Geography
Soils and Natural Vegetation
Soil Types of India
Indian soils for CGPSC: soil formation, the eight ICAR soil groups (alluvial, black, red-yellow, laterite and more), USDA orders and Chhattisgarh's soils.
Prerequisites
- Physiography of India: the Deccan trap, the plains and the plateau are the parent rocks and landforms of our soils
- Climate of India: rainfall and temperature decide how a rock weathers into soil
- Climate and Soils of Chhattisgarh: the state-level version of this page (Kanhar, Matasi, Dorsa, Bhata)
The Hook: From Red to Black on One Highway
Connect
Drive west from Raipur towards Nagpur. Around Raipur, Durg and the fields beside the road, the soil is mostly reddish-yellow. As you cross into Vidarbha the fields turn jet black, crack into deep polygons in April and grow cotton and soybean instead of paddy.
Same country, same monsoon, a few hundred kilometres apart. What makes one soil red and another black, and why does it matter for what a farmer can grow?
Why it matters: Prelims asks one exact detail per soil: where it is found, what it is rich or poor in, its local name and its best crop. Mains GS-III links soil to cropping patterns, productivity and land degradation, and expects a Chhattisgarh example.
What Soil Is and How It Forms
Soil (मृदा) is the thin top layer of the earth’s crust made of weathered rock particles, organic matter (humus), water and air. It forms very slowly and can be lost very fast, which is why it is treated as a non-renewable resource on a human time scale.
Five factors of soil formation
| Factor | What it does | Indian example |
|---|---|---|
| Parent material (मूल पदार्थ) | Supplies the minerals and texture | Deccan trap basalt gives black soil |
| Climate | The most important active factor: rainfall and temperature control weathering and leaching | Heavy rain + heat leaches silica and gives laterite |
| Relief | Slope controls drainage and how much soil stays | Thin soils on hill slopes, deep soils in valleys |
| Biological activity | Plants, bacteria and animals add humus | Thick organic peaty soils in wet coastal areas |
| Time | Older soils have better-developed layers | Old alluvium (bangar) vs new alluvium (khadar) |
Soil profile
A vertical cut through soil shows layers called horizons (संस्तर):
| Horizon | Content |
|---|---|
| A (topsoil) | Organic matter mixed with minerals; most biological activity; what erosion removes first |
| B (subsoil) | Material washed down from A plus weathered rock; less humus |
| C | Loose, partly weathered parent material |
| Bedrock | Unweathered parent rock below |
Classifying Indian Soils
| Classification | Basis | Key fact |
|---|---|---|
| Ancient Indian | Fertility | Urvara (fertile) and Usara (sterile) |
| ICAR (All India Soil Survey Committee, 1953) | Genesis, colour, composition, location | Eight major groups: the classification Prelims uses |
| USDA Soil Taxonomy (used by ICAR’s National Bureau of Soil Survey and Land Use Planning, NBSS&LUP, Nagpur) | Soil characteristics | Orders such as Inceptisols, Entisols, Alfisols, Vertisols, Aridisols |
Bridge to Chhattisgarh's local names
Soil scientists match the local soils of the Chhattisgarh plain to USDA orders: Kanhar = Vertisols (the black, clayey one), Dorsa = Alfisols, Matasi = Inceptisols and Bhata = Entisols (young, shallow, gravelly). So when a Mains answer mentions “Vertisols of Chhattisgarh”, it means Kanhar.
The Eight ICAR Soil Groups
1. Alluvial soil (जलोढ़ मिट्टी)
- Most widespread soil of India: about 40% of the total area (NCERT).
- Formation: deposited by rivers. Found in the northern plains (Indus–Ganga–Brahmaputra), in the river valleys, and in the deltas of the east coast (Mahanadi, Godavari, Krishna, Kaveri). Also in Gujarat plains.
- Two types:
- Khadar (खादर): new alluvium, renewed every flood, on the flood plains; finer and more fertile.
- Bangar (बांगर): old alluvium on higher ground away from the river; contains kankar (calcareous nodules).
