Soil : Healthy And Life-changing | ICAR Soil Classification – 8 Types of Soil

What is Soil?

Soil is the loose surface of the earth and it’s the material that covers most of the land and area. It consists of inorganic particles and organic matter.

In India, soil classification varied because of physical, chemical, biological, and fertility properties of soil as studies stated. Decades have been passed scientist and coworkers divide the classification as –

Ancient – Soil Classification i.e., only two main groups – Urvara (fertile) and Usara (sterile).

Modern Classification: in 1956, Soil survey of India studied the various characteristics and physical properties of soils in India. The National Bureau of Soil Survey and Land Use Planning, an institute under the control of ICAR – Indian Council of Agriculture Research has Classified types of Soil in India, into 8 categories

Soil Meaning in Hindi : मिट्टी | मृदा

On the surface of the earth, Soil is the best natural resource for the human race, the study of soil including soil formation, classification and mapping; physical, chemical, biological, and fertility properties of soils; and these properties in relation to the use and management of soils is said to be Soil Science.

Point to point about Soil

1. SOIL is the most important layer of the earth’s crust.
2. The soil is completely weathered
3. Particles are fine.
4. Loose and friable.
5. There is more aeration in the soil.
6. Our day-to-day needs i.e. our food and our clothing are almost based on crops, plants, trees that grow in the soil.
7. Microorganisms is more in number.
8. Higher organic matter content
9. Dark in colour.
10. High nitrogen content.
11. The various agents of gradation and weathering have acted upon the parent rock material to produce a thin layer of soil.
12. Generally, all nutrients are available in the soil.
13. On the earth’s surface mixture of rock debris and organic materials which develop Soil.
14. It’s fertile in nature.
15. Based on texture: Sandy, Clayey, Silty, Loam

Ancient – Soil Classification

In ancient times, soils used to be classified into two main groups – Urvara (fertile) and Usara (sterile).

Ancient – Soil Classification in 16th centrury A.D.

On the basis of their Inherent Characteristics and External Features:

• Texture,
• Colour,
• Slope of Land
• Moisture Content

Geographical Distribution by Surapala

• Jangala (arid)
• Anupa (marshy)
• Samanya (ordinary)

Based on Colour and Taste

1. Based on Colour

• Black
• White
• Pale
• Dark
• Red
• Yellow

1. Based on Taste

• Sweet
• Sour
• Salty
• Pungent
• Bitter
• Astringent

Based on Rig-Veda Soil classification

• Urvara (Fertile)
• Ushara (Barren)
• Maru (Desert)
• Aprahata (Fallow)
• Shadvala (Grassy)
• Pankikala (Muddy)
• Jalaprayah (Water)
• Kachchaha (Land contiguous to water)
• Sharkara (Full of pebbles)
• Sharkaravari (Sandy)
• Nadimatruka (Land water from river)
• Devamatruka (Rainfed)

Soil Definition:

Whitney (1892): Soil is a nutrient bin which supplies all the nutrients required for plant growth

Hilgard (1892): Soil is more or less a loose and friable material in which plants, by means of their roots, find a foothold for nourishment as well as for other conditions of growth”

Dokuchaiev (1900): Russian scientist – Father of soil science – Soil is a natural body composed of mineral and organic constituents, having a definite genesis and a distinct nature of its own.

Joffe (1936): “Soil is a natural body of mineral and organic constituents differentiated into horizons – usually unconsolidated – of variable depth which differs among themselves as well as from the underlying parent material in morphology, physical makeup, chemical properties and composition and biological characteristics”.

Jenny (1941): Soil is a naturally occurring body that has been formed due to combined influence of climate and living organisms acting on parent material as conditioned by relief over a period of time.

Ruffin and Simonson (1968): Soil is a mixture of Earth’s uppermost mantle of weathered rock and organic matter.

Agencies / Institutes involved in Soil Classification 

Soil survey of India was established in 1956, they studied the various characteristics and physical properties of soils in India. A lot of studies did on Indian soil, by The National Bureau of Soil Survey and Land Use Planning, an institute under the control of Indian Council of Agriculture Research.

SOIL: A dynamic natural body on the surface of the Earth

A dynamic natural body on the surface of the earth in which plants grow, composed of minerals and organic material and living forms.

BUCKMAN AND BRADY

ICAR Soil Classification: Types of Soil In India

ICAR [Indian Council of Agricultural Research] has Classified types of Soil in India, into 8 categories, on the basis of colour, composition, genesis and location, the soils in India have been classified into:

• Alluvial soil
• Arid soil
• Black soil
• Forest soil
• Laterite soil
• Peaty soil
• Red and Yellow soil
• Saline soil

Alluvial Soil

What is alluvial soil?

Alluvial soil is the most productive, rich in minerals, nutrients and organic matter because deposited by surface water, along with rivers, in floodplains and deltas (Mississippi Delta), stream terraces. Alluvial soil is also known as जलोढ़ मिट्टी in Hindi.

Alluvial Soil in India [Distribution]

• These soils cover about 40 per cent of the total area of the country.
• Alluvial soils are important and most widespread in the northern plains and the river valleys.
• These are depositional soils, transported and deposited by three important Himalayan river systems – the Indus, the Ganga and the Brahmaputra and this Soil extended in Rajasthan & Gujarat through a narrow corridor too and the Alluvial soil is also found in the eastern coastal plains particularly in the deltas of the Mahanadi, the Godavari, the Krishnaand the Kaveri rivers.

