Soil
1.
Soil is the mixture of rock
debris and organic materials which develop on the earth’s surface.
2.
The major factors affecting the
formation of soil are relief, parent material, climate, vegetation and other
life-forms and time
3.
Components of the soil are
mineral particles, humus, water and air.
4.
‘Horizon A’ is the topmost
zone, where organic materials have got incorporated with the mineral matter,
nutrients and water,
5.
‘Horizon B’ is a transition
zone between the ‘horizon A’ and ‘horizon C’, and contains matter derived from
below as well as from above. It has some organic matter in it,
6.
‘Horizon C’ is composed of the
loose parent material. This layer is the first stage in the soil formation
process and eventually forms the above two layers
7.
This arrangement of layers is
known as the soil profile
8.
Underneath these three horizons
is the rock which is also known as the parent rock or the bedrock
CLASSIFICATION
1.
In ancient times, soils used to
be classified into two main groups – Urvara and Usara
2.
Fertile and sterile
3.
In the 16th century A.D., soils
were classified on the basis of their inherent characteristics and external
features such as texture, colour, slope of land and moisture content in the
soil
4.
In the 16th century A.D., soils
were classified on the basis of their inherent characteristics and external
features such as texture, colour, slope of land and moisture content in the
soil
5.
Sandy, clayey, silty and loam,
etc.
6.
On the basis of colour -Red,
yellow, black, ET
Soil Survey
of India
1.
Established in 1956, The
National Bureau of Soil Survey and the Land Use Planning an Institute under the
control of the Indian Council of Agricultural Research (ICAR)
2.
The ICAR has classified the
Indian soils on the basis of their nature and character as per the United States
Department of Agriculture (USDA) Soil Taxonomy
(i) Inceptisols
(ii) Entisols
(iii) Alfisols
(iii) Alfisols
(iv) Vertisols
(vi) Ultisols
(vi) Mollisols
ICAR
classification on the basis of genesis, colour, composition and location,
(i) Alluvial soils
(ii) Black soils
(ii) Black soils
(iv) Laterite soils
(v) Arid soils
(vi) Saline soils
(vii) Peaty soils
(viii) Forest soils
Alluvial
Soils
1.
Widespread in the northern
plains and the river valleys
2.
40 per cent of the total area
of the country
3.
Depositional soils
4.
Transported and deposited by
rivers and streams
5.
Transported and deposited by
rivers and streams
6.
Peninsular region, they are
found in deltas of the east coast and in the river valleys
7.
Vary in nature from sandy loam
to clay
8.
Rich in potash but poor in
phosphorous
9.
Upper and Middle Ganga plain,
two different types of alluvial soils have developed
Khadarand Bhangar.
1.
Khadar is the new alluvium and
is deposited by floods annually, which enriches the soil by depositing fine
silts
2.
Bhangar represents a system of
older alluvium, deposited away from the flood plains
3.
Khadarand Bhangarsoils contain
calcareous concretions (Kankars
4.
More loamy and clayey in the
lower and middle Ganga plain and the Brahamaputra valley
5.
More loamy and clayey in the
lower and middle Ganga plain and the Brahamaputra valley
6.
Colour of the alluvial soils
varies from the light grey to ash grey
7.
Shades depend on the depth of
the deposition, the texture of the materials, time taken for attaining maturity
8.
Alluvial soils are intensively
cultivated.
Black Soil
1.
Includes parts of Maharashtra,
Madhya Pradesh, Gujarat, Andhra Pradesh and some parts of Tamil Nadu.
2.
Western part of the Deccan
Plateau
3.
And the north western part of
the Deccan Plateau,
4.
Western part of the Deccan
Plateau,
5.
Also known as the ‘Regur Soil’
or the ‘Black Cotton Soil
6.
Generally clayey, deep and
impermeable.
7.
Generally clayey, deep and
impermeable.
8.
There occurs a kind of
‘self-ploughing’
9.
The black soil retains the
moisture for a very long time
10.
Helps the crops, especially,
the rain fed ones, to sustain even during the dry season
11.
Chemically, the black soils are
rich in lime and also contain potash
12.
Lack in phosphorous, nitrogen
and organic matter.
13.
Soil ranges from deep black to
grey
Red and Yellow
Soil
1.
