Major Soil Types of India: Red Soils, Lateritic Soils & Alkaline Soils

Table of Contents

• Red Soils
  • Characteristics of Red Soils
  • Chemical Composition of Red Soils
  • Color of Red Soils
  • Distribution of Red Soils
  • Crops in Red Soils
• Laterite – Lateritic Soils
  • Chemical composition of Laterite – Lateritic Soils
  • Distribution of Laterite – Lateritic Soils
  • Crops in Laterite – Lateritic Soils
  • Economic value of Laterite – Lateritic Soils
• Forest – Mountain Soils
  • Distribution of Forest – Mountain Soils
  • Chemical properties of Forest – Mountain Soils
  • Crops in Forest – Mountain Soils
• Arid – Desert Soils
  • Distribution of Arid – Desert Soils
  • Chemical properties of Arid – Desert Soils
  • Crops of Arid – Desert Soils
• Saline – Alkaline Soils
  • Capillary action
  • Surface tension
  • What gives water droplet its shape?
  • Distribution of Saline – Alkaline Soils
• Peaty – Marshy Soils
  • Distribution of Peaty – Marshy Soils
  • Chemical Properties of Peaty – Marshy Soils
  • Crops of Peaty – Marshy Soils
• Characteristics of Indian Soils
• Problems Of Indian SoilsShareWhatsAppTweetEmail

Red Soils

• Red soils along with its minor groups form the largest soil group of India.
• The main parent rocks are crystalline and metamorphic rocks like acid granites, gneisses and quartzites.

Characteristics of Red Soils

• The texture of these soils can vary from sand to clay, the majority being loams.
• On the uplands, the red soils are poor, gravelly, and porous. But in the lower areas they are rich, deep dark and fertile.

Chemical Composition of Red Soils

• They are acidic mainly due to the nature of the parent rocks. The alkali content is fair.
• They are poor in lime, magnesia, phosphates, nitrogen and humus.
• They are fairly rich in potash and potassium.

Color of Red Soils

• The red colour is due to the presence of iron oxide.
• When limestone, granites, gneisses and quartzites are eroded the clay enclosed within the rocks remains intact with other forms of non-soluble materials.
• In oxidizing conditions, rust or iron oxide develops in the clay, when the soil is present above the water table giving the soil a characteristic red colour.
• The colour is more due to the wide diffusion rather than high percentage of iron oxide content.

Distribution of Red Soils

• These soils mostly occur in the regions of low rainfall.
• They occupy about 3.5 lakh sq km (10.6 per cent) of the total area of the country.
• These soils are spread on almost the whole of Tamil Nadu.
• Other regions with red soil include parts of Karnataka, south-east of Maharashtra, Telangana, Andhra Pradesh, Madhya Pradesh, Chhattisgarh, Odisha, Chota Nagpur plateau; parts of south Bihar, West Bengal, Uttar Pradesh; Aravalis and the eastern half of Rajasthan (Mewar or Marwar Plateau), parts of North-Eastern states.

Crops in Red Soils

• The red soils are mostly loamy and hence cannot retain water like the black soils.
• The red soils, with the proper use of fertilizers and irrigation techniques, give good yield of cotton, wheat, rice, pulses, millets, tobacco, oil seeds, potatoes and fruits.

Laterite – Lateritic Soils

• Laterite soils are mostly the end products of weathering.
• They are formed under conditions of high temperature and heavy rainfall with alternate wet and dry periods.
• Heavy rainfall promotes leaching (nutrients gets washed away by water) of soil whereby lime and silica are leached away and a soil rich in oxides of iron and aluminium compounds is left behind.
• ‘Laterite’ means brick in Latin. They harden greatly on loosing moisture.
• Laterite soils are red in colour due to little clay and more gravel of red sand-stones.

Chemical composition of Laterite – Lateritic Soils

• Laterite soils are rich in bauxite or ferric oxides.
• They are very poor in lime, magnesia, potash and nitrogen.
• Sometimes, the phosphate content may be high in the form of iron phosphate.
• In wetter places, there may be higher content of humus.

