古水稻土有机质演变规律及其腐殖质组成特征

发布时间：2019-04-13 09:21

【摘要】：土壤有机质是全球碳循环的重要组成部分,古水稻土经过了长期的封闭,土壤有机质及其腐殖质的组成是向复杂还是简单方向演变,其变化过程与机理怎样,目前还不是很清楚。为此,本项目以澧阳平原杉龙岗水稻土遗址剖面为研究对象,研究了古水稻土土壤有机质的演变规律及其腐殖质组成特征,分析了不同粒径团聚体古水稻土中有机质组成和分布特征,探讨了古水稻土红外光谱特征,以期为土壤碳释放与固定、碳的生物地球化学循环提供依据。主要研究结果如下：(1)杉龙岗水稻遗址剖面有机质含量变化范围为8.41-24.00 g/kg,其中,古水稻土层含量范围为9.5-12.3g/kg。从剖面空间分布上看,古水稻土有机质的变化趋势表现为耕作层犁底层潴育层母质层。同现代耕作水稻土相比,有机质含量较低、变化幅度较小。(2)古水稻土不同粒径团聚体的有机质含量表现为(5-2mm) (2-lmm) (1-0.25mm) (0.25mm)。从剖面空间分布上看,古水稻土不同粒径团聚体有机质的表现为,PA剖面耕作层犁底层,PB剖面犁底层耕作层潴育层,PC剖面潴育层耕作层犁底层母质层。同现代耕作水稻土相比,其有机质含量均大于现代耕作水稻土的犁底层、潴育层以及母质层。(3)古水稻土腐殖质各组分平均含量为胡敏素(3.66g/kg)胡敏酸(1.92g/kg)富里酸(0.95g/kg)。从剖面空间分布上看：古水稻土各形态腐殖质含量变化幅度较小并逐步趋于稳定。其中,胡敏酸含量随着土层深度增加呈逐渐增加的趋势；剖面PA、PB的富里酸含量呈下降趋势,PC呈上升趋势；剖面PA的胡敏素含量呈先下降后上升的趋势,剖面PB呈“下降—上升—下降”趋势,剖面PC则呈明显下降趋势。古水稻土的胡富比随着土层深度增加呈现上升趋势。同现代耕作水稻土相比,胡富比较低。(4)古水稻土结合态腐殖质平均含量为：松结合态(12.75g/kg)紧结合态(4.07g/kg)稳结合态(0.42g/kg),其相对含量最大的为松结合态(58.36%),其次是紧结合态(52.52%)；再次是稳结合态(9.82%)。从剖面空间分布上看：古水稻土各结合态腐殖质含量变化幅度较大,其中,剖面PA、PB松结合态含量呈下降趋势、稳结合态呈上升趋势、紧结合态呈下降。(5)古水稻土官能基团主要集中在卤素化合物和无机化合物。有机质对古水稻土官能团影响很大,其中,古水稻土中波数为1882cm-1,在去有机质后吸收峰弱化。古水稻土中波数为1631-470 cm-1段逐渐形成苯环、烯烃化合物增多且芳构化程度增加,卤素和无机化合物的结合力增强。由一阶倒数知,古水稻土与现代耕作水稻土相差不大,但在去有机质后之后,FD值表现不同：去有机质前去有机质后,且各FD峰值均有下降趋势。
[Abstract]:Soil organic matter is an important part of the global carbon cycle. After a long period of closure, the composition of soil organic matter and its humus evolves in a complex or simple direction. What is the change process and mechanism of the soil organic matter? It is not clear yet. Therefore, the evolution of soil organic matter and the characteristics of humus composition in ancient paddy soil were studied by using the section of Shanlonggang Paddy soil site in Liyang Plain as the research object. The composition and distribution characteristics of organic matter in ancient paddy soil with different particle size aggregates were analyzed. The infrared spectrum characteristics of ancient paddy soil were discussed in order to provide the basis for soil carbon release and fixation and biogeochemical cycle of carbon. The main results are as follows: (1) the content of organic matter varied from 8.41 to 24.00 g 路kg ~ (- 1) in the section of Shanlonggang Rice site, and 9.5g / 12.3g / kg ~ (- 1) g 路kg ~ (- 1) ~ (- 1) in the ancient rice soil layer. According to the spatial distribution of the profile, the change trend of the organic matter in the paleo-paddy soil is the parent material layer of the plough bottom and the retention layer. Compared with modern cultivated paddy soil, the content of organic matter is lower and the range of variation is smaller. (2) the content of organic matter in different grain diameter aggregates of ancient paddy soil is (5-2mm) (2-lmm) (1-0.25mm) (0.25mm). According to the spatial distribution of the profile, the organic matter of the aggregates of different grain diameters in the paleo-paddy soil is as follows: plough bottom of PA section, plough layer of PB profile, ploughing layer of PC profile and plough parent layer of plough layer of PC profile. Compared with the modern cultivated paddy soil, the organic matter content of the paddy soil is higher than that of the plough bottom of the modern cultivated paddy soil. (3) the average content of humus in ancient paddy soil was 3.66g/kg humic acid (1.92g/kg) fulvic acid (0.95g/kg). According to the spatial distribution of the profile, the variation range of humus content in all forms of Paddy soil is relatively small and tends to be stable gradually. Among them, the content of humic acid increased gradually with the increase of soil depth, the content of fulvic acid in profile PA,PB decreased and the content of PC increased. The content of humin in profile PA decreased at first and then increased. The PB in section showed a trend of "decrease-rise-decline", while the profile PC showed a trend of obvious decrease. The Hu-Fu ratio of ancient paddy soil increased with the increase of soil depth. Compared with modern cultivated paddy soil, Hu Fu is lower. (4) the average content of combined humus in ancient paddy soil is as follows: loose-bound (12.75g/kg) tight-bound (4.07g/kg)-stable-bound (0.42g/kg); The largest relative content is loose junctions (58.36%), followed by compact junctions (52.52%). The third is stable binding state (9.82%). From the view of spatial distribution of profile, the content of humus in each combined state of ancient paddy soil changed greatly, among which, the content of PA,PB loose jointed state in the profile showed a decreasing trend, and the content of stable bound state showed an upward trend. The compact state decreased. (5) the functional groups of ancient paddy soil were mainly concentrated in halogen compounds and inorganic compounds. The organic matter has a great influence on the functional groups of ancient paddy soil, in which the wave number in the ancient paddy soil is 188.2 cm ~ (1), and the absorption peak weakens after the removal of organic matter. In the ancient paddy soil, the wave number was 1631 ~ 470 cm-1, the benzene ring was formed gradually, the olefin compound increased and the degree of aromatization increased, and the binding power between halogen and inorganic compound increased. According to the reciprocal of the first order, the difference between the ancient paddy soil and the modern cultivated paddy soil is not significant, but after the removal of organic matter, the value of FD is different: after the removal of the organic matter, the peak values of the former and the latter have a downward trend.
【学位授予单位】：湖南农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S153.62

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