Knowledge Resource Center for Ecological Environment in Arid Area
| 施氮和轮作对黄土高原旱区土壤温室气体排放的影响 | |
| 其他题名 | Effects of Nitrogen Fertilization and Rotation on Greenhouse Gases Emissions on Arid-highland of the Loess Plateau |
| 姜继韶 | |
| 出版年 | 2015 |
| 学位类型 | 博士 |
| 导师 | 郭胜利 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 农田生态系统是温室气体（N2O、CH4和CO2）重要的排放源，其排放量分别占全球N2O、CH4和CO2总排放的60%、50% 和10%。全球干旱和半干旱地区农田面积占全球农田总面积的80%，贡献了全球粮食总产量的60%。我国旱地约占国土总面积的70%，干旱半干旱耕地占总耕地面积的43%，主要分布在西北地区。我国西北黄土高原为典型的雨养农业区，面积60万km2，其中农田面积14.58万km2，70%属于雨养农业。施氮和轮作是本地区重要的农田管理措施，但二者对土壤温室气体排放的影响尚不完全清楚。 本研究以黄土高原主要的粮食作物春玉米和冬小麦为主要研究对象。于2013–2014年在中国科学院长武黄土高原农业生态试验站春玉米大田设置5个不同的氮肥处理：对照处理（不施用氮肥（N0））；传统施氮处理（Con）；优化施氮处理（Opt）；优化施氮添加硝化抑制剂处理（Opt+DCD）；优化施氮使用缓控肥处理（Opt+SR），研究不同氮肥管理措施对温室气体（CO2、N2O和CH4）排放/吸收以及氮肥利用效率的影响。同时利用生态试验站的长期定位试验，选取小麦-小麦-糜子-豌豆轮作系统作为研究对象，于2010年7月到2013年6月研究不同作物轮作次序对土壤呼吸和温度敏感性的影响。主要获得以下结论： （1）施氮显著提高了春玉米生长季土壤的累积呼吸量（P<0.05），但是四个施氮处理之间土壤呼吸无显著差异。与对照相比，施氮处理累积呼吸量2013年提高了35%，2014年提高了54%，但施氮显著降低了土壤呼吸温度敏感性（Q10）（P<0.05），施氮处理的Q10较对照2013年降低了27%，2014年降低了17%。施氮显著提高了春玉米地上部生物量和根系生物量（P<0.05）。施氮处理根系生物量较对照处理2013年提高了0.32倍，2014年提高了1.23倍。施氮对土壤温度和水分无显著影响，根系生物量是施氮条件下导致土壤呼吸差异的重要生物因素。 （2）三个优化施氮处理显著减少了N2O的年累积排放量，农田温室效应（Global warming potential，GWP），以及总温室气体排放强度（Greenhouse gas intensity，GHGI）。与传统的N2O年累积排放量（1.9 kg N2O-N ha–1）相比，Opt+DCD 处理N2O累积排放量下降的最多（48%），其次为Opt+SR处理（38%），下降最少的为Opt处理（28%）。施氮和大于40 mm降雨事件是N2O排放的主要控制因素。其中施氮后10天内的排放量占全年排放量的26%，并与施氮后10天内的硝态氮平均含量呈显著的线性正相关关系。2013年，由降雨诱导的N2O排放量占全年的6.4%，2014年为12.5%。N2O排放因子变化范围为0.12%?0.55%。黄土高原雨养区农田土壤是大气CH4的弱吸收汇，不同施氮模式对大气CH4的吸收没有显著的影响。Con，Opt，Opt+DCD和Opt+SR 四个处理的GWP分别为788，536，344，441 kg CO2-eq ha?1。与传统施氮相比，Opt, Opt+DCD和Opt+SR处理的GHGI分别降低了29%，54%和42%。 （3）三种优化施氮模式虽然减少了20%的施氮量，但并没有减少春玉米的产量，各施氮处理的产量在2013年为9.61?10.46 Mg ha?1，2014年为11.41-12.23 Mg ha?1。5种施氮模式土壤剖面0?100 cm和100?200 cm的硝态氮残留量分别介于：33.5?148.9、24.8?92.8 N kg ha?1之间。与Con（225.9 N kg ha?1）相比，Opt、Opt+DCD和Opt+SR土壤剖面0?200 cm的硝态氮残留量降幅分别为47.2%、48.5%和45.5%。三种优化施氮处理之间硝态氮残留差异不显著（P>0.05）。优化施氮处理氮肥农学效率和氮肥偏生产力显著大于传统施氮处理。 （4）在小麦-小麦-糜子-豌豆轮作系统中，虽然冬小麦生长阶段土壤呼吸（1.63 μmol m?2s?1）显著小于糜子（2.40 μmol m?2s?1）和豌豆阶段（2.21 μmol m?2s?1），但是冬小麦生长阶段的土壤呼吸温度敏感性（2.76）却显著高于糜子（1.85）和豌豆阶段（1.47）。轮作系统中Q10随着作物生长季的平均温度的升高呈现指数下降的趋势，当温度超过15 °C时，Q10趋于稳定（1.8）。此外Q10随着作物生长季的平均水分的增加而增加，但当土壤水分大于14.7%时，Q10却出现下降的趋势。在全球变暖的情况下，模拟农业生态系统土壤呼吸时（特别是耐寒作物）必须考虑作物生长阶段的土壤温度和水分。 |
| 英文摘要 | Agricultural ecosystem is an important emitter of N2O, CH4 and CO2, accounting for 60%, 50% and 10% of the global N2O, CH4 and CO2 emissions, respectively. The rainfed farmland area accounts for 80% of the total farmland area. The Loess Plateau of northwest China covers more than 600,000 km2 , consists of typical semiarid and arid areas with rainfed farming, and provides about 40% of the local food needs. Since 1980s, nitrogen fertilization has been the main way to increase crop yields and soil nutrients. Nitrogen managements and crop rotation is two important management measures in the rain-fed farmland on the Loess Plateau. However, the effects of Nitrogen managements and crop rotation on greenhouse gas is not yet clear. Spring maize and winter wheat, with their regionally representative, were chosen for this study. Five treatments were considered in the rain-fed spring maize cropland, including control (CK), conventional N fertilization rate (Con), optimal N fertilization rate (Opt), optimal N fertilization rate plus