Soil Resources

Answer the following questions

Question 1(a)

What is the soil? Name the four types of soil.

Answer

Soil is the thin mixture of small rock particles and rotting organic matter that covers the surface of the earth. The four types of soil are-

1. Alluvial soil
2. Black soil
3. Red soil
4. Laterite soil

Question 1(b)

State any two factors responsible for the formation of soil.

Answer

Two factors responsible for the formation of soil are —

1. Weathering
2. Erosion

Question 1(c)

(i) How can you say that soil has evolved over millions of years?

(ii) Name one important constituent of soil that adds fertility to the soil.

Answer

(i) Soil changes with age - As a soil ages, it gradually starts to look different from its parent material. That is because soil is dynamic. Its components—minerals, water, air, organic matter, and organisms—constantly change.

(ii) One important constituent of soil that adds fertility to the soil is humus.

Question 1(d)

Give a geographical reason for each of the following:

(i) The colour of alluvium soil varies in different areas.

(ii) Khadar is more fertile than bhangar soil.

(iii) Black soil has a kind of self-ploughing characteristic.

Answer

(i) The colour of alluvium soil varies in different areas because its shades depend on the depth of deposition, the texture of the materials and the time taken for maturity.

(ii) Khadar is more fertile than bhangar soil as new layers are deposited year after year during monsoon floods.

(iii) Black soil has a kind of self-ploughing characteristic because during dry season, it shrinks and develops big cracks which help in air circulation. This characteristic causes a kind of self-ploughing.

Question 2(a)

How are alluvial soils formed?

Answer

Alluvial soil is formed by the sediments brought down by rivers. The rivers deposit very fine particles of soil called alluvium in their plains during the course of their long journey. The resultant alluvial soil is known as riverine soil.

Question 2(b)

Mention any two advantages of alluvial soil.

Answer

Two advantages of alluvial soil are-

1. It is light and porous. So, it is easily tillable.
2. It is suitable for the growth of a large variety of rabi and kharif crops.

Question 2(c)

(i) Why is soil a valuable resource for India?

(ii) Why is black soil considered a productive soil?

Answer

(i) Soil is a valuable resource for India because agriculture is the main occupation in India. Soil supports agriculture and it is the source of nutrients for many forms of life.

(ii) Black soil is considered a productive soil because it has high moisture retention capacity and more clay content which responds well to irrigation. It is suitable for the cultivation of cotton, jowar, wheat, linseed, gram, citrus fruits and vegetables, tobacco and sugarcane.

Question 2(d)

Give a geographical reason for each of the following:

(i) Different regions in India have different kinds of soil for agriculture.

(ii) Alluvial soils vary in texture.

(iii) Nearly all types of crops grow well in riverine soils.

Answer

(i) Different regions in India have different kinds of soil for agriculture because India is a vast region with varied natural environment. Several physiographic regions and different types of climate lead to the formation of different types of soil in different regions.

(ii) Alluvial soils vary in texture as in the upper reaches of the river valleys, the soil is dry, coarse, porous and sandy. Soil particles are large and non-uniform but as we move further down a river valley, the soil particles become smaller and more uniform. They are more compact and more moist.

(iii) Nearly all types of crops grow well in riverine soils because alluvial soil is a mixture of sand, clay and silt. It is rich in mineral and easily tillable. Its composition makes it suitable for the growth of a variety of crops.

Question 3(a)

Give two characteristic features of the soil found most suitable for growing cotton and sugarcane in Maharashtra.

Answer

Black soil is suitable for growing cotton and sugarcane in Maharashtra. Its characteristics are-

1. It is black in colour.
2. It has high quantities of lime, iron, magnesium and generally poor percentage of phosphorus, nitrogen and organic matter.

Question 3(b)

Name one soil of volcanic origin commonly found in India. Name one crop widely grown on this soil.

Answer

One soil of volcanic origin commonly found in India is black soil. Cotton is widely grown on this soil.

Question 3(c)

(i) Name the process by which Laterite soil is formed.

(ii) Mention one disadvantage of Laterite soil.

Answer

(i) Laterite soil is formed as a result of atmospheric weathering of rocks under the conditions of high rainfall and temperature with alternate wet and dry periods. It is the residual soil formed by leaching due to tropical rains.

(ii) One disadvantage of Laterite soil is that it does not retain moisture and hence, is infertile.

