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43-605: A Calcisol in the World Reference Base for Soil Resources (WRB) is a soil with a substantial secondary accumulation of lime . Calcisols are common in calcareous parent materials and widespread in arid and semi-arid environments. Formerly Calcisols were internationally known as Desert soils and Takyrs . Calcisols are developed in mostly alluvial , colluvial and aeolian deposits of base -rich weathering material. They are found on level to hilly land in arid and semi-arid regions. The natural vegetation

86-674: A draft. This draft was presented at the 15th World Congress of Soil Science in Acapulco in 1994. At the same congress, the WRB was established as an ISSS working group replacing the IRB. At the 16th World Congress of Soil Science in Montpellier in 1998, the first edition of the WRB was published. At the same congress, the ISSS endorsed the WRB as its correlation system for soil classification. (In 2014,

129-421: A map unit not just one soil is indicated but an association of soils. For this purpose, WRB uses the following nomenclature: Soils representing smaller areas are ignored in the denomination of the map unit. For codominant and associated soils, it is allowed to use less principal qualifiers than would correspondent to the used map scale level. The use of specifiers is not recommended due to the generalization that

172-457: A minimum thickness and therefore a horizontal appearance. The diagnostics have names (e. g. argic horizon, stagnic properties, fluvic material). The classification comprises two levels: The first level has 32 Reference Soil Groups (RSGs). At the second level, for further differentiation a set of qualifiers is added to the name of the RSG. There are 202 qualifiers in total. For every RSG, there

215-510: A similar approach as the French référencial pédologique (1992, 1995, 2008). Contrary to that, the USDA soil taxonomy is strongly hierarchical and has six levels. The classification in WRB is based mainly on soil morphology (field and laboratory data) as an expression of pedogenesis . Another difference with USDA soil taxonomy is that soil climate is regarded only as a soil-forming factor and not as

258-472: A soil characteristic. The WRB is not meant to replace national soil classification systems, which, for their area, may be more detailed than the WRB. The WRB is edited by a working group of the International Union of Soil Sciences (IUSS). The current chair of the working group is Cezary Kabala ( Wroclaw University of Environmental and Life Sciences , Poland, since 2022). The current vice-chair

301-400: A soil to a certain RSG. In a defined sequence, the key asks for the presence or absence of certain diagnostics in a certain depth range. In addition, the key asks for single characteristics, e. g., a certain clay content or a certain base saturation. The soil belongs to the first RSG, for which it fulfils the set of criteria. The qualifiers available for use with a particular RSG are listed in

344-519: A soil-forming process) apply. Stagnic is found further up in the list. Therefore, the soil has to be named until now Albic Stagnic Luvisol. From the list of the supplementary qualifiers, Siltic (silty from 0 to 60 cm), Loamic (loamy from 60 cm downwards), Aric (ploughed), Cutanic (clay coatings), Differentic (the clay migration led to a significant difference in clay content), Endic (the argic horizon starts below 50 cm) and Ochric (relatively small concentrations of organic carbon) apply. Bringing

387-453: A soil. Depending on the purpose of the map or according to national traditions, at any scale level, elective qualifiers may be added. They may be additional principal qualifiers from further down the list and not already used in the soil name, or they may be supplementary qualifiers. They are placed using the above-mentioned rules for supplementary qualifiers; principal qualifiers first, then supplementary qualifiers. The WRB recommends that on

430-400: Is Stephan Mantel ( International Soil Reference and Information Centre (ISRIC), The Netherlands, since 2018). Chairs of the WRB working group and responsible first authors of the WRB editions are: Seppe Deckers (Belgium, 1st edition 1998), Erika Michéli (Hungary, 2nd edition 2006) and Peter Schad (Germany, 3rd edition 2014 and 4th edition 2022). The WRB working group has a homepage that

473-512: Is a list of available qualifiers, which are subdivided into two types: Qualifiers may be principal for some RSGs and supplementary for others. The names of the RSGs and the qualifiers start with capital letters. They must be given in English and must not be translated into any other language in order to guarantee that a certain soil has the same name all over the world. A key is used for allocating

