,尿素和硫酸铵处理的N₂O排放速率与累计排放量明显提高,其中尿素对N₂O排放速率的影响大于硫酸铵,且随着土壤水含量的增加,尿素和硫酸铵处理的N₂O排放速率均呈先增大后减小的变化趋势。施氮后土壤自养硝化和异养硝化作用中N₂O排放速率均有所提高,且施氮处理自养硝化对N₂O排放的贡献大于异养硝化作用,但尿素与硫酸铵对自养和异养硝化过程N₂O排放贡献的影响存在差异。硫酸铵提高了自养硝化对N₂O排放的贡献,降低了异养硝化的贡献,分别由CK的31.0%提高到49.0%,以及从63.0%降低至5.3%;尿素却同时降低了自养硝化和异养硝化对N₂O排放的贡献,分别由31.0%降低到25.0%及由63.0%降低到1.7%。【结论】碱性水稻土N₂O释放速率随土壤水含量的增加呈先增加后减小的趋势,不同土壤水含量下尿素的N₂O累积释放量均高于硫酸铵。添加氮肥降低了异样硝化对N₂O释放的贡献,硫酸铵与尿素分别由自养硝化和反硝化作用起主导作用。因此,旱地土壤施用尿素、水田施用铵态氮肥有利于减少N₂O释放。更多还原

【Abstract】 【Objective】The effects of soil water content and nitrogen fertilizer type on alkaline paddy soil N₂O release and release route were clarified,which provided a scientific basis for improving nitrogen use efficiency and reducing soil N₂O release.【Method】In this experiment,fluvo-aquic soil was used as the tested soil,soil moisture contents were adjusted through indoor culture,which was adjusting the maximum water holding capacity（WHC）to be 50%,80%,100%,120%and 160%,applying two types of nitrogen fertilizers: urea and ammonium sulfate（N 100 mg/kg）. Acetylene（C₂H₂,10 Pa）and oxygen（O₂,100 kPa）were used to inhibit the autotrophic nitrification process and denitrification process of different nitrogen fertilizer types during 100% WHC. N₂O release,nitrate nitrogenand ammonium nitrogen contents were determined by gas chromatography and flow analyzer.【Result】The results showed that compared with no fertilization treatment（CK）,urea and ammonium sulfate treatments significantly increased soil N₂O emission rate and cumulative emissions,and the effects of urea was greater than that of ammonium sulfate,and N₂O emission rate increased first and then decreased with the increase of water content. The N₂O emission rate of soil autotrophic nitrification and heterotrophic nitrification increased after nitrogen application,and the contribution of autotrophic nitrification to N₂O emission was greater than that of heterotrophic nitrification. However,the effects of urea and ammonium sulfate on the contribution of autotrophic nitrification and heterotrophic nitrification to N₂O emissions were different. The application of ammonium sulfate increased the contribution of autotrophic nitrification to N₂O emissions from 31.0%（CK）to 49.0% and reduced the contribution of heterotrophic nitrification from 63.0% to 5.3%;while urea reduced both the contribution of autotrophic nitrification and heterotrophic nitrification to N₂O emissions,from 31.0% to 25.0% and 63.0% to 1.7%,respectively.【Conclusion】With the increase of soil water content,the release rate of alkaline paddy soil N₂O increases first and then decreases. The cumulative release amount of urea N₂O under different water contents is higher than that of ammonium sulfate. The addition of nitrogen fertilizer reduces the contribution of heterogeneous nitrification to N₂O release. Ammonium sulfate and urea are dominated by autotrophic nitrification and denitrification,respectively. Therefore,the application of urea in dry soil and the use of ammonium nitrogen fertilizer in paddy field are beneficial to reduce N₂O release.更多还原