【作者】 张萍；

【导师】 沈新平； 沈明星；

【作者基本信息】 扬州大学 ， 生态学， 2012， 硕士

【摘要】 农田温室气体排放与农田碳汇是现代农业生态系统过程研究的两个核心,稻麦两熟制是长江中下游地区主体的农田种植方式,因此探索稻麦两熟制下不同土壤管理方式对农田温室气体排放及碳循环的机理,明确其效应,对高产粮食产区农田生态系统的合理管理具有理论与实践意义。本文利用苏州农业科学院长期定位肥料试验田及不同耕作深度试验田为研究背景,通过研究长期施单独和结合有机肥施用不同配合情况的三要素(N、P、K)化肥以及土壤不同耕作深度下,稻麦轮作农田CO2、CH4和N20排放特征以及土壤固碳效应,并在大田试验的基础上,建立农田管理数据库,利用DNDC模型对观测数据进行模拟,主要研究结果如下：1.不同肥料配比长期定位施肥能显著影响农田温室气体排放及固碳效应。有机肥施用后既明显增加农田CO2、CH4和N20的排放,排放量分别增加42.9%、59.1%和14.9%；也显著提高了表层土壤有机碳密度15.4%。NP肥和NPK肥长期施用能明显提高CO2排放,不同配施N、P、K肥对CH4排放无影响,而在有机肥配施下有N肥和NP肥处理N20排量明显提高。施有机肥能增加表层土壤的有机碳密度及固碳量,而与NPK肥无关,但有机肥的增施后全球增温潜势(GWP)也明显大于仅施化肥处理,仅从温室气体减排和碳汇协同提高的角度考虑,不施有机肥为太湖地区农田合理施肥制度。2.不同耕作深度影响农田温室气体排放及固碳效应。麦季深耕导致麦田CO2排放显著最高,且后季稻田CH4排放显著降低；麦季9cm耕作深度,显著提高农田N20的周年排放量。麦季适当深耕对中上层土壤有较好的固碳效应。稻季不同耕作深度对农田碳排与碳汇也有不同影响。从轮作周期来看,稻麦周年不同耕作组合对农田CO2、CH4和N20排放的影响有较大差异；从不同耕作深度耕作层土壤有机碳密度及固碳效应来看,麦季4cm+稻季17-18cm耕作深度土壤固碳量最大,达到13182g,稻麦两季均为9cm耕作深度最不利于耕作层土壤固碳效应。总体来看,无论在短时间尺度,还是长时间尺度,稻麦两季均为17-18cm耕作深度的GWP最高；稻麦两季浅耕,特别是稻季浅耕,有利于温室气体的减排以及对GWP的控制。从温室气体减排和碳汇协同提高的角度考虑,麦季4cm(灭茬免耕)+稻季17-18cm(耕翻水旋)模式为太湖地区农田合理土壤耕作制。3.DNDC模型能应用于太湖地区稻田CO2、CH4和N20排放的研究,但对麦季CH4和N20排放通量的模拟还需加强和改进。更多还原

【Abstract】 Cropland and carbon sink where greenhouse gas emitted from are two cores on modern agricultural ecological system study. Rice-wheat rotation is a main planting pattern in the middle-lower Yangtze area. Which together make study on the mechanism and effect of greenhouse gas emitted from cropland and carbon cycle affected by soil management has the theory and practice significances for reasonable management of farmland ecosystem in high yield grain areas. This paper took long-term fertilization test and different tillage depths test in Su Zhou academy of agricultural science as research background. It was used to study not only the characteristics of CO2, CH4and N2O emitted from rice-wheat rotation field but also the effects of carbon fixation of soil under the conditions of long-term different combined application of fertilizer (N, P, K), manure and different tillage depths. And on the basis of the field experiment, we built cropland management database and used DNDC model to simulate the observed data. The following items are the main conclusion of this paper:1. Different fertilizers combined with application of long-term fertilization has a significant impact on greenhouse gas emissions and carbon fixation effects. Compared with single fertilizer, the application combined with organic manure fertilizer can increase CO2, CH4and N2O emissions, which increased42.9%,59.1%and14.9%respectively. At the same time, the results show organic carbon density of the surface soil can significantly increase by15.4%. Long-term application of NP and NPK may improve CO2emissions; while the combined application of N, P and K has no effect on CH4emissions, the combined application of manure and N, NP can obviously increase N2O emissions. Organic manure fertilizer will increase organic carbon density on the surface soil and solid carbon fixation, but it has nothing to do with the combined application of N, P and K. And its GWP is obviously higher than single fertilizer’s. Considered from the greenhouse gas emissions reduction and carbon sinks improvent, not organic fertilizer for farmland is the rational fertilization system of Taihu Lake region.2. Different tillage depths can also affect greenhouse gas emissions and carbon fixation effects. Deep tillage in wheat season will lead to the highest CO2emissions and reduce CH4emissions of the next paddy field; and9cm tillage depth of wheat season may improve N2O annual emissions. Appropriate deep tillage in wheat season is good for the effects of carbon fixation in middle and upper soil layer. And different tillage depths in rice season have different influences to greenhouse gas emissions and carbon fixation effects. During the whole rotation cycle, different tillage depths of rice and wheat seasons have different CO2, CH4and N2O emissions.4cm tillage depth of wheat season and17-18cm tillage depth of rice season have the highest carbon fixation in arable soil layers, which reaches13182g.9cm tillage depth in both rice and wheat season is not good for the effects of carbon fixation. Overall, in the short or long time scale,17-18cm tillage depth of rice and wheat seasons has the highest GWP. Shallow tillage in the whole rotation cycle, especially in the rice season, has good influences on greenhouse gas emissions reduction and greenhouse effect mitigation. Considered from the greenhouse gas emissions reduction and carbon sinks improvent,4cm tillage depth of wheat season and17-18cm tillage depth of rice season is the rational tillage system of Taihu Lake region.3. DNDC model can be applied to the research of CO2, CH4and N2O emitted from rice field in Tai Lake region, but it is need to strengthen and improve the simulation of CH4and N2O emitted from wheat field.更多还原