Contenido

Para los suelos, la experiencia ha mostrado que un sistema natural, es decir, suelos agrupados por sus propiedades intrínsecas, conductas, o génesis, resulta en clases que pueden ser interpretadas para muchos usos diversos. Esto es en contraste con una clasificación técnica, como la «Clasificación de Capacidad de Fertilización», donde los suelos se agrupan de acuerdo con su ajuste a un uso específico.

Risk of degradation

Natural systems are based strictly on the presumed genesis of soil, but modern systems (both very hierarchical ones like the Soil Taxonomy and low hierarchical ones like the World Reference Base for Soil Resources) use objective criteria, from morphology to field to laboratory tests, as much as possible, to reduce disagreements between classifiers.

In soil mapping, as practiced in the United States, soil classification usually means using criteria based on soil morphology adding characteristics developed during soil formation. Criteria are designed to guide choices in land use and soil management. As indicated, that is a hybrid hierarchical system of both natural and objective criteria. The Soil Taxonomy provides core criteria to differentiate soil mapping units. That is a substantial revision of the «1938 USDA soil taxonomy»[note 1]​ which was a strictly natural system.

The soil mapping units of a soil taxonomy thus based are further grouped into classes of technical classification systems. The "use capacity classes", the hydromorphic soil"), and the "flower field" are some examples.

In addition to soil classification systems, there are also vernacular soil classification systems. Vernacular (descriptive) systems have been used for millennia, while systems based on scientific evidence were of relatively recent development.

Objective classification

Currently there is a strong tendency to use two classifications that can be classified as international, these are the Soil Taxonomy, presented by the Soil Survey Staff of the United States, and the World Reference Base for Soil Resources, edited by a Working Group of the International Union of Soil Sciences - IUSS). (Russia, Germany, among others).

These are classifications that use quantitatively measurable soil properties as differentiating characters, in the field or in the laboratory. Furthermore, these differentiating characters are very numerous, so that the established classes are defined in a very rigorous and precise way. When using quantitative criteria, classes can be defined in such a way that they are mutually exclusive.

These two classifications avoid subjectivity as much as possible, unlike what happened with the classifications that preceded them:

By always using properties that can be quantified in some way, the qualitative criteria, so used in previous classifications, are not used. Those criteria of "high content of organic matter", "poor in bases", etc., which lent themselves to enormous confusion, (for example, the term "high" was interpreted in a very different way depending on the soils to which each researcher was accustomed) have been replaced by "percentage of organic matter greater than 1%", "degree of saturation < 50%", etc.

Genetic considerations are avoided, which, being subjective to different interpretations, can create confusion. However, given the importance of soil formation processes, those properties that are the direct result of the action of these processes are used as differentiating characters. That is why although strictly speaking these are morphometric classifications, we can classify them as morphogenetic. However, the properties important for land use are also taken into account.

Another important advantage of these classifications is that they refer to both virgin and agricultural soils. The soil is classified as it is found in reality and when classifying it it is not necessary to idealize it as it would be if it had not been tilled, as was the case with other previous classifications.

Previous nomenclatures such as ABC") are defined on qualitative genetic criteria, which causes important disparities in use among soil scientists. To avoid this inconvenience, the Soil Survey Staff of the USA introduced the concept of diagnostic horizons"), the use of which has been imposed in many systems.

A diagnostic horizon is a morphometrically defined horizon, with the greatest possible precision, with field and laboratory data, for use in soil classification.

These horizons are defined in a much more complete way than is done for the ABC nomenclature, and quantitative criteria are also used, which were totally absent.

On the other hand, there are other differentiating characters that are not horizons and are called diagnostic properties. They are essential elements for classification and are defined in a similar way to diagnostic horizons.

The diagnostic horizons and diagnostic properties are not all common for both classifications. Nor are the definitions of the horizons and properties defined in exactly the same way in both systems.

FAO Classification

The FAO has chosen popular names used in previous classifications to name its classes, discarding all popular terms that could lead to confusion, for example: brown soils, arid soils, etc. Another difference with respect to the Soil Taxonomy lies in the absence of the humidity and temperature regimes so frequently used in the American classification.

