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In soil science, podzols (known as spodosols in China and the United States of America and podosols in Australia) are the typical soils of coniferous, or boreal forests. They are also the typical soils of eucalypt forests and heathlands in southern Australia, while in Western Europe podzols develop on heathland, which is often a construct of human interference through grazing and burning. Many podzols in this region may have developed over the past 3000 years in response to vegetation and climatic changes. In some British moorlands with podzolic soils there are brown earths preserved under Bronze Age barrows (Dimbleby, 1962). Podzol means "under-ash", and is derived from the Russian под (pod) + зола́ (zola); the full form is "подзо́листая по́чва" (podzolistaya pochva, "under-ashed soil"). It likely refers to the common experience of Russian peasants of plowing up an apparent under-layer of ash (leached or E horizon) during first plowing of a virgin soil of this type. Podzols are able to occur on almost any parent material but generally derive from either quartz-rich sands and sandstones or sedimentary debris from magmatic rocks, provided there is high precipitation.〔Chesworth, W. (Eds.), 2008. ''Encyclopedia of soil science'', The Netherlands.〕 Most podzols are poor soils for agriculture due to the sandy portion, resulting in a low level of moisture and nutrients. Some are sandy and excessively drained. Others have shallow rooting zones and poor drainage due to subsoil cementation. A low pH further compounds issues, along with phosphate deficiencies and aluminium toxicity. The best agricultural use of podzols is for grazing,〔 although well-drained loamy types can be very productive for crops if lime and fertilizer are used. The E horizon, which is usually thick, is low in Fe and Al oxides and humus. It is formed under moist, cool and acidic conditions, especially where the parent material, such as granite or sandstone, is rich in quartz. It is found under a layer of organic material in the process of decomposition, which is usually thick. In the middle, there is often a thin layer of . The bleached soil goes over into a red or redbrown horizon called rusty soil. The colour is strongest in the upper part, and change at a depth of progressively to the part of the soil that is mainly not affected by processes; that is the parent material. The soil profiles are designated by the letters A (topsoil), E (eluviated soil), B (subsoil) and C (parent material). In some podzols, the E horizon is absent—either masked by biological activity or obliterated by disturbance. Podzols with little or no E horizon development are often classified as ''brown podzolic'' soils, also called umbrisols or umbrepts. ==Geographic distribution== Podzols cover about worldwide and are usually found under sclerophyllous woody vegetation.〔FAO, 2006. ''World reference base for soil resources'', Rome.〕 By extent podzols are most common in temperate and boreal zones of the northern hemisphere but they can also be found in other settings including both temperate rainforests and tropical areas.〔Spaargaren, Otto. Podzols. ''Encyclopedia of Soil Science'', pp. 580–581.〕 In South America podzols occur beneath ''Nothofagus betuloides'' forests in Tierra del Fuego. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Podzol」の詳細全文を読む スポンサード リンク
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