Lesson: Soil

Question: 1

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

Solution:

(iii)

Question: 2

The water holding capacity is the highest in

(i) Sandy soil

(ii) Clayey soil

(iii) Loamy soil

(iv) Mixture of sand and loam

Solution:

(ii)

Question: 3

Match the items in Column I with those in Column II:

Solution:

(i) - (b)

(ii) - (c)

(iii) - (a)

(iv) - (e)

(v) - (d)

Question: 4

Explain how soil is formed.

Solution:

The process of soil formation is a very long process. It initiates with the breaking down of rocks into smaller fragments with the action of running water, wind and moving glacier. These small broken rock particles accumulate over the ages to form soil. In due course, when plants grow on the soil, these shed their leaves to which decay form the topmost layer of the soil called 'humus'.

Question: 5

How is clayey soil useful for crops?

Solution:

Clayey soil is made up of tightly packed very small particles, leaving little space for air in between. Since water can be retained in the tiny gaps between the particles of clay, it makes such kind of soil heavy as they have the ability to hold more water than the other kinds of soil. Apart from this, clayey soil is rich in organic mineral content. These characteristics of clayey soil make it useful for some kind of cereal crops, such as, wheat, gram and paddy.

Question: 6

List the differences between clayey soil and sandy soil.

Solution:

Question: 7

Sketch the cross section of soil and label the various layers.

Solution:

Question: 8

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.

Solution:

Quantity of water = 200 mL

Percolation time = 40 min

Percolation rate (mL/min)

=  Quantity of water ( in mL ) Time taken to percolate ( in min ) = 200 mL 40 min MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqr1ngB PrgifHhDYfgasaacH8srps0lbbf9q8WrFfeuY=Hhbbf9v8qqaqFr0x c9pk0xbba9q8WqFfea0=yr0RYxir=Jbba9q8aq0=yq=He9q8qqQ8fr Fve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakqaabeqaaa baaaaaaaaapeGaeyypa0Jaaeiia8aadaWcaaqaa8qacaqGrbGaaeyD aiaabggacaqGUbGaaeiDaiaabMgacaqG0bGaaeyEaiaabccacaqGVb GaaeOzaiaabccacaqG3bGaaeyyaiaabshacaqGLbGaaeOCaiaabcca paWaaeWaaeaapeGaaeyAaiaab6gacaqGGaGaaeyBaiaabYeaa8aaca GLOaGaayzkaaaabaWdbiaabsfacaqGPbGaaeyBaiaabwgacaqGGaGa aeiDaiaabggacaqGRbGaaeyzaiaab6gacaqGGaGaaeiDaiaab+gaca qGGaGaaeiCaiaabwgacaqGYbGaae4yaiaab+gacaqGSbGaaeyyaiaa bshacaqGLbGaaeiia8aadaqadaqaa8qacaqGPbGaaeOBaiaabccaca qGTbGaaeyAaiaab6gaa8aacaGLOaGaayzkaaaaaaqaaiabg2da98qa daWcaaqaaiaabkdacaqGWaGaaeimaiaabccacaqGTbGaaeitaaqaai aabsdacaqGWaGaaeiiaiaab2gacaqGPbGaaeOBaaaaaaaa@762A@  

Therefore, Percolation rate = 5mL/min

Question: 9

Explain how soil pollution and soil erosion could be prevented.

Solution:

The following are the ways to prevent soil pollution:

        i.            Avoiding dumping of non-biodegradable items in soil

      ii.            Before industrial wastes are disposed, those are treated to make them harmless.

    iii.            Using manure instead of chemical fertilizers

    iv.            Using natural pesticides

      v.            Reduce the use of polythene and plastic bags

The following are the ways to prevent soil erosion:

        i.            Planting trees in large scale

      ii.            Adopting better farming techniques, like crop rotation and mixed farming

    iii.            Terrace farming in hilly regions

    iv.            Prohibiting over-grazing of grasslands

      v.            Building embankment at river banks

Question: 10

Solve the following crossword puzzle with the clues given:

Solution:

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.

Solution:

Across

2. EROSION

5. POLYTHENE

6. CLAY

7. EARTHWORM

Down

1. WIND

3. WHEAT

4. SANDY

5. PROFILE