CBSE Class 11 Geography Soils Notes

IMPORTANCE OF SOILS

1.provide support & nutrients to the plants

2.plants provide food and clothes are grown over the soils

3.Provide shelter to microorganisms

4.Supply nutrients to plants 

The major factors affecting the formation of soil are 1.relief, 2.parent material, 3.climate, 4.vegetation 5.life-forms and 6.time. 7. human activities

Components of the soil

1.mineral particles, 2.humus, 3.water 4. air.

Structure of the soil

If we dig a pit on land and look at the soil, we find that it consists of three layers which are called horizons.

‗Horizon A‘ is the topmost zone, where organic materials have got incorporated with the mineral matter, nutrients and water, which are necessary for the growth of plants.

‗Horizon B‘ is a transition zone between the ‗horizon A‘ and ‗horizon C‘, and contains matter derived from below as well as from above. It has some organic matter in it, although the mineral matter is noticeably weathered.

‗Horizon C‘ is composed of the loose parent material. This layer is the first stage in the soil formation process and eventually forms the above two layers. This arrangement of layers is known as the soil profile. Underneath these three horizons is the rock which is also known as the parent rock or the bedrock. Soil, which is a complex and varied entity has always drawn the attention of the scientists.

CLASSIFICATIONOF SOILS

In ancient times, soils used to be classified into two main groups – Urvara and Usara, which were fertile and sterile, respectively. In the 16th centrury A.D., soils were classified on the basis of their inherent characteristics and external features such as 1. texture, 2. colour, 3. slope of land and 4. moisture content in the soil.

Based on texture, main soil types were identified as 1.sandy, 2.clayey, 3.silty and 4.loam, etc. On the basis of colour, they were 1.red, 2.yellow, 3.black, etc. the ICAR has classified the Indian soils on the basis of their nature and character as per the United States Department of Agriculture (USDA) Soil Taxonomy.

(i) Inceptisols (ii) Entisols (iii) Alfisols (iv) Vertisols (v) Aridisols (vi) Ultisols (viii) Others

On the basis of genesis, colour, composition and location, the soils of Indiahave been classified into: (i) Alluvial soils(ii) Black soils(iii) Red and Yellow soils(iv) Laterite soils(v) Arid soils (vi) Saline soils(vii) Peaty soils(viii) Forest soils.

Alluvial Soils

1.Alluvial soils are widespread in the northern plains and the river valleys.

2.These soils cover about 40 per cent of the total area of the country.

3.They are depositional soils, transported and deposited by rivers and streams.

4.Through a narrow corridor in Rajasthan, they extend into the plains of Gujarat.

5.In the Peninsular region, they are bound in deltas of the east coast and in the river valleys.

6.They are generally rich in potash but poor in phosphorous.

7.In the Upper and Middle Ganga plain, two different types of alluvial soils have developed, viz. Khadar and Bhangar. Khadar is the new alluvium and is deposited by floods annually, which enriches the soil by depositing fine silts.

8.Bhangar represents a system of older alluvium, deposited away from the flood plains.

9.Both the Khadar and Bhangar soils contain calcareous concretions (Kankars). These soils are more loamy and clayey in the lower and middle Ganga plain and the Brahamaputra valley.

10.The sand content decreases from the west to east.

11.The colour of the alluvial soils varies from the light grey to ash grey. Its shades depend on the depth of the deposition, the texture of the materials, and the time taken for attaining maturity.

Black Soil

1.Black soil covers most of the Deccan Plateau which includes parts of Maharashtra, Madhya Pradesh, Gujarat, Andhra Pradesh and some parts of Tamil Nadu.

2. In the upper reaches of the Godavari and the Krishna, and the northwestern part of the Deccan Plateau, the black soil is very deep.

4.These soils are also known as the ‗Regur Soil‘ or the ‗Black Cotton Soil‘.

5.The black soils are generally clayey, deep and impermeable.

6.They swell and become sticky when wet and shrink when dried. So, during

the dry season, these soil develop wide cracks.

7.Chemically, the black soils are rich in lime, iron, magnesia and alumina.

8.They also contain potash. But they lack in phosphorous, nitrogen and organic matter.

9.The colour of the soil ranges from deep black to grey.

Red and Yellow Soil

1.Red soil develops on crystalline igneous rocks in areas of low rainfall in the eastern and southern part of the Deccan Plateau.

2.Along the piedmont zone of the Western Ghat, long stretch of area is occupied by red loamy soil.

Yellow and red soils are also found in parts of Odisha and Chattisgarh and in the southern parts of the middle Ganga plain.

3.The soil develops a reddish colour due to a wide diffusion of iron in crystalline and metamorphic rocks.

4.It looks yellow when it occurs in a hydrated form.

5.The fine-grained red and yellow soils are normally fertile,

6.whereas coarse-grained soils found in dry upland areas are poor in fertility.

7.They are generally poor in nitrogen, phosphorous and humus.

Laterite Soil

1.Laterite has been derived from the Latin word ‗Later‘ which means brick.

2.The laterite soils develop in areas with high temperature and high rainfall.

3.These are the result of intense leaching due to tropical rains.

4.With rain, lime and silica are leached away, and soils rich in iron oxide and aluminum compound are left behind.

5.Humus content of the soil is removed fast by bacteria that thrives well in high temperature.

6.These soils are poor in organic matter, nitrogen, phosphate and calcium, while iron oxide and potash are in excess.

