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Soil: Taxonomy
Published in Yeqiao Wang, Landscape and Land Capacity, 2020
In keying out soils to the order level, Gelisols are the first possibility. The important criterion is the presence of permafrost (generally within a meter of the soil surface). Histosols key out next, these soil are dominated by organic soil materials (at least 40 cm) in the upper 80 cm. Spodosols follow, having spodic diagnostic horizons. Andisols have andic soil properties (high exchange capacity and water holding capacity). Oxisols are extremely weathered and dominated by Fe and Al oxides (oxic horizon). Vertisols are dominated by shrink-swell clays that results in a self-mixing soil. Aridsols may have a number of diagnostic horizons such as argillic, calcic, cambic as long as they are in aridic (dry) moisture regimes. Ultisols have argillic horizons and low base saturation (<35%). Mollisols have mollic epipedons and a base saturation throughout the profile greater than 50%. These soils may have calcic or argillic horizons. Alfisols almost always have argillic horizons, but unlike Ultisols their base saturation is >35%. Inceptisols are weakly developed soils typically with cambic horizons. Entisols are the least developed, characterized by a lack of diagnostic horizons or epipedons other than ochric, and key out last.
Introduction
Published in Bujang B. K. Huat, Arun Prasad, Sina Kazemian, Vivi Anggraini, Ground Improvement Techniques, 2019
Bujang B. K. Huat, Arun Prasad, Sina Kazemian, Vivi Anggraini
In Southeast Asia, central Africa, and North and South America, the major soil type is utisols. Utisols, commonly known as “red clay” soils, are soils that have formed in humid areas and are intensely weathered. In India, the major soils types are utisols and vertisols. Vertisols are soils in which there is a high content of expansive clay, known as montmorillonite, which forms deep cracks in drier seasons or years. Vertisols typically form from highly basic rocks, such as basalt. In the case of the Middle East, parts of the United States and eastern Australia, the main soil type is aridisols. Aridisols (or desert soils) are formed in an arid or semi-arid climate. Aridisols dominate the deserts and xeric shrublands which occupy about one-third of the Earth’s land surface. In central Africa and the northern part of South America, oxisols are the common soil type. The main processes of soil formation of oxisols are weathering and humification. Oxisols are always a red or yellowish color due to the high concentration of iron, aluminum oxides and hydroxides. They also contain quartz and kaolin, plus small amounts of other clay minerals and organic matter.
Desertification
Published in A. Monem Balba, in Arid Ecosystems, 2018
Thus under arid ecosystems (Lal49): Entisols that are derived from recent deposits and have sand texture are easily eroded.Aridisols contain low organic matter. Desert pavement on its surface indicates past erosion of fine soil particles.Mollisols contain relatively high organic matter, thus they are less eroded.Alfisols contain well-defined argillic horizon. They are highly erodible by water.Vertisols contain considerable clay proportion, thus they have low infiltrability and high runoff. They form larger and deep cracks and are highly susceptible to erosion.
The drivers for the collapse of Lake Haramaya and proposed integrated rehabilitation strategies
Published in International Journal of River Basin Management, 2023
Sitotaw Haile Erena, R. Uttama Reddy, Awol Akmel Yesuf
Soil type: The watershed is rich in different soil types. Among these soil types, the buffer zone lies within two of the soil type chromic vertisols and dystric gleysols. Both soils have a pH value less than 6.5. Gleysols are wetland soils with bluish subsoil located in the areas with shallow groundwater. The vertisols are better fertile soils composed of 30–95% of clay.