Distribution of Laterite – Lateritic Soils

• Laterite soils cover an area of 2.48 lakh sq km.
• Continuous stretch of laterite soil is found on the summits of Western Ghats at 1000 to 1500 m above mean sea level, Eastern Ghats, the Rajmahal Hills, Vindhyan, Satpuras and Malwa Plateau.
• They also occur at lower levels and in valleys in several other parts of the country.
• They are well developed in south Maharashtra, parts of Karnataka etc. and are widely scattered in other regions.

Crops in Laterite – Lateritic Soils

• Laterite soils lack fertility due to intensive leaching.
• When manured and irrigated, some laterites are suitable for growing plantation crops like tea, coffee, rubber, cinchona, coconut, arecanut, etc.
• In some areas, these soils support grazing grounds and scrub forests.

Economic value of Laterite – Lateritic Soils

• Laterite and lateritic soils provide valuable building material.
• These soils can be easily cut into cakes but hardens like iron when exposed to air.
• As it is the end-product of weathering, it cannot be weathered much further and is durable.

Forest – Mountain Soils

• These soils occupy about 2.85 lakh sq km or 8.67% of the total land area of India.
• They are mainly heterogeneous soils found on the hill slopes covered by forests.
• The formation of these soils is mainly governed by the characteristic deposition of organic matter derived from forests and their character changes with parent rocks, ground-configuration and climate.
• Consequently, they differ greatly even if they occur in close proximity to one another.

Distribution of Forest – Mountain Soils

• In the Himalayan region, such soils are mainly found in valleys, less steep and north facing slopes. The south facing slopes are very steep and exposed to denudation and hence do not support soil formation.
• Forest soils occur in Western and Eastern Ghats also.

Chemical properties of Forest – Mountain Soils

• The forest soils are very rich in humus.
• They are deficient in potash, phosphorus and lime.
• They require good deal of fertilizers for high yields.

Crops in Forest – Mountain Soils

• They are suitable for plantations of tea, coffee, spices and tropical fruits in peninsular forest region.
• Wheat, maize, barley and temperate fruits are grown in the Himalayan forest region.

Arid – Desert Soils

• The desert soils consist of Aeolian sand (90 to 95 per cent) and clay (5 to 10 per cent).
• They cover a total area of 1.42 lakh sq km (4.32%).
• The presence of sand inhibits soil growth. Desertification of neighboring soils is common due to intrusion of desert sand under the influence of wind [Aeolian sand].

Distribution of Arid – Desert Soils

• Occur in arid and semi-arid regions of Rajasthan, Punjab and Haryana. The sand here is blown from the Indus basin and the coast by the prevailing south-west monsoon winds.
• Sandy soils without clay factor are also common in coastal regions of Odisha, Tamil Nadu and Kerala.

Chemical properties of Arid – Desert Soils

• They are usually poor in organic matter.
• Some desert soils are alkaline with varying degree of soluble salts like calcium carbonate.
• Calcium content increases downwards and the subsoil has ten times more calcium.
• The phosphate content of these soils is as high as in normal alluvial soils.
• Nitrogen is originally low but some of it is available in the form of nitrates.

Crops of Arid – Desert Soils

• Phosphates and nitrates make these soil fertile wherever moisture is available.
• There is a possibility of reclaiming these soils if proper irrigation facilities are available.
• In large areas, only the drought resistant and salt tolerant crops such as barley, cotton, millets, maize and pulses are grown.

Saline – Alkaline Soils

• In Saline and Alkaline Soils, the top soil is impregnated (soak or saturate with a substance) with saline and alkaline efflorescences (become covered with salt particles).
• Undecomposed rock fragments, on weathering, give rise to sodium, magnesium and calcium salts and sulphurous acid.
• Some of the salts are transported in solution by the rivers.
• In regions with low water table, the salts percolate into sub soil and in regions with good drainage, the salts are wasted away by flowing water.
• But in places where the drainage system is poor, the water with high salt concentration becomes stagnant and deposits all the salts in the top soil once the water evaporates.
• In regions with high sub-soil water table, injurious salts are transferred from below by the capillary action as a result of evaporation in dry season.

Capillary action Capillary action is the ability of a liquid to flow in narrow spaces without the assistance of, and in opposition to, external forces like gravity. The force behind capillary action is surface tension. Surface tension Surface tension is the elastic tendency of liquids (a membrane like surface) that makes them acquire the least surface area possible. Surface tension causes insects (e.g. water striders), usually denser than water, to float and stride on the water surface. Surface tension offers the necessary buoyant force (buoyancy) required for an object to float in water [Ships flots because of difference in density as well surface tension]. What gives water droplet its shape? When a water droplet is freely falling, it acquires a spherical shape. When a water drop is on a surface, it acquires the shape of a hemisphere (half a sphere). All this is due to surface tension.

