i usually

Geographic

2022

We explain what soil is and how it is composed. In addition, classification of soils and their different characteristics.

The soil is a highly varied and multifaceted surface.

What is the soil?

The soil is the shallowest portion of the Earth crust, made up mostly of rock residues from erosive processes and other physical and chemical alterations, as well as organic matter resulting from the biological activity that takes place on the surface.

The soil is the most visible portion of the planet Earth, where we sow the crops, build our houses and bury our dead. It is an extremely varied and multiform surface, on which the climatic events like rain, wind, etc.

In the same way, the ground is the scene of complex processes chemical and physical, as well as a ecosystem underground of small animals and abundant microorganisms, whose presence directly impacts its fertility.

Soils are formed by the destruction of rock and the accumulation of different materials over the centuries, in a process that involves numerous physical, chemical and biological variants, which results in an arrangement in well differentiated layers, such as those of a pie, observable at points of failure or fracture of the earth's crust.

How is the soil composed?

Soil is made up of solid, liquid and gaseous ingredients, such as:

  • Solid. The mineral skeleton of the soil is mainly composed of rocks, such as silicates (micas, quartz, feldspars), iron oxides (limonite, goethite) and aluminum (gibbsite, boehmite), carbonates (calcite, dolomite), sulfates (aljez), chlorides, nitrates and solids of organic or organic-mineral origin, such as the different types of humus.
  • Liquids. Abounds Water on the ground, but not always in a pure state (as in deposits) but loaded with ions and salts and various organic substances. The water in the soil moves by capillarity, depending on the permeability of the soil, and transports numerous substances from one level to another.
  • Fizzy. The soil presents various atmospheric gases such as oxygen (O2) and carbon dioxide (CO2), but depending on the nature of the soil it may also have the presence of gaseous hydrocarbons such as methane (CH4) and nitrous oxide (N2O). Soil gases are tremendously varied.

Soil characteristics

The soil has elements of importance for plant life.

The properties and characteristics of the soil are enormously varied, according to the type of soil and the particular history of the region where it is found. But in broad strokes we can identify the following characteristics:

  • Variability. Soils generally have components that are not very homogeneous in their size and constitution, so that despite showing themselves as a homogeneous mixtureIn fact, they have rocks and elements of different sizes and diverse nature.
  • Fertility. The possibility of soils to host nutrients derived from nitrogen, sulfur and other elements of importance for plant life, is called fertility and is related to the presence of water and organic material, and with the porosity of the soil.
  • Mutability. Although the processes of soil change are long-term and we cannot verify them directly, it is true that they are constantly mutation physics and chemistry.
  • Solidity. The soils present different properties physical, including solidity and texture: there are some more compact and rigid, others more malleable and soft, depending on their particular geological history.

Types of soils

There are various types of soil, each the result of different formation processes, the result of sedimentation, wind deposition, weathering and organic waste. They can be classified according to two different criteria, which are:

According to its structure. Can we talk about:

  • Sandy soils. Unable to retain water, they are scarce in organic material and therefore not very fertile.
  • Limestone soils. They are abundant in calcareous minerals and therefore in salts, which gives them hardness, aridity and a whitish color.
  • Humid soils. Of black earth, they are abundant in decomposing organic matter and they retain water very well, being very fertile.
  • Clay soils. Composed of fine yellowish grains that retain water very well, which is why they tend to flood easily.
  • Stony soils. Composed of rocks of different sizes, they are very porous and do not retain water at all.
  • Mixed soils. Mixed soils, usually between sandy and clayey.

According to their physical characteristics. Can we talk about:

  • Lithosols. Thin layers of soil up to 10cm deep, with very low vegetation and also called “leptosols”.
  • Cambisols. Young soils with initial accumulation of clays.
  • Luvisols. Clay soils with a base saturation of 50% or higher.
  • Acrisols. Another type of clay soil, with a base saturation of less than 50%.
  • Gleysols. Soils with constant or almost constant water presence.
  • Fluvisols. Young soils from fluvial deposits, generally rich in calcium.
  • Rendzina. Soils rich in organic matter on limestone.
  • Vertisols. Clay and black soils, located near runoffs and rocky slopes.
!-- GDPR -->