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516-642: Is currently hosted by the ISRIC. It provides the following: The classification is based on diagnostic horizons , diagnostic properties and diagnostic materials , altogether called diagnostics . Diagnostic materials are materials that significantly influence soil-forming processes ( pedogenesis ). They may be inherited from the parent material or be the result of soil-forming processes. Diagnostic properties are typical results of soil-forming processes or reflect specific conditions of soil formation . Diagnostic horizons are typical results of soil-forming processes showing

559-441: Is light-coloured, and the upper part is darker. In the clay-richer horizon, we observe redoximorphic features; the oximorphic and the reductimorphic features sum up to 30% of the exposed area, the intensive colours found in the interiors of the aggregates. In spring, reducing conditions occur. The soil is ploughed regularly. Laboratory characteristics: The laboratory analyses confirm the high cation exchange capacity per kg clay in

602-597: Is mainly taken from Table 2 (Chapter 1) of the WRB Manual. Soils with thick organic layers Soils with strong human influence Soils with limitations to root growth Soils distinguished by Fe/Al chemistry Pronounced accumulation of organic matter in the mineral topsoil Accumulation of moderately soluble salts or non-saline substances Soils with clay-enriched subsoil Note: The exchangeable base cations are given in cmol c kg . Soils with little or no profile differentiation Our example soil has

645-412: Is optional: The number of qualifiers used in a map legend depends on the scale. The WRB distinguishes three map scale levels : Correlating the map scale levels with concrete scales is difficult because selecting a map scale level depends very much from the homogeneity/heterogeneity of the landscape. The principal qualifiers are added before the name of the RSG following the rules explained for naming

688-474: Is required when making maps. In map legends, the names of the RSGs are given in plural; in all other cases they are given in singular. The WRB Manual comprises seven chapters and six annexes. The seven chapters are followed by six annexes: This is the list of the 32 Reference Soil Groups in the sequence of the key (Chapter 4 of the WRB Manual), including the codes (Chapter 6 of the WRB Manual). This list

731-759: Is sparse and dominated by xerophytic shrubs and trees and/or ephemeral grasses. Dryness, and in places also stoniness and/or the presence of a shallow petrocalcic horizon , limit the suitability of Calcisols for agriculture. If irrigated, drained (to prevent salinisation ) and fertilised , Calcisols can be highly productive under a wide variety of crops. Hilly areas with Calcisols are predominantly used for low volume grazing of cattle , sheep and goats . Many Calcisols occur together with Solonchaks that are actually salt-affected Calcisols and/or with other soils with secondary accumulation of lime that do not key out as Calcisols. The total Calcisol area may well amount to some 10 million square kilometres, nearly all of it in

774-635: 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 USDA soil taxonomy' from 1960. The next step

817-511: The USDA soil taxonomy also received the status of a correlation system.) At the 18th World Congress of Soil Science in Philadelphia in 2006, the second edition of the WRB was presented, and at the 20th World Congress of Soil Science in Jeju in 2014, the third edition. An update of the third edition was issued in 2015. Whereas the second edition was only suitable for naming soils, the third and

860-566: The FAO soil classification. Drafts were presented in 1982 and 1990. In 1992, the IRB working group decided to develop a new system named World Reference Base for Soil Resources (WRB) that should further develop the Revised Legend of the FAO soil classification and include some ideas of the more systematic IRB approach. Otto Spaargaren ( International Soil Reference and Information Centre ) and Freddy Nachtergaele (FAO) were nominated to prepare

903-499: The United States. A soil family category is a group of soils within a subgroup and describes the physical and chemical properties which affect the response of soil to agricultural management and engineering applications. The principal characteristics used to differentiate soil families include texture, mineralogy, pH, permeability, structure, consistency, the locale's precipitation pattern, and soil temperature. For some soils

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946-406: The United States. Horizons marked by clay, iron, humus and hard pans and soil features such as the expansion-contraction of clays (that produce self-mixing provided by clay), temperature, and marked quantities of various salts are used as distinguishing features. The great group categories are divided into three kinds of soil subgroups : typic, intergrade and extragrade. A typic subgroup represents

