不同粒级土壤团聚体添加秸秆对温室气体排放的影响

发布时间：2018-03-11 01:37

本文选题：温室气体　切入点：秸秆还田　出处：《华中农业大学》2017年硕士论文　论文类型：学位论文

【摘要】：农业生态系统是重要的温室气体排放源。秸秆还田是重要的农业措施,能够有效避免秸秆焚烧造成的营养物质的浪费和对环境的污染,同时秸秆还田会向土壤提供丰富的养分元素,刺激土壤微生物的活性,进而影响土壤有机质的矿化。土壤团聚体对有机质有保护作用。不同粒级团聚体的性质不同,对有机质的保护也不尽相同。因此不同粒级团聚体在添加秸秆后有机质的矿化作用可能不同,这会进一步影响土壤C、N循环,从而影响土壤温室气体的产生与排放。秸秆还田及不同粒级团聚体对温室气体排放特征的影响及机制目前尚不清楚。为了探究砂壤土不同粒级团聚体添加秸秆对温室气体排放的影响,本研究选取荆州潮土为研究对象,设计不同粒级团聚体添加秸秆的室内培养试验。主要的研究结果如下:(1)秸秆添加显著增加了CO_2和N_2O的排放通量和累积排放量(0.25-1 mm粒级团聚体的N_2O气体排放除外),对CH_4排放无显著影响。(2)未添加秸秆各处理的CO_2排放通量无显著差异。添加秸秆后四个粒级团聚体CO_2平均排放通量和累积排放量由大到小依次为0.25 mm、1-2 mm、0.25-1 mm和全土。四个粒级中,0.25 mm粒级团聚体添加秸秆后CO_2累积排放量增加最多,约为未添加秸秆处理的11倍;0.25-1 mm粒级团聚体添加秸秆后CO_2累积排放量增加最少,约为未添加秸秆处理的7倍。未添加秸秆处理中,N_2O平均排放通量由大到小依次为0.25-1 mm、1-2 mm、全土、0.25 mm粒级,N_2O累积排放量由大到小依次为1-2 mm、0.25-1 mm、全土、0.25 mm粒级。添加秸秆后,四个粒级N_2O平均排放通量和累积排放量由大到小依次为1-2 mm、全土、0.25 mm、0.25-1 mm粒级。其中,0.25-1 mm粒级团聚体在添加秸秆后N_2O排放通量和累积排放量都有明显减小,其他三个粒级的N_2O排放在添加秸秆后都有增加。不同粒级团聚体对CH_4排放无显著影响。(3)氧化酶活性、水解酶活性、可溶性有机碳(DOC)、矿质氮等性质在不同粒级团聚体之间存在差异,添加秸秆后的变化各不相同,对温室气体排放的影响也不同。在所有的土壤性质中,纤维二糖水解酶(CB)、亮氨酸氨基肽酶(LAP)、β-N-乙酰葡萄氨糖苷酶(NAG)、酚氧化物酶(pox)、DOC和NO_3~--N是对CH_4、CO_2和N_2O这3种温室气体排放影响最大的土壤性质集合,能够解释80.3%的温室气体排放,DOC和NO_3~--N可以解释32.3%的温室气体排放,CB、LAP、NAG和pox能够解释53.8%的温室气体排放。其中,LAP和DOC对CH_4、CO_2和N_2O这3种温室气体的排放都有正的贡献。
[Abstract]:Agroecosystem is an important source of greenhouse gas emissions, and straw return is an important agricultural measure, which can effectively avoid the waste of nutrients and environmental pollution caused by straw burning. At the same time, returning straw to the field will provide rich nutrients to the soil, stimulate the activity of soil microorganisms, and then affect the mineralization of soil organic matter. Soil aggregates have protective effect on organic matter. The properties of different aggregates are different. Therefore, the mineralization of organic matter may be different with the addition of straw, which will further affect the cycling of Con N in soil. It is not clear that the effect and mechanism of straw returning to the field and different aggregates on greenhouse gas emission. In order to explore the effects of straw on greenhouse gas emission in sandy loam soil, the effect of straw on greenhouse gas emission is not clear. The impact of greenhouse gas emissions, In this study, Jingzhou tidal soil was chosen as the research object. The main results were as follows: (1) Straw addition significantly increased the emission fluxes of CO_2 and N2O and the cumulative emission of N2O from 0.25-1 mm aggregate. There was no significant difference in CO_2 emission fluxes between different treatments without straw addition. The average emission fluxes and cumulative emissions of CO_2 of the four aggregates were 0.25 mm / 1-2 mm ~ (-1) mm and 0.25 ~ (-1) mm, respectively. The accumulative CO_2 emission of 0.25mm grain aggregate increased the most when straw was added into the four grains. The accumulative CO_2 emission increased the least after adding straw to 0.25-1 mm agglomerate, which was about 11 times as much as that of untreated straw. The average emission flux of N2O in the unadded straw treatment was 0.25 ~ (-1) mm ~ (-1) mm ~ (-1) mm ~ (-2) mm, and the cumulative emission of N _ 2O was 1 ~ 2 mm ~ (0.25 mm) and 0.25 mm ~ (-1) mm, respectively. The average emission fluxes and accumulative emissions of N2O were 1-2 mm and 0.25 mm ~ 0.25 mm respectively, and the N _ 2O emission fluxes and accumulative emissions of 0.25 ~ (-1) mm aggregate decreased obviously after adding straw. The emission of N2O from the other three grains increased after adding straw. Different aggregates had no significant effect on the emission of CH_4. The properties of soluble organic carbon (DOC), mineral nitrogen and so on are different among different aggregates, the changes of straw are different, and the effects on greenhouse gas emissions are also different. In all soil properties, Cellular-disaccharide hydrolase, leucine aminopeptidase, 尾 -N-acetyl-glucosaminosidase, phenol oxide enzyme poxosidase DOC and NO_3~--N are the sets of soil properties that have the greatest effect on the emission of CH4CO2 and N2O3 greenhouse gases. NO_3~--N and DOC can explain the greenhouse gas emission of 32.3% and pox can explain 53.8% greenhouse gas emission, among them, both LAP and DOC have positive contribution to the emission of Ch _ 4O _ 2 and N _ 2O.
【学位授予单位】：华中农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X71;S141.4

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