7.Hence, laterites are not suitable for cultivation; however, application of manures and fertilizers are required for making the soils fertile for cultivation.

8.Red laterite soils in Tamil Nadu, Andhra Pradesh and Kerala are more suitable for tree crops like cashewnut.

9.Laterite soils are widely cut as bricks for use in house construction. These soils have mainly developed in the higher areas of the Peninsular plateau.

10 The laterite soils are commonly found in Karnataka, Kerala, Tamil Nadu, Madhya Pradesh and the hilly areas of Odisha and Assam.

Arid Soils

1.Arid soils range from red to brown in colour.

2.They are generally sandy in structure and saline in nature. In some areas, the salt content is so high that common salt is obtained by evaporating the saline water.

3.Due to the dry climate, high temperature and accelerated evaporation, they lack moisture and humus.

4.Nitrogen is insufficient and the phosphate content is normal.

5. Lower horizons of the soil are occupied by ‗kankar‘ layers because of the increasing calcium content downwards.

6. The ‗Kankar‘ layer formation in the bottom horizons restricts the infiltration of water, and as such when irrigation is made available, the soil moisture is readily available for a sustainable plant growth.

7.Arid soils are characteristically developed in western Rajasthan, which exhibit characteristic arid topography.

8.These soils are poor and contain little humus and organic matter.

SOILS IN INDIA
1.They are also known as Usara soils.
2.Saline soils contain a larger proportion of sodium, potassium and magnesium, and thus, they are infertile, and do not support any vegetative growth.
3.They have more salts, largely because of dry climate and poor drainage. They occur in arid and semi-arid regions, and in waterlogged and swampy areas.
4. Their structure ranges from sandy to loamy.
5.They lack in nitrogen and calcium. Saline soils are more widespread in western Gujarat, deltas of the eastern coast and in Sunderban areas of West Bengal.
6. In the Rann of Kuchchh, the Southwest Monsoon brings salt particles and deposits there as a crust. Seawater intrusions in the deltas promote the occurrence of saline soils. In the areas of intensive cultivation with excessive use of irrigation, especially in areas of green revolution, the fertile alluvial soils are becoming saline.
7.Excessive irrigation with dry climatic conditions promotes capillary action, which results in the deposition of salt on the top layer of the soil. In such areas, especially in Punjab and Haryana, farmers are advised to add gypsum to solve the problem of salinity in the soil.

Peaty Soils
1.They are found in the areas of heavy rainfall and high humidity, where there is a good growth of vegetation.
2.Thus, large quantity of dead organic matter accumulates in these areas, and this gives a rich humus and organic content to the soil.
3.Organic matter in these soils may go even up to 40-50 per cent. These soils are normally heavy and black in colour.
4.At many places, they are alkaline also.
5.It occurs widely in the northern part of Bihar, southern part of Uttaranchal and the coastal areas of West Bengal, Orissa and Tamil Nadu.

Forest Soils
1.Forest soils are formed in the forest areas where sufficient rainfall is available.
2.The soils vary in structure and texture depending on the mountain environment where they are formed.
3.They are loamy and silty on valley sides and coarse-grained in the upper slopes.
4.In the snow-bound areas of the Himalayas, they experience denudation, and are acidic with low humus content.
5.The soils found in the lower valleys are fertile.

SOIL DEGRADATION
1. Soil degradation can be defined as the decline in soil fertility, when the nutritional status declines and depth of the soil goes down due to erosion and misuse.
2.Soil degradation is the main factor leading to the depleting soil resource base in India.
3.The degree of soil degradation varies from place to place according to the topography, wind velocity and amount of the rainfall.

SOIL EROSION
1.The destruction of the soil cover is described as soil erosion. The soil forming processes and the erosional processes of running water and wind go on simultaneously.
2. There is a balance between these two processes.
3.The rate of removal of fine particles from the surface is the same as the rate of addition of particles to the soil layer. Human activities too are responsible for soil erosion to a great extent.
4.The human population increases, the demand on the land also increases.
5.Forest and other natural vegetation is removed for human settlement, for cultivation, for grazing animals and for various other needs.
6.Wind and water are powerful agents of soil erosion because of their ability to remove soil and transport it.
7.Wind erosion is significant in arid and semi-arid regions.
8 In regions with heavy rainfall and steep slopes, erosion by running water is more significant.
9.Water erosion which is more serious and occurs extensively in different parts of India, takes place mainly in the form of sheet and gully erosion.
10 Sheet erosion takes place on level lands after a heavy shower and the soil removal is not easily noticeable.
11.But it is harmful since it removes the finer and more fertile top soil. Gully erosion is common on steep slopes.
12.Gullies deepen with rainfall, cut the agricultural lands into small fragments and make them unfit for cultivation.
12.A region with a large number of deep gullies or ravines is called a badland topography. Ravines are widespread, in the Chambal basin.
13.Besidesthis, they are also found in Tamil Nadu and West Bengal.
14The country is losing about 8,000 hectares of land to ravines every year.
15.Deforestation is one of the major causes of soil erosion.
16.Plants keep soils bound in locks of roots, and thus, prevent erosion. They also add humus to the soil by shedding leaves and twigs.
Forests have been denuded practically in most parts of India but their effect on soil erosion are more in hilly parts of the country.
A fairly large area of arable land in the irrigated zones of India is becoming saline because of over irrigation.
The salt lodged in the lower profiles of the soil comes up to the surface and destroys its fertility.
Chemical fertilizers in the absence of organic manures are also harmful to the soil. Unless the soil gets enough humus, chemicals harden it and reduce its fertility in the long run. This problem is common in all the command areas of the river valley projects, which were the First beneficiaries of the Green Revolution. According to estimates, about half of the total land of India is under some degree of degradation. Every year, India loses millions of tons of soil and its nutrients to the agents of its degradation, which adversely affects our national productivity. So, it is imperative to initiate immediate steps to reclaim and conserve soils.

