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Retisol
A Retisol is a Reference Soil Group of the World Reference Base for Soil Resources (WRB). Retisols are characterized by clay migration and an additional specific feature: The clay-poorer and lighter coloured eluvial horizon intercalates netlike into the clay-richer more intensely coloured illuvial horizon. The illuvial horizon is the diagnostic ''argic horizon'', and the intercalation is called ''retic'' properties (Latin: rete = net). Retisols were newly introduced with the third edition of the WRB in 2014. They include the narrower defined Albeluvisols of the first and second edition (1998 and 2006), which were abolished in 2014. The definition of the Retisols resembles the definition of the Podzoluvisols of the Legend (1974) and the Revised Legend (1988) of the FAO soil classification. Horizonation A typical horizon sequence according to the FAO Guidelines for Soil Description is: * A – mineral topsoil, usually with relatively low organic matter concentrations * E – hor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
World Reference Base For Soil Resources
The World Reference Base for Soil Resources (WRB) is an international soil classification system for naming soils and creating legends for soil maps. The currently valid version is the fourth edition 2022. It is edited by a working group of the International Union of Soil Sciences (IUSS). WRB, 4th edition (2022) Background History Since the 19th century, several countries developed national soil classification systems. During the 20th century, the need for an international soil classification system became more and more obvious. From 1971 to 1981, the Food and Agriculture Organization (FAO) and UNESCO published the Soil Map of the World, 10 volumes, scale 1 : 5 M). The Legend for this map, published in 1974 under the leadership of Rudi Dudal, became the FAO soil classification. Many ideas from national soil classification systems were brought together in this worldwide-applicable system, among them the idea of diagnostic horizons as established in the '7th approximation to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cation Exchange Capacity
Cation-exchange capacity (CEC) is a measure of how many cations can be retained on soil particle surfaces. Negative charges on the surfaces of soil particles bind positively-charged atoms or molecules (cations), but allow these to exchange with other positively charged particles in the surrounding soil water. This is one of the ways that solid materials in soil alter the chemistry of the soil. CEC affects many aspects of soil chemistry, and is used as a measure of soil fertility, as it indicates the capacity of the soil to retain several nutrients (e.g. K+, NH4+, Ca2+) in plant-available form. It also indicates the capacity to retain pollutant cations (e.g. Pb2+). Definition and principles Cation-exchange capacity is defined as the amount of positive charge that can be exchanged per mass of soil, usually measured in cmolc/kg. Some texts use the older, equivalent units me/100g or meq/100g. CEC is measured in moles of electric charge, so a cation-exchange capacity of 10 cmolc/kg coul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stagnosol
A Stagnosol in the World Reference Base for Soil Resources (WRB) is soil with strong mottling of the soil profile due to redox processes caused by stagnating surface water. Stagnosols are periodically wet and mottled in the topsoil and subsoil, with or without concretions and/or bleaching. The topsoil can also be completely bleached (albic horizon). A common name in many national classification systems for most Stagnosols is pseudogley. In the USDA soil taxonomy, many of them belong to the Aqualfs, Aquults, Aquents, Aquepts and Aquolls. They are developed in a wide variety of unconsolidated materials like glacial till, and loamy aeolian, alluvial and colluvial deposits and physically weathered siltstone. Stagnosols occur on flat to gently sloping land in cool temperate to subtropical regions with humid to perhumid climate conditions. The agricultural suitability of Stagnosols is limited because of their oxygen deficiency resulting from stagnating water above a dense subsoil. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Stagnation
Water stagnation occurs when water stops flowing. Stagnant water can be a major environmental hazard. Dangers Malaria and dengue are among the main dangers of stagnant water, which can become a breeding ground for the mosquitoes that transmit these diseases. Stagnant water can be dangerous for drinking because it provides a better incubator than running water for many kinds of bacteria and parasites. Stagnant water can be contaminated with human and animal feces, particularly in deserts or other areas of low rainfall. Water stagnation for as little as six days can completely change bacterial community composition and increase cell count. Stagnant water may be classified into the following basic, although overlapping, types: * Water body stagnation (stagnation in swamp, lake, lagoon, river, etc.) * Surface and ground waters stagnation * Trapped water stagnation. The water may be trapped in human artifacts (discarded cans, plant pots, tires, dug-outs, roofs, etc.), as well a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acrisol
An Acrisol is a Reference Soil Group of the World Reference Base for Soil Resources (WRB). It has a clay-rich subsoil and is associated with humid, tropical climates, such as those found in Brazil, and often supports forested areas. In the USDA soil taxonomy, Acrisols correspond to the Humult, Udult and Ustult suborders of the Ultisols and also to Oxisols with a kandic horizon and to some Alfisols.CHESWORTH, WARD. Encyclopedia of Soil Science. 2001. pp. 22-24 The Acrisols low fertility and toxic amounts of aluminium pose limitations to its agricultural use, favouring in many places its use for silviculture, low intensity pasture and protected areas. Crops that can be successfully cultivated, if climate allows, include tea, rubber tree, oil palm, coffee and sugar cane. See also *Soil horizon *Soil type A soil type is a taxonomic unit in soil science. All soils that share a certain set of well-defined properties form a distinctive soil type. Soil type is a technical term of soil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lixisol