Red soil develops on
crystalline igneous rocks in areas of low rainfall in the eastern and southern
part of the Deccan Plateau
2.
Along the piedmont zone of the
Western Ghat, long stretch of area is occupied by red loamy soil
3.
Yellow and red soils are also
found in parts of Orissa and Chhattisgarh and in the southern parts of the
middle Ganga plain
4.
Develops a reddish colour due
to a wide diffusion of iron in crystalline and metamorphic rocks
5.
Fine-grained red and yellow
soils are normally fertile
6.
Coarse-grained soils found in
dry upland areas are poor in fertility
7.
Generally poor in nitrogen,
phosphorous and humus
Laterite
Soil
1.
Derived from the Latin word
‘Later ‘which means brick
2.
Develop in areas with high
temperature and high rainfall
3.
Result of intense leaching due
to tropical rains
4.
With rain, lime and silica are
leached away, and soils rich in iron oxide and aluminium compound are left
behind
5.
Humus content of the soil is
removed fast by bacteria that thrives well in high temperature.
6.
While iron oxide and potash are
in excess
7.
Not suitable for cultivation
8.
Application of manures and
fertilisers are required for making the soils fertile for cultivation
9.
Red laterite soils in Tamil
Nadu, Andhra Pradesh and Kerala are more suitable for tree crops like cashewnut
10.
Laterite soils are widely cut
as bricks for use in house construction
11.
Mainly developed in the higher
areas of the peninsular plateau
12.
Commonly found in Karnataka,
Kerala, Tamil Nadu, Madhya Pradesh and the hilly areas of Orissa and Assam
Arid Soils
1.
Arid soils range from red to
brown in colour
2.
Generally sandy in structure
and saline in nature.
3.
The salt content is so high
that common salt is obtained by evaporating the saline water
4.
Due to the dry climate, high
temperature and accelerated evaporation, they lack moisture and humus
5.
Nitrogen is insufficient and
the phosphate
6.
Content is normal
7.
Lower horizons of the soil are
occupied by ‘kankar’ layers because of the increasing calcium content downwards
8.
The ‘Kankar ’layer formation in
the bottom horizons restricts the infiltration of water,
9.
The soil moisture is readily
available for a sustainable plant growth
10.
Characteristically developed in
western Rajasthan, which exhibit characteristic arid topography
11.
Soils are poor and contain
little humus and organic matter
Saline
Soils
1.
Also known as Usara soils
2.
Saline soils contain a larger
proportion of sodium
3.
Potassium and magnesium, and
thus, they are infertile,
4.
Do not support any vegetative
growth
5.
More salts, largely because of
dry climate and poor drainage
6.
Occur in arid and semi-arid
regions, and in waterlogged and swampy areas
7.
Structure ranges from sandy to
loamy
8.
Lack in nitrogen and calcium
9.
Saline soils are more
widespread in western Gujarat, deltas of the eastern coast and in Sunderban
areas of West Bengal
10.
Rann of Kuchchh, the Southwest
Monsoon brings salt particles and deposits there as a crust
11.
Seawater intrusions in the
deltas promote the occurrence of saline soils.
12.
Areas of intensive cultivation
with excessive use of irrigation, especially in areas of green revolution, the
fertile alluvial soils are becoming saline
13.
Excessive irrigation with dry
climatic conditions promotes capillary action, which results in the deposition
of salt on the top layer of the soil.
14.
Punjab and Haryana, farmers are
advised to add gypsum to solve the problem of salinity in the soil
Peaty Soils
1.
Found in the areas of heavy
rainfall and high humidity
2.
Organic matter in these soils
may go even up to 40-50 per cent
3.
Soils are normally heavy and
black in colour
4.
Occurs widely in the northern
part of Bihar, southern part of Uttaranchal and the coastal areas of West
Bengal, Orissa and Tamil Nadu
Forest
Soils
1.
Formed in the forest areas
where sufficient rainfall is available
2.
They are loamy and silty on
valley sides
3.
Coarse-grained in the upper
slopes
4.
In the snow-bound areas of the
Himalayas, they experience denudation
5.
Acidic with low humus content
6.
Soils found in the lower
valleys are fertile
SOIL DEGRADATION
1.
Decline in soil fertility, when
the nutritional status declines and depth of the soil goes down due to erosion
and misuse
2.
Soil degradation is the main
factor leading to the depleting soil resource base in India
3.
