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Physical Geography of Northern Eurasia
Soils of Northern Eurasia
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| Physical Geography Index | The Holocene
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Azonal Soils
Peat swamp soils or histosols mostly occur in tundra, taiga, and forest-steppe zones.
They cover about 1.5 million km2 or 6.7 per cent of the total FSU (Karavaeva,
1982). In the European territory, they occur in the north-west between Belarus in the
south-west and the Arkhangelsk and Vologda regions in the northeast. They are widely
distributed in the Asiatic part. Histosols develop under the conditions of waterlogging by
both atmospheric and ground waters and moisture-demanding vegetation. The organic peat
horizon forms as a result of plant decay. It may be divided into several subhorizons
according to the degree of decomposition of plant remains and their botanical
characteristics. Soils have very low pH, base saturation and contents of gross forms of
nitrogen, phosphorus, and potassium.
Alluvial soils occur on floodplains under meadow and wetland vegetation. Because of
inundation by spring floods, ground water often occurs in the soil profiles. Soil
properties vary greatly because of the layering of alluvial sediments. Gley processes and
hydrogenic iron accumulation are typical.
Andosols develop in Kamchatka and the Kuril islands on ash sediments under herbaceous
forests with Betula ermanii. Their profiles are characterized by intermingling dark humic
horizons and weakly transformed volcanic sands and ashes (Sokolov, 1973). Andosols have
high humus contents (5-10 per cent) in the upper subaerial humic horizons and a low pH.
These soils are developed mostly on sands, silt, and sandy loams.
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History of Soil Cover >>>
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