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DAILY
CLASS NOTES
Geography

Soils of India
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Soils of India
Chernozem Soils:

 The prime instances of chernozems and their variations are discovered in connection

with steppe or prairie vegetation.

 The scant rainfall in these regions results in incomplete leaching, giving rise to the

formation of a calcium-rich horizon deep within the soil profile.

 Above this lies a deep, dark soil layer that can reach up to a metre in thickness.

 Humus content in this layer often does not exceed ten percent, and the dark colour is

linked to the alkaline-rich mineral matrix.

 Chernozems exhibit a well-developed crumb structure.

 The preferred parent material for this soil type appears to be loess, which is prevalent

in the mid-western regions of North America, Russia, and northern China.

Chestnut Soils:

 Chestnut soils are situated on the arid side of the Chernozem belt, occurring naturally

in areas with low grass-steppe vegetation.

 The illuvial carbonate layer is closer to the surface compared to chernozems, and these

soils generally have a lower organic content.

Podzols (Ash-soil):

 The cheluviation process(Cheluviation is the process in which the metal ions in the

upper layer of the soil are combined with organic ligands to form coordination

complexes or chelates, moving downwards through eluviation and then depositing.) has

a distinct impact, leading to the development of soils featuring a characteristic bleached

E horizon.

 In certain profiles, humus is transported down the profile, accumulating as a humus-

enriched B horizon, resulting in a humus podzol.

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 In other cases, there is a notable concentration of iron oxide at this level, forming an

iron podzol.

 Occasionally, this manifests as an iron-pan, hindering drainage and giving rise to a

gley podzol.

 These three types of Podzols are most prevalent in cool climates immediately south of

the tundra region, typically associated with coniferous forests.

Intrazonal Types: These soils are present within the broader context of zonal soils. They are

well-developed and reflect the influence of local factors such as relief, parent material, or

age, rather than being primarily shaped by climate and vegetation.

Hydromorphic Soils:

Hydromorphic soils undergo gleying and are associated with marshes, swamps, or poorly

drained upland areas. Two main types can be distinguished based on the water-table

position in the profile: groundwater gleys, where the water is below the surface, and

surface-water gleys.

Gleying is essentially the process of waterlogging and reduction in soils. In waterlogged soils,

where water displaces air in pores, oxygen is rapidly consumed by microbes that feed on

soil organic matter.

Calcimorphic Soils:

Calcimorphic soils form on calcareous parent material. Rendzinas, found in Britain, are

dark, organic-rich soils associated with chalk rock. Another Calcimorphic soil is terra rossa,

predominantly a mineral soil located mainly in the Mediterranean region. Its upper

horizons are clay-rich and reddish in colour, creating a distinct contrast with the parent

material.

Halomorphic (Saline) Soils:Halomorphic (saline) soils are primarily located in deserts, with

three common types in this category.

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1. Solanchak (white alkali soils) develop in depressions and display white salt crusts during

dry periods.

2. Solonetz (black alkali soils) result from intense alkalinization and are characterised by

the presence of sodium carbonate.

3. Solodic soils form when leaching, in the presence of excess sodium, leads to the loss of

clays and sesquioxides, resulting in a bleached, eluviated horizon that resembles a

podzol.

USDA Soil Taxonomy

The US Department of Agriculture has recently implemented a soil classification system

that relies on observed soil properties rather than genetic considerations.

There are twelve (12) soil orders, primarily distinguished by properties reflecting a

significant course of development, with a notable focus on the presence or absence of

diagnostic horizons.

1. Alfisols – Named for aluminium ("al") and iron ("f"), two key elements in these soils.

2. Andisols – Soils rich in volcanic ash, formed from magma in Andes Mountains

volcanoes.

3. Aridisols – Dry soils.

4. Entisols – Recently formed soils.

5. Gelisols – Soils in permafrost areas.

6. Histosols – Soils predominantly composed of organic matter.

7. Inceptisols – Young soils in their early developmental stages.

8. Mollisols – Soft soils.

9. Oxisols – Soils containing significant amounts of oxygen-containing compounds.

10. Spodosols – Ashy soils.

11. Ultisols – Soils depleted of their nutrient bases through leaching.

12. Vertisols – Soils where material from O and A horizons falls through surface cracks

and accumulates below deeper horizons.