989-440: The United States. This permits very specific descriptions of soils. A soil phase of series , originally called 'soil type' describes the soil surface texture, slope, stoniness, saltiness, erosion, and other conditions. Name of soil orders in soil taxonomy with their major characteristics: Order: Entisols Order: Alfisols Soil temperature regimes, such as frigid, mesic, and thermic, are used to classify soils at some of

1032-442: The above at any time during their development. The soil suborders within an order are differentiated on the basis of soil properties and horizons which depend on soil moisture and temperature. Forty-seven suborders are recognized in the United States. The soil great group category is a subdivision of a suborder in which the kind and sequence of soil horizons distinguish one soil from another. About 185 great groups are recognized in

1075-450: The arid and semi-arid subtropics of both hemispheres. World Reference Base for Soil Resources 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

1118-574: The basic or 'typical' concept of the great group to which the described subgroup belongs. An intergrade subgroup describes the properties that suggest how it grades towards (is similar to) soils of other soil great groups, suborders or orders. These properties are not developed or expressed well enough to cause the soil to be included within the great group towards which they grade, but suggest similarities. Extragrade features are aberrant properties which prevent that soil from being included in another soil classification. About 1,000 soil subgroups are defined in

1161-430: The clay-richer horizon and the dominance of exchangeable base cations over exchangeable Al in the subsoil. In the topsoil, we find 20% clay , 10% sand , and 70% silt ; in the subsoil, 35% clay, 8% sand, and 57% silt. Organic matter concentrations in the topsoil are intermediate. The naming of the soil consists of four steps. Question 1: Does the soil have diagnostic horizons, properties and materials? The soil has

1204-665: The codes of Chapter 6 of the WRB Manual gives us the following short name: LV-stn.abm-sia.lon-ai.ct.ed.oh. USDA soil taxonomy USDA soil taxonomy (ST) developed by the United States Department of Agriculture and the National Cooperative Soil Survey provides an elaborate classification of soil types according to several parameters (most commonly their properties) and in several levels: Order , Suborder , Great Group , Subgroup , Family , and Series . The classification

1247-612: The criteria also specify the percentage of silt, sand and coarse fragments such as gravel, cobbles and rocks. About 4,500 soil families are recognised in the United States. A family may contain several soil series which describe the physical location using the name of a prominent physical feature such as a river or town near where the soil sample was taken. An example would be Merrimac for the Merrimack River in New Hampshire. More than 14,000 soil series are recognised in

1290-484: The depth-related specifiers Ano- and Endo- to construct the subqualifiers Anosiltic and Endoloamic. The stagnic properties occur only in the subsoil and the albic horizon around 50 cm. This means that we can use the subqualifiers Endostagnic and Amphialbic. Using these specifiers does not change the position of the qualifiers in the soil name. Now, the soil name is: Amphialbic Endostagnic Luvisol (Anosiltic, Endoloamic, Aric, Cutanic, Differentic Endic, Ochric). Using

1333-483: The difference between mean summer and winter temperatures is less than 6 °C, then add "Iso" at the front of the name of the Soil Temperature Class. The soil moisture regime, often reflective of climatic factors, is a major determinant of the productivity of terrestrial ecosystems, including agricultural systems. The soil moisture regimes are defined based on the levels of the groundwater table and

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1376-473: The following characteristics: Field characteristics (described according to Annex 1 of the WRB Manual): A soil developed from loess shows a marked clay increase in around 60 cm depth and clay coatings in the clay-richer horizon. According to the landscape setting, we presume that high-activity clays dominate. In the field, a pH of 6 is measured in the subsoil. The lower part of the clay-poorer topsoil

1419-547: The following diagnostics: Question 2: To which RSG does the soil belong? We have to go through the key, RSG for RSG. This soil is not a Histosol, not an Anthrosol, not a Technosol etc. Finally, we end up with the Luvisol . This is the first RSG in the key, the criteria of which our soil completely fulfils. Question 3: Which qualifiers apply? From the list of the principal qualifiers, Stagnic (stagnic properties and reducing conditions) and Albic (light colours resulting from

