SOIL DEGRADATION: TYPES, CAUSES AND CONSEQUENCES - BIOLOGY - 2025

The degradation of soil is a serious problem that involves the reduction or total loss of physical productivity, chemical, biological and economic land. One of the inherent drawbacks of the process is the enormous speed with which soils disintegrate, and the extremely slow rates of regeneration of the same.

This phenomenon encompasses the loss of massive amounts of land. For example, in the European Union it is estimated that approximately 52 million hectares are affected by degradation processes. This alarming figure corresponds to almost 16% of its territory.

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Degradation is a process that occurs over a wide variety of timescales: it can occur in a single storm, spanning decades and many spatial scales.

The factors that promote soil degradation are extremely varied, and many are related, making it difficult to study and specify.

Among the most prominent are soil erosion - considered the most serious - caused by effects of air or water, alterations in temperatures and in the structure caused by human activity, pollution, encrotation, flooding, desertification, chemical deterioration, among others.

Soil degradation is not a specific problem of our time. In fact, the term has been in use since the time of great thinkers and philosophers. Plato, for example, described the phenomenon of degradation and associated it with the deforestation of ecosystems.

What is soil?

The soil comprises the superficial portion of the earth's crust. Given its composition rich in fauna and flora, it is considered biologically active. The soil is formed thanks to the disintegration processes of the various rocks, as well as the decomposition and residues of the activities of living organisms that reside on it.

The appropriate properties of a soil were defined by the authors Archer and Smith in 1972, as "those that provide the maximum availability of water and at least 10% of air space in the soil subjected to a suction of 50 mb".

Following this principle, the density should range between 1.73 g / cm ³ for sandy loam soils, 1.50 g / cm ³ for sandy loam, 1.40 g / cm ³ for smooth loam soils and 1, 20 g / cm ³ for clay loam soils.

When these, and other soil properties, are modified and lose their structure and fertility, it is said that the soil is undergoing a degradation process.

Types of soil degradation

There are different classifications of soil degradation. For some it can be divided into degradation of fertility and soil contamination.

Fertility degradation and soil contamination

In the loss of fertility there is a significant decrease in the capacity of said soil to be able to support and promote the development of living organisms, while contamination is determined by the increase of harmful or toxic substances in the composition of the soil.

On the other hand, we can also classify them as biological, physical, chemical, water and wind degradation.

Biological degradation

Biological degradation refers to the increased mineralization of humus that exists in the surface layer of the earth, being an immediate consequence of physical degradation. These soils experience loss of nutrients and lead to increased runoff and erosion.

Physical degradation

Physical degradation consists of the reduction of the content of organic matter, as a consequence of the felling of the vegetation cover and the excessive practice of inappropriate crops.

The diagnostic characteristic is the decrease in porosity and the soil exhibits a compact and caked texture.

Chemical degradation

Chemical degradation, also called "base washing", is an event where the water component drags essential nutrients for plants into deeper regions of the soils.

This phenomenon leads to the deterioration of fertility and greatly lowers the pH values ​​of the soil, making it more acidic.

It can also occur due to the increased concentration of certain toxic components, such as aluminum. Although chemical pollution can occur from natural sources, the most common is that humans cause an imbalance in the composition of the land, thanks to the use of pesticides and fertilizers.

Water degradation

The cause of water degradation is water, which affects the breakdown and transport of soil elements.

Wind degradation

Wind degradation is a phenomenon that occurs due to the intervention of the wind, causing a sweep, abrasion and drag of soil particles.

Causes

Erosion

Soil erosion is a natural phenomenon of loss of soil particles that has been part of the dynamics of geology for thousands of years, forming part of geological processes and climatic changes.

Thus, the concept of erosion is broad, being a physical, chemical and anthropogenic process. If we remove humans from the equation, the loss of soils caused by erosion would be offset by the generation of new soils in other areas.

Currently, erosion has become a very serious problem that affects almost 2 billion hectares of land worldwide.

This number corresponds to an area larger than that of the United States and Mexico combined. Annually, between 5 and 7 million hectares of land prone to tillage activity are lost.

Erosion is classified as water and wind. The first is the cause of 55% of the deterioration mentioned previously, while wind power causes around 33%.

Climate change

Climate change leads to the alteration of precipitation and evopotranspiration patterns, which can lead to increased land degradation.

For example, in countries with very marked seasons, the climate is a crucial factor. The dry and arid periods are characterized by little rainfall, while the rainy seasons are mostly torrential, easily eroding the land.

Floods and landslides

These natural phenomena are related to the volume of rainwater and the intensity with which it falls.

Consequences

Soil degradation encompasses a wide range of consequences, which impact both its structure, composition and productivity. The first is the loss of ions and nutrients, such as sodium, potassium, calcium, magnesium, among others.

Soil fertility is reduced by the decrease in organic matter content. They also decrease the number of organisms living in the soil.

The loss of the soil structure and the dispersion of the particles by the drops of water in the bare soil cause the superficial sealing of the soil, which makes it difficult for the water and the roots of the plants to enter.

The porosity of the soil, the infiltration capacity and the capacity to retain water and humidity are diminished and in turn affect the plants that make life in the soil. In addition, runoff values ​​increase and thus its erosion potential.

The loss of fine materials located on the surface makes it difficult to support the root system of plants, and therefore their anchoring to the substrate.

Short and long term consequences

The consequences can also be classified on a temporal level: in the short term, soil degradation causes a decrease in production, which influences an increase in operating costs. In this case, as time passes, the soil will need more and more fertilizers and the production will be much less.

On the other hand, in the long term the effects can include the total infertility of the lands, the abandonment and the desertification of the territory.

Stages of the soil degradation process

Degradation usually occurs in three stages: the first consists of the gradual destruction of the original characteristics of the soil. This stage is practically imperceptible, since it can be quickly corrected with the use of fertilizers and other products. Thus, a virtually unchanged production is achieved.

This is followed by a more pronounced loss of soil organic matter. Stage two is characterized by a structural collapse of the lands. In addition, there is superficial damage that prevents the infiltration of water and the correct penetration of the roots of the plants.

The last stage of damage consists of collapses of the pore space. There is a high rate of erosion and it is difficult to operate agricultural machinery in the area. Productivity at this point is usually minimal or non-existent.

The time of passage between one stage to another depends on the degree of intensity of land use and the implementation of inappropriate practices in cultivation.

Solutions

As we mentioned, the main cause of soil degradation is erosion. To counteract its effects, two methods have been proposed: one biological and one physical.

The first consists of adapting crops to the soil, such as replacing annual crops with perennials; while physical techniques are based on the construction of terraces and dams, prevention of the formation of ravines and the management of basins.

In addition, there must be environmental policies that reduce the use of excess chemicals, fertilizers and pesticides. A viable alternative is agroecology tools, which have become very popular today.

References

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