基于Meta-analysis对我国保护性耕作农田土壤固碳减排效应及其潜力的研究

发布时间：2018-05-10 17:42

本文选题：保护性耕作 + Meta分析　；参考：《中国农业大学》2017年博士论文

【摘要】：保护性耕作具有保土、保水、培肥、省工、省时等优点,在全球范围内得到了广泛的应用和推广。因其生态服务功能,保护性耕作被认为是缓解气候变化的一项重要的策略,但不同研究中保护性耕作对土壤固碳、温室气体排放和作物产量影响的结果仍存在较大差异。因此,在大尺度上探明保护性耕作的土壤固碳减排及作物产量效应,对于我国保护性耕作的发展具有重要的意义。本研究基于我国2016年以前公开发表的200多篇关于保护性耕作措施下土壤碳、温室气体排放、作物产量变化的文献,应用Meta分析系统评价了我国不同耕作措施(翻耕秸秆不还田,PT0;翻耕秸秆还田PTR;免耕秸秆不还田,NT0;免耕秸秆还田,NTR)下土壤有机碳含量及储量、温室气体排放(CH4和N2O)、作物产量的变化及其影响因素,并估算了我国NTR的固碳潜力以及对粮食生产的影响,取得了以下主要结果:(1)与PT0相比,NT0和NTR的全土层土壤有机碳含量分别显著提高了 5.5%和8.2%,全土层土壤有机碳储量分别显著提高了 4.0%和8.1%(P0.05);而与PTR相比,NTR有机碳含量及储量分别显著提高了 4.7%和6.8%(P0.05)。秸秆还田增强了免耕的固碳效果,但NTR提高土壤有机碳含量及储量多限于0~(-1)0 cm 土层。进一步对固碳效应影响因素分析的结果表明,较高的土壤pH值、避免过高的土壤水分和温度、以及长期连续应用NTR,可以增强NTR固碳效果。(2)与PT0相比,NT0显著降低了 30.0%在稻田中CH4的排放;NTR分别显著增加了 82.1%、25.5%和20.8%在稻田、酸性土壤及其应用初期(5年内)中N20的排放(P0.05)。采用NTR导致N2O排放增加,在一定程度上抵消了因CH4减排对缓解气候变化的贡献。在旱地条件下,与PT0相比,NT0表现出一定促进CH4吸收效果;NTR表现出减少N2O排放趋势。对温室气体排放影响因素分析的结果表明,在NT0和NTR下,合理施肥、避免过高的土壤湿度和延长应用年限能够增强其减排效果。(3)一般情况下,NT0会导致作物产量降低,但如配以秸秆还田,NTR则具有一定的增产效应。研究结果表明,与PT0相比,NTR能显著增产4.6%(P0.05),特别是在连续应用免耕10年以上,产量显著提高21.3%(P0.05)。土壤质量(有机碳含量、收获期土壤储水量、有效氮、有效钾)的提高是NTR下作物产量增加的主要原因。同时,在水稻、小麦等作物上、相对温暖的区域、干旱或较湿润的区域、弱碱性土壤、中等肥力土壤及合理施氮等条件下使用NTR,增产效果更为明显。(4)对全国保护性耕作固碳速率与潜力分析的结果表明,与PT0相比,NTR全国平均固碳速率为0.52 Mg C hm2 yr~(-1)。在当前应用规模下,NTR的土壤有机碳全国固碳量为5.73 Tg C yr~(-1),最大固碳潜力为45.10 Tg C yr~(-1);综合其温室气体的减排效应,NTR总固碳量可以增加到5.91 Tg Cyr~(-1)。全面实施NTR条件下,我国农田土壤总固碳潜力为48.93 TgCyr~(-1)同时,我国主要粮食作物(小麦、水稻和玉米)的总产量可以提高0.3～4.3%。
[Abstract]:Conservation tillage has been widely used and popularized in the world because of its advantages of soil conservation, water conservation, fertilizer cultivation, labor saving and time saving. Because of its ecological service function, conservation tillage is considered as an important strategy to mitigate climate change. However, the effects of conservation tillage on soil carbon sequestration, greenhouse gas emissions and crop yield are still quite different in different studies. Therefore, it is of great significance for the development of conservation tillage in China to investigate the soil carbon sequestration emission reduction and crop yield effect of conservation tillage on a large scale. This study is based on more than 200 articles published in China before 2016 on soil carbon, greenhouse gas emissions, crop yield changes under conservation tillage practices. Meta analysis system was used to evaluate the soil organic carbon content and reserves under different tillage measures (tillage straw not returning to field PT0, tillage straw returning field PTR, no-tillage straw returning to field NT0, no-tillage straw returning to field), and soil organic carbon content and reserves. Carbon sequestration potential of NTR in China and its effect on grain production were estimated. The main results are as follows: (1) compared with PT0, the soil organic carbon content of NT0 and NTR increased by 5.5% and 8.2%, respectively, and the soil organic carbon storage increased significantly by 4.0% and 8.1%, respectively, and compared with PTR, the organic carbon content of the whole soil layer increased significantly by 5.0% and 8.2%, respectively, and compared with that of PTR, the organic carbon content of the whole soil layer was increased significantly by 4.0% and 8.1%, respectively. The volume and reserves increased by 4.7% and 6.8% respectively. Straw returning to the field enhanced the carbon sequestration effect of no-tillage, but the increase of soil organic carbon content and storage by NTR was limited to 0 ~ (10) ~ (-1) cm soil layer. The results of further analysis on the influencing factors of carbon sequestration effect show that higher soil pH value can avoid excessive soil moisture and temperature. Compared with PT0, the carbon sequestration effect of NTR was significantly decreased by 30.0%, and the emission of CH4 increased significantly by 82.1% and 20.8% in paddy field, respectively, and in acidic soil and its initial application (within 5 years), the emission of N20 was increased significantly by P0.055.The results showed that the carbon sequestration effect of NTR was increased by 30.0% in comparison with that of PT0, and that in rice field was significantly increased by 82.1% and 20.8%, respectively. The introduction of NTR resulted in an increase in N2O emissions, which to some extent offset the contribution of CH4 emission reductions to climate change mitigation. Under dry land conditions, compared with PT0, NT0 can promote the absorption of CH4 and reduce N2O emission. The results of analysis on the factors affecting greenhouse gas emissions showed that under NT0 and NTR, reasonable fertilization, avoiding excessive soil moisture and prolonging the application years could enhance the emission reduction effect. However, if the straw was returned to the field with NTR, it had a certain effect of increasing yield. The results showed that compared with PT0, it could significantly increase the yield of P0.05N, especially in the continuous application of no-tillage for more than 10 years. The improvement of soil quality (organic carbon content, soil water storage, available nitrogen, available potassium) is the main reason for the increase of crop yield under NTR. At the same time, on crops such as rice, wheat, relatively warm areas, arid or humid areas, weak alkaline soils, The results showed that the average carbon sequestration rate of PT0 was 0.52 mg C hm2 YR-1 compared with that of PT0. Under the current application scale, the national carbon sequestration of soil organic carbon of NTR is 5.73 Tg C yrr ~ (-1), and the maximum carbon sequestration potential is 45.10 Tg C ~ (YR) ~ (-1), and the total carbon sequestration of NTR can be increased to 5.91 TG Cyr-1 by synthesizing its greenhouse gas emission reduction effect. Under the condition of full implementation of NTR, the total carbon sequestration potential of farmland soil in China was 48.93 TgCyrc-1). At the same time, the total yield of main grain crops (wheat, rice and maize) could be increased by 0.3% and 4.3%.
【学位授予单位】：中国农业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S154.1

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