Soil groups

1. Soil Groups
Indian soils are formed with different types of minerals. The
parent rocks have been originated in different forms and
these are formed after many years. The name of the soil
groups of India are as follows:
1. Alluvial Soils
2. Black soils
3. Red Soils
4. Laterites & Lateritic Soils
5. Other Groups A. Brown hill soil
B. Peaty Soil
C. Salt Affected Soil

2. Alluvial Soils
It is originated from such types of parent materials
which are being transported from one place to another.
The transported from one place to another. The
transportation of these parent materials may be from
different means viz. water, ice, wind, gravitation etc.
Alluvial soils are formed due to transportation
network of water courses and rivers and get deposited
either on flood plains or on river banks.

3. These are two types whose descriptions are given below
1. New Alluviams: It is locally known by the name of Khadar.
These are newly formed alluviams. These are sandy and light
in colour. These are sandy and light in colour. These are coarse
textured soils. Less kankers are found in these soils. Soil
horizonation either is very little or absent in these soils. These
soils are very productive in nature.
2. Old Alluviams: Locally this is known as Bhangar. Clay
content is more in these types of soils; hence, are fine textured
soils. These are dark in colour and contain kankers in
sufficient quantities. Hard and impervious layer is found in
lower horizons of these types of soils. Due to the presence of
this impervious layer, the drainage becomes difficult. The hard
and impervious layer in only formed if the sodium content is
more in the soil.

4. Important Soil Charactersitcs:
• These soils are very deep and are found in different colours.
• The colour of these types of soils varies from light- brown to
yellow brown or dark brown in colour.
• These are the lime containing soils. Some of the alluvial soils
are excessively saline and sodic in nature.
• The formation of hard and impervious layer in lower
horizons is the common characteristics of these soils.
• The formation of hard layer is frequently observed in those
soils which are being used for cultivation for long time.
• The formation of hard layer due to the lime surface
aggregation of soil particles resulted from leached silica.

5. Black Soil:
Origin:
• This soil are known as ‘Regurs’ in central India.
• The soils are found in situ mainly from basalt trapped rocks
or from the transportation of parent materials.
• They are form from two types of parent rocks i.e. Deccan
and Rajmahal traps which are volcanic crops.
• Lime and soda lime feldspar are found in these rocks which
are alkaline in nature.

6. Important Characteristics:
• The clay content is more in these soils which varies from
35-60 %, however, sometimes it may be up to 80% in lower
portions of valleys or depression.
• Black soils have clay which are swelling and shrinking in
nature. Due to this properties of clays, of 50 cm or even
more wide cracks are formed. Owing to formation of
cracks, continuous churning process goes on these soils.
• Crumb or granular structure is found in black soils.
• These soils have the problems of poor drainage and low
permeability.
• The black colour of these soil is due to clay- humus
complexes and magnetide mineral and some extent because
of organic matter (0.5 -1.0%) .
• These soil generally contain lime and are of light alkaline
in reaction.

7. • Cation Exchange Capacity of these soil is high which may
vary from 30-50 m.eq. Exchangeable quantities of calcium
and magnesium is more in black soils.
• These soils are deficient in nitrogen phosphorus and
organic matters.
Land use:
• They are very fertile.
• Cotton, cereals, sorghum, soybean etc. are mainly grown in
these soils in M.P. Gujarat and Maharashtra. Sugarcane is
being grown in black soils under irrigated condition. In
states of Maharashtra and Andhra Pradesh.

8. Problems and management:
• The main problem of these soils is the very narrow limit of soil
moisture in which ploughing of field, intercultural operations or field
preparation could be done.
• If these soils are ploughed at excess moisture, the soil come out of
ploughing becomes very hard after drying and if these soils are
ploughed at lower moisture levels, the big clods are found.
• Thus good field preparation is not possible therefore and appropriate
moisture level is required for any tillage operation in these soils.
Infiltration of water is very slow in black soil.
• There is problem of drainage also W.H.C. of these soils is high
however, plants are unable to absorb this water after a certain limit
and show symptoms of water deficit.
• The availability of different micro nutrients is being affected
negatively due its alkaline nature. As this soil are with poor drainage
inherently, therefore, soils salinity and sodicity may develop if proper
drainage is not provided under irrigated conditions.

