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Soil Erosion
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- 2. Head Up • Grade:10 Date: Friday May 20, 2022 • Subject: Agricultural Science Topic: Soil • Sub-Topic: Soil Erosion • Objectives: • 1. Define Soil Erosion • 2. Differentiate between Natural and Accelerated Soil Erosion • 3. Pose arguments on the effects of soil erosion on the environment and agriculture
- 3. What comes toyour mind?
- 4. What is SoilErosion? •Soil erosion is the process by which soil particles are carried away from one area and deposited (put or set down) in another area. This is normally caused by water or wind (agents of soil erosion).
- 5. Types of SoilErosion There are 2 types of Soil Erosion: Natural Soil Erosion and Accelerated Soil Erosion
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- 7. This takes placein an undisturbed natural environment as a result of: 1.Running water on slope areas with loose soil 2.Landslides of loose, saturated (fully soaked) soil. 3.Strong winds blowing over loose soil in dry areas
- 8. 4. Sea wavespounding the land in coastal areas- waves pound rocks into pebbles and pebbles into sand. Waves and currents sometimes transport sand away from beaches, moving the coastline farther inland.
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- 10. This takes placeas a result of the activities of human beings who disturb the natural environment. These include: 1.Burning the vegetation on the land, including slash and burn 2.Overgrazing of pastures by livestock 3.Deforestation- The cutting down and removal of trees 4.Mining and quarrying operations 5.Over weeding or brush cutting to closely to the soil 6.Unsuitable cultural or soil conservation practices on hilly terrain
- 11. Some Causes ofSoil Erosion
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- 14. •Cause - Impactof heavy raindrops •Effect- Soil dislodges and splashes up on plants. They are also carried away by running water.
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- 16. •Cause- Running waterdislodges soil particles •Effect- Soil particles move downhill as a sheet of soil.
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- 18. •Cause- Water runningdown a slope of land with no plants •Effect- Creates many tiny channels called rills where the soil has eroded.
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- 20. •Cause- Heavy rainfalland fast flowing water on a slope. •Effect- Rills become more eroded. This leads to wider, deeper channels called gullies.
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- 22. •Cause- Heavy rainfallon loose soil on a slope. •Effect- Loose soil slides away when it is saturated.
- 23. Loss of TopSoil
- 24. •Cause- Running waterin hill or mountain areas. •Effect- If soil is not protected by a cover crop, organic matter or mulch, it can be lost.++++++++++++++++++++++++++++++++++++
- 25. Silting up ofwater courses floods because the level of seabed rise and is uneven
- 26. •Cause- Soil particlescarried away by running water •Effect- Causes silting up of streams and rivers, eventually leading to flooding of a river basin.
- 27. Alluvial soil deposits Alluvialsoils are soils deposited by surface water
- 28. •Cause- Soil particlesbrought down mountainous slopes by streams and rivers •Effect- Alluvial soil deposits form at the mouths of rivers and on river banks.
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- 30. •Soil Creep- Strongwinds can cause soil creep. This is the gradual movement of loose soil particles such as sand on the soil surface. •Saltation- Saltation of soil particles occur when strong winds cause loose soil particles to leap (jump) suddenly, stay in the air for a while then fall to the ground forming heaped areas of soil.
- 32. Effects of soilerosion •Loss of fertile land •Pollution and sedimentation in water bodies that sees a decline in marine life •Degraded lands hold less water and are more prone to flooding. •Rills and gullies make cultivation harder.
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- 34. Activity • 1. Janelives in the desert. One day she noticed that some sand particles were blown into the air then fell to the ground after a while. • i. What is a possible name for this process? (1 mark) • ii. What was the agent of soil erosion? • 2
- 35. •. Tell whetherthese acts of soil erosion are natural or accelerated •i. In the dessert, strong winds blow over the soil in dry areas. •Ii. Farmer brown burns the vegetation on his farm. •iii. Cows feed in the same pasture for a very long time. •Iv. Water running down a steep slope.
- 36. • 3. Namethe type of erosion in the following pictures.