Contenido

Existen dos clasificaciones , una según su estructura y otra de acuerdo a sus formas físicas.

Soil classification

Soil can be classified according to its texture: fine or coarse, and by its structure: flocculated, aggregated or dispersed, which defines its porosity that allows greater or lesser circulation of water, and therefore the existence of plant species that need more or less high concentrations of water or gases.

The soil can also be classified by its chemical characteristics, by its colloid absorption power and by its degree of acidity (pH), which allows the existence of vegetation more or less in need of certain compounds.

Non-evolved soils are raw soils, very close to the parent rock and barely contain any organic matter. They are the result of erosive phenomena or the recent accumulation of alluvial deposits. Of this type are polar soils and deserts, both rock and sand, as well as beaches.

Poorly evolved soils depend largely on the nature of the parent rock. There are three basic types: ránker, rendzina and steppe soils.

In evolved soils we find all types of humus, and a certain independence from the parent rock. There is a great variety and these include the soils of temperate forests, those of regions with high rainfall (Precipitation (meteorology)), those of temperate climates and the Mediterranean red soil. In general, if the climate is favorable and the location is accessible, most of these lands are today occupied by agricultural operations.

It constitutes a complex set of physical, chemical and biological elements that make up the natural substrate in which life develops on the surface of the continents. The soil is the habitat of a specific biota of microorganisms and small animals that constitute the edaphon. The soil is typical of emerged lands, with hardly any equivalent counterpart in aquatic ecosystems. It is important to emphasize that the soil understood in this way does not extend over all terrains, but in many spaces what is stepped on is fresh rock, or a rock altered only by weathering, a regolith.

From a biological point of view, the most important soil characteristics are its permeability, related to porosity, its structure and its chemical composition. Soils retain the mineral substances that plants need for their plant nutrition and that are released by the degradation of organic remains. Good soil is a primary condition for agricultural productivity.

In the natural environment, the most complex and powerful soils (coarse) accompany ecosystems with greater biomass "Biomass (ecology)") and diversity, of which they are both a product and a condition. In this sense, from the point of view of the hierarchical organization of ecosystems, the soil is an ecosystem in itself and a subsystem of the ecological system of which it is a part.

The conception of the term fertility has been modified over time and is currently closer to the concept of productivity than anything else. That is, what offers nutritional potential to a soil is not only its nutrient content, but also all those chemical, physical and biological factors that influence the availability and accessibility of nutrients by the plant. It is relatively often forgotten that the secret to achieving the concrete expression of all the potential of a soil lies in contributing to the articulated action of each of its particular fractions. In other words, you have to know each of these components of the soil and, above all, the way in which they are interacting with the rest in order to be able, through management, to achieve their best expression.

High crop yields are the result of multiple factors that begin with a good diagnosis of soil fertility and the quality of irrigation water. It is important to use an adequate sampling system, a good analysis procedure and reasonable analytical quality control in the laboratory. The next step is to carry out a good interpretation of the analysis results and subsequently generate an appropriate fertilization recommendation, based on a specific performance goal. The other factors involve convenient management of tillage, whether conventional or conservation, an adequate decision regarding genotypes and sowing dates to be used, an adequate arrangement of the plants in the field to capture the greatest amount of radiation, a correct decision on forms and times of fertilization, adequate management of the health of the crop, a good water supply and adequate soil aeration (Castellanos, 1858).

The study of soil dynamics shows that it follows an evolutionary process to which the concepts of ecological succession are fully applicable. The formation of deep and complex soil requires, under natural conditions, long periods of time and minimal disturbance. Where environmental circumstances are more favorable, the development of a soil from a raw geological substrate requires hundreds of years, which can be thousands in less favorable climates, topographies and lithologies.[2]​.

The processes that form the soil start with the physical and chemical weathering of the raw rock. It continues with the first establishment of a biota, in which lichens frequently occupy a prominent place, and the development of the first vegetation. The contribution of organic matter sets in motion the constitution of the edafon. This is formed by a community of decomposers, bacteria and fungi, especially detritivores, such as springtails or diplopods, and also includes the roots of plants, with their mycorrhizae.[3]​The system thus formed recycles the nutrients that circulate through the food chain. Evolved, deep, moist and permeable soils usually have earthworms, oligoghetto soil-eating annelids, in their edaphon, which in turn favors a better mixture of organic and mineral fractions and soil fertility.

