都市土壌の持続的保全・管理に向けた類型化手法の適用性

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The soil classification system applied for urban parks in western Tokyo was examined in this study whether it could be generalized as a standard technique for planning and sustainable use of urban parks. Comparative studies on land creating history, use, management and soil physical-chemical properties of urban parks were conducted in Aichi and Osaka prefectures. The two-dimension coordination system composed of grading method and use supported the applicability of subdividing urban soils into soil units regardless of soil types. The soil properties in grassland area represented a pedogenetic succession regulated by grading method, use, and management. Green space is expected to relieve the warming phenomenon in urban areas. Although natural soils in urban areas are disturbed and transformed to artificial soil as results of surface filling or mixing of construction waste and garbage, soil has been recognized as natural resource in urban planning (USDA, 2005). A new classification system of urban park soils designed under the recognition of the soil forming process is required to create a symbiotic urban environment. Takeda et al. (2006) studied urban park soils in western Tokyo and proposed a soil classification system to subdivide urban park soil into soil units by investigating land-creating history, use, management and soil physical-chemical properties. The objective of this study is to examine whether the above-mentioned methodology could be generalized as a standard technique for planning and sustainable use of urban area. Comparative studies on land-creating history, use, management and soil physical-chemical properties were investigated in Banpaku park and Hattori green park, Osaka prefecture, and Aichi forest park and Odaka green park, Aichi prefecture. In addition, artificial and natural soils developed under a non-park use in the campus of Tokyo Institute of Technology, Yokohama were investigated to discuss the applicability of the classification system. A total of 86 samples collected from the surface layer (0-5cm) and the second layer (5-15cm) in preservation forest, grassland, bare land, and wood-chip sections, were applied for soil analyses. Soil profile, soil compactness, water content, pH (H_2O) and pH(NaF), total carbon content, C/N ratio, and Melanic Index were examined to obtain soil characteristics. The pH(NaF) values of the investigated soils, except Campus soils in Yokohama area,the second layer of Odaka green park and Banpaku park, were under 9.2,which assigned non-andic (non-volcanic) property to their parent materials(soil matrix). The surface soils in grassland section had low C/N ratio compared with those in other sections. Bare land section was characterized with low water content and low total carbon, and high soil compactness. The physical-chemical features of the second layers were regulated by the stress of miscellaneous urban fill depending on specific land creating history. In order to extract the diagnostic layers with soil properties for each section in parks, a standard radar chart was defined independently by area using the average values of soil properties in preservation forest section. The diagnostic of the surface and the second layers, represented by a radar chart, had similar features with those of Tokyo area. From the obtained results, we confirmed that the examined classification system could be applied for subdividing urban park soils into soil units regardless of soil types. Furthermore, the matrix of combined diagnostic of surface and second layers in grassland soils exhibited a regularity of pedological succession on the base of grading method, use, and management. Further consideration is expected to develop a quantitative methodology for estimating resource value of urban soils.
社団法人日本建築学会の論文
2007-04-30

都市土壌の持続的保全・管理に向けた類型化手法の適用性

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