5 th science 8.soil erossion sub unit- 8.1 introduction formation of soil layer 8.2 formation of...

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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