Lixisols are a Reference Soil Group of the World Reference Base for Soil Resources (WRB). They are soils with subsurface accumulation of low activity clays and high base saturation. They develop under intensive tropical weathering conditions and subhumid to semi-arid climate. See also * Soil type A soil type is a taxonomic unit in soil science. All soils that share a certain set of well-defined properties form a distinctive soil type. Soil type is a technical term of soil classification, the science that deals with the systematic categoriz ... References Further reading * W. Zech, P. Schad, G. Hintermaier-Erhard: Soils of the World. Springer, Berlin 2022, Chapter 9.3.1. External links profile photos (with classification)WRB homepage profile photos (with classification)IUSS World of Soils {{Soil type Pedology Types of soil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alisol
An Alisol is a Reference Soil Group of the World Reference Base for Soil Resources (WRB). Alisols have an ''argic horizon'', which has a high cation exchange capacity. In the subsoil, the base saturation is low. There exist mixed forms, for example 'Stagnic Alisol', that are mainly Alisol, but also contain components that are found in Stagnosols. Alisols occur in tropical and humid subtropical climates, but are also found in temperate regions.Chesworth, Ward (editor); ''Encyclopedia of Soil Science''; p. 36. ISBN Compared to Lixisols, Acrisols and Ferralsols, Alisols have much higher-activity clays and are likely to be found on younger terrains or more geologically active regions such as Kyushu and Chugoku. Agricultural use Alisols are acidic (increased by limited drainage) and therefore need liming, contain few nutrients and therefore need fertilizer, and do not have much surface coherence so are easily eroded. Aluminium and manganese toxicity is a very serious problem in Alis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luvisol
Luvisols are a group of soils, comprising one of the 32 Reference Soil Groups in the international system of soil classification, the World Reference Base for Soil Resources The World Reference Base for Soil Resources (WRB) is an international soil classification system for naming soils and creating legends for soil maps. The currently valid version is the fourth edition 2022. It is edited by a working group of the Inte ... (WRB). They are widespread, especially in temperate climates, and are generally fertile. Luvisols are widely used for agriculture. Distribution Luvisols cover 500–600 million ha of land area, mainly in the temperate zones. They form on a wide variety of mineral parent materials. In Mediterranean regions, the formation of hematite can produce red-coloured Chromic Luvisols. Description and formation The main characteristic of Luvisols is an argic horizon, a subsurface zone with higher clay content than the material above it. This typically arises as clay is was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Base Saturation
Cation-exchange capacity (CEC) is a measure of how many cations can be retained on soil particle surfaces. Negative charges on the surfaces of soil particles bind positively-charged atoms or molecules (cations), but allow these to exchange with other positively charged particles in the surrounding soil water. This is one of the ways that solid materials in soil alter the chemistry of the soil. CEC affects many aspects of soil chemistry, and is used as a measure of soil fertility, as it indicates the capacity of the soil to retain several nutrients (e.g. K+, NH4+, Ca2+) in plant-available form. It also indicates the capacity to retain pollutant cations (e.g. Pb2+). Definition and principles Cation-exchange capacity is defined as the amount of positive charge that can be exchanged per mass of soil, usually measured in cmolc/kg. Some texts use the older, equivalent units me/100g or meq/100g. CEC is measured in moles of electric charge, so a cation-exchange capacity of 10 cmolc/kg co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clay
Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay particles, but become hard, brittle and non–plastic upon drying or firing. Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impurities, such as a reddish or brownish colour from small amounts of iron oxide. Clay is the oldest known ceramic material. Prehistoric humans discovered the useful properties of clay and used it for making pottery. Some of the earliest pottery shards have been dated to around 14,000 BC, and clay tablets were the first known writing medium. Clay is used in many modern industrial processes, such as paper making, cement production, and chemical filtering. Between one-half and two-thirds of the world's population live or work in buildings made with clay, often ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silt
Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel when dry, and lacks plasticity when wet. Silt also can be felt by the tongue as granular when placed on the front teeth (even when mixed with clay particles). Silt is a common material, making up 45% of average modern mud. It is found in many river deltas and as wind-deposited accumulations, particularly in central Asia, north China, and North America. It is produced in both very hot climates (through such processes as collisions of quartz grains in dust storms) and very cold climates (through such processes as glacial grinding of quartz grains.) Loess is soil rich in silt which makes up some of the most fertile agricultural land on Earth. However, silt is very vulnerable to erosion, and it has poor mechanical properties, making construction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the Roman Republic it became the dominant language in the Italian region and subsequently throughout the Roman Empire. Even after the fall of Western Rome, Latin remained the common language of international communication, science, scholarship and academia in Europe until well into the 18th century, when other regional vernaculars (including its own descendants, the Romance languages) supplanted it in common academic and political usage, and it eventually became a dead language in the modern linguistic definition. Latin is a highly inflected language, with three distinct genders (masculine, feminine, and neuter), six or seven noun cases (nominative, accusative, genitive, dative, ablative, and vocative), five declensions, four verb conjuga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
