Soil Erosion: Causes And Solution
Nobody likes to travel in a car on a road that is full of potholes. It is very uncomfortable to the travelers. It also caused wear and tear on the car. Potholes are cause by the wearing away of the surface soil by the pool of water left on the road after a downpour. The wearing away of the surface on the road or farmland is known as soil erosion.
Provision of gutters on both side of the road helps the pool of water to drain away. Thus, the road is made durable. Wherever you live, you see gullies whether small or big on tarred roads. They are caused by the wearing away of the top soil on roads by heavy rainfall. When this happens from year to year, gullies appear on such roads.
A good evidence of soil erosion is the sand that collects inside gutters as water flows along them. Have you ever thought about where the sand comes from? It comes from the surface of the road.
In this article, you will learn about soil erosion, what cause it and how it can be controlled.
What Causes Soil Erosion?
Human beings through various activities cause erosion. Some of the human activities that bring about erosion include
1. Bush burning
Despite the local governments by laws against burning of bushes, bushes are still set on fire for different reasons. Some people burn bushes during game hunting while other burn bushes in order to make new grass grow up for feeding cattle. Bushes also burn accidentally when stumps of cigarette are thrown away carelessly. The fire used for cooking on a farm may also spread to the bush, causing bush burning. When the bush is burnt, the surface of the ground is exposed, making it possible for rain and wind to remove the top soil, thereby cause erosion.
Usually, farmer cut the vegetation before tilling the ground on which they intend to plant their crops. Both the removal of vegetation and tilling of the ground aid erosion.
3. Growth of towns
As towns grow and houses have to be built, bushes have to be cleared. This exposes the soil to erosion. Also, roofs of houses collect rainwater and create heavy downpour unto the soil. If roofs were not there , rainwater would fall as individual drops to the ground with less impact.
4. The construction
Road of roads involves clearing of bushes and the use of heavy equipment such as graders, to work on the ground surfaces. The soil is distributed by these heavy equipment, resulting in the tearing of the soil and thus erosion.
In order to build factories, bushes are cleared; the clearing of bushes exposes the soil to erosion. Also, vibrations from the industrial machines and equipment help to break the
soil and expose it to erosion.
6. Building of market
Development of new towns necessitates building of markets. In order to build new markets, bushes are cleared. When this is done, the soil is expose to erosion.
Long ago, most of the land was covered by vegetation plants. As a result, drops of rain which first fell on the leaves of plant before reaching the ground did not strike ground with the force with which they fell. The force was reduced by the leave of plants, so that the raindrops reach the ground gently, soaking into the soil. Also, plant that covered and protected the surface of the ground prevented the rainfall that flowed of the ground from carrying the soil particles away.
As time went on, human being through various activities removed the plant cover over the ground. The effect of this is that raindrops hit the ground surface hard, loosen the soil and find it easy to carry soil particles as it flows. Wind can also carry soil particles from one place to another. These activities cause the wearing of the surface soil. This wearing away of the surface soil is referred to as soil erosion.
To investigate erosion in a school compound
Here are some materials you are required to buy: Umbrella, floodwater, filter, paper funnel.
This activity should be carried out during the rainy season.
1. Go out with an umbrella when it is ruining. Collect one cup full of floodwater on the surface of the ground, using a bowl.
2. Put your filter paper inside the funnel and pour the floodwater you collect through it.
3. Place another cup under the funnel to collect the water passing through the filter paper.
4. After the water has all filtered through, bring out the filter paper to dry in the sun.
5. What do you observe in the filter paper where did the material you found come from?
Control of Soil Erosion
Control of soil erosion can be done in several ways describe below:
1. Planting of trees and grass
Planting of trees or grass can help to control erosion. The trees and grass break the force of raindrops on the soil. Trees that can do this most are bamboo and cashew trees, especially in sandy soil since they have extensive root systems, which are capable of holding the soil. Carpet grass can also reduce erosion on the playing field of a school.
2. Making ridges across the slope
If ridges are made across a hillside farmland, the flood that runs down will be blocked and erosion reduced. If, however, ridges are made along the slope the water will be fast and erosion will be enhanced.
Terracing is the making of a series of ridges or steps that resemble a staircase on a slope. This makes water flowing down the slope to slow down at every step, thus breaking the speed of the flow.
4 Strip cropping.
Crops that provide vegetation cover for soils and those that do not can be planted in alternate strip across a slope, so that the effect of rain flood in expose part is check by the vegetation in covered parts. An example is the planting of cover crops and other crops in strip. The effect of this is that the cover crop provides vegetation cover over strips of the soil.
Covering beds, ridges, or mounds in a farm with dry grass is called mulching. Mulching has several benefits such as reducing the loss of soil moisture, controlling the growth of weeds and keeping the soil cool. With respect to erosion, mulching reduces the force of raindrops on the soil, and this reduces erosion. Mulching is the control method employed by using dry grass to cover ridges and mounds in the farm. This reduces loss of soil moisture. It keeps the soil cool and reduces the growth of weeds. The dry grasses break the impact of raindrops on the soil and therefore limit erosion.
6. Cover crops
Cover crops are plants, which are grown to improve the condition of the soil e.g. velvet beans (mucuna).A cover crop prevent erosion by covering the soil and by not allowing raindrops to fall directly on the soil. Cover crops can be planted on fallow farm plots.
7. Cross bars
Crossbars are ridges made in a farm to stop the rushing of floodwater from one part of the farm to another. This reduces the speed of floodwater as a bump reduces the speed of traffic on the road. In this way, crossbar reduces erosion. The flow of rainwater from one end of the farm to another can be reduced by making crossbar in between ridges in the farm.
Prevention of Soil Erosion
While control of soil erosion become necessary when soil erosion has taken place, prevention of soil erosion can be carried out before erosion threatens. Controlling the activities mentioned above can help to prevent soil erosion.
Demonstrating how erosion can be controlled using sandbags
Procedure (class project)
1. Locate a road in your school compound that is being destroyed by erosion.
2. Fill about fifty empty cement bags with sand.
3. Make sure the mouth of each bag is tied.
4. Arrange the bags to form a bump across the road.
5. Let the bump be check every week for two mounts during the rainy season. What do you notice?
6. Record your observations.
Demonstrating control of erosion by using short pieces of gmelina plant
Procedure (class project)
1. Locate a road in your school compound that is being destroyed by erosion
2. Cut about thirty pieces of glemina plant (glemina grow easily).
3. Dig a small hole of about 20 cm deep in the ground across the road.
4. Make the stick stand all along the hole while making sure the bases are well covered with soil.
5. Put two or three palm frond (leaves) across the stick in such way that the palm frond remain on the stick forming a kind of obstacle against the flow of water.
6. Check this obstacle for about three months during the rainy season. What do you notice?
Demonstrating the control of erosion by planting cover crops
1. Locate a part of your school that suffers erosion.
2. Fill that portion back with loamy sand.
3. Plant calopogonium or any other crop like centrosema, stylocanthes gracilis, or mucuna pruriens (vetvet beans).
4. Remove the cover crop after the rainy season.
5. Observe the soil. What do you notice?