[Geography] Soils in India

Soils in India

 Synopsis:

(01) Soil classification based on

(02) Major Soil types in India

(03) Soils and their composition

(04) Soils and the States

(05) Soils and crops

(06) Soils and percentage of coverage

(07) Soil types – by depth

(08) Soil Erosion in India

(01) Soil classification based on:

Soil types are classified according to many more factors. They are classified on the basis of

ü      colour

ü      depth

ü      pH

ü      productivity

ü      texture and

ü      process of formation

 (02) Major soil types in India:

            Indian Council of Agricultural Research (ICAR) has divided Indian Soils into 8 major types:

(i)                Alluvial Soils

(ii)              Black Soils

(iii)           Red Soils

(iv)            Laterite Soils

(v)               Forest and Mountain Soils

(vi)            Arid and Desert Soils

(vii)          Saline and Alkaline Soils

(viii)       Peat and Marshy Soils

 (02.1) Alluvial Soils:

·        These soils occur along rivers and represent the soil materials that have been deposited by the rivers during flood.

·        Usually they are very productive soils

·        Deficient in nitrogen, humus and phosphorus

·        As the name suggests, alluvial soils are formed from alluvial deposits of rivers from mountainous region of Himalayas

·        These soils are found in North India in Indo-Gangetic and Brahmputra flood plains

·        The soils are relatively fertile and good for crop cultivation

·        Also these soils have low density, which implies that their shearing strength is low.

·        Can be divided into

ü      Khadar (new) and

ü      Bhangar (old)

 (02.2) Back Soils:

·        These are mostly clay soils and form deep cracks during dry season.

·        An accumulation of lime is generally noticed of varying depths.

·        Known as “Black cotton soils” because of their dark brown colour and suitability for growing cotton

·        Also known as Indian regurs

·        Deficient in nitrogen, phosphoric acid and organic matter but rich in calcium, potash and magnesium

·        Central India and Deccan plateau mainly constitutes this type of soil.

·        These are residual deposits formed trap or basalt rocks.

·        These soils contain essential clay minerals as montmorillonite

 (02.3) Red Soils:

·        Soils have developed on crystalline tocks u prolonged weathering in hot climate

·        Soils are rich in mineral ‘kaolinite’

·        Red soils have two broad classes:

(a) Red loam with cloddy structure and allow content of concretionary materials; and

(b) Red earths with loose, Permeable top soil and a high content of secondary concretions. Generally these soils are light textured with porous and friable structure and there is absence of lime Kankar and free carbonates. They have neutral to acidic reaction and are deficient in nitrogen humus, phosphoric acid and lime.

 (02.4) Laterite Soils:

·        Soils are red to reddish yellow in colour due to the presence of iron oxide

·        Low in Nitrogen, Phosphorus, Potash, lime and magnesia

·        These soils are formed in-situ under conditions of high rainfall with alternation dry and wet periods

·        On account of heavy rainfall there is an excessive leaching of soil colloids and silica hence the soils are porous

·        Lateritic soils are formed from chemical decomposition of rocks

·        These soils are found in Central, Eastern and South India

·        These are residual soils formed from basalt and have high specific gravity

 (02.5) Forest and Mountain Soils:

·        These soils occur at high elevations as well as at low elevations, where the rainfall is sufficient to support trees.

·        These soils are very shallow, steep, stony, and infertile for the production of field crops.

·        However, they serve a very useful purpose by supplying forest product such as timber and fuel.

 (02.6) Arid and Desert Soils:

·        These are mostly sandy soils that occur in the low rainfall track

·        They are well supplied with soluble salts but are low in nitrogen and organic matter and have a high pH value

·        These are quite productive

·        These are often subjected to wind erosion

·        These soils are found in Thar desert in Indian state of Rajasthan

·        The soils are formed from arid conditions with practically negligible rainfall

·        This type of soil is highly pervious and having low density

·        It requires densification to increase its bearing capacity and shearing strength

·        Commonly recognised plant that grows in these soils are cactus

 (02.7) Saline and Alkaline Soils:

·        These soils are found scattered within all the major types of soils

·        These soils occur in areas having a little more rainfall than the areas of desert soils.

·        They show white incrustation of salts of calcium & Magnesium and sodium on the surface.

·        These are poor in drainage and are infertile.

