Download What is soil degradation? Ans

Chapter-6
Soil
1. Choose the right answer from the four alternatives given below.
(i) Which one of the following is the most widespread and most productive category of
soil?
(a) Alluvial Soil
(c) Black Soil
(b) Laterite Soil
(d) Forest Soil
Ans: (a) Alluvial Soil
(ii) ‘Regur Soil’ is another name for the.
(a) Saline Soil
(c) Black Soil
(b) Arid Soil
(d) Laterite Soil
Ans: (c) Black Soil
(iii) Which one of the following is the main reason for the loss of the top soil in India?
(a) Wind erosion
(c) Excessive leaching
(b) Water erosion
(d) None of these
Ans: (a) Wind erosion
(iv) Arable land in the irrigated zones of India is turning saline due to which of the
following reasons?
(a) Addition of gypsum
(c) Over irrigation
(b) Over grazing
(d) Use of fertilizers
Ans: (c) Over irrigation
2. Answer the following questions in about 30 words.
(i)
What is soil?
Ans: Soil is a layer of unconsolidated material at the surface of the earth which has
been derived from rocks and organic matter through agencies of decay and
disintegration.
(ii)
What are the main factors responsible for the formation of soil?
Ans: The main factors in the formation of the soils are parent rock material, relief,
climate and vegetation of the area.
(iii)
Mention the three horizons of a soil profile.
Ans: ‘Horizon A’ is the topmost zone.
‘Horizon B’ is a transition zone.
‘Horizon C’ is composed of the loose parent material.
(iv)
What is soil degradation?
Ans: Defined as the decline in soil fertility, when the nutritional status declines and
depth of the soil goes down due to erosion and misuse.
(v)
What is the difference between Khadar and Bhangar?
Ans:
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Khadar
Found in the lower level in the
plains near the rivers.
Loamy, porous soil.
More fertile compared to Bhanger.
New layers are developed after
monsoon floods.
Bhanger
Found at the higher level in the plains at
the river terraces away from rivers
Clayey and non-porous soil.
Less fertile compared to Khadar due to
old deposite.
3. Answer the following questions in not more than 125 words.
(i)
What are black soils? Describe their formation and characteristics.
Ans: These soils are also known as the ‘Regur soil’ or ‘Black cotton soil’ as these soils
are best for cotton growing. They are developed on basaltic rocks of the Deccan
plateau which falls under the semi-arid climatic regime.
The black soils are generally clayey, deep and impermeable. They swell and become
sticky when wet and shrink when dried. So, during the dry season, these soil develop
wide cracks. The colour of the soil ranges from deep black to grey. Chemically, the
black soils are rich in lime, iron, magnesia and alumina. They also contain potash, but
they lack in phosphorous, nitrogen and organic matter.
(ii)
What is soil conservation? Suggest some measures to conserve soil.
Ans: It is a methodology to maintain soil fertility, prevent soil erosion and
exhaustion and improve the degraded condition of the soil.
Important methods to reduce the erosion of soil:
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controlled grazing
terraced farming
ban on shifting cultivation
contour bunding
Regulated forestry
cover cropping
mixed forming
crop rotation
(iii)
How do you know that a particular type of soil is fertile or not? Differentiate
between naturally determined fertility and culturally induced fertility.
Ans: To determine the fertility of soil, we have to know the inherit
characteristics and external features of the soil such as texture, colour, slope
of land and humus in the soil.
Naturally determined fertility: the fertility which is seemed naturally in the
soil is called naturally determined fertility. It includes the texture, colour and
moisture in the soil.
Culturally induced fertility: When the soil is made fertile by adding other
chemical contents such as fertilizers and other manures.