Q.1. State True (T) or False (F).
(i) Plantation prevents soil erosion.
(ii) Sandy soil is used to make pottery.
(iii) Use of polythene should be banned to avoid soil pollution.
(iv) Soil is important for life on the earth.
(v) Each layer of soil is same in feel (texture), colour, depth and chemical composition.
(vi) The loamy soil also has humus in it.
Q.2. Fill in the blanks.
(i) In addition to the rock particles, the soil contains ____,____, ____ and ____.
minerals, organic matter, air, water.
(ii) The water holding capacity is the highest in ____.
(iii) In desert soil erosion occurs through ____.
(iv) ____ soil can hold very little water.
(v) Soil is of different types: ____, ____ and ____.
clayey, loamy, sandy
(vi) The uppermost horizon is generally dark in colour as it is rich in ____ and ____.
Q.3. Which type of soil is the best for making pots, toys and statues?
Clayey soil is used to make pots, toys and statues.
Q.4. Why the uppermost horizon is generally dark in colour?
The uppermost horizon is generally dark in colour as it is rich in humus and minerals.
Q.5. Which type of soil is best for growing paddy?
For paddy, soils rich in clay and organic matter and having a good capacity to retain water are ideal.
Q.6. Which type of soil retains the highest amount of water and which retains the least?
Clayey soil retains the highest amount of water and sandy soil retains the least.
Q.7. How is clayey soil useful for crops?
Clayey soil is useful for crops because:
(i) It is good at retaining water.
(ii) It is rich in organic matter.
Q.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.
Amount of water = 200 ml
Percolation time = 40 min
Therefore, percolation rate = Amount of water(ml)/Percolation Time(min)
= 200 ml/40 min = 5ml/min.
Q.9. What are the properties of sandy soil?
Properties of sandy soil are:
(i) Sand particles are quite large.
(ii) Sand particle cannot fit closely together, so there are large spaces between them. These spaces are filled with air. So, the sand is well aerated.
(iii) Water can drain quickly through the spaces between the sand particles. So, sandy soils tend to be light and dry.
Q.10. What is humus?
The rotting dead matter in the soil is called humus.
Q.11. Name some soil pollutants.
Polythene bags, plastics, waste products, chemicals and pesticides.
Q.12. Which soil horizon has a lesser amount of humus but more of minerals?
B-horizon or the middle layer
Q.13. What kind of soil should be used for making matkas and surahis?
Clayey soil should be used for making matkas and surahis.
Q.14. Why do air above the soil shimmer on a hot summer day?
On a hot summer day, the vapour coming out of the soil reflects the sunlight and thus, the air above the soil seems to shimmer.
Q.15. What is weathering?
Soil is formed by the breaking down of rocks by the action of wind, water and climate. This process is called weathering.
Q.16. Which natural resource supports the growth of plants by holding the roots firmly and supplying water and nutrients?
Soil supports the growth of plants by holding the roots firmly and supplying water and nutrients.
Q.17. Which soil has the highest percolation rate?
Sandy soil has the highest percolation rate.
Q.18. Wheat are grown in the fine clayey soils. Give reason.
Crops such as wheat are grown in the fine clayey soils, because they are rich in humus and are very fertile.
Q.19. What is called soil moisture?
Soil holds water in it, which is called soil moisture. The capacity of a soil to hold water is important for various crops.
Q.20. What is silt?
Silt occurs as a deposit in river beds. The size of the silt particles is between those of sand and clay.