9. RED SOILS:
Origin:
• These soils are formed from granites, gneiss and other
metamorphic rocks. They have been formed either in situ or
disintegrated matters of rocks washed from rain water are
accumulated at lower places after transportation.
Distribution:
• Red and yellow soils are mainly formed in Southern
peninsular of India which includes the states of Tamil Nadu,
Karnataka, Maharashtra, A.P. and M.P. etc. They are also
found in some of the North Eastern states i.e. Bihar,
Jharkhand, West Bengal and U.P.

10. Important Characteristics:
• They include red loams, red gravelly soils and red earths. These soils
are medium to excessively weathered.
• The soils are dominated by iron or aluminum.
• Red soils are deficient in humus.
• They are red to yellow in colour because soils particles ate coated with
layers of ferric oxides.
• Texture of red soils varies from sandy loam to heavy clay; however,
texture is loam to clay loam in general.
• Red soils are shallow to very deep and are having good drainage the
pH of the soils are varies from 6.0-7.5.
• The Cation Exchange Capacity and base saturation is medium to low
in these soils.
• They are dominated by kaolinite and illite clays and they have carbon:
nitrogen ration of about 10 and deficient in nitrogen and phosphorus
but sufficient in potassium.

11. Land use:
Despite limitation these soils are capable of growing cereals, minor millets
groundnut, maize, soybean, Jute, gram, Potato and plantation crops like
tea, cocoa, cashew, grapes, banana, papaya, mango etc.
Problems and management:
After drying these soils form hard crust which affects the germination of
zone seeds and aeration in the soil. Lower horizons of these soils become
hard due illuviation which restricts the proper root development. These
soils are dominated by kaolinite and illite types of clays, hence WHC is
less. These soils are erosive in nature due to excessive drainage and surface
runoff. These soils have poor fertility and are deficient in nitrogen sulfur
calcium etc. The CEC of red soils are also red fixation of phosphorus in
these soils.

12. Laterites and Lateritic soils:
Origin:
The literal meaning of laterites is ‘rock’. These soils are formed in sub-
tropical and tropical climates. The climate of these regions is of
alternatively wet and dry seasons. Under high rainfall situations, the
alkaline silica gets leached from parent rocks and there is majority of
iron and aluminum oxides on the surface horizons of the soil.
The end product of this process is termed as ‘laterties’. In this process,
sesquioxides are remained which upon drying get converted into
irreversible oxides of iron and aluminum.
Distribution:
These soils are found in Odisha, Maharashtra, Kerala, Tamil Nadu and
on the peaks of hills and plateau of North- Eastern regions.

13. Important Characteristics:
Hydrated oxides or the mixture of iron and aluminum are essentially found
in the soil profile of red soils. Sometimes, these are also called as ‘honey
comb structure’. These soils are purplish or brick red or they are brown to
yellowish in colour.
A soil may be classified as lateritic when layers of cellular concretion of
iron and vesicular honey comb ferruginous masses are formed in the soil
profile. The bases like calcium, magnesium, potassium and sodium get
leached down in these soils. The pH value is less. These soils are dominated
by kaolinite and illite clays, hence water holding capacity and cation
exchange capacity of these soils is less. The soils are well drained in porous
in nature.
Land Use:
The soils are suitable for cultivation of rice, banana, coconut, cocoa, tea,
rubber.

14. Problems and management:
• These soils are deficient in phosphorus and there is
problem of high capacity of phosphorus fixation. More
acidity is found in these soils.
• Under acidic conditions, the solubility of iron and
aluminum is increased hence they become available in
excessive amounts so they become toxic to plants.
• These soils are coarse textured in nature, therefore, their
water holding capacity is less.