Soil Conservation

Question. Define the term Pedogenesis.
Answer: Process of soil formation is called Pedogenesis.

Question. Soil basically contains silica, clay, chalk and humus.
⦁ With respect to alluvial soil, answer the questions.
(i) What are its types?
(ii) Where is it found?
(iii) State its characteristics.
(iv) Crops grown in it.
Answer: Alluvial Soil- Is of two types- A- Deltaic coastal B-Inland Alluvium Deltaic alluvial soil of the South Indian River is darker while those of Himalayan river yellowish. Inland alluvial soil is of two types. Bhangar and Khadar. Bhangar is old alluvial soil whereas Khadar is new alluvial soil.
This soil is called ex-situ.
Distribution-Punjab, Haryana, Uttar Pradesh, Bihar, West Bengal.
Characteristics.
1- Found at a depth of 500 m.
2- Yellow in colour.
3-Rich in potash, humus and lime.
4- Deficient in Nitrogen.
Crops: It is suitable for rice, wheat, pulses, sugarcane jute etc.

Question. What is soil erosion? Suggest methods to control it.
Answer: Soil erosion: The removal of top layer of soil by the agency of air, water and the human activities is called soil erosion.
Measures to control it:
Stop deforestation:, b. Afforestation, reforestation, c. Control overgrazing, contour ploughing etc.

Question. Differentiate between sheet erosion and gully erosion.
Answer : Sheet erosion : The slow removal of thin layers of soil Occurs on gentle slopes Found in the plains of Brahmaputra ( Assam) ,Ganga,( UP) Kosi ( Bihar).
Gully erosion : Formation of deep gullies by cutting the bedrock.
Occurs in steep slopes Found in Chambal valley ( M.P.)and other plateau areas.

Question. What is soil conservation?
Answer: Soil Conservation- Measures undertaken to prevent the loss and destruction of soil to maintain the productivity of soil is called Soil conservation.

Question. State the agronomic methods of soil conservation.
Answer: These are the measures taken while carrying out the agricultural activities. Agronomic Measures include
⦁ Growing leguminous plants, adding fertilizers and rotating crops.
⦁ Practicing strip cropping and terraced farming.
⦁ Slash and burn method or jhooming or shifting cultivation has been legally banned.
⦁ Farmers conserve grazing areas (pastures) by limiting the time of grazing of their cattle.
⦁ Planting of shelter belts perpendicular to the direction of winds.
⦁ To stop deforestation and undertake reforestation as well as Afforestation.

Question. Suggest the mechanical measures to control the soil erosion.
Answer : 
Mechanical Measures include
Contour ploughing and contour bunding.
Plugging of gullies.
Constructing check dams across the rivers and watershed management.

Question. With respect to black soil, answer the question:
(i) How is it formed?
(ii) Its distribution,
(ii) its characteristics and
(iv) Crops grown in it.
Answer: BLACK SOIL/Regur soil/lava soil:
(i)It is volcanic in origin and formed by the disintegration of Basalt rocks.
It is formed in Situ. (found in the area where it is formed)
It is also known as black cotton soil.
Distribution-Occurs mainly in Deccan trap covering the parts of states of Maharashtra, Gujarat, MP, A..P & Southern Tamil Nadu.
Characteristics
1-Colour varies from black to chestnut brown
2- Rich in iron, potash & lime
3- Retains moisture
4-Develops cracks when moisture is lost from it.(Self ploughing)
Crops Grown: Cotton, Jowar, Wheat, Sugarcane, Gram.

Question. With respect to laterite soil, answer the following. (i) How is it formed? (ii) Its distribution, (ii) its characteristics and (iv) Crops grown in it.
Answer: It is formed by weathering of laterite rocks. Laterite soil is formed by leaching of Laterite rocks.
Leaching-Removal of Lime & Silica from the rocks due to alternate wet & dry spells is called Leaching.
Distribution- Andhra Pradesh, Tamil Nadu, WB, Summits of western & Eastern Ghats, Goa & Kerala.
Characteristics-
1-Red in colour as it contains iron oxide
2-Poor in nitrogen & rich in lime.
3-Acidic and does not retain the moisture. One should use organic fertilizer.
Crops grown- Cashew & tapioca, coffee.

Question. With respect to Red soil, answer the following.
(i) How is it formed?
(ii) Its distribution,
(ii) Its characteristics and
(iv) Crops grown in it.
Answer: It is formed by weathering of crystalline and metamorphic rocks.
Distribution- Tamil Nadu, Karnataka, Chhattisgarh, Orissa.
Characteristics:
1-Red in color due to the presence of Iron Oxide.
2- Poor in nitrogen & lime.
3- Rich in Potash.
4- Does not retain the moisture
5-Responds to fertilizers.
Crops grown: Wheat, Rice, Millets, Cotton, Sugarcane, Pulses.

Give reasons:

Question. Soils at different places are different.
Answer: Soil formation depends upon parent rock, relief features, climatic conditions, plant and animal life of that place etc. As these conditions are not same throughout India, the soils are of different types.

