【作者】 孙文娟；

【导师】 黄耀；

【作者基本信息】 南京农业大学 ， 土壤学， 2006， 博士

【摘要】 为缓解温室气体引起的气候变暖，对减排增汇技术的研究已成为目前全球变化领域新的热点。对农业生态系统而言，提高土壤碳的固定与收集，不仅可降低环境压力，而且对粮食安全亦具极其重要的意义。清楚认识和客观评价我国农业土壤有机碳贮量的演变趋势及其成因，对我国制订合理的减排增汇措施无疑是至关重要的。 氮肥施用被认为是提高作物生物量和产量的最为有效的途径，而目前我国多数地区氮肥的过量施用不仅导致其利用率下降，还带来一系列的环境问题。理解氮素营养与农业植被呼吸作用的关系，并在此基础上评价氮肥投入对作物固碳效益的影响，将有助于全球变化背景下农业生态系统碳氮耦合研究的开展。 本研究目的是：初步阐明我国1980～2000年农田土壤有机碳贮量的变化，为制定耕地土壤管理政策、促进土壤碳固持和减少碳损失提供依据；以华东地区为例，初步阐明我国区域农田土壤氮贮量的变化，及与有机碳变化的关系；阐明氮素营养与作物呼吸作用的关系；探讨氮肥施用对作物固碳效益的影响。 本研究采用文献调研和实验研究的方法。通过对中国期刊网和维普科技期刊网收录文献的检索，获得全国1993年以来关于区域农田土壤有机碳变化测定结果及演变趋势的文献，运用数据整合分析方法（meta-analysis）探讨我国农田土壤碳贮量和区域农田氮贮量变化。试验研究则采用盆栽试验和大田试验相结合的方法，定量研究氮素营养对作物呼吸作用和氮肥施用对作物固碳的影响。盆栽试验设定常规、不同施氮水平、不同种植密度、不同播种期处理。大田试验处理为不同施氮水平。本研究气样的采集和分析采用静态暗箱-气相色谱法。作物呼吸系数（R_a，单位生物量呼吸作用的CO₂排放量）通过逐步收割法获得。 研究结果显示：1980～2000年间占我国农田面积53％～59％的土壤有机碳呈明显增加趋势。华东和华北地区增加最为明显，东北地区呈总体下降趋势。20年间全国农田土壤有机碳贮量增加了408～546Tg，其中表土（20cm）增加量为311～401Tg。水稻土和潮土有机碳增加明显，黑土下降显著。20年来，我国农田水稻土有机碳增加230～297Tg，潮土增加68～73Tg，黑土减少62～67Tg。 1980～2000年华东区（不包括山东省）土壤全氮贮量增加了12.7～27.8Tg，其更多还原

【Abstract】 The observed and projected increase in emission of greenhouse gases, with attendant effects on global warming, have raised interests in identifying mitigation options. Terrestrial C sequestration involves capture of atmospheric C through photosynthesis and storage in biota and soil. As a significant contributor to the regional carbon budgets, agro-ecosystem plays an important role in terrestrial ecosystem carbon cycling. In comparison with natural ecosystems of forest and grassland, agro-ecosystem is much complex due to human being activities, particularly the application of synthetic N fertilizer which was considered as an effective practice to promote crop production, also augments C inputs to the soil and hence, often increases soil organic carbon (SOC).It has been well recognized that the addition of N fertilizer promotes crop tissue N and the tissue N changes as crop growing. Numerous studies have demonstrated that plant photosynthetic capacity correlated strongly with leaf N concentration and a linear relationship existed between plant respiration and tissue N for forest. However, crop respiration regulated by tissue N is still far from being understood. Though previous studies indicated that the augmentative effect of fertilization on crop productivity would decrease as the fertilizer application exceeds a certain rate, all these results came from the evaluation of fertilizer application on photosynthesis in physiological views or on production benefit in economic views. Moreover, the influence of N application on crop respiration and a synthetic assessment on crop carbon sequestration with different rates of fertilizer N application is not very clear.The objectives of this study are, 1) to evaluate the changes in SOC at national scale over the last two decades by pooling and analyzing a mass of data sets from published papers towards providing a scientific basis in making soil management policy, enhancing soil C sequestration and reducing soil C loss; 2) to address the changes of total nitrogen更多还原