【作者】 芮雯奕；

【导师】 张卫建；

【作者基本信息】 南京农业大学 ， 生态学， 2009， 博士

【摘要】 众多研究已经证实,通过陆地生态系统进行土壤固碳,是近期内减缓全球气候变化行之有效的技术途径。农田生态系统土壤环境受人类干扰严重,其土壤碳储量、稳定性和变化趋势受农田管理模式及技术的影响显著。在合理的农田管理模式与技术下,农田土壤可以成为大气碳的一个“汇”,固碳潜力巨大。因此,确定农田土壤的碳汇大小、固碳潜力是制订区域碳排放清单和公平合理的国际环境协议的重要科学依据。2007年12月在印尼巴厘岛召开的联合国气候变化大会上通过了启动2012年后应对气候变化谈判的路线图,世界各国尤其是发达国家和地区纷纷启动一系列大型综合项目,以明确本国的农田土壤碳情况,以在国际环境谈判上赢得主动权。日益增多的研究显示,我国农田尤其是稻田土壤的固碳潜力巨大,可为国民经济发展提供更大的减排空间。但是,至今关于我国农田土壤的固碳效应大小,以及不同管理模式的固碳潜力大小仍很不明确,面临着日益加重的国际固碳减排压力,我国急需进行农田土壤固碳效应及潜力估算,明确农田土壤增碳的调控途径,为即将编写的第二次国家气候变化评估报告和制定农业应对气候变化的相关战略和政策措施提供科学依据和参考。长江三角洲地区(长三角)是我国具有悠久水稻种植历史的区域之一,由于经济快速发展而引起的高CO2排放问题不容忽视。该地区农业生产发展水平较高,耕地质量监测体系建设比较完善。1980年以来,积累了大量农田土壤有机碳长期监测和田间试验研究数据,可为区域农田土壤固碳效应及其潜力研究提供宝贵材料。本研究以长三角农田为研究对象,旨在明确该地区农田土壤固碳技术对土壤固碳的影响及其潜力,探讨农田固碳技术推广应用的激励机制,为我国农田土壤固碳潜力估算和固碳措施选择及配套政策制定提供决策依据和技术参考。本研究以长期监测数据为基础,利用GIS空间分析技术分析20余年来长三角地区农田土壤有机碳含量时间和空间变化特征；通过影响因素分析,探讨自然因素和人为因素对农田土壤有机碳含量的影响和作用；以长期定位试验数据为基础,利用Meta-analysis分析方法研究该地区典型固碳技术的固碳效应；在试验的基础上,基于情景假设,利用RothC模型对典型固碳技术在该地区的固碳潜力进行模拟和探讨；采用农户调研和生产调查的方法,结合农户行为模型分析,明确该地区典型农田固碳技术的应用现状,并对影响农户应用固碳技术行为的因素进行分析；最后,探讨并提出促进该地区农田土壤固碳技术推广和应用的激励机制,主要研究结果如下：自上世纪80年代初以来,长三角地区农田土壤是大气CO2的一个“汇”。2006年农田土壤有机碳含量比上世纪80年代初平均高出19.5个百分点。不同土壤类型有机碳含量均有不同程度的增加,在长三角主要的农田土壤中,以潮土的有机碳含量增幅最大,增加了56.5个百分点,提高到10.8g/kg,水稻土提高了11.0个百分点。农田土壤有机碳含量空间分布差异显著,‘总体而言呈现南部高北部低的趋势,从土壤有机碳含量空间分布的变化看,长三角地区北部农田土壤有机碳含量增加较为明显,呈现出“碳汇”功能趋势。20余年来,长三角农田土壤有机碳含量的空间变异增大,长期水稻种植下的水田利用方式对农田土壤有机碳含量的增加具有积极贡献。农田土壤有机碳含量的半方差函数分析表明,其变程由1980年的274.9km下降为41.5km,块金值占基台值比(C0/(C0+C))由1980年的28.1%增加为49.8%。由随机因素如耕作制度、农业管理等引起的变异在总变异中的比重加大,而气候、土壤类型、成土母质等结构性因素引起的变异变小。影响因素分析表明,在长三角地区,人为因素降低了自然等环境因素对土壤有机碳含量的影响比重,在长三角农田土壤有机碳的管理中具有重要的作用,尤其是长期保持的稻作模式对区域农田土壤碳增加效应突出。秸秆还田和有机肥施用能够显著提高土壤有机碳含量,有机肥施用的平均固碳时间效应要高于秸秆还田。Meta-analysis分析表明,平均7年的试验期内,秸秆还田的固碳效应为0.41t C ha-1 yr-1。而平均14年的试验期内,有机肥施用的固碳效应平均达到0.34 t C ha-1 yr-1,少免耕的固碳效应则不显著。种植制度对农田土壤固碳也存在一定的影响,一年三熟种植条件下,秸秆还田的固碳效应比一年两熟下高出0.35 t ha-1yr-1。相应的有机肥施用下,一年三熟较一年两熟高出0.30 t ha-1 yr-1。固碳技术的固碳时间效应也存在差异,有机肥固碳持续期约为40年而秸秆还田约为20年。全量秸秆还田、1.5tC有机肥+半量秸秆、3tC有机肥施用情景下长三角农田土壤呈现出较高的固碳潜力。利用RothC模型模拟了不同固碳技术情景下长三角地区农田土壤有机碳动态,结果表明,前20年,半量秸秆还田情景下年均固碳速率达到0.37tha-1 yr-1,全量还田则达到0.70t ha-1 yr-1。施用1.5tC有机肥和3tC有机肥情景下平均固碳速率则分别达到0.36t ha-1 yr-1和0.68t ha-1 yr-1。1.5tC有机肥+半量秸秆情景下平均固碳速率为0.69t ha-1 yr-1。固碳潜力的空间分布表明,在半量秸秆还田或1.5tC有机肥施用情景下,长三角农田土壤固碳潜力呈现北部高南部低的总体趋势,在全量秸秆还田、3tC有机肥、以及1.5tC有机肥+半量秸秆情景下,长三角南部地区仍呈现较高的固碳潜力。影响长三角农户固碳技术应用行为的因素呈现显著的地区差异。农户调查结果表明,不同地区农户固碳技术的应用现状存在显著的差异,作物秸秆还田程度、有机肥施用情况差异明显。基于农户固碳技术应用行为的影响因素分析发现,在经济较为发达的地区,对于秸秆还田与否,农户更多的是从秸秆处理的边际成本出发,而相对略欠发达地区,对于秸秆还田与否,农户主要考虑秸秆的使用效益。对于有机肥而言,畜禽养殖与否以及富余劳动力水平是影响有机肥使用的关键因素。因此,在制定促进农田土壤固碳技术的激励政策时,要充分考虑地区农业生产以及农户生产经营的基本特征及其差异,有效促进农田固碳技术最大可能的应用和推广。进行可持续的农户自我发展机制、参与式的技术实施与推广机制、公平有效的政府配套保障机制三个主要方面的激励创新。要进一步提高农户自身对农业废弃物资源的高效循环利用,增强实现农业以及自身可持续发展的意识；创新实施以及推广机制,提高推广实施成效；完善多元化的补偿激励机制、生态效益补偿机制、产业扶持机制以及技术支撑服务机制。通过实施激励机制,促进农户更广泛深入的应用农田土壤固碳技术。并且,应将农田土壤固碳作为一项长期政策纳入到地区农业可持续发展的道路上来。更多还原

【Abstract】 Soil carbon sequestration is a growing research topic that addresses one important aspect of an overall strategy for carbon management to help mitigate the increasing emissions of CO2 in the global climate change research. Carbon in agricultural soils is disturbed by anthropic management acutely, but it still can act as sinks for carbon dioxide and other greenhouse gases through the recommend management practices in soils. To know the effect of soils on carbon sequestration and also its potential contributes to the drawing of justice and reasonal list of carbon mitigation, and international envrioment agreement. The "Bali roadmap" was adopted for a future international agreement on climate change in the United Nations climate change conference in Bali in December,2007. After that, for the initiatives in the climate change negotiate, a lot of integrated programs on soil carbon in agricultural land were started up by nations in the world, especial in developed countries.Increasing evidences demonstrated that the agricultural soils especial paddy field soils had large potential on carbon sequestration. Therefor, it can play an