The main cause of soil formation is weathering, which consists of the alteration that rocks experience in contact with water, air and living beings.[4]​The following can be distinguished:.

Biological activity can contribute to both physical and chemical weathering.

Soil can form and evolve from most rock materials, as long as they remain in a certain position long enough to allow the previous stages. They can be differentiated:

Soil formation is a process in which rocks are divided into smaller particles, mixing with decomposing organic matter. The bedrock begins to break down due to freeze-thaw cycles, rain, and other environmental forces:

The main cause of soil destruction is erosion, which consists of the wear and fragmentation of materials on the earth's surface due to the action of water, wind, etc. The fragments that break off are called debris.

Soils can be destroyed by rain. These wash the soil (leachate), removing all the nutrients it needs to be fertile, the trees cannot then grow and deforestation occurs, which leads to desertification.[5]​.

Deforestation is one of the main causes of biodiversity loss and environmental degradation on a global scale. According to the Food and Agriculture Organization of the United Nations (FAO), around 10 million hectares of forests are lost each year in the world, mainly due to agricultural expansion, livestock farming and logging.[6]​The impacts of deforestation also extend to soils and water resources. The disappearance of vegetation cover increases erosion, accelerates the loss of nutrients and reduces the infiltration capacity of water, which results in greater runoff and increased flooding. Studies by the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) warn that more than 25% of the world's land surface already presents some degree of degradation, with direct consequences on food production and the stability of ecosystems.[7]​.

Deforestation plays a decisive role in climate change. According to the Intergovernmental Panel on Climate Change, land use, including deforestation, accounts for approximately 23% of net anthropogenic greenhouse gas emissions.[8]​.

Soil conservation will be achieved with the education of people. We must keep in mind that soil is formed over a period of thousands and thousands of years, thanks to the action of factors such as wind, temperature and water. These slowly break down the rocks until they are reduced to small particles, which when joined with the remains of plants and animals make up the soil.

Once formed, the soil is protected and preserved by the vegetation that grows on its surface. When humans cut down trees and leave soil particles exposed to the action of the sun, wind and water, the dreaded erosion occurs. The vegetation layer is dragged to the bottom of the oceans, and those fertile lands are transformed into deserts. Said impoverishment of the soil is also caused by weeding with a hoe, by burning, by the exaggerated use of herbicides and fertilizers, among others.

To stop the destruction of this resource, it is urgent to start planting trees and defending native forests. The farmer must acquire the healthy habit of rotating crops, of tracing furrows in a different direction to the slope of the land, of planting living barriers to prevent particles from rolling. It is everyone's commitment to protect water sources, such as rivers and streams, conserving all the vegetation in the basin.

Los componentes del suelo se pueden dividir en sólidos, líquidos y gaseosos.

Solids

This set of components represents what could be called the mineral skeleton of the soil. Among these solid components of the soil, the following stand out:

Liquids

This fraction is formed by a dissolution due to the most common salts and ions such as Na, K, Ca, Cl, NO, as well as a wide series of organic substances. The importance of this liquid phase in the soil lies in the fact that it is the vehicle for the chemical substances within the system.

Water in soil can be related to the solid skeleton in three different ways:

Gases

The gas fraction is fundamentally made up of atmospheric gases and has great variability in its composition, due to the consumption of O, and the production of CO. The first is always less abundant than in the open air and the second more, as a consequence of the respiratory metabolism of living beings in the soil, including roots and fungi. Other common gases in poorly drained soils are methane (CH) and nitrous oxide (Nitrogen Oxide (I)) (NO).

Se entiende la estructura de un suelo como la distribución o diferentes proporciones que presentan los distintos tamaños de las partículas sólidas que lo conforman, y son:.

Los componentes sólidos, no quedan sueltos y dispersos, sino más o menos aglutinados por el humus y los complejos órgano-minerales, creando unas divisiones horizontales denominadas horizontes del suelo.