The FAO has developed two systems for working with soils:

The «Legend of the Soil Map of the World», by FAO/UNESCO, was established in 1974 and was subsequently revised, introducing profound modifications to its classification scheme, developing the «Revised Legend of the Soil Map of the World» in 1988.[4] Profound changes have been introduced at all levels (diagnostic horizons, diagnostic properties, diagnostic materials, Soil Groups and Soil Units).

Initially this classification was designed to provide a common working tool for all soil scientists on the planet. Specifically as a legend of a small-scale world soil map (1:5,000,000), to carry out a first assessment of the world's soil resources. Mainly developed to work with small scales (general maps). It represents a fairly intuitive classification system, very effective from a didactic point of view and very useful for not very detailed soil studies.

More than a classification system, it is simply a legend to define the soil classes of the Soil Map of the World at a scale of 1:5,000,000. This system has had wide acceptance worldwide and has been universally accepted as a very useful reference system. The FAO system was replaced in 1998 by the World Reference Base for Soil Resources.

World Reference Base for Soil Resources (WRB) Classification

The World Reference Base for Soil Resources (WRB) is an international soil classification system for soil nomenclature and soil map legending. It is edited by a Working Group of the International Union of Soil Sciences - IUSS.

The WRB comprises two levels: the First Level has 32 Soil Reference Groups (GSR); The Second Level consists of the name of the GSR combined with a set of primary and supplementary qualifiers.

The WRB uses diagnostic horizons, properties and materials, and also simple characteristics (such as a certain texture or base saturation) to assign a soil the appropriate Soil Reference Group (GSR). A key is used for this assignment.

For the Second Level of the classification, qualifiers are used, which have a unique definition. The qualifiers available for use with a GSR are listed in the key along with the GSR. They are divided into main and supplementary qualifiers. Primary qualifiers are important for the subdivision of soils in a GSR. They are hierarchical and are presented in the order of their importance. The supplementary qualifiers are not hierarchical and are used in the following way: first the qualifiers referring to the texture, then the other qualifiers according to alphabetical order. Primary qualifiers are added in front of the GSR name. The sequence is from right to left, that is, the highest qualifier in the list is placed closest to the name of the GSR. Supplementary qualifiers are added after the GSR name in parentheses and separated from each other by commas. The sequence is from left to right. To name a soil, all applicable qualifiers must be added.

For map legends the number of qualifiers depends on the scale.

Soil Taxonomy Classification

Classifies soils by nomenclature of:.

The orders are:

La taxonomía de suelos de USDA, o sintéticamente y más generalizada Soil Taxonomy, desarrollada y coordinada internacionalmente por el Ministerio de Agricultura de los Estados Unidos (en inglés, el United States Department of Agriculture y su subsidiaria Natural Resources Conservations Service) da una clasificación de suelos acorde a varios parámetros.

Aridisols

Most aridisols are enriched with calcium carbonate. In these soils it is found as fine crystals dispersed in the matrix.

Gelisols

Soils affected by permafrost.

Mollisols

Mollisols are geographically associated with grassland vegetation, which is why they are often known as grassland soils. They have been formed under different types of them; Thus, Boul et al (1980) comment on the different heights they reached (greater than 12 m, less than 30/50 cm or intermediate) whose effect, through their biomass, affects the thickness of the molic horizon, through profit processes, in environments with a tendency towards neutrality and abundant intervention of edaphic organisms.

In some areas, transitional to more humid climates, for example in the Maicao area and to the south of it, there is the presence of mollisols as a result of greater biomass and humification of the soil; They are especially calciustolls, haplustolls, aridic, lithic, salothidic or terrértic. (Soto X, 2010) taken from (Malagon et al 1987).

In Colombian mollisols, despite theoretically higher proportions of humic acids and types of chernozemic and eutrophic humus, climatic conditions are not favorable. The high contribution of grass biomass related to these soils in other parts of the world (central plains of the United States, Canada, Argentina); The prairie conditions provided high contents of organic materials; of which 50 percent is incorporated annually into the soil in its A horizon.