Question 3(d)

Give a geographical reason for each of the following:

(i) Deltaic alluvium is more fertile than the coastal alluvium.

(ii) Black soil is largely found in the Deccan Trap region.

(iii) Black soil is often referred to as Cotton soil or Regur soil.

Answer

(i) Deltaic alluvium is more fertile than coastal alluvium as new layers are deposited year after year during monsoonal floods. Also, deltaic alluvium is composed of fine silt and clay whereas coastal alluvium is full of lime nodules.

(ii) Black soil is found in the Deccan trap region because this region is formed due to the deposition of lava produced by the volcanic eruption. When lava rocks breaks down into finer particles due to weathering, it results in the formation of the black soil.

(iii) Black soil is often referred to as Cotton soil or Regur soil because it is black in colour and is suitable for cotton cultivation.

Question 4(a)

State the two sub-categories into which alluvial soil is generally divided. Which one of them is superior to the other? Why?

Answer

Two sub-categories into which alluvial soil is generally divided are khadar and bhangar.

Khadar is superior to bhangar because it is more fertile as new layers are deposited year after year during monsoon floods.

Question 4(b)

What are the characteristics of alluvial soil?

Answer

The characteristics of alluvial soil are:

1. Colour — The colour of alluvial soil varies from light grey to deep black.
2. Texture — In the upper reaches of the valleys, the soil is dry, coarse, porous and sandy with large and non-unifrom soil particles. In the lower reaches of the river valley, the soil particles become smaller and more uniform and more moist.
3. Minerals — It varies in nature from sandy loam to clay. It is fertile with minerals like iron, magnesia, alumina, potash and lime but poor in phosphorus, nitrogen and organic matter.

Question 4(c)

(i) Which soil is suitable for growing coffee in Karnataka?

(ii) Mention two main characteristics of this soil.

Answer

(i) Laterite soil is suitable for growing coffee in Karnataka.

(ii) Two main characteristics of this soil are-

1. It is red in colour due to the presence of iron oxide.
2. It is of a coarse texture, soft and friable.

Question 4(d)

Give a geographical reason for each of the following:

(i) Laterite soil is useful for construction purpose.

(ii) Soils of the Western Ghats are affected by wind erosion.

(iii) The foothills of the Himalayas are prone to excessive soil erosion.

Answer

(i) Laterite soils are used as a building material because they become hard like iron when exposed to air. So, they are used as a building material. Laterite soils are red in color due to the presence of iron oxide. These soils are generally coarse in texture and friable and porous in nature.

(ii) Soils of the Western Ghats are affected by wind erosion because a large chunk of Western zone is arid or semi-arid and wind erosion is a result of extreme form of soil degradation due to aridity.

(iii) The foothills of the Himalayas are prone to excessive soil erosion because the vegetation over there is very less. There are not many plant or tree roots to hold the soil in place, which makes the foothills of the Himalayas prone to excessive soil erosion.

Question 5(a)

Name two States in India where Regur soil is found.

Answer

Regur soil is found in Maharashtra and Madhya Pradesh.

Question 5(b)

Give two points of difference between Regur and Alluvial soil.

Answer

Question 5(c)

(i) Besides cotton, name the crops which grow well in Regur soil.

(ii) In what way does Regur soil help agriculture?

Answer

(i) Besides cotton, jowar, wheat, linseed, gram, citrus fruits and vegetables, tobacco and sugarcane grow well in Regur soil.

(ii) Regur soil helps agriculture as it is very fertile. In any season, it has moisture stored in its subsoil. This allows dry farming as well. In dry season, it forms big cracks which help in air circulation, and causes a kind of self ploughing.

Question 5(d)

Give a geographical reason for each of the following:

(i) Jowar is grown in Maharashtra.

(ii) Bajra is grown in Rajasthan.

(iii) Sugarcane is grown in Uttar Pradesh.

Answer

(i) Jowar is grown in Maharashtra because of the black regur soil which is rich in lime, potash-magnesium, carbonates, allumina and calcium.

(ii) Bajra is grown in Rajasthan because of the sandy soil found in this region. It is rich in soluble salts.

(iii) Sugarcane is grown in Uttar Pradesh because the climatic conditions and presence of alluvial soil support the cultivation of sugarcane.