Question. Khadar is more fertile than Bhangar soil.
Answer: Khadar is new alluvial soil which gets renewed every year. Hence it is more fertile as its minerals are not been used by crops much.
Bhangar soil is old soil which is been used for long time for growing crops and hence its fertility is less. More ever it is not renewed every year. Hence…

Question. Laterite soil is less fertile.
Answer: Laterite soil is formed by leaching where lot of nutrients gets lost from it either by percolation or by washing away with it.
As the nutrients are less in it, it is less fertile.
Moreover it is acidic in nature.

Question. Crop rotation is important for soil conservation.
Answer: Crop rotation includes growing crops like wheat, rice, and millets etc which exhaust soils by absorbing nutrients from it followed by growing leguminous crops which fix the atmospheric nitrogen and thus increase its fertility.

Question. Fertilizers are to be added to Red Soil to grow crops.
Answer: Red soil is poor in nutrients like nitrogen, humus, lime etc.
Moreover it is slightly acidic in condition. That is why manuring is essential to grow crops in it.

Question. Soil conservation is the need of hour.
Answer: (i) Soil formation is extremely slow process whereas soil erosion is much faster. Thus the soil is getting eroded at much faster rate and its fertility is decreasing.
For cultivation, soil is must. That is why soil conservation is necessary.

Question. Deforestation and overgrazing are to be controlled.
Answer: Roots of trees and grass hold the soil and thus prevent its erosion.
They reduce the speed of water and thus control the rate of erosion.
Thus to protect soil, deforestation and overgrazing are to be controlled.

Question. Organic fertilizers must be used in laterite or red soil.
Answer: Both of these soils are acidic in nature. Chemical fertilizers are mainly consisting of bases in it and if used in these soils, the acid and base will combine to form salt and water. Thus soil will be become salty and will become useless for cultivation. That is why…

Board Questions

Question. Name the type of soil found on the summits of the Eastern Ghats.
Answer: Laterite soil is the soil found on the summits of the Eastern Ghats.

Question. What is laterite soil? 
Answer: Laterite soils are those formed under alternating wet and dry spells. They are composed of a mixture of hydrated oxides of aluminum and iron. They are poor in nitrogen, potash, lime. They are low in fertility but respond favorably to manuring and leaching of soil of its nutrients.

Question.Differentiate between sheet erosion and gully erosion.
Answer: When topsoil gets eroded from very large areas due to fast flowing rivers, it is called sheet erosion. It occurs on areas of gentle slope. Gully erosion occurs when running water etches out deep rivers creating a bad land topography in an otherwise normal landscape.Mainly occurs where the steep slope lies.

Question. Name the four major soils types found in India leaving out desert and mountain soil.
Answer: The major soils of India are — (a) Alluvial soil, (b) Black soil (c) Red soil, (d) Laterite soil.

Question. Why is laterite soil unsuitable for the cultivation of crops? Name an area in India, where this soil is found.
Answer: Laterite soil is unsuitable for cultivation due to leaching which renders the topsoil infertile. An area in India, where laterite soil is found is the summits of Western and Eastern Ghats.

Question. Give a single word for each of the following: 1. The loose rock material, together with humus, forming the uppermost layer of the earth's crust and serving as a source of food and moisture for plants.
Answer: Top soil. 2. The process of percolation by which valuable mineral nutrients are washed down from the top layer of the soil only to deposit them in the lower layers, thereby making the topsoil infertile.(1996) A. The answer is — Leaching.

Question. Name two important agents of erosion. For each, state one method of controlling the erosion caused.
Answer:Two important agents of erosion are running water and wind. —To prevent erosion by running water, dams and barrages can be built which check the speed of water down the slopes, afforestation along hill slopes also check speed of water. —To prevent erosion by wind, indiscriminate felling of trees must be stopped and area under plantation and forests must be increased.

Question. Give two characteristic features of the soil found most suitable for growing cotton and sugarcane in Maharashtra. 
Answer: The soil found suitable is black soil. Its characteristics are (a) It is volcanic in origin, (b) Found mainly over the Deccan trap, rocky regions of Maharashtra and parts of Gujarat and Madhya Pradesh (c) Has the self-ploughing capacity, (d) Highly retentive of moisture, (e) Sticky when wet, dry when fine grained.

Question. State two methods of soil conservation.
Answer: The two methods of soil conservation are — Contour binding, / Planting of more trees. / Overgrazing to be stopped, (any two)

Question. Explain the need for soil conservation in India. State two methods of soil conservation.
Answer: Its a process of controlling soil erosion and maintaining the fertility of soil.Soil can be conserved by the following methods -
(i) Reforestation
(ii) cover plants
(iii) shelter belts
(iv) terraced cultivation.

Question. With reference to red soils in India: Name two states, where it is found.(2000)
Answer: (i)It is found in Tamil Nadu / Karnataka / Orissa / Andhra Pradesh / Madhya Pradesh / Goa. (Any two) State two disadvantages of this soil.(2000) A. The disadvantages of this soil are: (a)It is poor in humus, nitrogen, lime, phosphorous, (b)Not retentive of moisture.

Question. How does the soil of the Ganga-Yamuna plain differ from that of central Maharashtra?
Answer: Soil found in Ganga-Yamuna plain is alluvial soil, whereas soil found near central Maharashtra is black soil. Alluvial soil is a transported soil. Black soil is formed in situ.

