Soil
Q1. Tick the most suitable answer in
question 1 and 2.
In addition to the rock particles, the soil contains
(i) Air and water
(ii) Water and plants
(iii) Minerals, organic matter, air and water
(iv) Water, air and plants
Answer:
In addition to the rock particles, the soil contains
(iii) Minerals, organic matter, air and water.
Q2. The water holding capacity is
the highest in
(i) Sandy soil
(ii) Clayey soil
(iii) Loamy soil
(iv) Mixture of sand and loam
Answer:
The water holding capacity is the highest in
(ii) Clayey soil
Q3. Match the items in Column I with
those in Column II:
|
Column I |
Column II |
|
(i) A home for living organisms |
(a) Large particles |
|
(ii) Upper layer of the soil |
(b) All kinds of soil |
|
(iii) Sandy soil |
(c) Dark in colour |
|
(iv) Middle layer of the soil |
(d) Small particles and packed
tight |
|
(v) Clayey soil |
(e) Lesser amount of humus |
Answer:
|
Column I |
Column II |
|
(i) A home for living organisms |
(b) All kinds of soil |
|
(ii) Upper layer of the soil |
(c) Dark in colour |
|
(iii) Sandy soil |
(a) Large particles |
|
(iv) Middle layer of the soil |
(e) Lesser amount of humus |
|
(v) Clayey soil |
(d) Small particles and packed
tight |
Q4. Explain how soil is formed.
Answer:
Soil is formed through the process of weathering. Weathering is a process of
physical breakdown and chemical decomposition of rocks and minerals near or at
the surface of the earth. This physical and chemical decomposition is primarily
done by wind, water, and climate. As a result of these processes, large rock
pieces are converted into smaller pieces and eventually to soil.
Q5. How is clayey soil useful for
crops?
Answer:
Following are the properties of clayey soil:
1.
It has very good water holding
capacity.
2.
It is rich in organic matter.
For growing crops such as wheat,
gram, and paddy, the soil that is good at retaining water and rich in organic
matter is suitable. Therefore, clayey soils having these characteristics are
useful for such kind of crops.
Q6. List the differences between
clayey soil and sandy soil.
Answer:
|
Clayey Soil |
Loamy Soil |
|
(i) It has much smaller particles. |
(i) It has much larger particles. |
|
(ii) It can hold good amount of
water. |
(ii) It cannot hold water. |
|
(iii) It is fertile. |
(iii) It is not fertile. |
|
(iv) Air content is low. |
(iv) Air get trapped between the
particles. |
|
(iv) Particles are tightly packed |
(iv) Particles are loosely packed |
|
(iv) Good for growing various
crops. |
(iv) Not suitable for growing
crops. |
Q7. Sketch the cross section of soil
and label the various layers.
Answer:
Q8. Razia conducted an experiment in
the field related to the rate of percolation. She observed that it took 40 min
for 200 mL of water to percolate through the soil sample. Calculate the rate of
percolation.
Answer:
9. Explain how soil pollution and
soil erosion could be prevented.
Answer:
Prevention of soil pollution:
The persistent build-up of toxic compounds in the soil is defined as soil
pollution. To prevent soil pollution, its causes must be controlled.
1.
Reduce the
use of plastics: Plastics and polythene bags destroy
the fertility of soil. Hence, these should be disposed off properly and if
possible, their use should be avoided.
2.
Industrial
pollutants: Some waste products from industries
and homes pollute soil. These pollutants should be treated chemically to make
them harmless before they are disposed off.
3.
Insecticides: Other pollutants of soil include pesticides and
insecticides. Therefore, excessive use of these substances should be avoided.
Prevention of soil erosion:
Removal of the upper fertile layer of the soil (top soil) by strong wind and
flowing water is known as soil erosion. Following steps can be taken to reduce
soil erosion:
1.
Mass awareness to reduce
deforestation for industrial purposes.
2.
Helping local people to regenerate
degrading forest.
3.
Planting trees.
10. Solve the following crossword
puzzle with the clues given:
Across
2. Plantation prevents it.
5. Use should be banned to avoid soil pollution.
6. Type of soil used for making pottery.
7. Living organism in the soil.
Down
1. In desert soil erosion occurs through.
3. Clay and loam are suitable for cereals like.
4. This type of soil can hold very little water.
5. Collective name for layers of soil.
Answer:
Across
2. Plantation prevents it. → Erosion
5. Use should be banned to avoid soil pollution. → Polythene
6. Type of soil used for making pottery. → Clay
7. Living organism in the soil. → Earthworm
Down
1. In desert soil erosion occurs through. → Wind
3. Clay and loam are suitable for cereals like. → Wheat
4. This type of soil can hold very little water. → Sandy
5. Collective name for layers of soil. → Profile