important role in reducing the stress of greenhouse gas mitigation for the country. However, the effect and potential for carbon sequestration in cropland soils still has a lot of uncertainty in China. It is exigent of understanding about the effect and potential of cropland soils for carbon sequestration, and also the measures to realize it. As a developed region which has long history of rice cultivation in China, carbon emission in Yantze delta plain was considerable. Base on abundant material such as long-term field observation dataset, our objectives were to assess the carbon sequestration effect and potential of carbon sequestration thchonogies applied in Yangtze delta plain, and in turn to establish incentive mechanism for carbon sustainable management in this region.Spatial characteristics analysis on soil organic carbon content changes about more than 20 years based on long-term observation data was done using GIS technology, firstly. Secondly, the role of natural factors and anthropic factors on soil organic carbon content were discussed through the factors analysis; Thirdly, carbon sequestration effect of typical carbon sequestration technologies in this study region was analyzed through the Meta-analysis of long-term field experiments data. Then, based on the peasant household survey, and analysis with of peasant household behavior model, the application status of typical carbon sequestration technologies and the affect factors that influence farmer behavior of carbon sequestration technologies application were disscussed, respectively; The cropland soil carbon sequestration potential under the scenarios assumption that the use of typical carbon sequestration technologies in this region was simulated using Rothc model; Finally, to sum up the results of above, the incentive innovation system to promote soil carbon sequestration technologies application in the region was designed. The all results are as follows:The soil organic carbon content of cropland increased in general and was a sink for carbon dioxide since 1980 in Yangtze delta plain. The soil organic carbon content was 19.5% higher in 2006 than that in 1980. The enhancement of soils varied in different soil types and was highest in fluviogenic soil which its soil organic carbon content increased from 6.9g/kg to 10.8g/kg. The soil organic carbon content of paddy soil enhanced 11.0%. The distribution characteristics of soil organic carbon content changed in different periods but showed a trend of higher in the south and lower in the north in general. Soil organic carbon content of cropland in north of Yangtze delta plain increased significantly on average and showed the trend for carbon sink.Geostatistics method, conducted by Geographic Information System (GIS), was applied to analyze the spatial variability of soil organic carbon content in cropland. The results showed that the spatial variability of soil organic carbon content in the recent 20 years increased. The range was 41.5km in 2006 while it was 274.9km in 1980. The ratio of null and sill(Co/(Co+C)) enhanced from 28.1% to 49.8%. It can be concluded that the variability induced by random factors such as farming system or agricultural management increased. In the other hand, the variability induced by structural factors such as climate, soils types or soil parent material. Factors analysis indicated that anthropogenic factors reduced the influence of natural factors on soil organic carbon content, and showed rather important effect on the soil organic carbon management. In particular, the special cropping pattern in paddy field contributed to carbon sink in this region. This dissertation conducted Meta-analysis to compare the carbon sequestration rate and duration of several typical carbon sequestration technologies in Yangtze delta plain.The results showed that there were significant effects of straw returning and animal manure application on carbon sequestration, which could