by Dilip Kumar Chandra PGT Biotechnology JNV Raipur CG

2. Soil is the top most layer of
the earth’ crust .
Soil is a mixture .
Soil is very necessary for the
growth of plants.
Soil provides support to the plants .
Soil is a rich source of organic and in
organic substances .

3. FORMATION OF SOILFORMATION OF SOIL
• Formation of soil is a natural process and it is aFormation of soil is a natural process and it is a
continuous process . The soft layers of rockcontinuous process . The soft layers of rock
erode due to wind and rains . Under certainerode due to wind and rains . Under certain
circumstancescircumstances
• Rain water collected in the cracks of rocksRain water collected in the cracks of rocks
freezes and increases in volume. As a result thefreezes and increases in volume. As a result the
rock breaks into small pieces. This type ofrock breaks into small pieces. This type of
breaking up of rocks is calledbreaking up of rocks is called
“WEATHERING OF ROCKS”“WEATHERING OF ROCKS”
• Soil is formed due to changes in temperatureSoil is formed due to changes in temperature
and climate.and climate.

4. DO YOU KNOWDO YOU KNOW
Formation of one inch of soilFormation of one inch of soil
takes 500- 1500 years .takes 500- 1500 years .

5. CONSTITUENTS OF SOILCONSTITUENTS OF SOIL
• When the land is dug we see different colouredWhen the land is dug we see different coloured
layers of soillayers of soil
• Soil has three distinct layers.Soil has three distinct layers.
• 1.1. TOP SOILTOP SOIL
• 2. SUB SOIL2. SUB SOIL
• 3.BED ROCK3.BED ROCK
Layers of soil

6. TOP SOILTOP SOIL..
• The top most layer containsThe top most layer contains
decayed and decaying plant anddecayed and decaying plant and
animal matter. This is calledanimal matter. This is called
FERTILE SOIL OR ORGANICFERTILE SOIL OR ORGANIC
SOIL.SOIL.

7. SUB SOILSUB SOIL
This is the middle layer which isThis is the middle layer which is
harder than the top soil . It hasharder than the top soil . It has
soluble mineral salts and organic soilsoluble mineral salts and organic soil
in small quantities. This soil isin small quantities. This soil is
known asknown as sub soilsub soil

8. BED ROCKBED ROCK
This has a pieces of rock and many layersThis has a pieces of rock and many layers
of rock .This form the lower and is veryof rock .This form the lower and is very
hard . This can not be dug with ordinaryhard . This can not be dug with ordinary
implements. This is known asimplements. This is known as “bed rock”“bed rock”

9. IMPORTANT FEATURES OFIMPORTANT FEATURES OF
FERTILE SOIL.FERTILE SOIL.
• Fertile soil is porous inFertile soil is porous in
naturenature
• Fertile soil is light in weightFertile soil is light in weight
• Fertile soil is having capacityFertile soil is having capacity
to hold waterto hold water
• Fertile soil is rich inFertile soil is rich in
• organic and inorganicorganic and inorganic
substances.substances.
EARTH WORM

10. TYPES OF SOILTYPES OF SOIL
Soil is mainly grouped in to fourSoil is mainly grouped in to four
types depending upon the colour ,types depending upon the colour ,
its constituents and structure ofits constituents and structure of
particles .They areparticles .They are

11. BLACK SOIL RED SOIL
ALLUVIAL SOIL LATERRITE SOIL

12. RED SOILRED SOIL
Red soil is mainly found in SouthRed soil is mainly found in South
India. The presence ofIndia. The presence of iron oxideiron oxide isis
responsible for its red in colour. Itresponsible for its red in colour. It
has particles of clay and sandy soil.has particles of clay and sandy soil.
Ex:-Ex:-Tea and coffee.Tea and coffee.

13. BLACK SOILBLACK SOIL
Black soil is the most suitable forBlack soil is the most suitable for
agriculture. The reason for black inagriculture. The reason for black in
colour is the decomposed constituents ofcolour is the decomposed constituents of
the organic substances. Moisture contentthe organic substances. Moisture content
is great in this soil. It is found in theis great in this soil. It is found in the
northern part of Karnataka . This type ofnorthern part of Karnataka . This type of
soil is suitable for the growth ofsoil is suitable for the growth of CottonCotton
and Ground nutand Ground nut..

14. ALLUVIAL SOILALLUVIAL SOIL
The soil on the beach and river banksThe soil on the beach and river banks
is mainly made up of sand and is fertileis mainly made up of sand and is fertile
. This soil is known as alluvial soil.. This soil is known as alluvial soil.
Ex- River banks.Ex- River banks.

15. LATERITE SOILLATERITE SOIL
Generally this soil isGenerally this soil is red or reddishred or reddish yellow inyellow in
colour.colour. It looks likeIt looks like honey comb .honey comb . It has lessIt has less
amount of calcium and is found in areas whereamount of calcium and is found in areas where
there is heavy rainfall. When the moisture inthere is heavy rainfall. When the moisture in
the soil reduces to reasonable quantity this soilthe soil reduces to reasonable quantity this soil
is dug and made in tois dug and made in to bricks.bricks. By theirBy their
structure and composition The soil is alsostructure and composition The soil is also
classified in three types.1. sandy soil , clay soilclassified in three types.1. sandy soil , clay soil
and loamy soil.and loamy soil.

16. EROSION OF SOILEROSION OF SOIL
The running water during rainsThe running water during rains
carries the soil.carries the soil.Flowing waterFlowing water
Blowing wind carry soil along withBlowing wind carry soil along with
them.them. The process of loss of top soilThe process of loss of top soil
by wind and water is calledby wind and water is called soilsoil
erosion.erosion.

18. CAUSES FOR SOIL EROSIONCAUSES FOR SOIL EROSION
11. Deforestation .. Deforestation .
2. Over grazing of animals in2. Over grazing of animals in
grasslands.grasslands.
3. Growing the crops in the same3. Growing the crops in the same
land year after year.land year after year.
4. Unscientific use of soil.4. Unscientific use of soil.

19. Deforestation
Over Gragzing

20. METHODS OF PREVENTINGMETHODS OF PREVENTING
SOIL EROSION.SOIL EROSION.
• The erosion of top soil by wind and waterThe erosion of top soil by wind and water
is prevented by growing grass and trees.is prevented by growing grass and trees.
• Ploughing at right angles in slopes .Ploughing at right angles in slopes .
• The soil erosion on slopes can be checkedThe soil erosion on slopes can be checked
by ploughing in furrows.by ploughing in furrows.
• To prevent erosion of soil crops are grownTo prevent erosion of soil crops are grown
in strips . This is known as strip farming.in strips . This is known as strip farming.

21. Strif farming Reforestation

22. REVIEWREVIEW
1. What do you mean by weathering of rocks ?1. What do you mean by weathering of rocks ?
2. What are the important features of top soil?2. What are the important features of top soil?
3. Name the various types of soil.3. Name the various types of soil.
4. What is soil erosion?4. What is soil erosion?
5.What are the causes of soil erosion?5.What are the causes of soil erosion?
6. What are the preventive measures of soil6. What are the preventive measures of soil
erosion?erosion?

23. ASSIGANMENTASSIGANMENT
1. What is soil1. What is soil
2. How soil is formed2. How soil is formed
3. Name the different types of soil3. Name the different types of soil
4.What is soil erosion4.What is soil erosion

24. PROJECTPROJECT
Visit a near by field and collectVisit a near by field and collect
different types of soil and observedifferent types of soil and observe
colour and texture of soilcolour and texture of soil

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