soil erosion definition

Soil Erosion: Definition, Causes And Consequences

Last modified on 2020, February 21th

Although soil erosion is a natural process, human activities over the past decades have greatly accelerated it. In fact, according to UNESCO, land degradation is undermining the well-being of two-fifths of humanity, driving species extinct and intensifying climate change. According to a senior UN official, all of the world’s topsoil could be gone within 60 years.

Soil Erosion Simple Definition

Soil erosion is a gradual process of movement and transport of the upper layer of soil (topsoil) by different agents – particularly water, wind, and mass movement – causing its deterioration in the long term.

What Is Soil Erosion? A Soil Erosion Scientific Definition

According to a Pereira and Muñoz-Rojas (2017) synthesis, soil erosion is one of the major causes, evidence of, and key variables used to assess and understand land degradation. Soil erosion is a consequence of unsustainable land use and other disturbances, such as fire, mining, or intensive agricultural uses. The loss of soil may have serious impacts on the quantity and quality of soil ecosystem services, with serious economic, social, and political implications.

What Types Of Soil Erosions Exist?

Soil erosion is a complex process that depends on soil properties, ground slope, vegetation, and rainfall amount and intensity. According to Montgomery, modifications in land use are one of the most impactful ways of accelerating soil erosion. These changes then have a cascade effect as the loss of fertile topsoil cover sends millions of tons of sediments into lakes and reservoirs, changing ecosystems and impacting agricultural production and water quality. This has been the case with the Bo River in Vietnam.

According to Al-Kaisi from Iowa State University, there are 5 main types of soil erosion: 1) sheet erosion by water; 2) wind erosion; 3) rill erosion (happens with heavy rains and usually creates smalls rills over hillsides); 4) gully erosion (when water runoff removes soil along drainage lines) and 5) ephemeral erosion that occurs in natural depressions. But as we have briefly mentioned, if it wasn’t for human-made activities, soils would be less susceptible to erosion. What are the causes behind soil erosion then?

Main Causes And Impacts Of Soil Erosion

The most effective way of minimizing erosion is to guarantee a permanent surface cover on the soil surface, such as trees, pasture or meadow. However, compared to original forest soils, the soil in pasture fields and croplands have less capacity to hold up and are more susceptible to erosion. These soils also have less capacity to absorb water, which makes flooding (and its economic, social and environmental impacts) more common.

1. Deforestation For Agriculture Is One Of The Causes Of Soil Erosion

The increasingly high demand of a growing population for commodities such as coffee, soybean, palm oil or wheat is clearing land for agriculture. Unfortunately, clearing autochthonous trees and replacing them with new tree crops that don’t necessarily hold onto the soil increases the risks of soil erosion. With time, as topsoil (the most nutrient-rich part of the soil) is lost, putting agriculture under threat.

2. Soil Erosion Is Also Caused By Overgrazing, Which Causes Floods Too

Overgrazing is caused by intensive cattle raising. As plants don’t have the recovery period they need, they end up being crushed and compacted by cattle. In this process, topsoil sediments are transported elsewhere. As for the remaining soil, it can lose its infiltration capacity, which means more water getting lost from the ecosystem and a harder time for new plants to grow.

3. Agrochemicals Cause Soil Erosion And Degradation

The use of chemicals under the form of pesticides and fertilizers on (often) monocultural crops is a very usual way of helping farmers improve their yields. However, the excessive use of phosphoric chemicals ends up causing an imbalance of microorganisms in the soil moisture, stimulating the growth of harmful bacteria. As the soil gets degraded, the risk of erosion increases and the sediments sweep (via the actions of water and wind) into rivers and nearby regions, possibly contaminating nearby ecosystems.

4. Construction And Recreational Activities

Setting up buildings and roads also have their share of responsibility when it comes to soil erosion as they don’t allow for the normal circulation of water. Instead, it runs off to flood nearby lands, speeded up erosion in these areas. Moreover, motor-based activities such as motocross also have the potential to disturb ecosystems and change (even if at a smaller scale compared with other causes) and erode the soil.

The Importance Of Soil, Especially Topsoil

Soil is a very important resource that allows the production of food, fiber, or forages. Despite it being a renewable resource, it renews slowly – generating three centimeters of topsoil takes 1,000 years. Therefore, protecting it is very important to guarantee effective long-term agriculture.

The main problem associated with soil erosion is that it comes along a decrease in soil productivity. A study based on the results of 40 soil associations reported that the effects of soil erosion on soil productivity was mostly the result of subsoil properties such as soil water availability, root growth or plow layer fertility – which impact yield results. In the ends, with an unfavorable subsoil, erosion is easier and yields and productivity are more greatly affected.

From Soil Erosion To Soil Regeneration

Despite the fact human activities have accelerated soil erosion, there are ways of repaying the damage we have created. From reforestation to windbreaks, stone walls or more sustainable agriculture techniques. Let’s analyze them in greater detail.

Fighting Soil Erosion Via Sustainable Farming Practices

Regenerative agriculture techniques have the potential to preserve and restore ecosystems and habitats and improve the quality and health of the soil.

Protecting The Soil By Planting Windbreaks

Windbreaks are linear plantings of shrubs and trees with the goal of improving crop production, protect the soil, people and livestock. According to FAO, windbreaks can reduce wind velocities for a distance approximately 15 times the height of the tallest trees. As a result, there is a lower rate of soil loss across large crop areas.

Stone Walls To Prevent Soil Erosion

According to Camera et. al (2018) the sediments accumulating behind the dry-stone walls create suitable land for farming and prevent soil erosion.

Reforestation Helps Protect The Soil

According to FAO, reforestation helps reduce sedimentation rates in downstream valleys. According to this UN agency, reforestation on unstable land and around water regions such as rivers increases the water-retention capacity of land and improve water quality, both of which benefit food production. Moreover, according to a recent Nature study, reforestation also has a tremendous potential to help fight climate change as trees capture huge amounts of CO2.

Conservation Tillage And Soil Erosion

Conservation tillage stands dor as any form of tillage that minimizes the number of tillage passes. Conservation tillage techniques have the potential to reduce the vertical movements of soil. In this way, more crop residues are left on the soil surface which reduces the soil’s exposure to water or wind erosion.

[Image credits to erosion on Shutterstock]

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