Distribution of Saline – Alkaline Soils

• Saline and Alkaline Soils occupy 68,000 sq km of area.
• These soils are found in canal irrigated areas and in areas of high sub-soil water table.
• Parts of Andhra Pradesh, Telangana, Karnataka, Bihar, Uttar Pradesh, Haryana, Punjab (side effects of improper or excess irrigation), Rajasthan and Maharashtra have this kind of soils.
• The accumulation of these salts makes the soil infertile and renders it unfit for agriculture.
• In Gujarat, the areas around the Gulf of Khambhat are affected by the sea tides carrying salt-laden deposits. Vast areas comprising the estuaries of the Narmada, the Tapi, the Mahi and the Sabarmati have thus become infertile.
• Along the coastline, saline sea waters infiltrate into coastal regions during storm surges (when cyclones make landfall) and makes the soil unfit for cultivation. The low lying regions of coastal Andhra Pradesh and Tamil Nadu face this kind of soil degradation.

Peaty – Marshy Soils

• These are soils with large amount of organic matter and considerable amount of soluble salts.
• The most humid regions have this type of soil.
• They are black, heavy and highly acidic.

Distribution of Peaty – Marshy Soils

• Kottayam and Alappuzha districts of Kerala where it is called kari.
• Also occur in the coastal areas of Odisha and Tamil Nadu, Sunderbans of West Bengal, in Bihar and Almora district of Uttarakhand.

Chemical Properties of Peaty – Marshy Soils

• They are deficient in potash and phosphate.

Crops of Peaty – Marshy Soils

• Most of the peaty soils are under water during the rainy season but as soon the rains cease, they are put under paddy cultivation.

Characteristics of Indian Soils

• Most soils are old and mature. Soils of the peninsular plateau are much older than the soils of the great northern plain.
• Indian soils are largely deficient in nitrogen, mineral salts, humus and other organic materials.
• Plains and valleys have thick layers of soils while hilly and plateau areas depict thin soil cover.
• Some soils like alluvial and black soils are fertile while some other soils such as laterite, desert and alkaline soils lack in fertility and do not yield good harvest.
• Indian soils have been used for cultivation for hundreds of years and have lost much of their fertility.

Problems Of Indian Soils

• Soil erosion (Himalayan region, Chambal Ravines etc.), deficiency in fertility (Red, lateritic and other soils), desertification (around Thar desert, rain-shadow regions like parts of Karnataka, Telangana etc.), waterlogging (Punjab-Haryana plain) salinity and alkalinity (excessively irrigated regions of Punjab, Haryana, Karnataka etc.), wasteland, over exploitation of soils due to increase in population and rise in living standards and encroachment of agricultural land due to urban and transport development
  .

Major Soil Types of India: Alluvial Soils & Black Soil

Table of Contents

• Major Soil Types of India
• Alluvial Soils
  • Characteristics of Alluvial Soils
  • Chemical properties of Alluvial Soils
  • Distribution of Alluvial Soils in India
  • Crops in Alluvial Soils
  • Geological divisions of alluvial soils
    • Bhabar
    • Terai
    • Bhangar
    • Khadar
• Black Soils
  • Characteristics of Black Soils
  • Colour of Black Soils
  • Chemical Composition of Black Soils
  • Distribution of Black Soils
  • Crops in Black SoilsShareWhatsAppTweetEmail

Soil Types of India – Alluvial Soils – Black Soils – Characteristics, Chemical properties, Distribution, Divisions: Bhabar, Terai, Bhangar, Khadar.

Major Soil Types of India

• Geologically, Indian soils can broadly be divided into soils of peninsular India and soils of extra-peninsular India.
• The soils of Peninsular India are formed by the decomposition of rocks in situ, i.e. directly from the underlying rocks.
• Soils of Peninsular India are transported and re-deposited to a limited extent and are known as sedentary soils.
• The soils of the Extra-Peninsula are formed due to the depositional work of rivers and wind. They are very deep. They are often referred to as transported or azonal soils.

