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Variations in Soils and their Mineralogy in the Kulubi Area,Harar, Ethiopia

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dc.contributor.author Wolde, Begashaw
dc.date.accessioned 2018-07-02T08:33:39Z
dc.date.available 2018-07-02T08:33:39Z
dc.date.issued 1981-07
dc.identifier.uri http://localhost:80/xmlui/handle/123456789/5344
dc.description.abstract The geology, geomorphology and soils of the Kulubi area, in eastern Ethiopia, are described. The succession of rocks in the region comprises Precambrian rocks consisting of gneisses, granites, and raigraatit - es overlain by a trachyte flow; Lower Sandstone Unit (Triassic to Lower Jurassic) consisting of a lov/er arenaceous and an upper calca-^ reous sub-units; Limestone Unit (Lower Jurassic to Middle-Cretaceous) consisting of sandy and fossiliferous carbonate rocks; Upper Sandstone Unit (Middle Cretaceous) consisting of a crossbedded, parallel-bedded, calcareous, and massive and laminated sub-units with Mesozoic volcanic intercalations; Tertiary basalts and Quaternary sediments., The three stages in the geomorphological evolution of the area include a Late Cretaceous-early Cenozoic peneplatation; Trappean tectonics and formation of basin-plains; and renewed erosion associated with the rift tectonics* The major soils in the region are Vertisols, Entisols, and Mollisols. The Vertisols occupy depressions in alluvial plains and scattered spots on Hie'uplands and are developed on basalt and alluvium. They are ddep, clayey soils with low chromas and values. Chemically, they are very slightly alkaline, very low to medium- .in organic matter, low in total nitrogen, and very low to low in phosphorous. These are the least productive soils.The Entisols occur on alluvium and on steep slopes of basalts, sandstones and gneisses. r They are dark grayish and reddish brown, shallow and discontinuous, loamy soils. They are slightly acid to very slightly alkaline, low to medium in organic matter and total nitrogen, and medium to high in phosphorous. Their occurrence on either actively eroding or flooding surfaces significantly reduces their agricultural productivity. The Idollisols are the dominant soils occupying flat to gentle slopes on all theparent materials excepting the basalt. Those are brownish-blaclc and reddish-brown, shallow to deep, clay, clay loam, and sandy clay loam soils. They are strongly acid to slightly alkaline. The organic matter and available phosphorous contents differ widely. They have a low to medium total nitrogen. These are the most productive soils. Comparison of these soils in terms of their textures, pHs, and organic-matter contents indicates that topography is the main soil-forming factor controlling the morphological, physical, and chemical properties of these soils. en_US
dc.language.iso en en_US
dc.publisher Addis Ababa Universty en_US
dc.subject Geomorphology and soils en_US
dc.title Variations in Soils and their Mineralogy in the Kulubi Area,Harar, Ethiopia en_US
dc.type Thesis en_US

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