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Effect of soil structure on water and solutes movement

土壤结构对水和溶质运动的影响

基本信息

批准号：
01420043
负责人：
MARUYAMA Toshisuke
金额：
$ 19.26万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1991
项目状态：
已结题

项目摘要

Effect of soil structure on water and solutes movement was examined visually as the basis of soil water movement. Consequently following results were obtained. The method developed here made it easier to evaluate macropore structure quantitatively.(1) Stereo radiograph was obtained efficiently by infiltlating a contrast medium into undisturbed soil sample using soft X-ray, so pore structure was observed with 3-D images.(2) It was shown that specific soil structure was made with time according to land-use, such as paddy field and upland field.(3) Rotted rice roots are found inside the macropores in paddy field not only on the microscopic photos but also on the radiographic photos. These facts reveals macropores are made by rice roots in paddy field, and that it contributed significantly in transferring the matter in soils.(4) Fluid movement inside the soil which has not been reported until now was observed. It shows the fact that fluid moves inside rather small number of macropores in which fluids moves faster than others. Furthermore, it also became possible to calculate the permeability directly on photos by measuring the diameters of macropores. Some features were discussed on permeability comparing these datum with the results of usual permeability tests. At this point, further discussion is expected on relationships between two datum.(5) Because water retentivity depends on micropores, difficulty in explaining the relationships between moisture characteristic curve and soil structure is recognized.

直观地考察了土壤结构对水分和溶质运移的影响，为土壤水分运移提供了依据。从而得到了以下结果。这种方法使定量评价大孔隙结构变得更加容易。(1)利用软X射线将造影剂渗透到未受干扰的土样中，获得高效的立体射线照片，从而用三维图像观察孔隙结构。(2)根据土地利用的不同，如水田和旱地，特定的土壤结构随着时间的推移而形成。(3)不仅在显微照片上，而且在射线照片上，在稻田的大孔隙内发现了腐烂的稻根。这些事实表明，稻田中的大孔隙是由稻根形成的，它对土壤中物质的迁移起到了重要的作用。(4)观察到了土壤中的液体运动，这一现象目前还没有报道。它表明了这样一个事实，即流体在数量相当少的大孔隙中运动，其中流体的运动速度比其他大孔隙快。此外，还可以通过测量大孔直径直接在照片上计算渗透率。通过与常规渗透率试验结果的对比，探讨了渗透率的一些特点。在这一点上，两个基准之间的关系有待于进一步的讨论。(5)由于水分保持率依赖于微孔隙，因此很难解释水分特征曲线与土壤结构之间的关系。