- Composition: generally rich in potash, poor in phosphorus. Texture changes from sandy loam to clay; coarser in the upper Ganga plain and near the hills, finer in the delta.
- Crops: rice, wheat, sugarcane, jute, pulses and oilseeds. The most intensively farmed soil in India.
2. Black soil (काली मिट्टी), “Regur” or “black cotton soil”
- Formation: weathering of basalt of the Deccan trap (lava flows), together with the semi-arid climate.
- Where: most of the Deccan plateau: Maharashtra (the core), western Madhya Pradesh, Gujarat (Saurashtra), parts of Karnataka, Telangana, Andhra Pradesh and Tamil Nadu. In Chhattisgarh, the western plain near the Maikal foothills (the local Kanhar).
- Properties:
- Clayey, deep and highly moisture-retentive; good for dry farming.
- Swells when wet and develops wide cracks when dry. The cracks let air in, so it is called “self-ploughing” soil.
- Becomes sticky when wet and is hard to plough without the right moisture.
- Composition: rich in lime, iron, magnesia and alumina, also potash; poor in phosphorus, nitrogen and organic matter.
- Crops: cotton (hence “black cotton soil”), soybean, jowar, wheat, gram, linseed, sugarcane, citrus.
3. Red and yellow soil (लाल और पीली मिट्टी)
- Formation: on crystalline igneous and metamorphic rocks (granite, gneiss) in areas of low to moderate rainfall in the eastern and southern Deccan.
- Colour: red from the diffusion of iron (iron oxide) in the rocks; yellow where the iron is in a hydrated form.
- Where: Odisha, Chhattisgarh (the most extensive soil of the state), Jharkhand, eastern Madhya Pradesh, Tamil Nadu, Karnataka, the southern parts of the middle Ganga plain and the piedmont of the Western Ghats.
- Composition: poor in nitrogen, phosphorus and humus. Fine-grained red-yellow soils are reasonably fertile; coarse-grained ones in dry uplands are poor.
- Crops: with irrigation and fertiliser: rice, millets, pulses, groundnut, potato.
4. Laterite soil (लैटेराइट मिट्टी)
- Name: from the Latin “later” = brick. It hardens on exposure to air, so it is cut and used as building bricks.
- Formation: high temperature and heavy rainfall with alternate wet and dry seasons. Intense leaching washes out lime and silica; iron oxide and aluminium compounds stay behind. Humus is quickly destroyed by bacteria in the heat.
- Composition: poor in organic matter, nitrogen, phosphate and calcium; iron oxide and potash in excess. Usually acidic.
- Where: summits of the Western and Eastern Ghats, Karnataka, Kerala, Tamil Nadu, Madhya Pradesh, the hilly parts of Odisha and Assam, and the pat uplands of Surguja–Jashpur and parts of Bastar in Chhattisgarh.
- Crops: with manure and fertiliser: cashew (Tamil Nadu, Andhra Pradesh, Kerala), tea and coffee (hill slopes), rubber, tapioca.
5. Arid (desert) soil (शुष्क / मरुस्थलीय मिट्टी)
- Colour: red to brown; sandy, often saline.
- Where: western Rajasthan and adjoining arid areas.
- Composition: low humus and moisture; nitrogen is insufficient, phosphate is normal.
- Kankar layer: the calcium content increases downwards, and the lower horizon is cemented by kankar, which restricts the infiltration of water.
- Crops: with irrigation (for example the Indira Gandhi Canal area), wheat, mustard, cotton; otherwise bajra and pulses.
6. Saline and alkaline soil (लवणीय / क्षारीय मिट्टी)
- Local names: reh, kallar, thur, usar (ऊसर).
- Composition: high proportion of sodium, potassium and magnesium salts; infertile; poor in nitrogen and calcium.
- Where: arid and semi-arid areas, waterlogged and swampy areas; western Gujarat, the deltas of the east coast, the Sundarbans; the Rann of Kutch (salt from the sea breeze).
- Human-made salinity: in Punjab and Haryana, over-irrigation raises the water table and capillary action brings salts to the surface.
- Remedy: gypsum (जिप्सम) for alkaline soils, plus drainage and salt-tolerant crops.