Major groups:

• Alluvial soils,
• Black soils,
• Red soils,
• Laterite and Lateritic soils,
• Forest and Mountain soils,
• Arid and Desert soils,
• Saline and Alkaline soils and
• Peaty and Marshy soils.

Alluvial Soils

• Alluvial soils are formed mainly due to silt deposited by Indo-Gangetic-Brahmaputra rivers. In coastal regions some alluvial deposits are formed due to wave action.
• Rocks of the Himalayas form the parent material. Thus the parent material of these soils is of transported origin.
• They are the largest soil group covering about 15 lakh sq km or about 46 per cent of the total area.
• They support more than 40% of the India’s population by providing the most productive agricultural lands.

Characteristics of Alluvial Soils

• They are immature and have weak profiles due to their recent origin.
• Most of the soil is Sandy and clayey soils are not uncommon.
• Pebbly and gravelly soils are rare. Kankar (calcareous concretions) beds are present in some regions along the river terraces.
• The soil is porous because of its loamy (equal proportion of sand and clay) nature.
• Porosity and texture provide good drainage and other conditions favorable for agriculture.
• These soils are constantly replenished by the recurrent floods.

Chemical properties of Alluvial Soils

• The proportion of nitrogen is generally low.
• The proportion of Potash, phosphoric acid and alkalies are adequate
• The proportion of Iron oxide and lime vary within a wide range.

Distribution of Alluvial Soils in India

• They occur all along the Indo-Gangetic-Brahmaputra plains except in few places where the top layer is covered by desert sand.
• They also occur in deltas of the Mahanadi, the Godavari, the Krishna and the Cauvery, where they are called deltaic alluvium (coastal alluvium)
• Some alluvial soils are found in the Narmada, Tapi valleys and Northern parts of Gujarat.

Crops in Alluvial Soils

• They are mostly flat and regular soils and are best suited for agriculture.
• They are best suited to irrigation and respond well to canal and well/tube-well irrigation.
• They yield splendid crops of rice, wheat, sugarcane, tobacco, cotton, jute, maize, oilseeds, vegetables and fruits.

Geological divisions of alluvial soils

• Geologically, the alluvium of the Great plain of India is divided into newer or younger khadar and older bhangar soils.

Bhabar

• The bhabar belt is about 8-16 km wide running along the Shiwalik foothills. It is a porous, northern most stretch of Indo-Gangetic plain.
• Rivers descending from the Himalayas deposit their load along the foothills in the form of alluvial fans. These alluvial fans (often pebbly soils) have merged together to build up the bhabar belt.
• The porosity of bhabar is the most unique feature. The porosity is due to deposition of huge number of pebbles and rock debris across the alluvial fans.
• The streams disappear once they reach the bhabar region because of this porosity. Therefore, the area is marked by dry river courses except in the rainy season.
• The area is not suitable for agriculture and only big trees with large roots thrive in this belt.

Terai

• Terai is an ill-drained, damp (marshy) and thickly forested narrow tract (15-30 km wide) to the south of Bhabar running parallel to it.
• The underground streams of the Bhabar belt re-emerge in this belt. It is a swampy lowland with silty soils.
• The terai soils are rich in nitrogen and organic matter but are deficient in phosphate.
• These soils are generally covered by tall grasses and forests but are suitable for a number of crops such as wheat, rice, sugarcane, jute etc..
• This thickly forested region provides shelter to a variety of wild life.

Bhangar

• The Bhangar is the older alluvium along the river beds forming terraces higher than the flood plain (about 30 metres above the flood level).
• It is of a more clayey composition and is generally dark colored.
• A few metres below the terrace of the bhangar are beds of lime nodules known as “Kankar”.

Khadar

• The Khadar is composed of newer alluvium and forms the flood plains along the river banks.
• The banks are flooded almost every year and a new layer of alluvium is deposited with every flood. This makes them the most fertile soils of Ganges.
• They are sandy clays and loams, more dry and leached, less calcareous and carbonaceous (less kankary). A new layer of alluvium is deposited by river flood almost every year.

