パラグアイ中部・カピバリ地区の亜熱帯広葉樹林下の赤色土壌

概要

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A soil survey was carried out in the Capiibary area (ca. 27,000ha) in the central part of East Paraguay as part of a forest regeneration project in 1983. Soils of the area are all derived from Jurassic red sandstones and classified as Acrisols in the FAO/Unesco Soil Map of South America. Local relief condition, however, brings about variability of soil color and associated soil profile characteristics, such as horizon sequence and soil structure, through its control on the soil water regime. As a result a catenary sequence of the following 4 soil units was recognized; Ao1 (granular type), Ao2 (blocky type), Ao3 (crumb type), and Ag, where Ao denotes Orthic Acrisols and Ag Gleyic Acrisols. The weathering crust underlying the solum is constituted from ironstone layer, plinthitic layer and weathered red sandstone layer in the descending order. The higher members of the catenary sequence situated on plateau sites are considered capable of supporting forest regeneration, but the lowest member on valley slopes appears unsuitable because of its poor soil quality, i.e. strong acidity and extremely low base status.
1988-06-30