7. Peaty and organic soil (पीट / जैविक मिट्टी)
- Formation: heavy rainfall and high humidity, where dead plant matter piles up faster than it decays.
- Composition: very high organic matter (humus); heavy and black; can be alkaline or acidic.
- Where: northern Bihar, southern Uttarakhand, coastal West Bengal, Odisha and Tamil Nadu, and parts of Kerala.
- Use: rice and jute where drained.
8. Forest and mountain soil (वन / पर्वतीय मिट्टी)
- Where: forested hill and mountain slopes: Himalaya, Western and Eastern Ghats, north-east.
- Character: varies with altitude and slope: loamy and silty in valleys, coarse-grained on upper slopes. In the snow-bound higher Himalaya the soils are acidic with low humus; in the lower valleys they are fertile.
- Crops: tea, coffee, spices and tropical fruits where cleared; mostly under forest.
Soils of Chhattisgarh at a Glance
| Soil (ICAR group) | Where in Chhattisgarh | Local link |
|---|---|---|
| Red-yellow | Most extensive: large parts of the plain and the north | Matasi and Dorsa are mostly in this family |
| Red sandy | Bastar plateau | Light, porous; millets and upland paddy |
| Laterite | Pat uplands of Surguja–Jashpur, parts of Bastar | Bhata is the laterite-like upland soil |
| Black | Western plain near the Maikal range | Kanhar |
| Alluvial | Narrow strips along rivers such as the Mahanadi | Limited in extent |
For detail, local names and the slope sequence Bhata → Matasi → Dorsa → Kanhar, see Climate and Soils of Chhattisgarh.
Analysis: Soils and Indian Agriculture (Mains material)
- Soil decides the cropping pattern. Alluvium carries the rice–wheat system of the north, regur carries cotton and soybean in the Deccan, laterite carries plantation crops on the Ghats. In Chhattisgarh, moisture-retentive Kanhar allows a rabi crop of gram or linseed after paddy, while Bhata and Matasi stay single-cropped.
- Most Indian soils are nutrient-poor. Black, red-yellow and laterite soils are all low in nitrogen and phosphorus, which explains India’s dependence on fertilisers and the importance of soil testing.
- Imbalanced fertiliser use. Heavy use of urea relative to phosphorus and potash, and low organic manure, lower soil organic carbon and create micronutrient deficiencies (zinc, boron). The Soil Health Card scheme (2015) responds to this; see Soil Erosion and Conservation.
- Problem soils are reclaimable. Gypsum for alkaline usar land, lime for acidic laterite and red soils, drainage for waterlogged saline land.
- Chhattisgarh angle: the “Rice Bowl” depends on red-yellow soils that are light and low in nutrients. Diversification to pulses and oilseeds on Dorsa and Kanhar, and organic manure, improve both soil and income. See Agriculture and Irrigation in Chhattisgarh.
Memory Tricks
The eight ICAR groups: 'All Black Rivers Look Ancient, Saying Purely Forest'
Alluvial · Black · Red-yellow · Laterite · Arid · Saline · Peaty · Forest.
The first four are the big, widespread groups; the last four are regional or problem soils.
Rich in / poor in
- Black = “LIMA rich”: Lime, Iron, Magnesia, Alumina (+ potash). Poor in NPO: nitrogen, phosphorus, organic matter.
- Laterite = “Brick of Iron”: iron oxide and potash in excess; lime and silica leached out.
- Alluvial = “Pot rich, Phos poor”: potash rich, phosphorus poor.
Saline names: 'Reh Kallar Thur Usar'
Four names, one problem: salt. Cure with gypsum.
