Soil erosion is a type of soil degradation that naturally occurs on all land. There are many causes of soil erosion, most of them being the same as other forms of erosion: namely water, ice, wind, and gravity. The effects of soil erosion can include the loss of fertile land to floods or water pollution, among others.
What Causes Soil Erosion?
According to geoscientist R. P. C. Morgan, soil erosion is usually caused by a mixture of events that naturally occur as well as the influence of human activity, having affected regions such as those bordering the Mediterranean Sea or China for millennia.
The largest cause of soil erosion cannot be linked to a single major event or activity. So which of the following events most contributes to soil erosion? There’s no straight answer, and each situation is different.
Soil erosion is one of the side effects of heavy rain. Massive amounts of water can displace the top part of the soil, dispersing materials such as fine sand particles, organic matter, and silt. If the phenomenon continues over a longer period of time, even heavier sand and gravel particles will be displaced.
The most obvious and dramatic soil movement and erosion occur during short and intense thunderstorms. However, less intense but steady rainfall usually has the same effect, although it’s not as obvious.
Heavy farming is another major cause of soil erosion. Working the land by raising crops and through other agricultural activities will reduce the soil’s overall structure and the levels of organic matter within it, leaving it more vulnerable to the effects of heavy rain.
Tilling is the most significant farming-related factor in soil erosion, as the constant softening of the soil will enable erosion. An article published in Science Direct, “Evolution of the Plow Over 10,000 Years and the Rationale for No-Till Farming,” shows that farms where tilling is not used as a farming practice or is used sporadically, the chances of soil erosion significantly drop.
Another major contributor to soil erosion is the physical shape of a particular piece of land. If the land is on an incline, the slope will facilitate the fast movement of water during rainfalls, oversaturating the soil and greatly contributing to its erosion.
Vegetation helps keep the structure of soils, so the lack of plants and crops on a piece of land is known to contribute to the acceleration of soil erosion. If an area of land is naturally less populated with plants, it can be seen as a clue regarding that particular area’s predisposition for erosion.
Wind is also known to greatly reduce soil quality and cause erosion, especially when paired with another erosion-facilitating factor. Light winds, however, do not do any damage to the soil structure. The types of soils most affected by wind are light and sandy soils, which can be easily lifted and transported onto other plains.
Facts About Human Soil Erosion
Human soil erosion is an ever-increasing factor in the overall erosion and degradation of land. Here are the most important human soil erosion facts:
- According to recent studies, human activity causes as much as ten times more soil erosion than all the Earth’s natural processes combined.
- Studies made by University of Michigan geologist Bruce Wilkinson show that soil erosion caused by humans is by no means a new phenomenon. In fact, human influence on soil degradation, in general, can be traced back to the beginning of the first millennium. It is estimated that natural erosion affects about 60 feet of land every million years, while soil erosion in agricultural-heavy parts of the United States is estimated at 1,500 feet per million years, largely due to human influence. Other parts of the world show even higher erosion rates.
- The effects of deforestation on soil erosion are also massive. Removal of trees without reforestation affects the planet in a number of ways and soil erosion definitely is one of them. First, trees provide the soil with valuable dead organic material, through leaves, animal droppings, and fruit that falls to the ground; all of these help the soil retain its shape. Also, deforestation exposes the soil to rainfall and its resulting effects on the soil. The tree roots also contribute to the overall structure of the soil, further linking deforestation and erosion.
How Does Soil Erosion Affect Streams and Rivers?
The effects of soil erosion stretch beyond the affected lands; they also damage streams and rivers. An article published in the Journal of Hydrology, “An Analysis of the Processes of Riverbank Erosion,” by J.M. Hooke, describes how land displacement causes increased sedimentation and pollution in running waters, clogging them and greatly affecting all the flora and fauna in the area, such as fish and other species.
It also limits the ability of affected rivers and streams to absorb larger amounts of water, increasing the chances of a flood during rains. The narrowing of river canals can also make boat navigation impossible. Soil erosion behind seawalls is also a major issue, as it can cause a seawall to fail, leading to property damage.
Soil Erosion Effects
The effects of soil erosion can range from mild to catastrophic. The biggest effect is definitely the loss of topsoil, the fertile part of the land that can be used to grow plants. This alone can cause food shortages and famine in many parts of the world.
It also leads to further erosion, as the water won’t be as easily dispersed beneath the top part of the soil. Also, the lack of crops will reduce the organic nutrients in the soil, even more, leaving it barren for the long term.
Another major issue caused by soil erosion is possible water contamination and pollution. Since the water can’t be effectively absorbed by the land, runoffs will occur and carry fertilizer or pesticide with them.
The contaminated water can do further damage to the environment by poisoning and killing fish in nearby lakes and rivers. It also can make its way into sources of drinking water, becoming a real threat to the health of nearby populations.
Soil erosion is not a new problem for humankind, but it’s definitely a pressing one. Through careful farming and crop management, water control and drainage, as well as properly educating individuals about the dangers of soil erosion, the problem can gradually be eradicated and more fertile land will become available.
List of sources:
“Soil Erosion and Conservation,” R. P. C. Morgan
“Evolution of the Plow over 10,000 Years and the Rationale for No-Till Farming,” R. La, D.C. Reicosky, J.D. Hanson, Science Direct
“An Analysis of the Processes of Riverbank Erosion,” J.M. Hooke, Journal of Hydrology