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Indian Soils:

India is a diverse country with a variety of relief features, landforms, climatic realms and

vegetation types. These have contributed to the development of various types of soils in

India. India is predominantly an agricultural country. Much of Indian agriculture depends

upon the extent and qualities of soil. India is a large country and witness’s diverse range

of climatic and other natural conditions. The nature of soil in a place is largely influenced

by such factors as climate, natural vegetation and rocks. The Indian Council of Agricultural

Research (ICAR) established the All-India Land Use and Soil Survey Organization in 1953,

and the classification of Indian soils presented below is based on this organisation's

framework.The various types of soil found in India include alluvial soil, Laterite soil, Red

soil, Black soil, Desert soil, and Mountain soil.

Alluvial Soil:

Alluvial Soil, also known as 'Kachhari Soil,' is formed through the deposition of eroded

materials carried by rivers.Formed by the deposition of eroded materials carried by rivers.

Geographical Distribution:

 Found in river basins, deltaic regions, and floodplains.

 Predominantly present in the vast plains of northern India and in the deltaic parts of

rivers such as Mahanadi, Godavari, Krishna, and Kaveri, earning them the designation

of deltaic soils.

 Additionally located in the Assam valley, Gujarat, and the western and eastern coastal

plains.

 Covers an extensive area of 14.25 lakh square km, constituting approximately 43.4

percent of the total land area of the country.

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Characteristics of Alluvial Soil:

 Colour:Light brown and yellow.

 Texture:Predominantly loamy in most places. Sandy and smooth in other areas.

 Depth:Varies across regions-Maximum depth found below 600 metres in the Gangetic

plain.

 Nutrient Composition:Lacking in nitrogen, phosphorus, and vegetable content

(humus).Abundance of potash and lime, rendering them highly fertile.

 Well-suited for the development of irrigation facilities.

 Digging wells, tube wells, and canals is easier and less expensive.

 Ideal for intensive farming.

 Major crops grown include rice, wheat, sugarcane, cotton, oilseeds, pulses, tobacco,

and green vegetables.

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Sub-divisions of Alluvial Soils:

New Alluvial or Khadar Soils:

 Located in the lowland region near the riverbank, known as Khadar.

 More fertile due to the deposition of a new layer of alluvium annually.

 High moisture retention, attributed to a significant silica content.

 Also referred to as ‘Bet’ land.

Older Alluvial or Bangar Soils:

 Found in higher regions formed from old alluvial deposits, known as Bangar.

 Not reached by floodwaters.

 Rich in calcium deposits, including pebbles.

 Also known as ‘Dhaya.’

Terai Soils:

 Spread over the Terai region south of Bhabhar in Uttar Pradesh.

 Rich in nitrogen and organic matter but deficient in phosphate.

Coastal Alluvial Soils:

 Formed in coastal regions through the deposition by sea waves and rivers.

 Extends across most of the eastern coast and the northern part of the western coast
(from the Gulf of Khambhat to Mumbai).

Deltaic Alluvial Soils:

 Newest alluvial soils in the deltaic parts of rivers such as the Ganges-Brahmaputra,
Mahanadi, Godavari, Krishna, and Kaveri.

 Contain cheeka, contributing to their marshy and salty nature.

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 Rich in humus, potash, lime, magnesium, and phosphorus.

 Among the most fertile soils globally, with major crops like rice and jute cultivated in

these areas.

Black soils:

Formation of Black Soils:

These soils originated through the solidification of basic lava, which extensively covered the

Deccan plateau during volcanic activity. Consequently, they resulted from the weathering

of the Deccan Trap.

Geographical Distribution:

Black soils are prevalent in Maharashtra, Madhya Pradesh, Chhattisgarh, Andhra Pradesh,

Telangana, Gujarat, and Tamil Nadu, covering an expansive area of approximately 5 lakh

sq. km. Following alluvial soils, they constitute the most extensive soil type in the country.
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Characteristics:

 Categorised by colour, black soils are classified into three types: Shallow, Medium, and

Deep.

 They are permanent (in situ) soils, formed in their original locations and are

characterised by high concentrations of lime, iron, magnesium, calcium, carbonate,

aluminium, and potash (LIMCAP), while lacking in humus, phosphorus, and

nitrogen(Same as that of Alluvial).

 The black hue is a result of the high iron content.

 The particles in black soils are compact and fine, providing excellent moisture retention

capabilities, making them ideal for dry farming. These soils are clayey in nature.

Unique Features:

 One drawback is the formation of cracks in the upper layer during summer dryness,

promoting air circulation but making ploughing challenging.

 The soils become sticky in the rainy season, further complicating agricultural activities.

Despite these challenges, black soils are exceptionally well-suited for cultivating cotton,

earning them the moniker "black cotton soils."

 Alternately known as Regur, Tropical Black Earth, and Tropical Shernizam, these soils

have proven to be highly conducive for crops such as sugarcane, tobacco, wheat, and

oilseeds.
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