Don’t Confuse
| This | vs | That |
|---|---|---|
| Khadar: new alluvium, flood plain, more fertile | vs | Bangar: old alluvium, higher ground, kankar nodules |
| Kankar in bangar: calcareous nodules in old alluvium | vs | Kankar layer in arid soil: hard calcium layer that blocks infiltration |
| Red colour: iron diffused in crystalline rocks | vs | Yellow colour: same soil with iron in hydrated form |
| Laterite: leached by heavy rain and heat | vs | Arid soil: little leaching; salts and calcium accumulate |
| Black soil: Deccan trap basalt, moisture-retentive | vs | Red soil: granite and gneiss, porous, low moisture |
| Kanhar (Vertisol, black, clayey) | vs | Matasi (Inceptisol, yellow sandy loam) |
Common Mistakes
MCQ traps
- “Black soil is rich in nitrogen and phosphorus.” Wrong. It is rich in lime, iron, magnesia and alumina, and poor in nitrogen, phosphorus and organic matter.
- “Laterite soil forms in dry areas.” Wrong. It forms under heavy rainfall and high temperature, by leaching.
- “Black soil is the most widespread soil of India.” Wrong. Alluvial is (about 40%). Black soil is the typical soil of the Deccan lava plateau.
- “Red colour comes from humus.” Wrong. It comes from iron oxide.
- “Saline soils are treated with lime.” Lime corrects acidic soils. Alkaline (usar) soils are treated with gypsum.
- “The most extensive soil of Chhattisgarh is black soil.” Wrong. It is red-yellow; black (Kanhar) is limited to the western plain.
Practice
All questions below are original practice questions written in CGPSC style. They are not previous-year questions.
Level 1: Foundation
- The ICAR’s All India Soil Survey Committee (1953) divided Indian soils into ______ major groups.
- The new alluvium renewed by floods every year is called ______.
- Black soil is formed mainly from the weathering of ______ rocks of the Deccan trap.
Answers
- Eight.
- Khadar (old alluvium is bangar).
- Basalt (lava rocks).
Level 2: Prelims MCQs
Q1. Consider the following statements about black soil in India:
- It develops deep cracks in the dry season and is therefore called self-ploughing.
- It is generally rich in nitrogen and phosphorus.
- It has a high moisture-retention capacity.
Which of the statements given above is/are correct?
- (a) 1 only
- (b) 1 and 3 only
- (c) 2 and 3 only
- (d) 1, 2 and 3
Answer and explanation
(b) 1 and 3 only. Black soil swells when wet and cracks when dry, which aerates it (“self-ploughing”), and it holds moisture well, which suits dry farming of cotton. Statement 2 is the trap: it is rich in lime, iron, magnesia and alumina but poor in nitrogen, phosphorus and organic matter.
Q2. Match List I (Soil) with List II (Characteristic):
| List I | List II |
|---|---|
| A. Laterite | 1. Reh, kallar and thur |
| B. Saline | 2. Kankar layer restricts infiltration |
| C. Arid | 3. Lime and silica leached; used as bricks |
| D. Alluvial | 4. Khadar and bangar |
- (a) A-3, B-2, C-1, D-4
- (b) A-1, B-3, C-2, D-4
- (c) A-3, B-1, C-2, D-4
- (d) A-4, B-1, C-2, D-3
Answer and explanation
(c) A-3, B-1, C-2, D-4. Laterite is leached of lime and silica and hardens into brick. Saline soils are locally called reh, kallar, thur or usar. In arid soils the calcium content increases downwards and forms a kankar layer. Alluvium is divided into new khadar and old bangar.
Q3. The red colour of red soil is mainly due to:
- (a) high humus content
- (b) presence of iron oxide diffused in crystalline rocks
- (c) presence of calcium carbonate
- (d) high content of aluminium hydroxide
Answer and explanation
(b). Red soil develops on crystalline igneous and metamorphic rocks; the colour comes from iron diffused through them. Where the iron is hydrated the soil looks yellow, which is why the two are grouped as “red and yellow soil”.
Q4. Which of the following is used to reclaim alkaline (usar) soils in Punjab, Haryana and Uttar Pradesh?
- (a) Lime
- (b) Urea
- (c) Gypsum
- (d) Rock phosphate
Answer and explanation
(c) Gypsum. Gypsum (calcium sulphate) replaces the sodium that makes the soil alkaline, and the sodium is then washed out with drainage water. Lime is used for the opposite problem, acidic soils such as laterite.