La evolución natural del suelo produce una estructura vertical “estratificada” (no en el sentido que el término tiene en Geología) a la que se conoce como perfil. Las capas que se observan se llaman horizontes y su diferenciación se debe tanto a su dinámica interna como al transporte vertical.

El transporte vertical tiene dos dimensiones con distinta influencia según los suelos. La lixiviación, o lavado, la produce el agua que se infiltra y penetra verticalmente desde la superficie, arrastrando sustancias que se depositan sobre todo por adsorción. La otra dimensión es el ascenso vertical, por capilaridad, importante sobre todo en los climas donde alternan estaciones húmedas con estaciones secas.

Se llama roca madre a la que proporciona su matriz mineral al suelo. Se distinguen suelos autóctonos, que se asientan sobre su roca madre, lo que representa la situación más común, y suelos alóctonos, formados con una matriz mineral aportada desde otro lugar por los procesos geológicos de transporte.

Horizons

Soil horizons are a series of horizontal levels that develop inside the soil and have different characteristics of composition, texture, adhesion, etc. The soil profile is the vertical organization of all these horizons.

Classically, three fundamental horizons are distinguished in complete or evolved soils, which from the surface downwards are:

The characters, texture and structure of the horizons can vary widely, ranging from an A horizon of centimeters to meters.

Another shorter explanation is the following.

The depth of the soil depends on factors such as the slope, which allows the earth to be dragged by the water, and the nature of the bedrock. Limestone, for example, erodes more than sandstone, so it produces more decomposition products. But the most important factor is the climate and the erosive effect of atmospheric agents.

The texture of the soil is determined by the proportion of the sizes of the particles that make it up. For soils in which all particles have a similar granulometry, several classifications are used internationally, differing from each other mainly at the boundaries between the different classes. In an increasing order of granulometry, soil types can be classified as clay, silt, sand, gravel, pebbles and blocks "Block (rock)").

Depending on how materials with different grain sizes are mixed, in addition to their degree of compaction, the soil will present different characteristics such as its permeability or its water retention capacity and its ability to use waste as fertilizer for plant growth.

To name the different types of soil that we can find in the world, various types of classifications have been developed that, using different criteria, establish different soil typologies. Among these classifications, the most used are:

Today, the most used classifications are fundamentally based on the soil profile, conditioned by the climate. A double division is followed: climatic zone and, within each zone, the degree of evolution. Within this, three main edaphic models can be referred to, which would respond to the following names:

Vegetable soil is soil that has a certain amount of organic matter produced by autotrophic organisms. It provides the chemical elements necessary for the development of plants, animals and humans.

Plants and certain autotrophic microorganisms are the only living forms capable of producing organic matter; they capture carbon dioxide from the air and from the soil, water and the mineral salts dissolved in it. Thanks to sunlight and chlorophyll, they transform these substances into organic matter, which is used by the rest of living beings, through food chains.

When plants and animals die, the organic matter returns to the soil and undergoes decomposition by the action of decomposer organisms. These convert it into simple substances that can be used again by plants. This entire process forms the vegetal soil, the basis of agricultural activity.

Plant soil can be worn down by the decrease in minerals used by the same plants that grow in it.

According to its composition, the topsoil is sandy, clayey, rocky and organic.

It constitutes the basis of the diet of many soil animals, with whose remains humus is formed.

The soil is vitally important because it intervenes in the water cycle and the cycles of the elements and it is where a large part of the energy and matter transformations of all ecosystems take place.

Furthermore, as its regeneration is very slow, soil must be considered a non-renewable and increasingly scarce resource, because it is subject to constant processes of degradation and destruction of natural or anthropogenic origin.

The 68th session of the UN General Assembly declared 2015 the International Year of Soils (A/RES/68/232). The International Year of Soils 2015 aims to raise awareness and understanding of the importance of soil for food security and essential ecosystem functions.

The Food and Agriculture Organization of the United Nations (FAO) is responsible for implementing the International Year of Soils 2015 (IYA) within the framework of the Global Soil Partnership and in collaboration with governments and the secretariat of the United Nations Convention to Combat Desertification (UNCCD).