Black Soils

• The parent material for most of the black soil are the volcanic rocks that were formed in the Deccan Plateau (Deccan and the Rajmahal trap).
• In Tamil Nadu, gneisses and schists form the parent material. The former are sufficiently deep while the later are generally shallow.
• These are the region of high temperature and low rainfall. It is, therefore, a soil group typical to the dry and hot regions of the Peninsula.

Characteristics of Black Soils

• A typical black soil is highly argillaceous [Geology (of rocks or sediment) consisting of or containing clay] with a large clay factor, 62 per cent or more.
• In general, black soils of uplands are of low fertility while those in the valleys are very fertile.
• The black soil is highly retentive of moisture. It swells greatly on accumulating moisture. Strenuous effort is required to work on such soil in rainy season as it gets very sticky.
• In summer, the moisture evaporates, the soil shrinks and is seamed with broad and deep cracks. The lower layers can still retain moisture. The cracks permits oxygenation of the soil to sufficient depths and the soil has extraordinary fertility.

Colour of Black Soils

• The black colour is due to the presence of a small proportion of titaniferous magnetite or iron and black constituents of the parent rock.
• In Tamil Nadu and parts of Andhra Pradesh, the black colour is derived from crystalline schists and basic gneisses.
• Various tints of the black colour such as deep black, medium black, shallow black , a mixture of red and black may be found in this group of soils.

Chemical Composition of Black Soils

• 10 per cent of alumina,
• 9-10 per cent of iron oxide,
• 6-8 per cent of lime and magnesium carbonates,
• Potash is variable (less than 0.5 per cent) and
• phosphates, nitrogen and humus are low.

Distribution of Black Soils

• Spread over 46 lakh sq km (16.6 per cent of the total area) across Maharashtra, Madhya Pradesh, parts of Karnataka, Telangana, Andhra Pradesh, Gujarat and Tamil Nadu.

Crops in Black Soils

• These soils are best suited for cotton crop. Hence these soils are called as regur and black cotton soils.
• Other major crops grown on the black soils include wheat, jowar, linseed, virginia tobacco, castor, sunflower and millets.
• Rice and sugarcane are equally important where irrigation facilities are available.
• Large varieties of vegetables and fruits are also successfully grown on the black soils.
• This soil has been used for growing a variety of crops for centuries without adding fertilizers and manures, with little or no evidence of exhaustion
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Factors that influence soil formation in Indian Conditions

Table of Contents

• Factors that influence soil formation in Indian Conditions
  • Parent Material
    • Ancient crystalline and metamorphic rocks
    • Cuddapah and Vindhyan rocks
    • Gondwana rocks
    • Deccan basalts
    • Tertiary and Mesozoic sedimentary rocks
  • Relief
  • Climate
  • Natural VegetationShareWhatsAppTweetEmail

Soil formation in Indian Conditions – Factors that influence soil formation: Parent Material – Gondwana rocks & Deccan basalts, Relief, Climate & Natural Vegetation.

Factors that influence soil formation in Indian Conditions

• Parent Material
• Relief
• Climate
• Natural Vegetation

Parent Material

• The rocks from which soils are formed are called parent materials.
• In most of the cases, the parent material determines the colouration, mineral composition and texture of the soil.
• In some cases, the soil formed may or may not have the same physical properties of the parent rock.
• Climatic factors induce chemical changes which also affect physical properties of the soil.
• The surface rocks are exposed to the process of weathering. In this process, the rocks are converted into fine grains and provide a base for the soil formation.
• In Indian Conditions, parent material is generally categorized into:

1. Ancient crystalline and metamorphic rocks
2. Cuddapah and Vindhyan rocks
3. Gondwana rocks
4. Deccan basalts
5. Tertiary and Mesozoic sedimentary rocks of extra peninsular India {Rock System}

Ancient crystalline and metamorphic rocks

• They are the Oldest rocks [(pre-Cambrian era)(formed due to solidification of molten magma about 4billion years ago)].
• They form the ‘Basement Complex’ of peninsular India.
• They are basically granites, gniesses and schists.
• These rocks are rich in ferromagnetic materials and give rise to red soils on weathering.
• The red colour of these soils is due to the presence of iron oxide.

Cuddapah and Vindhyan rocks

• They are ancient sedimentary rocks (4000 m thick).
• On weathering they give calcareous [containing calcium carbonate; chalky] and argillaceous [consisting of or containing clay] soils.
• The soil is mostly devoid of metalliferous minerals.

