1

Class 4 – Soil – Question and Answers

1. The layer below the topsoil is called

(a) subsoil

(b) bedrock

(c) gravel

(d) clay

(a) subsoil

2. Which one of the following consists of tiny stones and does not hold water well?

(a) Gravel

(b) Sand

(c) Clay

(d) Humus

(a) Gravel

3. Which type of soil becomes lumpy and sticky when wet?

(a) Sandy

(b) Clayey

(c) Loamy

(d) Gravel

(b) Clayey
 2

4. Which one of the following is the best soil for growing plants?

(a) Sandy

(b) Clayey

(c) Loamy

(d) Gravel

(c) Loamy

5. What happens when we do not grow crops using the correct methods?

(a) Soil erosion increases

(b) Soil erosion decreases

(c) Soil is conserved

(d) Soil fertility is increased

(a) Soil erosion increases

B. Write two examples for each of the following.

1. Types of soil ..........

Sandy, Clayey

2. Layers of soil ..........

Topsoil, Subsoil

3. Causes of soil erosion..........

Heavy rainfall, Cutting down of trees

C. Write one word for the following.

1. The kind of soil that is rough and gritty Sandy soil

2. The kind of soil that is sticky when wet _______

Clayey soil

3. The top layer of the Earth's surface in which plants grow _______

Topsoil

4. The layer of soil that has large pieces of rock and not much water _______

Gravel

5. Soil that is very good for growing plants and is rich in humus _______

Topsoil

6. Removal of topsoil by the action of wind and water _______

Soil erosion

D. Fill in the blanks with the correct words.

1. _______ (Animals/Plants) need soil to grow.

Plants

2. _______ (Gravel/Clay) consists of tiny stones and does not hold water well.

Gravel

3. _______ (Loamy/Sandy) soil is usually very good for growing plants.

Loamy

4. Soil profile refers to the _______ (layers/composition) of soil.

layers

5. Soil erosion _______ (increases/decreases) when we cut down trees.

increases
 4
E. Short answer questions.

1. How are big rocks broken down into smaller pieces?

Big rocks are broken down by wind and water into smaller pieces.

2. What is weathering?

Big pieces of rocks are broken down by wind and water into smaller and smaller
pieces till we get a fine powder. This process is called weathering.

3. What is soil?

The top layer of the Earth's surface, which consists of sand, remains of dead
plants and animals, and minerals with some amount of water and air in it is called
soil.

4. What is soil made up of?

Soil is made up of different types of soil particles:

• Sand: These are the largest soil particles.

• Silt: These particles are smaller than sand particles but bigger than clay particles.

• Clay: These are the smallest soil particles.

Other than these, soil also contains small stones and pebbles called gravel,
minerals (such as iron, calcium and potassium) and humus (which is formed from
the remains of dead plants and animals). Soil also contains some amount of air
and water.

5. How is soil important for life on Earth?

Plants grow in soil, and it is home to many insects and animals. Plants produce
food. They also give out oxygen, which is needed by humans and animals to stay
alive.

6. What is loam?

Soil that consists of clay, sand, and humus is called loam.

7. What is soil conservation?

Protection of soil from erosion is known as soil conservation.

8. What is crop rotation?

The practice of growing different crops in the same area is called crop rotation.

F. Long answer questions.

1. Describe the three main types of soil.

There are mainly three types of soil, depending upon the amount of different soil
particles present in it. These are sandy soil, loamy soil, and clayey soil.
• Sandy soil: This soil has a greater proportion of sand particles. Sandy soil feels
rough and gritty and non-sticky when wet. It does not hold much water and drains
most of it.
• Loamy soil: This soil has roughly equal proportions of sand, clay, and silt. Loamy
soil is the best soil for plant growth. It is rich in nutrients and humus and allows
water to pass through easily.
• Clayey soil: This soil has a greater proportion of clay particles. Clayey soil feels
smooth when dry and lumpy and sticky when wet.

2. Describe the soil profile with a labelled diagram.

Soil profile refers to the layers of soil. They are named as A, B, and C. A is the
topsoil. It is the uppermost layer of soil and contains fine particles of sand, clay,
humus, water, and air. As it contains humus, it gives all the necessary nutrients to
the plants growing in it. B is called the subsoil. It is the middle layer of soil, present
below the topsoil and contains broken pieces of rock. It contains very little humus
but has water. C is called the bedrock. It is the bottom layer of soil and is quite
deep inside the Earth. It has large pieces of rock. There is not much water.
 6

3. What is soil erosion? What are the causes of soil erosion?

The removal of the fertile topsoil by the action of wind and water is called soil
erosion. The causes of soil erosion are strong winds, heavy rainfall and cutting
down of trees.

4. Give any three steps that we can take to conserve soil.

(i)Trees should be planted to replace the ones that are cut down.
(ii) Different types of crops should be grown on a farmland so that the soil gets
time to recover its fertility. This practice of growing different crops in the same area
is called crop rotation.
(iii) Trees and bushes should be planted in open lands. This practice does not
allow the wind to blow at full force and take away the topsoil.