Contenido

Para los suelos, la experiencia ha mostrado que un sistema natural, es decir, suelos agrupados por sus propiedades intrínsecas, conductas, o génesis, resulta en clases que pueden ser interpretadas para muchos usos diversos. Esto es en contraste con una clasificación técnica, como la «Clasificación de Capacidad de Fertilización», donde los suelos se agrupan de acuerdo con su ajuste a un uso específico.

Risk of degradation

Natural systems are based strictly on the presumed genesis of soil, but modern systems (both very hierarchical ones like the Soil Taxonomy and low hierarchical ones like the World Reference Base for Soil Resources) use objective criteria, from morphology to field to laboratory tests, as much as possible, to reduce disagreements between classifiers.

In soil mapping, as practiced in the United States, soil classification usually means using criteria based on soil morphology adding characteristics developed during soil formation. Criteria are designed to guide choices in land use and soil management. As indicated, that is a hybrid hierarchical system of both natural and objective criteria. The Soil Taxonomy provides core criteria to differentiate soil mapping units. That is a substantial revision of the «1938 USDA soil taxonomy»[note 1]​ which was a strictly natural system.

The soil mapping units of a soil taxonomy thus based are further grouped into classes of technical classification systems. The "use capacity classes", the hydromorphic soil"), and the "flower field" are some examples.

In addition to soil classification systems, there are also vernacular soil classification systems. Vernacular (descriptive) systems have been used for millennia, while systems based on scientific evidence were of relatively recent development.

Objective classification

Currently there is a strong tendency to use two classifications that can be classified as international, these are the Soil Taxonomy, presented by the Soil Survey Staff of the United States, and the World Reference Base for Soil Resources, edited by a Working Group of the International Union of Soil Sciences - IUSS). (Russia, Germany, among others).

These are classifications that use quantitatively measurable soil properties as differentiating characters, in the field or in the laboratory. Furthermore, these differentiating characters are very numerous, so that the established classes are defined in a very rigorous and precise way. When using quantitative criteria, classes can be defined in such a way that they are mutually exclusive.

These two classifications avoid subjectivity as much as possible, unlike what happened with the classifications that preceded them:

By always using properties that can be quantified in some way, the qualitative criteria, so used in previous classifications, are not used. Those criteria of "high content of organic matter", "poor in bases", etc., which lent themselves to enormous confusion, (for example, the term "high" was interpreted in a very different way depending on the soils to which each researcher was accustomed) have been replaced by "percentage of organic matter greater than 1%", "degree of saturation < 50%", etc.

Genetic considerations are avoided, which, being subjective to different interpretations, can create confusion. However, given the importance of soil formation processes, those properties that are the direct result of the action of these processes are used as differentiating characters. That is why although strictly speaking these are morphometric classifications, we can classify them as morphogenetic. However, the properties important for land use are also taken into account.

Another important advantage of these classifications is that they refer to both virgin and agricultural soils. The soil is classified as it is found in reality and when classifying it it is not necessary to idealize it as it would be if it had not been tilled, as was the case with other previous classifications.

Previous nomenclatures such as ABC") are defined on qualitative genetic criteria, which causes important disparities in use among soil scientists. To avoid this inconvenience, the Soil Survey Staff of the USA introduced the concept of diagnostic horizons"), the use of which has been imposed in many systems.

A diagnostic horizon is a morphometrically defined horizon, with the greatest possible precision, with field and laboratory data, for use in soil classification.

These horizons are defined in a much more complete way than is done for the ABC nomenclature, and quantitative criteria are also used, which were totally absent.

On the other hand, there are other differentiating characters that are not horizons and are called diagnostic properties. They are essential elements for classification and are defined in a similar way to diagnostic horizons.

The diagnostic horizons and diagnostic properties are not all common for both classifications. Nor are the definitions of the horizons and properties defined in exactly the same way in both systems.

FAO Classification

The FAO has chosen popular names used in previous classifications to name its classes, discarding all popular terms that could lead to confusion, for example: brown soils, arid soils, etc. Another difference with respect to the Soil Taxonomy lies in the absence of the humidity and temperature regimes so frequently used in the American classification.