Question. Name the soil known for its self-ploughing quality and capacity to hold moisture. Name one cash crop for which it is most suited. 
Answer: The soil known for its self-ploughing capacity is black soil. The cash crop that grows best is cotton/sugarcane.

Question. Name one state in India which mostly has red soil?
Answer: The state that has red soil is Tamil Nadu / Karnataka / Goa / parts of Andhra Pradesh / Orissa, (any one)

Question.(i) Which soil do you associate with the Deccan Trap?
(ii) State one advantage of this soil.
Answer: (i) The soil that is associated with the Deccan Trap is black soil/ regur soil/ volcanic soil/ lava soil. (ii) One advantage of this soil is that it is fine grained and retains moisture / It is rich in lime, iron, potash, alumina, calcium / It does not undergo leaching.

Question. Mention two characteristics of red soil. 
Answer: 1, Red soil is porous, and friable and not retentive of moisture.
2. It is generally poor in lime, nitrogen, phosphorous and humus.
3. It rsponds to fertilizers.
4.it is rich in iron oxide which gives it red colour.

Question. How is Regur soil formed? Mention four important properties of Regur soil.
Answer: Regur soil is formed due to denudation of lava flow rocks. Its four important properties are as follows:
(i) It is self-irrigatory
(ii) It is a deep fine grained soil
(iii) It is dark in colour
(iv) It is rich in lime, iron and potash.

Question. What is the meaning of leached soil? 
Answer: It is the process by which soluble substances such as organic and mineral salts are washed out of the upper layer of a soil into a lower layer by percolating rainwater.

Question. State two differences between black soil and alluvial soil.
Answer: Black soil : Residual, formed by denudation of lava rocks, contains iron, lime, potash, magnesium, deficient in Phosphorous and organic matter or humus, retentive of moisture, sticky when wet cracks are developed during dry season. Alluvial soil: formed by sediments rich in potash and lime (transported soil) deficient in nitrogen and phosphoric acid And humus.

Question. What is conservation of soil? Suggest methods to control it.
Answer: Soil conservation refers to the steps taken to protect the soil from erosion.It includes maintaining the fertility of soil. Two farming techniques are : contour ploughing, terrace farming, multiple cropping terracing, multiple cropping, mulching crop rotation, strip cover cropping, contour bunding.

Question. Mention two ways by which soil can get nitrogen.
Answer: By growing legumes, by crop rotation, cover crops, by adding nitrogenous fertilizer or by adding manure.

Question. Name the transported soil most widely found in India. State the two sub-categories into which it is generally divided. What are the local names and which one of them is superior to the other?(1996)
Answer: Transported soil most widely found in India is alluvial soil. Sub-categories — Old alluvium / Bangar, New alluvium / Khadar. Khadar is more superior to them as the floods replenish it.

Question. How is red soil formed? State two reasons for the low productivity of red soil. 
Answer:It is formed by the disintegration of the metamorphic rocks. It is less productive as it is
(i) Deficient in nitrogen and phosphoric acid
(ii) Poor in humus and organic matter.
(iii)Coarse texture soil
(iv) Nonretentive of water.

Question. How is alluvial soil formed? Why is this soil agriculturally important?
Answer: Alluvial soils are formed by deposit of silt brought by rivers. Rich in potash, humus, lime, hence are agriculturally very important.

Question. Name two important agents of erosion. For each, state one method of controlling the erosion caused.
Answer: They are Water and wind.

1. Method of controlling erosion by water—
(a) contour ploughing,
(b) step farming
(c) afforestation.

2. Method of controlling erosion by wind—
(a) planting shelter belts,
(b) afforestation.

Question. Why is the soil in the valley of the river Godavari different from that found in the valley of the river Yamuna? 
Answer: Soil found near the valley of the River Godavari is black soil. Soil found near the valley of the River Yamuna is alluvial soil. Black soil is formed due to disintegration of basalt. It is volcanic in origin. It is formed in the place where it is found (in situ), whereas alluvial soils are formed by the denudation of different types of rocks and the deposition of sediments by rivers.

Question. Give one difference between the following: Khadar soil and Bhangar soil. 
Sheet erosion and Wind erosion.
Answer: On Next Page (page no 8)
(ii) Sheet erosion is the removal of a thin layer of top layer of soil due to erosion caused by running water. Wind erosion is caused in arid lands with little rain by wind.

Question. Which soil is found suitable for growing coffee in Karnataka 
Answer: The soil found suitable for growing coffee is Laterite soil/Red soil.

Question. Give reasons as to why: a. Red soil is red in colour.
Answer: Due to High iron oxide content.
b. Large tracts in Maharashtra are covered with black soil.
Answer: Maharashtra is made up of lava tracts (Deccan Trap region) which when weathered is reduced to black soil. Formed in situ because of solidification of lava during the volcanic activity.
c. Man is largely responsible for soil erosion.
Answer: Because of faulty farming practices and deforestation, overgrazing, quarrying, mining, increasing urbanisation.

Question. State two main differences between alluvial soil and red soil.
Answer:Two main differences between alluvial and red soils are as follows: Alluvial soil is a transported soil, while red soil is residual. Alluvial soil is highly moisture retentive, while red soil is not.

Question. (a) Name the soil which is formed due to high temperature and heavy rainfall with alternating wet and dry periods.
Answer: Laterite soil.
b. Write any two characteristics of red soil.
Answer: (1) Red soil is light in texture.
(2)Red in colour because of its iron oxide content, colour varies from chocolate brown to yellow.Rich in potash.
(3)Porous, friable but not retentive of moisture.
(4)Poor humus content.
(5)Becomes fertile with proper use of fertilizer and irrigation.

