We explain the types of soil and the characteristics of sandy, limestone, humiferous, clayey soils and more.
What are the types of soils?
Soil or earth is called the most superficial region of our planet's crust, the only biologically active one a product of the disintegration of rocks and the accumulation of organic matter. It is a layer subject to the action of climatic elements and human action: it is there where we plant crops, extract minerals and build our nations.
Soils are of vital importance, since the transformations of energy and matter occur within them. They can be considered a fundamental and non-renewable resource of our planet, especially when we refer to fertile and arable soils. They are not uniformly distributed in the world, but vary according to geographical features and climatic conditions.
There are several points of view from which we can classify the different soils that exist. Some of them, for example, take into account the physical characteristics of the environment, thus distinguishing between young soils, thin soils, soils with water deposits or with clay accumulation.
However, The most important classification is the one that distinguishes between soils based on their composition and structure that is, in the way they are formed. This last classification distinguishes between the types detailed below.
See also: Soil layers
sandy soils
As their name suggests, these soils are composed mainly of sand, that is, constitute loose fragments of very small rocks and minerals (between 0.063 and 2 mm). These soils have very little organic matter in comparison and are poorly able to retain water, making them neither fertile nor suitable for cultivation.
Even so, some plant species have adapted to life in them, using strategic resources to retain the available water in their bodies. Sandy soils are typical of coastal or desert regions.
limestone soils
Those soils that have a high content of calcareous salts (lime), typical of arid and dry places since water normally makes these chemical components flow and dilutes their concentration.
These are white or brownish soils, hard and easy to erode, which despite having a relative mineral wealth, are poorly suited for agriculture and cultivation. The limestone soils are typical of mountainous plateaus, arid plains and tundras that is, places where it rains sporadically, but when it rains, they flood.
humiferous soils
Humiferous soils are black or dark earth soils, since are rich in organic matter in the process of decomposition (humus). For this reason, they retain water very well, and are considered the most suitable for cultivation and agriculture.
Its formation occurs thanks to the accumulation and decomposition of animal and plant remains, so are typical of jungle, rural or high biotic regions.
Clay soils
As its name indicates, these are soils that have a high clay content, that is, remains of sedimentary rocks with aluminum silicates like feldspar or granite, so its color tends to range from white (higher purity) to orange (lower purity).
The main characteristic of these soils is that are very susceptible to water retention since its components tend to form colloids when hydrated, quickly becoming saturated and thus producing flooding.
In general, this makes them unsuitable for cultivation and agriculture, but through a mixture with humus and organic matter, they can be used for planting, as long as drainage and acidity are controlled. These floors are typical of humid temperate regions.
Stony soils
The stony soils are composed of rocks and rock fragments of large and varied sizes that is, they are soils recognizable to the naked eye as accumulations of stone.
These are complex soils, with little water retention capacity, whose management requires first removing the stones and often also leveling work, since are typical of mountainous regions. They are not good soils for agriculture, although some wild plant species are adapted to them.
Mixed soils
This last category contains soils that mix the properties of clay and sandy soils thus obtaining an intermediate type of soil that enjoys the advantages and disadvantages of both cases.
They can be more or less arid, depending on the climate of their regions, and Its fertility will depend largely on the presence of organic matter. In general, they can be classified according to their texture as fine and coarse, and according to their porosity as flocculated, aggregated or dispersed.
Continue with: Soil erosion
References
- “Soil” in Wikipedia.
- “The soil: an invisible universe” at the National University of La Plata.
- “Soil, differences according to its physical and chemical appearance” in the FAO.
- “Soil Types” in Boughton (United Kingdom).
- “Soil classification” in The Encyclopaedia Britannica.