Gondwana rocks

• These rocks are also sedimentary in nature and they are much younger.
• On weathering they give rise to comparatively less mature soils.
• The soil is more or less of uniform character but of low fertility.

Deccan basalts

• Volcanic outburst over a vast area of the Peninsular India many hundred million years ago gave rise to Deccan Traps.
• Basaltic lava flowed out of fissures covering a vast area of about ten lakh sq km.
• Basalts are rich in titanium, magnetite, aluminium and magnesium.
• Consequently the weathering of these rocks has given rise to soils of darker colour.
• The is fertile with high moisture holding capacity and is popularly known as ‘regur’ or black cotton soil.

Tertiary and Mesozoic sedimentary rocks

• Rocks of extra peninsular (plains and Himalayas) India have given rise to soils with high porosity.
• These soils are generally immature recent and sub recent rocks, result in alluvial soils on weathering.
• Alluvial fertile soils consist of fine silts and clay. These soils have little relation with the original rocks.
• On the other hand, the soils of peninsular plateau are generally coarse-grained and are closely related to the parent rocks. The peninsular soils are generally less fertile.

Relief

• The relief is the most important factor for soil formation in places with steep slopes like the hilly regions, edges of plateaus etc.
• Soil erosion on barren slopes is rampant and it hinders soil formation. Example: Chambal ravines, higher reaches of Himalayas where there is minimal or no forest cover (most on the steep southern slopes) etc.
• The areas of low relief or gentle slope generally experience deposition and have deep soils. Example: Indo-Gangetic plain.
• The exceptions in the plateau are river basins where the soil layers are sufficiently deep.

Climate

• Temperature and rainfall are the most important factors in soil formation.
• They determine the effectiveness of weathering of the parent material, the quantity of water seeping through the soil and the type of micro-organisms present therein.
• Two different parent materials may develop the same soil in the same type of climate. Similarly, the same parent material may produce two different types of soils in two different types of climates.
• The crystalline granites produce laterite soil in relatively moist parts of the monsoonal region and non-laterite soil in drier areas.
• Hot summer and low rainfall develops black soil as is found in some parts of Tamil Nadu irrespective of the parent rock.
• In Rajasthan, both granite and sandstone give birth to sandy soil under arid climate.
• In arid and semi-arid regions, evaporation always exceeds precipitation. There is little vegetation and the soils badly lack humus content. Hence the soils are invariably of light colour.
• In Rajasthan and the adjoining arid and semi-arid regions, excess of evaporation makes soils lime accumulating. Hence the soil is pedocal in nature [Pedocal is a subdivision of the zonal soil order. It is a class of soil which forms in semiarid and arid regions. It is rich in calcium carbonate and has low soil organic matter].
• In cold climates of the Himalayan region, the process of vegetation decay is very slow and the soils are acidic in nature.

In areas of heavy rainfall and high temperature, the soils are red or lateritic. Why?

• Torrential rainfall during the rainy season washes the upper soil and leaches the materials into deeper horizon.
• During the dry summer season the evaporation exceeds precipitation and through capillary action iron and aluminium oxides are transported to the surface making the soil red.
• In areas of alternate wet and dry climate, the leached material which goes deep down in the horizon is brought up and the blazing sun bakes the top soil so hard that it resembles a brick. Therefore, this soil is called lateritic which literally means brick.

Natural Vegetation

• Natural vegetation reflects the combined effects of relief and climate.
• The formation and development of soil is very much influenced by the growth of vegetation.
• The decayed leaf material adds much needed humus to soil thereby increasing its fertility.
• The densely forested areas contain some of the best soils in India. There is a close relationship between the vegetation types and soil types in India
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Soil Types: Sandy, Clayey & Loamy | Soil Profile (Soil Horizon)

Table of Contents

• Soil
• Soil Types – Sandy-Clayey-Loamy
  • O Horizon
  • A Horizon or Surface soil
  • E horizon
  • B Horizon or Subsoil
  • C Horizon or Parent rock
  • R Horizon or BedrockShareWhatsAppTweetEmail

Soil – Soil Types: Sandy – Clayey – Loamy. Soil Profile – Soil Horizon: O horizon, A Horizon, E horizon, B Horizon, C Horizon or Parent rock, R Horizon or Bedrock.