Question 6(a)

Name two states where red soil is found. Mention two important crops grown in this soil.

Answer

Two states where red soil is found are Tamil Nadu and Karnataka. Two important crops grown in this soil are rice and tobacco.

Question 6(b)

State two advantages of this type of soil.

Answer

Two advantages of this type of soil are-

1. It is porous, loose and aerated.
2. It is ideal for dry farming.

Question 6(c)

(i) How is red soil formed?

(ii) How is this soil suitable for dry farming?

Answer

(i) Red soil develops on old crystalline rocks. Under prolonged weathering by rainfall, ancient crystalline and metamorphic rocks of the peninsular plateau break up to form this soil.

(ii) This soil suitable for dry farming as it is formed in areas with poor rainfall.

Question 6(d)

Give a geographical reason for each of the following:

(i) Black soil is also called lava soil.

(ii) Red soil is red in colour and its colour varies from yellow to brown.

(iii) Jute is cultivated in West Bengal.

Answer

(i) Black soil is also called lava soil because it is formed by the denudation of volcanic rocks.

(ii) Red soil is red in colour as it contains large amounts f iron oxide. At several places, its colour changes and it appears brown or grey. It looks yellow when it occurs in a hydrated form.

(iii) Jute is cultivated in West Bengal because the alluvial soil found in West Bengal is very fertile and supports jute cultivation.

Question 7(a)

What is soil erosion? Name the areas of soil erosion in India-

(i) for wind erosion

(ii) for running water erosion

Answer

The removal of the top soil cover by water, wind and human activities is called soil erosion.

(i) Wind erosion affects the dry areas of Rajasthan, Gujarat and Haryana

(ii) Running water erosion affects the badlands of Chambal and Yamuna river, the piedmont zone of western Himalayas, the Chotanagpur plateau, the Tapi-Sabarmati valley and the regur soil area of Maharashtra.

Question 7(b)

Give two methods used to prevent soil erosion.

Answer

Two methods used to prevent soil erosion are-

1. Terrace farming
2. Shelter belts

Question 7(c)

(i) What is meant by soil conservation?

(ii) State two measures to conserve soil in hilly areas.

Answer

(i) Soil conservation means prevention of soil loss from erosion or prevention of reduced fertility of soil caused by over-use, acidification, salinisation or other types of soil contamination.

(ii) Two measures to conserve soil in hilly areas are-

1. Terrace farming- Terraces act as bunds and prevent soil erosion by running water.

2. Contour Ploughing- Ploughing along contours on a slope prevents soil erosion by running water.

Question 7(d)

Give a geographical reason for each of the following:

(i) Shelter belts reduce soil erosion in arid areas.

(ii) Rural development will influence soil conservation.

(iii) Water harvesting aids in soil conservation.

Answer

(i) Shelter belts reduce soil erosion in arid areas because planting trees in several rows checks wind erosion.

(ii) Rural development will influence soil conservation as in the programmes of rural development, villagers are provided with the techniques of how to improve vegetative cover and the steps required to be taken for preventing soil erosion. The farmers are briefed about the farming methods (such as strip cropping and shelter belts) to be followed to reduce soil erosion.

(iii) Water harvesting aids in soil conservation as it reduces soil erosion and flood hazards by collecting rainwater and reducing the flow of water which causes the removal of fertile top soil.

Question 8(a)

How does deforestation lead to soil erosion?

Answer

Deforestation exposes the soil to water and wind, which leads to soil erosion.

Question 8(b)

State two methods of controlling erosion of soil caused by running water.

Answer

Two methods of controlling erosion of soil caused by running water are construction of dams and plugging gullies.

Question 8(c)

Name two important agents of erosion. For each, state one method of controlling the erosion caused.

Answer

Two important agents of erosion are water and wind. Water erosion can be controlled by the construction of dams. Wind erosion can be controlled by making shelter belts.

Question 8(d)

Explain briefly the need for conservation of soil as a natural resource.

Answer

There is an acute need for conservation of soil as a natural resource because of its adverse effects which include the following-

1. Loss of fertile topsoil with its mineral content
2. Lowering of the water table
3. Drying of vegetation and extension of arid lands leading to an increase in the frequency of drought and floods
4. Silting of river and canal beds
5. Recurrence of landslides
6. Adverse effect on economic prosperity and cultural development