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Question 1
Answer the following in one word each:
(a) A dark brown or black mass of partially decomposed organic matter of dead plants and animals-
(b) The horizontal layers of soil one below the other in a vertical cross-section-
(c) Name the soil with the highest percolation rate-
(d) A type of soil formed due to deposition in riverbeds-
Answer
(a)Humus
(b) Horizons
(c) Sandy soil
(d)Silt
Question 2
Name the horizon of soil each of these features refers to:
(a) It has mostly large rocks.
(b) It is made up of sand, clay and pebbles.
(c) It is the topmost layer of soil.
(d) Hardly any roots reach this horizon of soil.
(e) It is rich in minerals.
(f) It is a home to soil organisms.
(g) Below it, is the hard rocky surface of the earth.
(h) It has a good amount of humus.
Answer
a. Horizon C
b. Horizon B
c. Horizon A
d. Horizon C
e. Horizon B
f. Horizon A
g. Horizon C
h. Horizon A
Question 3
Why is the seashore sandy?
Answer
Because rocks get converted to soil by weathering.
Question 4
Why are tar roads sloped on either side?
Answer
Tar roads have very low porosity so to allow rain to run off into gutters, tar roads sloped on either side.
Question 5
What qualities must a soil have for a plant to grow well?
Answer
(a)Water holding capacity
(b)Percolation rate
(c)Lots of humus
(d)Good amount of nutrients
Question 6
How do soil organisms obtain air?
Answer
The space between soil particles is filled with air which is used by organisms for their growth.
Question 7
What do you understand by percolation rate of soil?
Answer
The percolation rate is the rate (speed) at which water flows through the pores in the soil. The soil having high water holding capacity will have a low population rate and vice versa.
Question 8
Give two differences between sandy soil and loamy soil?
Answer
(a)Sandy soil contains large coarse sand particles but loamy soil contains large and fine particles of sand.
(b)Sandy soil has a very little humus while loamy soil contains a lot of humus.
Question 9
Mention two ways by which a farmer's field could get eroded?
Answer
(a)Inappropriate farming techniques such as the deep ploughing of the land two or three times a year to produce annual crops can lead to soil erosion.
(b)Over cultivation of crops and overgrazing by animals can cause the soil to lose its structure and binding capacity, which makes it easier to erode.
Question 10
Clayey soil gets waterlogged even when the rain does not have. Why?
Answer
Because it is very dense and less porous that does not allow the water to percolate.
Question 11
Excessive use of fertilizers is not beneficial for soil. Why?
Answer
The excessive use of chemical fertilizers reduces the fertility of the soil. It makes the soil hard and less porous. It also kill soil organisms which keep the soil fertile.
Question 12
Why do farmers grow cover crops?
Answer
A cover crop is grown to cover the land after harvesting the main crop. Cover crops prevent soil from being exposed to wind and flowing water, which prevent soil erosion.
Question 13
What are shelterbelts?
The force of wind and water can also be reduced by growing trees and shrubs on the boundaries of the fields. Rows of plants on the boundaries of fields are known as shelter belts.
Question 14
Why does water drain quickly from sandy soil?
Sand grains in sandy soil forms large spaces between the particles which makes sandy soil very porous and water moves rapidly through it, which is why it cannot hold water for a long time. Question 15
What is compost? Why is it beneficial to soil? Answer
(a)Compost is made by decomposition of plant waste.
(b)Compose improves the quality of soil.
(c)It loosens the soil and helps air and water to move more freely.
(d)It holds moisture and plant nutrients.
(e)It also serves as food for soil microorganisms, which make the soil fertile. Question 16
How is sandy soil different from clayey soil?
(a)Sandy soil contains large coarse sand particles while clayey soil contains fine particles made of clay.
(b)Sandy soils have a lot of air spaces between the particles while clayey soil have little air spaces between particles.
(c)Sandy soil is very porous while clayey soil is very dense and less porous.
(d)Sandy soil has little plant nutrients while clayey soil is rich in minerals.