Soil

• Soil is the thin top layer on the earth’s crust comprising rock particles mixed with organic matter.
• Pedology is the study of soils in their natural environment. Pedogenesis is the natural process of soil formation that includes a variety of processes such as weathering, leaching, calcification etc..
• The Soil formation is mainly related to the parent rock material, surface relief, climate and natural vegetation.
• The soil is formed by the breaking down of rocks by the action of wind, water and climate. This process is called

Soil Types – Sandy-Clayey-Loamy

• The soil is classified on the basis of the proportion of particles of various sizes.
• If soil contains greater proportion of big particles it is called sandy soil.
• If the proportion of fine particles is relatively higher, then it is called clayey soil.
• If the amount of large and fine particles is about the same, then the soil is called

1. Water can drain quickly through the spaces between the sand particles. So, sandy soils tend to be light, well aerated and dry.
2. Clay particles, being much smaller, pack tightly together, leaving little space for air. Unlike sandy soil, water can be held in the tiny gaps between the particles of clay. So clay soils have little air. But they are heavy as they hold more water than the sandy soils.
3. The best topsoil for growing plants is Loamy soil is a mixture of sand, clay and another type of soil particle known as silt. Silt occurs as a deposit in river beds. The size of the silt particles is between those of sand and clay. The loamy soil also has humus in it. It has the right water holding capacity for the growth of plants.

• Clayey and loamy soils are both suitable for growing cereals like wheat, and gram. Such soils are good at retaining water.
• For paddy, soils rich in clay and organic matter and having a good capacity to retain water are ideal.
• For lentils (masoor) and other pulses, loamy soils, which drain water easily, are required.
• For cotton, sandy loam or loam, which drain water easily and can hold plenty of air, are more suitable.

• A vertical section through different layers of the soil is called the soil profile.
• Each layer differs in feel (texture), colour, depth and chemical composition. These layers are referred to as
• A soil horizon is a layer generally parallel to the soil surface, whose physical characteristics differ from the layers above and beneath.
• Horizons are defined in most cases by obvious physical features, chiefly colour and texture.
• The uppermost horizon is generally dark in colour as it is rich in humus and minerals. The humus makes the soil fertile and provides nutrients to growing plants.
• This layer is generally soft, porous and can retain more water. It is called the topsoil or the A-horizon.
• The next layer has a lesser amount of humus but more of minerals. This layer is generally harder and more compact and is called the B-horizon or the middle layer.
• The third layer is the C-horizon, which is made up of small lumps of rocks with cracks.

O Horizon

• Layers dominated by organic material.
• Some O layers consist of undecomposed or partially decomposed litter (such as leaves, needles, twigs, moss, and lichens).
• They may be on top of either mineral or organic soils.

A Horizon or Surface soil

• It is the part of top soil.
• In this layer, organic matter is mixed with mineral matter.
• It is the layer of mineral soil with the most organic matter accumulation and soil life.
• This layer is depleted of (eluviated of) iron, clay, aluminum, organic compounds, and other soluble constituents.
• When depletion is pronounced, a lighter colored “E” subsurface soil horizon is apparent at the base of the “A” horizon.

E horizon

• “E” stands for eluviated layer.
• It is the horizon that has been significantly leached of clay, iron, and aluminum oxides, which leaves a concentration of resistant minerals, such as quartz, in the sand and silt sizes.
• These are present only in older, well-developed soils, and generally occur between the A and B horizons.

B Horizon or Subsoil

• It is subsurface layer reflecting chemical or physical alteration of parent material.
• This layer accumulates all the leached minerals from A and E horizon.
• Thus iron, clay, aluminum and organic compounds accumulate in this horizon [illuviation (opposite of eluviation)].

C Horizon or Parent rock

• Weathered parent material accumulates in this layer, i.e. the parent material in sedimentary deposits.
• It is a layer of large unbroken rocks.
• This layer may accumulate the more soluble compounds (inorganic material).

R Horizon or Bedrock

• This layer denotes the layer of partially weathered bedrock at the base of the soil profile.
• Unlike the above layers, R horizons largely comprise continuous masses of hard rock.
• Soils formed in situ will exhibit strong similarities to this bedrock layer.
• These areas of bedrock are under 50 feet of the other profiles
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