Q5. The local soil of the Chhattisgarh plain that corresponds to Vertisols (black, clayey, moisture-retentive soil) is:
- (a) Bhata
- (b) Matasi
- (c) Dorsa
- (d) Kanhar
Answer and explanation
(d) Kanhar. Kanhar is the deep, dark, clayey lowland soil, the local black soil, classed as Vertisols. Bhata corresponds to Entisols, Matasi to Inceptisols and Dorsa to Alfisols.
Level 3: Mains Answer Writing
Q1. (60 words) Why is black soil called “self-ploughing”, and why is it suited to cotton?
Model answer outline
- Intro: Black soil (regur) forms from Deccan trap basalt and is clay-rich.
- Self-ploughing: the clay swells when wet and shrinks into deep cracks when dry; the cracks aerate the soil and mix surface material into it.
- Cotton: high moisture retention carries the crop through dry spells; it is rich in lime, iron and potash.
- Conclusion: Hence the Deccan cotton belt (and Kanhar of western Chhattisgarh for rabi crops).
Q2. (150–200 words) Classify the major soils of India and explain how soil type shapes the agriculture of Chhattisgarh.
Model answer outline
- Intro: The ICAR (1953) recognises eight soil groups, shaped by parent rock, climate, relief, biota and time.
- Body:
- Alluvial (about 40%): northern plains and deltas; rich in potash; rice–wheat.
- Black: Deccan trap; moisture-retentive, self-ploughing; cotton, soybean.
- Red-yellow: crystalline rocks; poor in N, P, humus; needs fertiliser.
- Laterite: leached under heavy rain; plantation crops.
- Arid, saline, peaty, forest: specialised, often problem soils.
- Chhattisgarh angle: red-yellow soils dominate, so paddy is grown under monsoon rain with low input of nutrients. On the plain, farmers use slope-based names: Bhata (poor, upland), Matasi, Dorsa, Kanhar (black, fertile, allows a rabi crop on residual moisture). Laterite pats and red sandy Bastar soils suit millets and forestry.
- Conclusion: Soil testing, organic matter and crop diversification matched to each soil are the way to raise productivity in the “Rice Bowl”.
Quick Revision Table
| Fact | Detail |
|---|---|
| ICAR classification | All India Soil Survey Committee, 1953; 8 groups |
| USDA taxonomy body | NBSS&LUP, Nagpur |
| Most widespread soil | Alluvial, about 40% of area |
| Khadar / Bangar | New, flood plain / old, kankar nodules |
| Black soil | Deccan trap basalt; regur; self-ploughing; rich in lime, iron, magnesia, alumina; poor in N, P, humus |
| Red-yellow | Crystalline rocks; red = iron; yellow = hydrated iron; most extensive in Chhattisgarh |
| Laterite | Latin later = brick; leaching of lime and silica; cashew, tea, coffee |
| Arid soil | Western Rajasthan; kankar layer; phosphate normal, nitrogen low |
| Saline names | Reh, kallar, thur, usar; reclaim with gypsum |
| Peaty soil | Very high organic matter; Bihar, coastal WB, Odisha, Kerala |
| CG local soils | Kanhar = Vertisols; Dorsa = Alfisols; Matasi = Inceptisols; Bhata = Entisols |
Key Takeaways
Key Takeaways
- Soil forms from parent material, climate, relief, biota and time; climate is the most active factor.
- The ICAR (1953) gives eight groups; alluvial is the most widespread (about 40%).
- Black soil = Deccan basalt, moisture-retentive, self-ploughing, cotton; laterite = leached under heavy rain, brick-like, plantation crops.
- Most Indian soils are poor in nitrogen and phosphorus, which drives fertiliser use and soil testing.
- In Chhattisgarh, red-yellow soil dominates; the local Bhata–Matasi–Dorsa–Kanhar sequence maps to USDA Entisols–Inceptisols–Alfisols–Vertisols.
What’s Next
- Soil Erosion and Conservation: how these soils are lost and how to save them
- Forest Types of India: vegetation follows the same rainfall gradients as soil
- Agriculture of India: crops matched to soils
- Climate and Soils of Chhattisgarh
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