Alluvial Soil Characteristics

• These soils cover about 40 per cent of the total area of the country.
• Alluvial soils are important and most widespread in the northern plains and the river valleys.
• These are depositional soils, transported and deposited by three important Himalayan river systems – the Indus, the Ganga and the Brahmaputra and this Soil extended in Rajasthan & Gujarat through a narrow corridor too and the Alluvial soil is also found in the eastern coastal plains particularly in the deltas of the Mahanadi, the Godavari, the Krishnaand the Kaveri rivers.
• The alluvial soils vary in nature and consists of various proportions of sand, silt and clay.
• These are generally rich in Phosphoric acid, lime and potash, and is well known for its water holding capacity which makes it ideal for growing, crops grown in alluvial soil and sugarcane, paddy, wheat and other cereal crops.
• Such soils are more common in piedmont plains (the word pied+monte, derived from the Italian words pied= which means Foot and monte= Hill) such as Duars, Chos and Terai.
• Piedmont, an area at the base of a mountain range or a mountain is known as piedmont. Red loamy soil occupies a long stretch of area along the piedmont zone of Western Ghats.
• Apart from the size of their grains or components, soils are also described on the basis of their age.
• Due to its high fertility, regions of alluvial soils are intensively cultivated and densely populated.
• Soils in the drier areas, are more alkaline and can be productive after proper treatment and irrigation.

Geological divisions of alluvial soil

• Alluvial soils as a whole are very fertile. According to their age alluvial soils can be classified as old alluvial soil is called Bangar and new alluvial soil is called Khadar.
• Bangar:

1. Old alluvial soil is called bangar.
2. The bangar soil has higher concentration of kanker nodules than the Khadar.
3. Most of the soil part is clayey composition and is generally dark colored.

• Khadar:

1. New alluvial soil is called Khadar
2. It has more fine particles and is more fertile than the bangar.

Crops grown in Alluvial Soil

These are generally rich in Phosphoric acid, lime and potash, and is well known for its water holding capacity which makes it ideal for growing, crops grown in alluvial soil and sugarcane, paddy, wheat and other cereal crops.

Difference Between Soil and Sub-Soil

International System of Naming Soil Separates

According to the soil size, the soil particles are grouped into gravels, sands, silts, and clays which are termed as Soil Separates.

Soil Separates [Diameter range (mm) ]

• Coarse Sand (2.00-0.20)
• Fine Sand (0.20-0.02)
• Silt (0.02- 0.002)
• Clay (Below 0.002)

Edaphic factors of Soil

Plants grown in land completely depend on soil on which they grow. The soil factors that affect crop
growth are
1. Soil moisture
2. Soil air
3. Soil temperature
4. Soil mineral matter
5. Soil organic matter
6. Soil organisms
7. Soil reactions

Soil moisture

• Water is a principal constituent of a growing plant which it extracts from soil
• Water is essential for photosynthesis
• The moisture range between field capacity and the permanent wilting point is available to plants.
• Available moisture will be more in clay soil than sandy soil
• Soil water helps in chemical and biological activities of soil including mineralization
• It influences the soil environment Eg. it moderates the soil temperature from extremes
• Nutrient availability and mobility increases with increase in soil moisture content.

Soil air

• Aeration of soil is absolutely essential for the absorption of water by roots
• Germination is inhibited in the absence of oxygen
• O2 is required for the respiration of roots and microorganisms.
• Soil air is essential for nutrient availability of the soil by breaking down insoluble mineral to soluble salts
• For the proper decomposition of organic matter
• Potato, tobacco, cotton linseed, tea, and legumes need higher O2 in soil air
• Rice requires low level of O2 and can tolerate waterlogged (absence of O2) condition.

Soil temperature

• It affects the physical and chemical processes going on in the soil.
• It influences the rate of absorption of water and solutes (nutrients)
• It affects the germination of seeds and growth rate of underground portions of the crops like tapioca, sweet potato.
• Soil temperature controls the microbial activity and processes involved in the nutrient availability
• Cold soils are not conducive for rapid growth of most of agricultural crops

Soil mineral matter

• The mineral content of soil is derived from the weathering of rocks and minerals as particles of different sizes.
• These are the sources of plant nutrients eg; Ca, Mg, S, Mn, Fe, K etc

Soil Organic matter

• It supplies all the major, minor and micronutrients to crops
• It improves the texture of the soil
• It increases the water-holding capacity of the soil,
• It is a source of food for most microorganisms
• Organic acids released during the decomposition of organic matter enables mineralisation process thus releasing unavailable plant nutrients

Soil organisms:

• The raw organic matter in the soil is decomposed by different microorganisms which in turn releases the plant nutrients
• Atmospheric nitrogen is fixed by microbes in the soil and is available to crop plants through symbiotic (Rhizobium) or non-symbiotic (Azospirillum) association

Soil reaction (pH)

• Soil reaction is the pH (hydrogen ion concentration) of the soil.
• Soil pH affects crop growth and neutral soils with pH 7.0 are best for growth of most of the crops
• Soils may be acidic (<7.0), neutral (=7.0), saline and alkaline (>7.0)
• Soils with low pH is injurious to plants due high toxicity of Fe and Al.
• Low pH also interferes with availability of other plant nutrients

Components of Soil

• Mineral Matter (45%)
• Organic Matter (5%)
• Soil Water (25%)
• Soil Air (25%)

FAQ

References: | NCERT

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