What Causes Soil Erosion?

By Sarah Moore

Around the world, human activities are accelerating the rate of soil erosion, which has significant implications for the future of human life.

While soil erosion is a natural process, numerous human activities are increasing the rate at which we are losing soil, which has a detrimental impact on the productivity of agricultural land, nutrient availability in crops, carbon cycling, and even socio-economic conditions.

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Given the fact that soil is essential for 95% of our food source, it is important to understand how human activity causes soil erosion to protect this vital resource, as well as protect the planet from environmental damage.

What is soil erosion?

The process of soil erosion is both natural and man-made. It refers to the removal of the top layer of soil, in nature, this is caused by wind and water, although human activities can increase exposure to these elements. Another way humans induce soil erosion is via the agricultural process known as tillage.

First, the soil becomes detached, then it is moved, and finally, it is deposited. Because topsoil has high levels of organic matter, it is important for soil fertility and crop quality, therefore, when human activity accelerates the rates of topsoil removal it negatively impacts the agricultural potential of the land.

In addition, the deposition of the topsoil in other locations causes the pollution of bodies of water such as wetlands, lakes, and watercourses.

In nature, this process generally occurs at a slow pace, meaning that the reverse process of soil production can counter it. However, human activities are currently causing soil erosion to occur at rapid rates, causing several problems.

Particularly, the loss of topsoil is posing a huge threat to the future of food security as it reduces the fertility of the land and quality of the crops. Given that food demand continues to rise as the global population and urbanization increase, scientists are rapidly looking for ways to prevent and reduce the impact of the causes of soil erosion that are discussed below.

Deforestation

Deforestation is a major cause of soil erosion, perhaps the main cause. Trees and their roots provide the soil with an anchor, as well as shelter from the wind and rain. When forests are wiped out, the land becomes exposed, leaving it vulnerable to being washed or blown away by elements.

While the slash and burn technique of deforestation introduces significant volumes of carbon dioxide into the atmosphere it has become popular due to its speed and cost-effectiveness at clearing an area.

This technique in particular leaves soils vulnerable to the wind and rain, acting as a major contributor to soil erosion.

The World Wildlife Fund (WWF) estimates that as much as half of the world’s topsoil has already diminished because of deforestation. Since the beginning of the 20th century, it is estimated that 3.9 million square miles of forest have been lost. This huge loss of forest area has no doubt led to a significant increase in topsoil erosion.

Logging and mining

Logging, similar to deforestation, causes soil erosion as it removes the trees protecting the soil from the elements, anchoring it to the ground. Tree roots act to hold the soil together, and their leaves and branches form canopies that prevent the impact of the harsh elements.

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In addition, living trees produce leaf litter which is also vital in protecting the topsoil from erosion. Already the world has lost a significant portion of its forests to logging activities, resulting in not only topsoil erosion, but pollution of rivers, lakes, and estuaries, as well as polluting coral reef environments by introducing too much soil into these areas.

Mining is another major industry that directly adds to soil erosion. By its nature, mining requires the removal of earth to retrieve resources below the surface. Mining can destroy landscapes, not only removing earth but also removing the trees that are essential to maintaining the soil.

Agriculture

Agriculture relies on quality soil to grow quality produce. However, farming practices themselves, such as tillage and the grazing of animals, cause soil erosion.

Tillage is the process whereby land is prepared for growing crops. It involves using machinery to churn the land, leading it ready to plant seeds. This process has been linked to greater levels of soil erosion. One recent study showed that tillage is associated with greater levels of topsoil loss, whereas abandoning this process can lead to a 60% reduction in soil loss.

Also, grazing animals such as sheep add to soil erosion due to eating plants and grass and exposing the soil to the elements. The hooves of these animals pacing back and forth also act to churn up the ground, further adding to soil erosion.

Climate change

Finally, climate change also acts as a major contributor to soil erosion. Rising global temperatures are initiating more vigorous hydrological cycles, which are resulting in increased rainfall and more intense and regular storms. The effect is that more topsoil is becoming washed away by increased rainfall events.

These four factors are those that are having the greatest contributions to soil erosion, and without controlling and managing their influence on soil erosion, the world’s food security in future years will be under threat.

Further Reading

• All Agricultural Science Content
• Artificial Intelligence could help the agriculture industry meet increasing food demands
• Leaf litter converted to biochar could reduce N20 emissions from vegetable fields
• An analysis of the effects GM crops have on agriculture
• The use of natural hydrogels in food and agriculture practices