北海道網走地域の台地土壌に関する生成学的研究 : 第1報土壌の断面形態,一次鉱物組成および一般理化学性について

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An attempt is made in this report to classify the upland soils of the Abashiri district in eastern Hokkaido. As a result of a detailed reconnaissance soil survey, the genesis and geography of the soils are elucidated from the pedological point of view. Furthermore, general properties of the typical soil profiles (Nakazono, Koshitoshi and Heiwa soils) were examined by the mineralogical, mechanical and physico-chemical analysis. The topography of this district consists of two terraces and gentle slopes extending to hilly region behind the higher terraces. As shown in Fig. 1, most of the humic volcanic ash soil (the black aluminous soils mainly derived from ash-fall deposits under the humid climate and grass vegetation) are distributed on the lower terraces (10-20 m above the sea-level). On the other hand, the Pseudogleyed volcanic ash soils or sub-types of Acid brown earth are mainly distributed on the higher terraces (4080 m) and gentle hills (80-160m). The parent materials of these soils are mainly composed of hornblende-bearing augite hyperthene dacitic pyroclastics. The mode of emplacement of these materials are: (1) the pyroclastic deposits (ash-fall and Kutcharo pumice-flow deposits), and (2) the unconsolidated clastic deposits, such as, marine terrace deposits, creeping deposits such as silty clay with fragments shale mainly derived from mass-waste and solifluction. Under the above-mentioned natural environments, the following genetic soil types have been studied in this district (Figs. 2 and 3 ; Tables 1-4). 1) Pseudogleyed volcanic ash soil: This intrazonal soil is derived from ash-fall deposits which were erupted from unknown volcanos during the late Pleistocene and early Holocene periods, and which are distributed on the higher terraces and gentle hills. The morphology of the upper part of the profile (above (B)_g horizon) seems to closely resemble that of humic volcanic ash soil commonly developed on the lower terraces in this district. On the othar hand, the lower part (below (B)_g horizon) is chracterized by yellow mottles and greyed spots, heavy texture, as well as compact, plastic and sticky constituent. As a result of mechanical and mineralogical examination it is pointed out that this soil was composed of two different parent materials. Namely, the upper part of the solum, it is indicated that volcanic ash, showering at times, fell out through the process of concentration of humus. The general horizon sequence may be shown as A_p/A_3/(B)_g/C_g. This soil differentiated from the sub-types of Acid brown earth by relatively high contents of free alumina, higher adsorption capacity of phosphate and higher base saturation. 2) Pseudogleyed acid brown earth: This is the most dominant soil in this district, in other words, it is one of the pseudogleyed sub-types of Acid brown earth. The soil is mainly developed from the marine terrace deposits or creeping deposits. The general horizon sequence may be shown as A_o/A_l/A_3/B_l/B_<2g>/C_<1g>/C_<2g>. Its diagnostic feature is yellowish orange mottles in the B and C horizons. The soil has high exchange acidity, low base saturation, high base exchange capacity and small contents of free alumina. This sub-soil region can also be divided into two soils (Koshitoshi and Heiwa soils) respectively according to the differences between the parent materials in the lower part of solum and the hydrological conditions. It may be safely concluded that the genesis and distribution of the soil pattern of the Abashiri district should be closely related to the differences of parent material and the development of landscape. Further studies will be needed with regard to relation between the composition of humus or clay minerals of these soils and the pedogenesis of soil types.
帯広畜産大学の論文
1969-01-30

北海道網走地域の台地土壌に関する生成学的研究 : 第1報土壌の断面形態,一次鉱物組成および一般理化学性について

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北海道網走地域の台地土壌に関する生成学的研究 : 第1報 土壌の断面形態,一次鉱物組成および一般理化学性について

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北海道網走地域の台地土壌に関する生成学的研究 : 第1報土壌の断面形態,一次鉱物組成および一般理化学性について