enhance soil organic carbon content by 0.41t ha-1 yr-1 and 0.34t ha-1yr-l on average during the experiment period, respectively. Whereas there was no significant effect of reduced/no tillage on carbon sequestration in the study region. Greater effect of carbon sequestration was obtained in triple cropping systems with double rice seasons than double cropping systems with single rice season. Straw returning and animal manure application could enhance soil organic carbon content at the durations of about 20 and 40 years, respectively.The analysis based on peansant household investigation showed that the status of soil carbon sequestration technology application varied during different sites in this region. Factors analysis conducted by peasant household behavior model showed that the main factors which influenced the application behavior of carbon sequestration technology varied in different areas. In more developing regions, the margin cost of treatment with straw was crucial factor that influenced the behavior of straw returning, whereas the benefit of straw was priority considered in less developing regions. The pivotal factors which influenced the application behavior of animal manure were whether having livestock and poultry farming or not, as well as the level of surplus labor. It can be concluded that when establishing incentive policies for the popularization of carbon sequestration technologies in agricultural soils, full consideration should be given according to the basic characteristics of agricultural production in different areas.Soil organic carbon dynamics in Yangtze delta plain was simulated using RothC model under different scenarios. The results showed that carbon sequestration rate varied. It could reach at 0.37 t ha-1 yr-1 and 0.70t ha-1 yr-1 in the first 20 years on average under the scenarios of half straw returning and whole straw returning, respectively. Under the scenario of organic fertilizer utilization, carbon sequestration rate was 0.36t ha-1 yr-1 and 0.68t ha-1 yr-1 under 1.5t C and 3t C organic fertilizer application, respectively. The carbon sequestration effect was 0.69t ha-1 yr-1 under the compounding utilization of half straw returning and 1.5t C organic fertilizer, which was between the effects under whole straw returning and 3t C organic fertilizer scenarios. The spatial distribution of carbon sequestration potential seemed higher in the north of the region in the scenarios of half straw returning or 1.5tC organic fertilizer application. On the contrary, it was higher in the south of the region under the scenarios of others. In the terms of carbon sequestration cost, whole straw returning, application of 3 tC organic fertilizer and compounding utilization of half straw returning and 1.5t C organic fertilizer had the highest benefit-cost ratio.A comprehensive system of incentive mechanism innovation should be implemented in order to promote carbon sequestration technologies applications in cropland soils in this region. The main three aspects of incentive innovation, those was mechanism of strengthening the farmer’s sustainable self-development, the participatory mechanisms of technical implementation, and fair and effective mechanisms of the government supporting. To improve farmer’s awareness of efficiently recycling of agricultural wastes resources and the achievement of sustainable development of agriculture, as well as their own; To innovate and promote the implementation mechanisms, and thus to conduct the implementation effectively and efficiently; To improve a wide range of compensation incentives, eco-efficiency of the compensation mechanism, industry support mechanisms, as well as technical support service mechanisms; To inspire farmers for the application of agricultural soil carbon sequestration technologies more extensively, and also to take soil carbon sequestration as a long-term agricultural policy for sustainable development of agriculture.更多还原