nitrification inhibitor (Opt+DCD), and optimal N fertilization rate with slow release urea (Opt+SR), to determine the effect of optimized nitrogen (N) fertilization practices on greenhouse gas emissions and grain yields in the Loess Plateau, China. Furthermore, one three-year rotation system from the long-term field experiment was chosen for its regionally representative crop types, i.e., winter wheat, millet, pea, to explore the effect of each cropping phase on the soil respiration and Q10 values. The results were summarized as follows: (1) The cumulative soil CO2 emissions were 35% for 2013, 54% for 2014 greater in N treatment than in CK treatment. Though nitrogen fertilization significantly increased the cumulative soil CO2 emissions (P<0.05), it did decrease evidently the temperature sensitivity of soil respiration (P<0.05). The Q10 values in N treatment were decreased by 27% and 17% compared with CK treatment in 2013 and 2014, respectively. Nitrogen fertilization increased significantly aboveground biomass and root biomass (P<0.05). Root biomass in N treatment was 32% and 123% greater than that in CK treatment of 2013 and 2014, respectively. Nitrogen fertilization had no marked influence on soil temperature or moisture. Root biomass was critical biotical factor for variation of soil respiration under nitrogen fertilization. (2) The application of Opt, Opt+DCD, and Opt+SR treatments resulted in a significant decrease in annual cumulative N2O emission, net greenhouse gas (GWP) emission, and net greenhouse gas intensity (GWP I), but without significant decrease in grain yields. The greatest decrease of annual N2O emissions (48%) occurred in Opt+DCD treatment, followed by Opt+SR (38%) and Opt (28%). N fertilization and heavy rainfall event (>40 mm) were the main factors controlling N2O emissions. The cumulative N2O emissions within 10 days after N fertilization accounted for 26% of annual N2O emissions, and were positively associated with mean soil NO3-N content (P<0.05). The cumulative N2O emissions induced by heavy rainfall accounted for 6.4% of total annual N2O emissions in 2013 and 12.5% in 2014, respectively. The urea-derived annual mean N2O emission factor ranged from 0.12%?0.55%. The soil acted as a small sink for atmospheric CH4. There was no significant difference in CH4 uptake among the N fertilization practices. Compared with Con treatment, GWP was decreased by 31.2%, 52.5% and 45.0% in Opt, Opt+DCD, Opt+SR treatments in 2013, and by 32.8%, 60.5% and 43.0 in 2014 (P<0.05); and GWPI was decreased by 32.1%, 48.7% and 43.6% in 2013, and 25.4%, 58.7% and 39.7% in 2014, respectively. In conclusion, nitrification inhibitor was the most effective fertilization practice in the rain-fed regions of Loess Plateau. (3) The three optimized N treatments, which saved 20% of N fertilization against the current conventional agricultural N fertilization rate, did not significantly decrease g |
| 中文关键词 | 黄土高原 ; 施氮 ; 轮作 ; CO2 ; N2O ; 土壤呼吸温度敏感性 |
| 英文关键词 | Loess Plateau nitrogen fertilization rotation CO2 N2O Q10 |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 土壤学 |
| 来源机构 | 中国科学院水利部水土保持研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287581 |
| 推荐引用方式 GB/T 7714 | 姜继韶. 施氮和轮作对黄土高原旱区土壤温室气体排放的影响[D]. 中国科学院大学,2015. |
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