5 th science 8.soil erossion sub unit- 8.1 introduction formation of soil layer 8.2 formation of...
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5th SCIENCE
8.SOIL EROSSIONSub Unit- 8.1 Introduction 8.2 Formation of soil layerFormation of soil layer 8.3 ErosionErosion 8.4 TerracingTerracing 8.5 Preventing Soil erossionPreventing Soil erossion
What is soil erosion ?
»The reduction of soil cover on the land by water or wind is called soil erosion
Erosion:• Is the natural process
of soil being moved from one place and deposited in another.
• Is radically expedited by humanity’s use of land.
• Occurs primarily due to wind or water movement, or agricultural practices.
The thickness of the layer of soil on the land is not same in all places.
Formation of soil layer• The action of the
sun ,wind and rain results in the wearing down or weathering of rock and stones in to fine particles . These particles form a layer of the land.
Soil on land is carried away by flowing
water and wind this is called soil erossion
The movement
of stray animals
increases the danger
of soil erosion.
It takes 800 to 1000 years for a 2.5 cm thick layer of soil to form from rocks
Terracing:
• Terraced bean fields in Iowa
•Terraced rice paddies in Yunnan Province, China
Stretch of sloping agricultural land is divided in to smaller plots of the flat land called terraces.
Low mud walls or bunds are built on the outer sides of plots to block flowing water are called bunds
Designed as a method to make
steep areas arable, as well as retain
valuable topsoil from water erosion by slowing down the
movement speed of the water from one
step to another.
• Many terrace designs include either a small lip at the edge • or a band of native vegetation on lower gradient slopes.
•Sa Pa, Vietnam
Preventing Soil erossion
• 1)Planting trees
2)Growing grass
Planting trees around fields and growing
grass on open stretch of land
are simple ways of preventing soil
erosion.
Reserve areas for grazing of animals
• Q1). What are the causes of soil erosion?• flowing water and wind ,The movement of stray
animals are the causes of soil erosion• Q2).What are the advantages of planting trees?• Roots of plants hold soil particles in which they
grow, leaves that fall from trees cover the soil beneath so rain cannot loosen the soil. These are the advantages of planting trees
• Reference – Text Book, Cbsc ,Web.
Rayat Shikshan Sanstha , Karmveer Vidhyaprabhodhini Madhya Vibhag ,Satara
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