1462-603: The following edition can additionally be used for creating map legends. At the 22nd World Congress of Soil Science in Glasgow in 2022, the fourth edition was published. The 4th edition is an open access document under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. The WRB has two hierarchical levels (see below) and has in that sense

1505-480: The key, along with the RSG. Their number is from 40 to 79. All applying qualifiers must be added to the soil name. The principal qualifiers are added before the name of the RSG. The sequence is from right to left, i. e., the uppermost qualifier in the list is placed closest to the name of the RSG. If no other principal qualifier applies, the Haplic qualifier is used. The supplementary qualifiers are added in brackets after

1548-444: The list are separated by a slash (/), only one of them can be used. The slash signifies that these qualifiers are either mutually exclusive (e. g. Dystric and Eutric) or one of them is redundant with the redundant qualifier(s) listed after the slash(es). In the soil name, supplementary qualifiers are always placed in the order of the alphabet (exception: supplementary qualifiers related to the texture, see above), even if their position in

1591-611: The list differs from the alphabetical sequence due to the use of the slash. It is a general rule that qualifiers conveying redundant information are not used. Example: If a soil has the Calcaric qualifier (carbonates present) the Eutric qualifier (high base saturation) is not used. Qualifiers may be combined with specifiers (e. g. Epi-, Proto-) to form subqualifiers (e. g. Epiarenic, Protocalcic). The depth-related specifiers referring to layers are of special importance, although their use

1634-526: The lower levels of the Soil Taxonomy. The cryic temperature regime distinguishes some higher-level groups. These regimes are based on the mean annual soil temperature (MAST), mean summer temperature, and the difference between mean summer and winter temperatures all at a soil depth of 50 cm. It is normally assumed that the MAST (in °C) equals the sum of the mean annual air temperature plus 2 °C. If

1677-408: The name of the RSG and are separated from each other by commas. The sequence is from left to right. Supplementary qualifiers related to the texture, if applicable, are the first in the list. If several ones apply, they are placed in the sequence from the top to the bottom of the soil profile. All other supplementary qualifiers follow them and are used in alphabetical order. If two or more qualifiers in

1720-604: The orders end with the suffix -sol . The criteria for the different soil orders include properties that reflect major differences in the genesis of soils. The orders are: The percentages listed above are for land area free of ice. "Soils of Mountains", which constitute the balance (11.6%), have a mixture of those listed above, or are classified as "Rugged Mountains" which have no soil. The above soil orders in sequence of increasing degree of development are Entisols, Inceptisols, Aridisols, Mollisols, Alfisols, Spodosols, Ultisols, and Oxisols. Histosols and Vertisols may appear in any of

1763-427: The supplementary qualifiers into the correct order (first the textural qualifiers from the top to the bottom of the soil profile, then all others in alphabetical order), the soil is an Albic Stagnic Luvisol (Siltic, Loamic, Aric, Cutanic, Differentic, Endic, Ochric). Question 4: Which specifiers can be used to form subqualifiers? The soil is Siltic from 0 to 60 cm and Loamic from 60 cm downwards. We can use

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1806-692: Was originally developed by Guy Donald Smith , former director of the U.S. Department of Agriculture's soil survey investigations. A taxonomy is an arrangement in a systematic manner; the USDA soil taxonomy has six levels of classification. They are, from most general to specific: order, suborder, great group, subgroup, family and series. Soil properties that can be measured quantitatively are used in this classification system – they include: depth, moisture, temperature, texture, structure, cation exchange capacity, base saturation, clay mineralogy, organic matter content and salt content. There are 12 soil orders (the top hierarchical level) in soil taxonomy. The names of

1849-623: Was the Revised Legend of the Soil Map of the World, published in 1988. In 1982, the International Soil Science Society (ISSS; now: International Union of Soil Sciences , IUSS) established a working group named International Reference Base for Soil Classification (IRB). Chair of this working group was Ernst Schlichting  [ de ] . Its mandate was to develop an international soil classification system that should better consider soil-forming processes than

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