In the soil. Peaty Soils they
are found in the areas of heavy rainfall and high humidity,
4.
Where there is a good growth of vegetation.
Thus, large quantity of dead organic matter accumulates in these areas, and this
gives a rich humus and organic content to the soil.
5.
Organic matter in these soils may go even up
to 40-50 per cent. These soils are normally heavy and black in colour. At many
places, they are alkaline also.
6.
It occurs widely in the northern part of Bihar,
southern part of Uttaranchal and the coastal areas of West Bengal, Orissa and
Tamil Nadu.
7.
Forest Soils As the name suggests, forest
soils are formed in the forest areas where sufficient rainfall is available.
The soils vary in structure and texture depending on the mountain environment
where they are formed.
8.
They are loamy and silty on
valley sides and coarse-grained in the upper slopes. In the snow-bound areas of
the Himalayas, they experience denudation, and are acidic with low humus
content.
9.
The soils found in the lower valleys are
fertile. It is evident from the foregoing discussions that soils, their
texture, quality and nature are vital for the germination and growth of plant
and vegetation including crops.
10.
Soils are living systems. Like
any other organism, they too develop and decay, get degraded, respond to proper
treatment if administered in time.
11.
These have serious
repercussions on other components of the system of which they themselves are
important parts.
SOIL DEGRADATION
IN BROAD SENSE
1.
In a broad sense, soil
degradation can be defined as the decline in soil fertility,
2.
When the nutritional status
declines and depth of the soil goes down due to erosion and misuse.
3.
Soil degradation is the main
factor leading to the depleting soil resource base in India. The degree of soil
degradation varies from place to place according to the topography, wind
velocity and amount of the rainfall. Destruction of the soil cover is described
as soil erosion.
4.
The soil forming processes and
the erosional processes of running water and wind go on simultaneously
5.
There is a balance between
these two processes.
6.
Sometimes, such a balance is
disturbed by natural or human factors, leading to a greater rate of removal of
soil
Wind
erosion
1.
Wind erosion is significant in
arid and semi-arid regions
2.
In regions with heavy rainfall
and steep slopes, erosion by running water is more significant
3.
Sheet erosion takes place on
level lands after a heavy shower and the soil removal is not easily noticeable.
4.
Harmful since it removes the
finer and more fertile top soil.
Gully
erosion
1.
Gully erosion is common on
steep slopes. Gullies deepen with rainfall, cut the agricultural lands into
small fragments and make them unfit for cultivation
2.
A region with a large number of
deep gullies or ravines is called a badland topography
Ravines
1.
Ravines are widespread, in the
Chambal basin.
2.
The country is losing about
8,000 hectares of land to ravines every year
Others
1.
Eroded materials are carried
down to rivers and they lower down their carrying capacity, and cause frequent
floods and damage to agricultural lands
2.
Deforestation is one of the
major causes of soil erosion
3.
Plants keep soils bound in
locks of roots
4.
They also add humus to the soil
by shedding leaves and twigs
5.
Their effect on soil erosion
are more in hilly parts of the country
6.
A fairly large area of arable
land in the irrigated zones of India is becoming saline because of over
irrigation
7.
The salt lodged in the lower
profiles of the soil comes up to the surface and destroys its fertility
8.
This problem is common in all
the command areas of the river valley projects, which were the first
beneficiaries of the Green Revolution
9.
About half of the total land of
India is under some degree of degradation.
Ways to
curb soil erosion
1.
The first step in any rational
solution is to check open cultivable lands on slopes from farming
2.
And with a slope gradient of 15
- 25 per cent should not be used
3.
Terraces should carefully be
made.
4.
Should be regulated and
controlled by educating villagers about the consequences. Contour bonding,
Contour terracing
5.
Prevent gully erosion and
control their formation
6.
Constructing a series of check
dams.
7.
Special attention should be
made to control headward extension of gullies
8.
In arid and semi-arid areas, protect
cultivable lands from encroachment by sand dunes through developing shelter
belts of trees and agro-forestry.
9.
Lands not suitable for
cultivation should be converted into pastures for grazing.
10.
Central Soil Conservation
Board, set up by the Government of India, has prepared a number of plans for
soil conservation in different parts of the country
11.
Land use maps should be
prepared and lands should be put to right uses
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