紫色土旱地农田生态系统N2O排放
文献类型：学位论文
| 作者 | 项虹艳 |
| 学位类别 | 博士 |
| 答辩日期 | 2007 |
| 授予单位 | 中国科学院水利部成都山地灾害与环境研究所 |
| 授予地点 | 成都 |
| 导师 | 朱波 |
| 关键词 | 旱地 农田生态系统 系统N2O排放 土壤N2O排放 紫色土 |
| 学位专业 | 自然地理学 |
| 中文摘要 | N2O是重要的温室气体之一，由此引起的全球变暖和臭氧层破坏是当今重要的环境问题。紫色土农田生态系统是南方亚热带湿润区重要的生态系统之一，研究紫色土农田生态系统N2O排放对于编制我国温室气体排放清单和减排对策有重要的理论与实践意义。研究依托中国科学院盐亭紫色土农业生态试验站，采用静态暗箱和原状土柱－乙炔抑制法研究典型紫色土旱地农田生态系统（玉米－小麦轮作）N2O排放，分析了农田生态系统N2O排放以及土壤N2O排放季节变化特征以及影响因素，估算了生态系统N2O排放总量和N2O－N排放系数。获得以下主要结果和结论：（1）农田生态系统N2O表现为净排放，伴随施肥或降雨的出现，生态系统N2O排放速率明显增大，而其它时候排放速率较低；生态系统N2O排放速率变化范围为-1.9～319.8μgN.m-2.h-1。全年平均排放速率为46.5μgN.m-2.h-1。土壤N2O排放季节变化规律：夏季排放速率高，秋冬春三季排放速率很低，与温度变化比较一致，夏季受降水影响波动较大。全年土壤N2O平均排放速率为25.6g N•hm-2•d-1。（2）农田生态系统N2O排放受土壤温度、土壤水分、土壤中无机氮含量以及植株等因素的综合影响。5cm处土壤温度、水分以及无机氮含量与生态系统N2O排放量呈显著的线性正相关关系，三个因子对系统N2O排放影响大小顺序为：无机氮含量＞土壤温度＞土壤水分含量。植株的存在增加了N2O的排放，有作物参与的生态系统N2O全年平均排放速率较无作物参与的土壤N2O平均排放速率增加了44.3%。（3）氮肥施用促进了生态系统N2O排放。高氮、中氮以及不施氮处理N2O排放总量分别为4.95、3.86和1.64 kgN•hm-2。在本区常规施氮处理下（中氮，150 kgN•hm-2），N2O－N排放系数为0.74%。尿素、硫酸铵、硝酸钾三种氮肥品种处理下，土壤－植物系统N2O排放量分别为3.93、3.20和3.11 kg•hm-2。施用硝态氮肥能保证本区作物的经济产量，同时能减少系统N2O排放，减轻土壤氮素气态氮损失，从而可能降低对大气环境的负面影响。（4）无机氮含量、土壤温度与土壤N2O排放速率和反硝化速率呈显著正相关关系。降雨是导致土壤N2O排放增加的主要驱动因子。雨季土壤N2O排放总量和反硝化排放量占全年总排放量的91.3%，土壤中氮素损失（以N2O气态氮形式）主要发生在雨季，即发生在高温高湿的夏季。由降雨引发的反硝化作用是雨季土壤氮素损失（以N2O气态氮形式）的主要机制。（5） DNDC模型较好地模拟了玉麦轮作期内生态系统N2O排放速率的变化，基本上捕捉到了几次主要降雨以及施肥引起的N2O排放峰，峰值出现时间与实测值一致，排放速率和排放通量的模拟值与实测结果也较接近；但低估了小麦生长季N2O排放，同时模拟峰值与实际测定值偏差较大。DNDC模型的敏感性试验表明，影响本区系统N2O排放的主要因子包括温度、降雨量、pH值和土壤类型。（6）室内培养试验表明，土壤类型对N2O排放影响显著。高水分条件下砂土由于具有较强的矿化能力以及通透性较好，其N2O排放变化规律与砂粘壤以及粘壤的变化规律完全不一致。在土壤很湿的条件下（110%WFPS），砂土的N2O排放总量排放量显著高于砂粘壤和粘壤，砂土在水分条件很高的情况下具有较强的N2O排放潜力。 |
| 英文摘要 | N2O is an important greenhouse gas (GHS) and can bring about the environment issues because of its greenhouse effect and the depletion of O3. The agro-ecosystem of purple soil is one of the important ecosystems in the subtropical humid area in the South of China. Study on the emission of N2O of the agro-ecosystem can provide with theories and practice to establish countermeasures of mitigation GHS emission.The static chamber and undisturbed soil column-acetylene inhibition technique were used to study the N2O emission of upland agro-ecosystem at the Yanting agro-ecological experiment station of purple soil. Based on the observations of N2O emission from the upland agro-ecosystem, seasonal variation characteristics and the influencing factors were discussed in this paper. The total N2O emissions were also estimated. The main results were summarized as follows:(1) The agro-ecosystem emission showed net emission. The N2O emission kept lower，however it increased after the fertilization, happens of precipitation or fertilized with precipitation. The emission rate ranged from -1.9 to 319.8μgN.m-2.h-1, and the mean value was 46.5μgN.m-2.h-1 during the maize-wheat rotation through 2005-2006.The seasonal variations of N2O flux in the soil were much higher in the summer and very lower in the autumn, winter and spring. The changes of N2O flux was consistent with that of soil temperature at 5cm, but fluctuated hugely with precipitation in the summer. The average N2O flux in the soil was 25.6. g N•hm-2•d-1(2) Soil temperature, soil moisture, inorganic nitrogen contents and the plants were the main influencing factors on N2O emission of agro-ecosystem. There were significantly positive correlations between system N2O emission flux and inorganic nitrogen contents, soil temperature as well as soil moisture. The influencing factors were in sequence of inorganic nitrogen contents＞soil temperature at 5 cm.