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SOILS

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ü  Soil can be defined as an unconsolidated layer  formed from litho logically varying rocks by weathering agencies which is then modified by many organic and biochemical processes.

ü  The colour of soils depends upon factors such as their age, composition and the amount of water available to them and utilized by them.


SOIL GROUPS OF INDIA:


The Indian Council of Agricultural Research (ICAR) has divided Indian soils into eight major types.

ü  Red soils
ü  Black soils
ü  The Indo – Gangetic alluvium or alluvial soils
ü  The lateritic and late rite soils
ü  Forest and hill soils
ü  Alkaline and Saline soils.
ü  Desert soils
ü  Peaty and organic soils.

       

RED SOILS:

ü  Red Soils are mainly formed due to decomposition of ancient crystalline rocks like granites and gneisses and from rock types rich in minerals such as iron and magnesium. 


ü  The term ‘red soil’ is due to the wide diffusion of iron oxides through the materials of the soil.

ü  The Red soils are generally poor in nitrogen, phosphorous, humus.

ü  The Red soils are rich in potash.

ü  They are siliceous or aluminous in character.

ü  The Red soils cover almost the whole of Tamil Nadu, Karnataka, Andhra Pradesh, South Eastern Maharashtra, eastern parts of Madhya Pradesh, Parts of Orissa, Jharkhand and Bundelkhand. 

ü  The Red soils are most suitable for growing vegetables, rice, ragi and tobacco.

ü  Irrigation is a must for the red soils.


BLACK COTTON SOILS:
ü  The black soil is also called regur.


ü  These soils are derived from basalts of Deccan Traps.

ü  They derive their name from black colour.

ü  The black colour is due to the presence of Titanium.

ü  Black soils are fine, grained and highly argillaceous and consist of calcium and magnesium carbonates.

ü  Black soils contain high quantities of iron, aluminum, lime and magnesia.
ü  These soils generally show poor percentages of phosphorous, nitrogen and organic matter.



ALLUVIAL SOILS:

ü  These are essentially transformed soils.


ü  They form the most important and largest of all the soil groups.

ü  The alluvium is of two types.

·       The khadar

·       The bhangar (old Alluvium)

ü  The khadar is light in colour.

ü  The khadar is more siliceous in composition and composed of newer deposits.

ü  The bhangar or the old alluvium is composed of lime nodules (kankar) and has a clayey composition.

ü  Alluvial soils are found throughout the plains of northern India.

ü  In the Indian Peninsula, they are confined mainly to the river deltas on the east coast, the lower valleys of the Narmada and the Tapti, northern Gujarat and Chhattisgarh plains.

ü  The soils are suitable for the cultivation of cereals, pulses, oilseeds, cotton, sugarcane and vegetable.

ü  Alluvial soils favor jute cultivation in the eastern parts of the Indian plains.


LATE RITE AND LATERITIC SOILS:

ü  These soils possess a compact to vesicular mass.

ü  These are mainly composed of hydrated oxides of iron and aluminium.

ü  Laterisation is due to the loss of silica from the soil profile in humid regions where the process of leaching is widespread.

ü  Lateritic soils are deficient in nitrogen.

ü  The humus is absent except in the late rite soils developed in the forested areas such as western Karnataka.


       
FOREST SOILS:

ü  The forest soils are mostly found in forests and mountains.

ü  These soils have a high content of organic matter and nitrogen.

ü  Forest soils are deficient in potash, phosphorus and lime.

ü  Tea, coffee, tropical fruits and spices are obtained from plantations on these soils especially in South India.

ü  In some states the crops like Wheat, maize, barely are cultivated.

PERCENTAGE OF DIFFERENT SOILS IN THE TOTAL SOIL COVER OF INDIA

ü  Alluvial soils (riverine alluvium, coastal alluvium, deltaic alluvium, saline and alkali soils and calcareous alluvial soils) - 23.40 per cent.

ü  Sandy soils (grey brown soils and desert soils) - About 8.46 per cent

ü  Black soils (deep black, medium black and shallow black soils, and mixed red and black soils) –– 24.12 per cent.

ü  Red soils (red loamy soils, red gravelly sandy soils, and red yellow loamy soils) – 29.08 per cent.

ü  Laterite soils –– 4.30 per cent.

ü  Other soil groups (hill soils, sub - montane or podosolic soils, mountain meadow soils, terai soils, and skeletal soils) – 10.64 per cent.           
       

                        CROPS GROWN



Alluvial  -  Rice, wheat, sugarcane, oilseeds



   Black -Cotton, sugarcane, tobacco, oilseeds


Red -Wheat, rice, cotton, sugarcane, pulses.


Desert  -  Wheat, grams, melon, bajra (with irrigation).


Laterite -Coffee, rubber, cashewnut, tapioca.


Marshy                   -           Jute.



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