Question. Name one soil of volcanic origin commonly found in India. 
Answer: One soil that is of volcanic origin is — Regur soil/ Black soil/Black Cotton soil/Lava soil, (any one)

Question. Explain the following terms —
a. In situ Ans: In situ— The soils which are found where they are formed eg. black ,red and laterite soils are in situ.
b. Transported soil.
Answer: (i) Transported soil — These are soils which are carried down by agents of gradation such as river and wind. Ex. Alluvial soil
c. Humus:
Answer: It is the organic matter present in the soil formed by the decomposition of plants and animals.

Question. (a) Name two states in India where Regur soil is formed. In what ways does Regur soil help agriculture?
Answer: Regur soils are found in the Deccan trap, comprising the greater part of Maharashtra and Gujarat, Madhya Pradesh (any two). This soil has the property of holding moisture which is released to the plants during the dry period which is extremely useful in the un irrigated areas.

(b)Mention two main characteristics of Laterite soil.
Answer: i.These soils are porous and friable and not retentive of moisture. ii. They are poor in lime, nitrogen and humus.

Question. State the differences between alluvial soils found in the lower courses and the upper courses of rivers.
Answer: Upper course: They are coarse, porous and not so fertile. Lower course: They are fine grained and very fertile.

Exam Questions Chapter Soils Class 11 Geography 

Question. Where is laterite soil mainly found?
Answer: It is found on the summits of the Western and Eastern Ghats, Malwa plateau, parts of Andhra Pradesh, Tamil Nadu, Karnataka, Kerala, Odisha

Question. Name the 3 types of alluvial soil according the area of deposition.
Answer: • Deltaic Alluvium – found in the plains of the Ganga, Indus and Brahmaputra, Mahanadi, Godavari, Krishna and Kaveri.
• Inland Alluvium – This is found in the plains of the Ganga, Brahmaputra and of Punjab, Haryana, UP, Bihar.
• Coastal Alluvium – It is of Tidal origin and is found in the coastal strip of peninsula India and the coastal strip of Gujarat.

Question. How does Reafforestation help in soil conservation?
Answer: The roots of trees hold the soil together and prevents it from being carried away by wind or water.

Question. What are the differences between Black soil and Alluvial soil.
Answer: • Black Soil: *Residual soil, *formed by the denudation of lava rocks, *rich in lime, iron, magnesium, calcium, alumina and potash * moisture retentive * black to chestnut brown in colour * insitu *poor in humus
• Alluvial Soil: *Transported soil * formed by the sediments brought down by rivers * rich in potash and lime * yellow to light brown in colour *exsitu *rich in humus
Similarities between red soil and laterite soil. Both are red in colour due to the presence of iron oxide, both are infertile, friable, not moisture retentive, poor in organic matter, nitrogen, humus.

Question. Mention the two major factors which determine the type of soil found in India.
Answer: Climate and nature of the parent rock.

Question. Why does alluvial soil differ in texture?
Answer: It varies in texture as it is deposited by rivers. Coarse material is deposited in the higher altitude areas and fine material is deposited in the lower plain.

Question. Why is soil erosion by wind common in arid regions?
Answer: There is no vegetation or human habitation to reduce the velocity of wind or stop it from carrying away the soil. Arid regions do not support vegetation and since there are no roots to hold the soil together, the wind can carry the loose soil easily.

Question. What is meant by soil fertility?
Answer: The power of the soil to support vegetation is termed as fertility of the soil. A fertile soil has sufficient depth, adequate nutrients and high moisture content.

Question. Why is laterite soil not suitable for agriculture?
Answer: This soil is highly acidic and not moisture retentive. It is leached soil. It is good as building material since it becomes hard when dry.

Question. Mention the crops that grow on laterite soil.
Answer: Coffee, rubber, cashew, tapioca

Question. How does the soil of the Yamuna plain differ from that of Central Maharashtra?
Answer: The Yamuna plain has alluvial soil which is transported soil and Central Maharashtra has Black soil which is insitu soil

Question. Classify soils according to their colour and texture.
Answer: Sandy soil: 60% sand and 10% clay. It allows water to seep through easily. Clayey soil: More than 60% clay. It is moisture retentive. Loamy soil: It is a mixture of sand and clay and is very fertile soil.

Question. Explain the terms:-
Answer: • Residual Soil: These soils are formed where they are found eg. Black soil, Red soil. These are also termed as in-situ soils as they are formed where they are found.
• Transported Soil: These are soils which are carried down by agents of erosion such as rivers and winds eg. Alluvial soil, Loess. These are also termed as ex-situ soils.

Question. What is meant by Leaching?
Answer: Leaching is the process of percolation by which valuable mineral nutrients are washed down, due to heavy rainfall, from the top layer of soil to be deposited in the lower layers, thereby making the top soil infertile. This is also called desilication (lime and silica are leached away and iron and aluminum compounds remain).

Question. What is meant by wind erosion and what is its effect?
Answer: Wind erosion refers to the movement and deposition of soil particles by wind. It reduces the productive capacity of soil as most of the nutrients required by plants are carried away by the wind.

Question. How is alluvial soil formed?
Answer: It is formed by sediments brought down by rivers. Alluvial soils are the most important soils found in India and cover the largest area. These soils contribute the largest share to the agricultural wealth of India.