＞soil water content. The presence of plants enhanced the N2O emission with 44.3% of rate at absentce of plant.(3) Applying nitrogen fertilizer enhanced the N2O emission of agro-ecosystem. Total emission amounted to 4.95, 3.86 and 1.64 kgN•hm-2 in the HN, MN and unfertilized treatments, respectively. Under the conventional treatment (150 kgN•hm-2), the N2O emission factor was 0.74%. Total emission amounted to 3.93, 3.20 and 3.11 kgN•hm-2 in the UN (urea), AN (ammonium sulfate) and NN (potassium nitrate) treatments, respectively. The application of the NN could maintain the economic yields and decreased the N2O emission at the same time, so that it was possible to reduce the negative effects on the environment.(4) There were significantly positive correlations between soil temperature, soil inorganic nitrogen contents and either N2O flux from the soil or dentrification rate. The precipitation was the main driving factor for increasing the N2O emission rate.Total N2O or (N2O+N2) emissions in the rainy season accounted for 91.3% among the emissions during the maize-wheat rotation. The nitrogen loss (in the form of N2O) mainly happened in the rainy season, i.e. in the summer of high temperature and high humidity. The denitrification inspired by precipitation was the main mechanism which resulted in the nitrogen loss in the rainy season.(5)DNDC model simulated the changes of N2O emission of agro-ecosystem measured in the field properly, and caught the N2O flux peak after the fertilization or strong rainfalls. The peaks appeared at the same time, and both the mean of N2O emission rate and total emission were much close to in the simulated and the measured. However, the DNDC model underestimated the N2O emission rate at the non-farming stage during the wheat growing season, and the difference between simulated peaks and measured peaks was very big. The sensitivity tests showed that temperature, rainfall, pH and soil texture were the main factors influencing the N2O emission.（5）The laboratory incubation experiments showed that soil texture could significantly influence the N2O emission. Under the condition of high soil moisture (110%WFPS), the N2O emission characteristics in the sandy soil differed with that in the sandy clay loam and clay loam, owing to the strongly mineralization capacity and good aerated nature of the sandy soil. And the total emission from the sandy soil was significantly higher than that from the sandy clay loam and clay loam, which indicated that sandy soil had the strong N2O emission potential when the soil moisture was very high. |
| 学科主题 | 土壤学 |
| 语种 | 中文 |
| 公开日期 | 2010-10-21 |
| 分类号 | TK1;P73 |
| 源URL | [http://ir.imde.ac.cn/handle/131551/2258]  |
| 专题 | 成都山地灾害与环境研究所_成都山地所知识仓储（2009年以前） |
| 推荐引用方式 GB/T 7714 | 项虹艳. 紫色土旱地农田生态系统N2O排放[D]. 成都. 中国科学院水利部成都山地灾害与环境研究所. 2007. |
入库方式： OAI收割
来源：成都山地灾害与环境研究所
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