Contenido

Existen dos clasificaciones , una según su estructura y otra de acuerdo a sus formas físicas.

Soil classification

Soil can be classified according to its texture: fine or coarse, and by its structure: flocculated, aggregated or dispersed, which defines its porosity that allows greater or lesser circulation of water, and therefore the existence of plant species that need more or less high concentrations of water or gases.

The soil can also be classified by its chemical characteristics, by its colloid absorption power and by its degree of acidity (pH), which allows the existence of vegetation more or less in need of certain compounds.

Non-evolved soils are raw soils, very close to the parent rock and barely contain any organic matter. They are the result of erosive phenomena or the recent accumulation of alluvial deposits. Of this type are polar soils and deserts, both rock and sand, as well as beaches.

Poorly evolved soils depend largely on the nature of the parent rock. There are three basic types: ránker, rendzina and steppe soils.

In evolved soils we find all types of humus, and a certain independence from the parent rock. There is a great variety and these include the soils of temperate forests, those of regions with high rainfall (Precipitation (meteorology)), those of temperate climates and the Mediterranean red soil. In general, if the climate is favorable and the location is accessible, most of these lands are today occupied by agricultural operations.

It constitutes a complex set of physical, chemical and biological elements that make up the natural substrate in which life develops on the surface of the continents. The soil is the habitat of a specific biota of microorganisms and small animals that constitute the edaphon. The soil is typical of emerged lands, with hardly any equivalent counterpart in aquatic ecosystems. It is important to emphasize that the soil understood in this way does not extend over all terrains, but in many spaces what is stepped on is fresh rock, or a rock altered only by weathering, a regolith.

From a biological point of view, the most important soil characteristics are its permeability, related to porosity, its structure and its chemical composition. Soils retain the mineral substances that plants need for their plant nutrition and that are released by the degradation of organic remains. Good soil is a primary condition for agricultural productivity.

In the natural environment, the most complex and powerful soils (coarse) accompany ecosystems with greater biomass "Biomass (ecology)") and diversity, of which they are both a product and a condition. In this sense, from the point of view of the hierarchical organization of ecosystems, the soil is an ecosystem in itself and a subsystem of the ecological system of which it is a part.

The conception of the term fertility has been modified over time and is currently closer to the concept of productivity than anything else. That is, what offers nutritional potential to a soil is not only its nutrient content, but also all those chemical, physical and biological factors that influence the availability and accessibility of nutrients by the plant. It is relatively often forgotten that the secret to achieving the concrete expression of all the potential of a soil lies in contributing to the articulated action of each of its particular fractions. In other words, you have to know each of these components of the soil and, above all, the way in which they are interacting with the rest in order to be able, through management, to achieve their best expression.

High crop yields are the result of multiple factors that begin with a good diagnosis of soil fertility and the quality of irrigation water. It is important to use an adequate sampling system, a good analysis procedure and reasonable analytical quality control in the laboratory. The next step is to carry out a good interpretation of the analysis results and subsequently generate an appropriate fertilization recommendation, based on a specific performance goal. The other factors involve convenient management of tillage, whether conventional or conservation, an adequate decision regarding genotypes and sowing dates to be used, an adequate arrangement of the plants in the field to capture the greatest amount of radiation, a correct decision on forms and times of fertilization, adequate management of the health of the crop, a good water supply and adequate soil aeration (Castellanos, 1858).

The study of soil dynamics shows that it follows an evolutionary process to which the concepts of ecological succession are fully applicable. The formation of deep and complex soil requires, under natural conditions, long periods of time and minimal disturbance. Where environmental circumstances are more favorable, the development of a soil from a raw geological substrate requires hundreds of years, which can be thousands in less favorable climates, topographies and lithologies.[2]​.

The processes that form the soil start with the physical and chemical weathering of the raw rock. It continues with the first establishment of a biota, in which lichens frequently occupy a prominent place, and the development of the first vegetation. The contribution of organic matter sets in motion the constitution of the edafon. This is formed by a community of decomposers, bacteria and fungi, especially detritivores, such as springtails or diplopods, and also includes the roots of plants, with their mycorrhizae.[3]​The system thus formed recycles the nutrients that circulate through the food chain. Evolved, deep, moist and permeable soils usually have earthworms, oligoghetto soil-eating annelids, in their edaphon, which in turn favors a better mixture of organic and mineral fractions and soil fertility.