Question. Why do different regions of India have different kinds of soils?
Answer: This is because of different rocks which get weathered to form soil, different mineral

Question. Why is there a need to conserve soil in India?
Answer: • Loss of top fertile soil with its minerals leads tp loss of fertility and agricultural productivity
• Lowering of the underground water table and decrease in soil moisture
• Extension of arid regions, increase of droughts and floods
• Silting of river beds causing landslides

Question. Explain the terms:
Answer: i) Sheet erosion – the slow removal of a thin layer of the top soil due to heavy rainfall. It occurs in regions where the vegetation has been destroyed eg. Flood plains of Brahmaputra, Ganga, Kosi, Damodar, Chos of Punjab
(ii) Gully erosion – Due to heavy rainfall and prolonged erosion, the soil maybe removed by water flowing in definite paths down the slope, in channels. Gully erosion removes the nutrients and loose soil making land unfit for cultivation eg. Chambal, Mahi, Sabarmati valley. Badland is a region with a large umber of deep gullies or ravines eg. Chambal valley in Madhya Pradesh

Question. What is meant by Soil Profile?
Answer: It is the cross section of different layers of the soil consisting of top soil, sub soil, weathered parent rock and parent rock.

Question. What is the difference between the alluvial soil of the upper course and the lower course of a river
Answer: • Upper course – Soil is coarse, porous,, not so fertile, older, bhangar soil, calcareous clay
• Lower course – fine grained, fertile, newer, khadar soil, clayey loams

Question. Mention the main characteristics of Red soil.
Answer: • It is red in colour due to the presence of iron oxide.
• It is deficient in phosphoric acid, humus, nitrogen and lime (PHNL)
• It is formed insitu due to the decomposition of crystalline and metamorphic rocks.
• It is porous, friable and not moisture retentive.
• The productivity of Red soil increases with the use of fertilizers,

Question. Name the two types of alluvial soils and mention their differences.
Answer: The two types of alluvial soils are Khadar and Bhangar.
• Khadar : More fertile, replenished by the floods every year, new alluvium, found in the lower beds in the valley, fine texture, lighter in colour.
• Bhangar : Less fertile, not replenished by the floods, old alluvium, found on river terraces, coarse texture, darker in colour, contains lime nodules ( kankar)

Question. Why is there a need for soil conservation?
Answer: Soil supports all plant life, helps to increase agricultural production, helps to retain soil fertility. It takes years for soil formation. If soil is not conserved, the land becomes barren and cannot be cultivated.

Question. Mention the main characteristics of Black soil.
Answer: It is fertile soil rich in lime, iron, magnesium, calcium, alumina and potash ( LIMCAP) *It is moisture retentive and clayey *It is sticky when wet and hardens to form cracks when dry *It is fine grained and self ploughing * It is formed by the disintegration of basalt and is fine grained * It is insitu soil ( insitu means the soil is formed where it is found) * Poor in phosphorous, nitrogen and organic matter.

Question. Which type of soil is suitable for growing coffee in Karnataka?
Answer: Red Soil

Question. What is Soil?
Answer: Soil is the uppermost layer of the earth’s crust capable of supporting life. It is a mixture of inorganic materials like minerals and organic materials like humus.

Question. What is meant by Deccan Trap?
Answer: Trap means steps. It describes the step like formation of lava rocks that cover the Northwestern part of the Deccan Plateau.
Self ploughing- Black soil is known for its self ploughing nature because it is clayey soil and has much moisture in it. It also develops cracks during the summer which exposes it to sunlight and water from rains. Thus, it is easy to plough it.

Question. Mention the regions worst affected by erosion.
Answer: • Badlands of the Chambal and Yamuna
• Foothills of the western Himalayas
• Chota Nagpur Plateau
• Dry areas of Rajasthan, Gujarat and Haryana

Question. Mention the differences between Alluvial soil and Red Soil.
Answer: • Alluvial Soil - *Transported soil * Formed by the sediments brought down by rivers *Yellow to brown in colour * moisture retentive when compared to red soil
• Red soil – *Insitu soil *formed by the weathering of crystalline and metamorphic rocks *not moisture retentive * deficient in nitogen, humus and lime *red in colour due to the high iron content

Question. Mention the factors affecting soil formation.
Answer: • Weathering: Extremes of temperature ( desert regions), freezing and thawing of ice breaks down rocks
• Vegetation: The growth and decay of vegetation determines the humus content in the soil
• Biochemical processes in the soil: Bacteria and fungi cause the decay of plant and animal remains
• Nature of the parent rock: This affects the proportion of different minerals in the soil.
• Topography: Hill slopes have a thin layer of soil but plains and valleys have a thick layer of soil.

Question. Mention some methods of soil conservation.
Answer: *Terrace farming *Afforestation * Shelter Belts *Contour Ploughing *Strip Cropping * Construction of dams

Question. How does destruction of vegetation contribute to soil erosion?
Answer: egetation holds and binds the soil in one place. Due to cutting of trees, rain falls heavily on soil and washes it away easily.

Question. Mention 2 differences between the alluvial soil of the Northern plains and the coastal plains of India.
Answer: • Northern Plains – the alluvial soil is porous, sandy, coarser, light coloured
• Coastal Plains – Darker, more clayey, non porous, finer

Question. Mention the main crops grown on Red soils. Why does Red soil need irrigation?
Answer: Wheat, rice, cotton, sugarcane, pulses. Red soil needs irrigation as it is porous and does not retain moisture.

