UNIT 3:

Soil Erosion

What is Erosion?

Factors Affecting Soil Erosion

Types of Erosion

What is Erosion?

Soil erosion is the wearing away or washing away of topsoil by the main agents of erosion.

The main agents of soil erosion are

Wind
Water
Man

Erosion reduces soil fertility in the root zones of plants as well as the total store of nutrients in the soil.

The following also contribute to erosion:

Destruction of trees, shrubs and grasses in land preparation for planting if cups
Poor farm management: no crop rotation, failure to adhere to planting times, poor planting material...
Overstocking: this accounts for bare patches, compaction caused by trampling by animals...
Burning of vegetation

Factors Affecting Soil Erosion

Rainfall: The amount, intensity, duration and frequency of rainfall. Greater rainfall over short durations leads to greater erosion.
Topography: The higher the slope the greater the erosion.
Vegetation Cover: Vegetation reduces the impact of rainfall and holds soil in place.
Tillage: Proper tillage increases infiltration of water, reduces runoff and reduces erosion.
Nature of the Soil: The physical and chemical properties of the soil influences how easily it will erode.
Soil Moisture: Soils with a high water table and small pore spaces are more easily eroded.
Wind Velocity: High winds can loosen exposed soil causing them.

Types of Erosion

Splash Erosion

Bare soil is loosened slightly when raindrops strike it. If this happens on slopes the soil gradually moves downhill. Torrential downpours cause more erosion damage than light showers.

Splash erosion leads to sheet erosion which leads to rill erosion which leads to gully erosion.

Sheet Erosion

When soil particles (in thin sheets) from sloping land are removed by water runoff, the process is referred to as sheet erosion.

Rill Erosion

This is a feature of bare or sparsely vegetated sloping soils. It occurs when flowing water removes the soil forming finger like channels.

Gully Erosion

A large portion of the soil is removed by water in a short time, leading to the formation of deeper channels called gullies. These gullies can deepen further into ravines which can be 50 - 100 ft deep.

Below is the transcript for the above video.

Hello friends! Today we'll learn about soil erosion. Erosion is the process by which the surface of the earth is worn away mainly by the action of wind, water and glacier. Too much rain leads to flood and this flood water washes away the topsoil. This looks so harmful sometimes. Wind leads to erosion by picking up and carrying loose particles away and breaking off more particles. Also glaciers erode the soil by slowly carving out valleys and shaping the mountains. Farming, cutting down forests and the building of roads and cities are a few human activities that also lead to erosion. There are five main types of soil erosion.

Let's learn about them one by one! Come on!

Rain drop or splash erosion. The erosion caused because of falling rain drops on soil surface which crumbles the soil structure is known as raindrop or splash erosion sheet erosion. It is the uniform removal of topsoil from the land surface by the action of wind.

Hmm! The next one is rilll erosion, the most common form of erosion, which is observed during heavy rain through many streamlets and head cuts is called rill erosion.

Gully erosion: the headward, destabilized erosion which occurs due to the runoff of surface water along drainage lines is known as gully erosion.

Stream bank erosion: the washing up of soil away from banks of a stream or a river is called stream bank erosion.

Hmm! Some of the greatest effects of soil erosion are loss of topsoil, soil compaction, reduced organic matter, drainage, issues with plant reproduction and water pollution but we can reduce this in the following ways:

Crop rotation: growing crops in rotation reduces erosion as the layer of residue prevents topsoil from being carried away by wind and water.
Conservation tillage: conservation tillage methods such as no-till planting and diking leave field surface covered with crop residue that protects the soil from eroding forces.
Contour farming: planting crops and rows around a hill reduces the risk of erosion.
Strip farming: planting fields along strips alternated in a crop rotation is an effective measure to prevent soil erosion.
Terrace farming: planting on hillsides and a step-like formation is terrace farming.
Grass waterways: by planting grass in the field as it stabilizes the soil and provides an outlet for drainage.
Diversion structures: diversion structures cause water to flow along a desired path reducing the risk of erosion
planting trees: aah-ha very good my friend we should increase vegetation as much as possible.

Now you know a lot about soil erosion. Stay tuned for more videos! Bye-bye!

Soil Erosion Quiz

Soil erosion is the wearing away or washing away of topsoil by the agents of erosion.

a. True

b. False

Which of the following is not an agent of soil erosion?

a. wind

b. sun

c. water

d. man

Which of the following contribute to soil erosion?

a. removal of vegetation

b. poor farm management

c. overstocking

d. all of the above

e. none of the above

State briefly how each of the following factors influences soil erosion:

4. Rainfall

5. Topography

6. Vegetation

7. Tillage

8. Soil type

9. Soil moisture

10. Wind velocity

11. Which is the correct order of the development of erosion

a. splash>rill>sheet>gully

b. splash>sheet>rill>gully

c. sheet>splash>gully>rill

d. gully>rill>sheet>splash

Match the correct definition with the type of erosion?

12. Splash flowing water causes fingerlike channels in the soil

13. Erosion flowing water causes deep channels within the soil.

14. Rill soil is loosened by the impact of water drops

15. Gully soil particles are removed in thin sheets

Discussion

Let's do a review of the lesson...

Post under the appropriate topic in the Forums what you learnt, what you would like to learn and what you do not understand.

References

Grade 9 SCCP Curriculum Guide
HRS Academy. Causes of Soil Erosion in India <https://www.hrsacademy.in/agribank/agricultural-engineering/383/>
Image of Causes of Soil <https://hrsacademy.in/wp-content/uploads/2016/07/Fig.-22.4.jpg>
Image of Splash Erosion <https://lh3.googleusercontent.com/proxy/x4agAQxrr3KZURtgmeZGlXJQwW2h2JazJQgpV0UIByxDTkpj3BrdsDjamxPrpukRvpBkJwWuiBPxBpD3J5OgBCwMxEQKqnmMbAKj>
Image of Types of Erosion <https://encrypted-tbn0.gstatic.com/images?q=tbn%3AANd9GcTzZ9xvYvXDV4Qp5Q1BgdRhlyP286MooGmAIg&usqp=CAU>

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