The main cause of soil formation is weathering, which consists of the alteration that rocks experience in contact with water, air and living beings.[4]​The following can be distinguished:.

Biological activity can contribute to both physical and chemical weathering.

Soil can form and evolve from most rock materials, as long as they remain in a certain position long enough to allow the previous stages. They can be differentiated:

Soil formation is a process in which rocks are divided into smaller particles, mixing with decomposing organic matter. The bedrock begins to break down due to freeze-thaw cycles, rain, and other environmental forces:

The main cause of soil destruction is erosion, which consists of the wear and fragmentation of materials on the earth's surface due to the action of water, wind, etc. The fragments that break off are called debris.

Soils can be destroyed by rain. These wash the soil (leachate), removing all the nutrients it needs to be fertile, the trees cannot then grow and deforestation occurs, which leads to desertification.[5]​.

Deforestation is one of the main causes of biodiversity loss and environmental degradation on a global scale. According to the Food and Agriculture Organization of the United Nations (FAO), around 10 million hectares of forests are lost each year in the world, mainly due to agricultural expansion, livestock farming and logging.[6]​The impacts of deforestation also extend to soils and water resources. The disappearance of vegetation cover increases erosion, accelerates the loss of nutrients and reduces the infiltration capacity of water, which results in greater runoff and increased flooding. Studies by the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) warn that more than 25% of the world's land surface already presents some degree of degradation, with direct consequences on food production and the stability of ecosystems.[7]​.

Deforestation plays a decisive role in climate change. According to the Intergovernmental Panel on Climate Change, land use, including deforestation, accounts for approximately 23% of net anthropogenic greenhouse gas emissions.[8]​.

Soil conservation will be achieved with the education of people. We must keep in mind that soil is formed over a period of thousands and thousands of years, thanks to the action of factors such as wind, temperature and water. These slowly break down the rocks until they are reduced to small particles, which when joined with the remains of plants and animals make up the soil.

Once formed, the soil is protected and preserved by the vegetation that grows on its surface. When humans cut down trees and leave soil particles exposed to the action of the sun, wind and water, the dreaded erosion occurs. The vegetation layer is dragged to the bottom of the oceans, and those fertile lands are transformed into deserts. Said impoverishment of the soil is also caused by weeding with a hoe, by burning, by the exaggerated use of herbicides and fertilizers, among others.

To stop the destruction of this resource, it is urgent to start planting trees and defending native forests. The farmer must acquire the healthy habit of rotating crops, of tracing furrows in a different direction to the slope of the land, of planting living barriers to prevent particles from rolling. It is everyone's commitment to protect water sources, such as rivers and streams, conserving all the vegetation in the basin.

Los componentes del suelo se pueden dividir en sólidos, líquidos y gaseosos.

Solids

This set of components represents what could be called the mineral skeleton of the soil. Among these solid components of the soil, the following stand out:

Liquids

This fraction is formed by a dissolution due to the most common salts and ions such as Na, K, Ca, Cl, NO, as well as a wide series of organic substances. The importance of this liquid phase in the soil lies in the fact that it is the vehicle for the chemical substances within the system.

Water in soil can be related to the solid skeleton in three different ways:

Gases

The gas fraction is fundamentally made up of atmospheric gases and has great variability in its composition, due to the consumption of O, and the production of CO. The first is always less abundant than in the open air and the second more, as a consequence of the respiratory metabolism of living beings in the soil, including roots and fungi. Other common gases in poorly drained soils are methane (CH) and nitrous oxide (Nitrogen Oxide (I)) (NO).

Se entiende la estructura de un suelo como la distribución o diferentes proporciones que presentan los distintos tamaños de las partículas sólidas que lo conforman, y son:.

Los componentes sólidos, no quedan sueltos y dispersos, sino más o menos aglutinados por el humus y los complejos órgano-minerales, creando unas divisiones horizontales denominadas horizontes del suelo.

