| 摘要: |
| 【目的】 揭示耕层不同深度土壤N2O的排放机制，为农田土壤N2O减排和预测提供科学依据。【方法】 利用室内模拟试验，研究了西北地区冬小麦孕穗期、开花期和成熟期原状土壤，在相应田间水热条件下（温度：15，20，25 ℃；含水率：14.50%，18.70%），不同深度（5，10，15，20 cm）耕层土壤N2O的排放特征。【结果】 土壤N2O平均排放通量与土样NO3-N底物）含量有关，孕穗期（15 ℃）土样，因其NO3-N含量较高（10.09 mg/kg），故 N2O平均排放通量亦较大。在一定土壤NO3-N含量范围（3.18～4.12 mg/kg），不同深度土样的N2O平均排放通量与水热条件关系密切。孕穗期（15 ℃），较深土样N2O平均排放通量明显下降，其N2O平均排放通量表观滞留率显著增加，含水率较高土样表现更为突出；随着温度的升高（20，25 ℃），较深土样N2O平均排放通量明显升高，含水率较高土样增加明显，不同深度土样N2O平均排放通量几乎呈线性增加，其N2O平均排放通量表观滞留率明显减少。在孕穗期（15 ℃）水肥较充足的条件下，耕层土样N2O排放主要来自5～15 cm土层；随温度升高，较深土样对N2O排放的贡献则更为突出。【结论】 全球气候变暖将促使较深层次土壤中的N2O逸出地面，排入大气。 |
| 关键词: N2O排放通量 温度依变性 土壤深度 表观滞留率 |
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| 基金项目:国家科技基础性工作专项重点项目(2007FY110800)；教育部科技重点项目(209123)；陕西省自然科学基金资助项目(2006D05) |
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| Temperature and depth’s dependences on N2O emission in the cultivated layer soil |
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JIN Ling yuna DU Shuang tianb MA Lub JING Liu pingb LI Hui juna
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| Abstract: |
| 【Objective】 The research studied the mechanism of soil N2O emission at different depths to offer scientific bases for reducing farmland N2O discharge flux.【Method】 Soil samples from a wheat field were analyzed to study the characteristics of soil N2O emission under the filed hydrothermal conditions in a lab (temperature:15,20,25 ℃,soil moisture:14.50%,18.70%,soil depths:5,10,15,20 cm).【Result】 The average soil N2O flux was closely related to soil NO3-N content.Due to the higher NO3-N (10.09 mg/kg),soil N2O flux at the booting stage maintained a high level even at a lower temperature (15 ℃).When soil NO3-N content was in a certain range (3.18-4.12 mg/kg),soil hydro thermal conditions would control soil N2O emission at different depths.When soil temperature was low at 15 ℃,soil N2O flux in the deeper layer decreased obviously,and retention rate increased significantly,especially for the soils with high moisture. N2O flux from deeper soil increased obviously as soil temperature increased, N2O flux from different depths increased linearly and retention rate decreased significantly.At booting stage (15 ℃) with a good soil moisture and fertility,soil N2O flux was mainly from 5-15 cm layers.More N2O was released from deeper soil as soil temperature increased.【Conclusion】 Global warming increases N2O emission from deeper soil. |
| Key words: N2O flux soil temperature dependence variability soil depth apparent retention rate |
