WHAT IS THE COMPOSITION OF THE SOIL? - GEOGRAPHY - 2025

The composition of the soil is based on organic and inorganic matter, minerals, water and air. The soil is a superficial layer of the earth's crust in which different microorganisms, minerals, nutrients, plants and animals coexist.

The soil contains water and nutrients that allow us to produce food, raise animals, plant trees and plants, and obtain water and minerals.

Hence, the constant development of ecosystems depends on the soil. In addition, the soil serves as a support for plants and crops, softens the effects of the climate and favors the existence of water currents.

This important layer has been slowly forming over time due to the disintegration of its surface rocks by the combined action of wind, water and various changes in temperature.

This process through which the rock fragments become small and become part of the soil is known as weathering, which can be physical, chemical or biological.

In order to form the soil, the rocks mix with air, water and the different organic and inorganic remains from animals and plants.

The soil is of vital importance for plants as they use it to aerate their roots, retain water and supply their water and nutritional needs.

That is why the soil and its components are the main elements that allow the existence of life on the planet.

Main components of soils

The soil is made up of the following elements: minerals, organic and inorganic matter, water and air.

Minerals

Most of them come from bedrock in the soil, which slowly dissolves. They can also be the product of water and wind, which are responsible for dragging minerals from areas that are eroded.

The main minerals in the soil are phosphorus, potassium, calcium and magnesium, and they constitute the largest component of the soil, making up almost 49% of its totality.

It is also common to find quartz, clay, carbonates, sulfates and oxides and hydroxides of iron, manganese and aluminum.

Organic and inorganic matter

Organic matter is represented by the remains of vegetables, fungi, worms, insects and other animals that make life in the soil.

One of the main elements of organic matter is humus, a mixture made up of organic molecules from the decomposition of matter.

This mixture is vital, as it contributes to:

-Water retention to hydrate the soil

-Ion retention to facilitate ion exchange with plant roots

-Improve plant nutrition

-Avoid soil compaction

-Increase porosity.

The microorganisms that make life in matter are usually more than 20,000. Earthworms and insects are responsible for breaking up organic matter, while fungi and bacteria break down the matter, releasing its main nutrients.

In addition, these microorganisms are responsible for forming pores in the soil that allow aeration, water storage and growth of plant roots.

Inorganic matter contributes to making the soil fertile, being caused by weathering processes, which provides the soil with phosphorus, sulfur and nitrogen.

Water

It constitutes from 2 to 50% of the volume of the soil. It is essential to transport the nutrients that contribute to the growth of plants and facilitate the processes of chemical and biological decomposition.

Air

The air occupies the same volume as the water inside the soil as it is located in the pores, that is, the free spaces left by soil particles. The main gases that make up the soil are oxygen, nitrogen and carbon dioxide.

Oxygen helps them to maintain their tissues, transport the nutrients they need and carry out the processes of perspiration and nutrition.

Nitrogen stimulates the growth of plants above the ground, giving them the natural bright green color that characterizes them.

Carbon is a source of energy for microorganisms. It should be noted that the soil is the largest reservoir of carbon present in the atmosphere.

Soil horizons

If a vertical section of the soil is made, covering from its surface to the bedrock, several horizontal layers can be distinguished that are called horizons or soil profiles and that differ in their composition, color and texture.

Horizon 0

It is not defined as soil yet, but forms a small thin layer that contains organic matter without decomposing or decomposing. This horizon mostly contains living organisms.

Horizon A

It is quite rich in humus because it contains the highest density of fauna, flora, roots and microorganisms.

This horizon is usually one of the most affected by the actions of living beings and the climate.

Horizon B

Unlike the previous horizon, it has a higher plant content and is formed by the roots of trees and shrubs.

The number of microorganisms present is usually small.

Horizon C

In this case, the soil is made up of a parent rock that is partially altered by the effects of the climate and human beings, as well as the chemical and biological processes of the soil.

Horizon R

It is one of the purest horizons as it is formed by an unaltered bedrock. That is, simply a rocky material that has not yet undergone physical or chemical changes.

References

1. Composition of soil. Retrieved on August 20, 2017 from fao.org
2. Definition of soil. Retrieved on August 20, 2017 from de
3. DeGómez, T; Kolb, P. and Kleinman, S. (2015). Soil composition. Retrieved on August 20, 2017 from extension.org
4. Soil. Retrieved on August 20, 2017 from net
5. Soil. Retrieved on August 20, 2017 from fao.org
6. Soil. Retrieved on August 20, 2017 from pntic.mec.es
7. Mateo, P. and Romero, S. (2008). Agrotechnology. Retrieved on August 20, 2017 from educarm.es
8. Soil composition and formation. Retrieved on August 20, 2017 from dlib.indiana.edu
9. Soil horizons. Retrieved on August 20, 2017 from soils4teachers.org.