La evolución natural del suelo produce una estructura vertical “estratificada” (no en el sentido que el término tiene en Geología) a la que se conoce como perfil. Las capas que se observan se llaman horizontes y su diferenciación se debe tanto a su dinámica interna como al transporte vertical.

El transporte vertical tiene dos dimensiones con distinta influencia según los suelos. La lixiviación, o lavado, la produce el agua que se infiltra y penetra verticalmente desde la superficie, arrastrando sustancias que se depositan sobre todo por adsorción. La otra dimensión es el ascenso vertical, por capilaridad, importante sobre todo en los climas donde alternan estaciones húmedas con estaciones secas.

Se llama roca madre a la que proporciona su matriz mineral al suelo. Se distinguen suelos autóctonos, que se asientan sobre su roca madre, lo que representa la situación más común, y suelos alóctonos, formados con una matriz mineral aportada desde otro lugar por los procesos geológicos de transporte.

Horizons

Soil horizons are a series of horizontal levels that develop inside the soil and have different characteristics of composition, texture, adhesion, etc. The soil profile is the vertical organization of all these horizons.

Classically, three fundamental horizons are distinguished in complete or evolved soils, which from the surface downwards are:

The characters, texture and structure of the horizons can vary widely, ranging from an A horizon of centimeters to meters.

Another shorter explanation is the following.

The depth of the soil depends on factors such as the slope, which allows the earth to be dragged by the water, and the nature of the bedrock. Limestone, for example, erodes more than sandstone, so it produces more decomposition products. But the most important factor is the climate and the erosive effect of atmospheric agents.

The texture of the soil is determined by the proportion of the sizes of the particles that make it up. For soils in which all particles have a similar granulometry, several classifications are used internationally, differing from each other mainly at the boundaries between the different classes. In an increasing order of granulometry, soil types can be classified as clay, silt, sand, gravel, pebbles and blocks "Block (rock)").

Depending on how materials with different grain sizes are mixed, in addition to their degree of compaction, the soil will present different characteristics such as its permeability or its water retention capacity and its ability to use waste as fertilizer for plant growth.

To name the different types of soil that we can find in the world, various types of classifications have been developed that, using different criteria, establish different soil typologies. Among these classifications, the most used are:

Today, the most used classifications are fundamentally based on the soil profile, conditioned by the climate. A double division is followed: climatic zone and, within each zone, the degree of evolution. Within this, three main edaphic models can be referred to, which would respond to the following names:

Vegetable soil is soil that has a certain amount of organic matter produced by autotrophic organisms. It provides the chemical elements necessary for the development of plants, animals and humans.

Plants and certain autotrophic microorganisms are the only living forms capable of producing organic matter; they capture carbon dioxide from the air and from the soil, water and the mineral salts dissolved in it. Thanks to sunlight and chlorophyll, they transform these substances into organic matter, which is used by the rest of living beings, through food chains.

When plants and animals die, the organic matter returns to the soil and undergoes decomposition by the action of decomposer organisms. These convert it into simple substances that can be used again by plants. This entire process forms the vegetal soil, the basis of agricultural activity.

Plant soil can be worn down by the decrease in minerals used by the same plants that grow in it.

According to its composition, the topsoil is sandy, clayey, rocky and organic.

It constitutes the basis of the diet of many soil animals, with whose remains humus is formed.

The soil is vitally important because it intervenes in the water cycle and the cycles of the elements and it is where a large part of the energy and matter transformations of all ecosystems take place.

Furthermore, as its regeneration is very slow, soil must be considered a non-renewable and increasingly scarce resource, because it is subject to constant processes of degradation and destruction of natural or anthropogenic origin.

The 68th session of the UN General Assembly declared 2015 the International Year of Soils (A/RES/68/232). The International Year of Soils 2015 aims to raise awareness and understanding of the importance of soil for food security and essential ecosystem functions.

The Food and Agriculture Organization of the United Nations (FAO) is responsible for implementing the International Year of Soils 2015 (IYA) within the framework of the Global Soil Partnership and in collaboration with governments and the secretariat of the United Nations Convention to Combat Desertification (UNCCD).