黄土高原坝地层状土壤剖面孔隙分布特征
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张佐源(1995-),男,硕士研究生,主要从事土壤孔隙结构研究。E-mail:zuoyuanz@nwafu.edu.cn

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国家自然科学基金项目(42177345)


Pore Distribution Characteristics of Layered Soil Profile in Dam Land of Loess Plateau
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    摘要:

    以明确自然界中广泛存在的层状结构土壤孔隙分布特征为目的。选黄土高原典型坝地土壤剖面为研究对象,利用CT扫描技术分析耕作层、犁底层、心土层土壤三维结构,探讨层状土孔隙参数随土层结构变化及界面层孔隙特征。结果表明:(1)瘦长型孔隙(孔隙形状系数≤0.2)是各土层土壤孔隙的主要形态。各土层的孔隙参数具有明显差异。耕作层的总孔隙度最高,大孔隙(≥1 mm)分布较多;犁底层孔隙总数量最高,含有较多孤立的小孔隙(≥0.1~0.5 mm)和微小孔隙(≥0.06~0.1 mm),但连通性最差;心土层孔隙参数多数介于耕作层与犁底层之间。(2)坝地剖面层状土壤具有一定厚度的界面层,各孔隙参数均在土层界面位置存在突变点,具有明显分界现象。孔隙特征参数均呈过渡位置渐变、界面位置突变的规律。在界面层,犁底层土壤总孔隙度和连通性与耕作层相比,分别显著下降41.6%,69.8%;心土层在界面层的土壤总孔隙度和连通性与犁底层相比,分别显著增高30.4%,52.3%。(3)孔隙孔径大小与孔隙形态密切相关,大孔隙形态多呈瘦长型,而微小孔隙形状则多呈规则型。(4)土层越深,连通性与总孔隙度、孔隙总数量、孔径分布及孔隙形状的相关性越强。界面层出现改变相邻土层的土壤孔隙质量。人为作用改变耕作层和犁底层的土壤孔隙特征,主要表现在对耕作层翻耕扰动,使得犁底层被动承压,心土层由于受到干扰较小,土壤整体呈现自然状态。研究结果可丰富非均质土壤结构的认识,为从微观层面理解层状土壤孔隙特征及其对土壤水气热传输的可能影响提供科学依据。

    Abstract:

    The purpose of this study is to clarify the pore distribution characteristics of layered soil widely existing in nature. The soil profile of typical dam land in the Loess Plateau was taken as the research object, and the three-dimensional structure of topsoil, plow pan and core soil was analyzed by CT scanning technology. The changes of pore parameters of layered soil with soil structure and the pore characteristics of interface layer were discussed. The results showed that: (1) Slender pores ( pore shape coefficient ≤0.2 ) were the main forms of soil pores in each soil layer. The pore parameters of each soil layer were significantly different. The total porosity of the tillage layer was the highest, and the macropores (≥1 mm) were more distributed. The total number of pores in plow pan was the highest, containing more isolated small pores (≥0.1~0.5 mm) and tiny pores (≥0.06~0.1 mm), but the connectivity was the worst. The pore parameters of the core soil layer were mostly between the upper two layers. (2) The layered soil in the dam section had a certain thickness of the interface layer, and each pore parameter had a sudden change point at the interface of the soil layer, with obvious boundary phenomenon. The pore characteristic parameters showed the law of gradual change of transition position and abrupt change of interface position. In the interface layer, the total soil porosity and connectivity of the plow pan decreased by 41.6% and 69.8%, respectively, compared with the tillage layer. The total soil porosity and connectivity of the interface layer in the subsoil layer were significantly increased by 30.4% and 52.3%, respectively, compared with the plow pan. (3) The size of pores was closely related to the pore shape, with large pore morphology mostly slender and micropore shapes being regular. (4) The deeper the soil layer, the stronger the correlation between connectivity and total porosity, total number of pores, pore size distribution and pore shape. The appearance of interface layer changed the soil pore quality of adjacent soil layer. The artificial action changed the soil pore characteristics of the tillage layer and the plow pan, which was mainly manifested in the disturbance of the tillage layer, which made the plow pan passively pressure-bearing, while the soil layer was less disturbed, and the soil as a whole presented a natural state. The results of this study can enrich the understanding of heterogeneous soil structure and provide a scientific basis for understanding the characteristics of layered soil pores and their possible effects on soil water, air and heat transport at the micro level.

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张佐源, 夏彬, 郝旺林, 汪若瑶, 解嫣, 许明祥.黄土高原坝地层状土壤剖面孔隙分布特征[J].水土保持学报,2023,37(6):83~90

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  • 收稿日期:2023-03-13
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  • 在线发布日期: 2023-12-27
  • 出版日期: 2023-12-28