 (02.8) Peat and Marshy Soils:

·        These types of soils are found in Kerala, coastal track of Odisha, Sunderban area of West Bengal

·        When the vegetation growing in such wet places dies, it decomposes very slowly dues to excessive wetness of soils and after several hundreds of year a layer of partly decayed organic matter accumulates on the surface, giving rise to such peaty and marshy soils

·        These are black coloured, heavy and highly acidic soils

·        When properly drained and fertilized, these soils produce good crops of rice

(03) Soils and their composition:

#	Soils	pH range	Rich in	Lacks in
1	Alluvial	6.5 – 8.4	Calcium, Potash, Magnesium	Nitrogen, Humus
2	Black	6.5 – 8.4	Iron, Aluminium	Nitrogen, Phosphorous
3	Red	5.5 – 7.5	Potash. Lime	Nitrogen, Phosphorus, Humus
4	Laterite	< 5.5	Iron, Aluminium	Nitrogen, Minerals
5	Forest and Mountain	5.0 – 6.5	Humus	Potash, Phosphorous
6	Arid and Desert	7.6 – 8.4	Nitrogen	Phosphate
7	Saline and Alkaline		Magnesium, Calcium	Iron
8	Peat and Marshy		Aluminium, Iron	Lime

 (04) Soils and the States:

#	Soils	Mainly Found in
1	Alluvial	Punjab, Haryana, Delhi, Uttar Pradesh, Bihar, West Bengal, Asom, Parts of Gujarat, Rajasthan and Madhya Pradesh, Coastal areas of Odisha, Andhra Pradesh and Tamil Nadu
2	Black	Mainly in Deccan Plateau – Maharashtra, Gujarat, Madhya Pradesh, Karnataka, Andhra Pradesh, Telangana and Tamil Nadu
3	Red	Tamil Nadu, Karnataka, Maharashtra (South Eastern), Andhra Pradesh (Eastern), Telangana, Madhya Pradesh, Odisha, Chattisgarh, Jharkhand and North Eastern States
4	Laterite	Parts of Tamil Nadu, Odisha, Asom, Karnataka, Goa, Karnataka, Rajasthan and Meghalaya
5	Forest and Mountain	Jammu & Kashmir, Himachal Pradesh, Uttarakhand, Sikkim and Arunachal Pradesh
6	Arid and Desert	Rajasthan
7	Saline and Alkaline	Parts of Punjab, Haryana, Bihar, UP, Rajasthan
8	Peat and Marshy	Kerala, coastal areas of Odisha

(05) Soils and crops:

#	Soils	Main Crops
1	Alluvial	Rice, Wheat, Millets, Pulses, Maize, Sugarcane, Jute, Vegetables
2	Black	Cotton and Jowar [With proper irrigation, the soils can be used for cultivation of wheat, millets and sugarcane also]
3	Red	Rice, Millets, Gram, Sugarcane, Groundnut, Coconut, Ragi, Potatoes
4	Laterite	Tea, Coffee, Rubber and Cinchona (in higher elevations) Rice, Sugarcane, Gram (in lower elevations)
5	Forest and Mountain	Timber
6	Arid and Desert	Millet, Oat, Wheat
7	Saline and Alkaline	Millet, Wheat
8	Peat and Marshy	Poor for Agriculture

(06) Soils and % of coverage:

#	Soils	% of India’s Geographical Area
1	Alluvial	22.16
2	Black	29.69
3	Red	28.00
4	Laterite	02.62
5	Forest and Mountain	07.94
6	Arid and Desert	06.13
7	Saline and Alkaline	01.29
8	Peat and Marshy	02.17
(Not authenticated source; some doubts are there)

(07) Soil types – by depth:

Soil types according to depth are as follows:

(i) Shallow Soil - Soil depth less than 22.5cm. Only shallow rooted crops are grown in such soil, e.g. Paddy.

(ii) Medium deep soil - Soil depth is 22.5 to 45cm. Crops with medium deep roots are grown in this type of soil e.g. Sugar cane, Banana, Gram.

(iii) Deep soil - Soil depth is more than 45cm. Crops with long and deep roots are grown in this type a soil e.g. Mango, coconut

(08) Soil erosions in India:

·        Soil erosion in India is amongst the leading area of concern for India

·        It affects cultivation and farming in the country

·        Soil erosion leads to deprivation of physical characteristics of soils and damages plants and crops

·        In India, almost 45% of total geographical surface are is affected by serious soil erosion

·        Soil erosion in India mainly occurs due to:

ü      Gorge and gully

ü      Shifting cultivation

ü      Cultivated wastelands

ü      Sandy areas

ü      Deserts and water logging

·        Soil erosion by rain wand river that take place in hilly areas causes severe landslides and floods

·        Types of soil erosion in India:

ü      Geologic Erosion

ü      Accelerated Erosion

ü      Wind Erosion

ü      Water Erosion

ü      Sheet Erosion

ü      Gully Erosion

ü      Landslides / Slip Erosion

ü      Stream-Bank Erosion

·        Acute in hilly and dry regions

·        Remedy:

Ø     Afforestation

Ø     Contour cultivation

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