Question. Name some soil conservation schemes.
Answer: * Integrated Watershed management in catchments of flood prone areas * Reclaimation and development of ravine areas *Control of Shifting cultivation

Question. How can deserts be protected from soil erosion?
Answer: By planting trees perpendicular to the wind direction.

Question. Mention the main characteristics of alluvial soil.
Answer: • Transported or ex situ soil
• Rich in potash and lime
• Formed when the river deposits its load as it flows from the upper course to the lower course. In the upper course the soil is coarse, medium in the middle course and fine grained in the lower course.
Note: The alluvial soil of the Deccan is darker than that found in the Northern plains as it mixes with the black regur soil.

Question. Mention the farming techniques that help in soil conservation.
Answer: Contour ploughing, strip cropping, mixed farming, growing cover crops.

Question. What is Reafforestation?
Answer: It involves replanting of trees in areas which have been deforested. It is planting two saplings for every tree cut.

Question. Name the regions where Black soil is found.
Answer: It is found in the Deccan lava trap, in parts of Maharastra, Gujarat, Madhya Pradesh, Andhra Pradesh and Tamil Nadu.

Question. How is laterite soil formed?
Answer: It is formed by the leaching of laterite rocks due to high temperature, heavy rainfall and alternating wet and dry spells.

Question. Explain the terms:
Answer: i) Contour ploughing- It is a method of ploughing hillslopes along the contour lines to prevent washing down of soil.
ii) Strip Cropping- Growing different crops in strips in the same field to increase soil fertility and production.

Question. Why does Black soil need to be tilled after the first rains?
Answer: It is sticky when wet and forms cracks when dry. Black soil can hold a lot of moisture in it. It needs to be tilled after the first rain because it stores enough water required for farming. If more rain occurs before tilling then the Black soil is bound to become sticky and it becomes difficult for the farmers to work on such soil.

Question. How does man cause soil erosion?
Answer: Deforestation, overgrazing, shifting cultivation, industralisation, urbanization, mining, construction.

Question. What are the main crops that grow on alluvial soil?
Answer: Rice, wheat (food crops) sugarcane, cotton, oilseeds, jute, tobacco (cash crops)

Question. Why is the soil in the desert regions not suitable for agriculture?
Answer: It is porous, sandy, not moisture retentive, high in soluble salts, poor in humus.

Question. How is Black or Regur soil formed?
Answer: It is formed by the weathering of lava rocks or Basalt.

Question. How is Red soil formed and where is it mainly found?
Answer: Red soil is formed due to weathering of ancient crystalline and metamorphic rocks. The parent rocks are granite and gneiss. Red soils form the second largest soil group in India. These soils are found in parts of Tamil Nadu, Karnataka, Andhra Pradesh, Odisha, West Bengal. They are also found in parts of Meghalaya, Mizoram and Tripura.

Question. Give geographical reasons:
Answer: i) Terrace farming is an ideal soil conservation method for hill slopes – Terraces check the speed of running water and thus reduce the chance for erosion.
ii) Dry farming is preferred in areas of red soil – Red soil is ideal for dry farming since it is porous and does not retain moisture. It is coarse in texture and found in areas of low rainfall.
iii) Alluvial soil is extremely fertile – It contains minerals like iron, potash, lime. It is loamy, has sufficient depth, is renewed annually. It is transported soil

Question. What is meant by soil erosion?
Answer: It is the removal of the top soil by water, wind and human activities

Question. Why is Black soil mainly found in the Deccan Trap region? Why does Black soil not get leached?
Answer: The Deccan Trap is made up of lava or basaltic rocks and the disintegration leads to the formation of black soil. Black soil does not get leached as it is sticky when wet, is clayey and moisture retentive.

Question. Mention the main characteristics of laterite soil.
Answer: • It is leached soil.
• It is acidic, coarse and friable.
• It is not moisture retentive, not fertile and is porous, hardens when dry.
• It is red in colour due to the high iron content.
• It is poor in nitrogen, humus and lime.

Question. Mention two ways in which soils get nitrogen.
Answer: Growing leguminous crops, crop rotation, fertilizers, manure.

Question. How can deepening of river beds help in preventing soil erosion?
Answer: Deepening of river beds increases the capacity of the river to hold water which will then not overflow to cause soil erosion

Question. What is meant by Pedogenesis?
Answer: It is the process of soil formation.

Question. Name two agents of soil erosion and state a method of controlling the erosion caused.
Answer: • Water – afforestation, contour ploughing, step farming, plugging of gullies
• Wind – Planting of shelter belts, afforestation, contour ploughing

Question. State the characteristics of each of the soils named below that makes them most suitable for crop cultivation:
Answer: i) Black Soil: Moisture retentive, self ploughing, rich in lime, iron, calcium
ii) Red Soil: Rich in iron, potash, friable, does not get water logged, responds to manures or fertilizers

Question. What is meant by soil conservation?
Answer: It refers to the steps taken by man to prevent soil erosion and retain its fertility.

Question. Name the main crops grown on Black soil.
Answer: Cotton, sugarcane, rice, wheat, oilseeds, tobacco

Question. Name the soil:
Answer: i. Is good for the cultivation of cashew
ii. Covers almost all of West Bengal
iii. Is the result of leaching
iv. Good for growing cotton
v. Acidic soil
vi. Leached soil
vii. Formed from volcanic rocks
viii. Found on river terraces
ix. Good as building material
x. Cultivation possible when fertilizers are used

Please refer to attached file for CBSE Class XI Geography Soils Concepts