The FAO has developed two systems for working with soils:

The «Legend of the Soil Map of the World», by FAO/UNESCO, was established in 1974 and was subsequently revised, introducing profound modifications to its classification scheme, developing the «Revised Legend of the Soil Map of the World» in 1988.[4] Profound changes have been introduced at all levels (diagnostic horizons, diagnostic properties, diagnostic materials, Soil Groups and Soil Units).

Initially this classification was designed to provide a common working tool for all soil scientists on the planet. Specifically as a legend of a small-scale world soil map (1:5,000,000), to carry out a first assessment of the world's soil resources. Mainly developed to work with small scales (general maps). It represents a fairly intuitive classification system, very effective from a didactic point of view and very useful for not very detailed soil studies.

More than a classification system, it is simply a legend to define the soil classes of the Soil Map of the World at a scale of 1:5,000,000. This system has had wide acceptance worldwide and has been universally accepted as a very useful reference system. The FAO system was replaced in 1998 by the World Reference Base for Soil Resources.

World Reference Base for Soil Resources (WRB) Classification

The World Reference Base for Soil Resources (WRB) is an international soil classification system for soil nomenclature and soil map legending. It is edited by a Working Group of the International Union of Soil Sciences - IUSS.

The WRB comprises two levels: the First Level has 32 Soil Reference Groups (GSR); The Second Level consists of the name of the GSR combined with a set of primary and supplementary qualifiers.

The WRB uses diagnostic horizons, properties and materials, and also simple characteristics (such as a certain texture or base saturation) to assign a soil the appropriate Soil Reference Group (GSR). A key is used for this assignment.

For the Second Level of the classification, qualifiers are used, which have a unique definition. The qualifiers available for use with a GSR are listed in the key along with the GSR. They are divided into main and supplementary qualifiers. Primary qualifiers are important for the subdivision of soils in a GSR. They are hierarchical and are presented in the order of their importance. The supplementary qualifiers are not hierarchical and are used in the following way: first the qualifiers referring to the texture, then the other qualifiers according to alphabetical order. Primary qualifiers are added in front of the GSR name. The sequence is from right to left, that is, the highest qualifier in the list is placed closest to the name of the GSR. Supplementary qualifiers are added after the GSR name in parentheses and separated from each other by commas. The sequence is from left to right. To name a soil, all applicable qualifiers must be added.

For map legends the number of qualifiers depends on the scale.

Soil Taxonomy Classification

Classifies soils by nomenclature of:.

The orders are:

La taxonomía de suelos de USDA, o sintéticamente y más generalizada Soil Taxonomy, desarrollada y coordinada internacionalmente por el Ministerio de Agricultura de los Estados Unidos (en inglés, el United States Department of Agriculture y su subsidiaria Natural Resources Conservations Service) da una clasificación de suelos acorde a varios parámetros.

Aridisols

Most aridisols are enriched with calcium carbonate. In these soils it is found as fine crystals dispersed in the matrix.

Gelisols

Soils affected by permafrost.

Mollisols

Mollisols are geographically associated with grassland vegetation, which is why they are often known as grassland soils. They have been formed under different types of them; Thus, Boul et al (1980) comment on the different heights they reached (greater than 12 m, less than 30/50 cm or intermediate) whose effect, through their biomass, affects the thickness of the molic horizon, through profit processes, in environments with a tendency towards neutrality and abundant intervention of edaphic organisms.

In some areas, transitional to more humid climates, for example in the Maicao area and to the south of it, there is the presence of mollisols as a result of greater biomass and humification of the soil; They are especially calciustolls, haplustolls, aridic, lithic, salothidic or terrértic. (Soto X, 2010) taken from (Malagon et al 1987).

In Colombian mollisols, despite theoretically higher proportions of humic acids and types of chernozemic and eutrophic humus, climatic conditions are not favorable. The high contribution of grass biomass related to these soils in other parts of the world (central plains of the United States, Canada, Argentina); The prairie conditions provided high contents of organic materials; of which 50 percent is incorporated annually into the soil in its A horizon.