Topic 14: Soils of India

Soil is the thin skin on which India's food security rests — and it is as varied as the land itself. This chapter reads that variety. It begins with the controllers of soil formation (parent rock, climate, relief, organisms, time) and the soil profile (O–A–B–C–R horizons), then classifies India's soils (ICAR / USDA taxonomy). It walks the major soil types — alluvial (the great food bowl), black/regur (the cotton soil), red & yellow, laterite, arid/desert, saline & alkaline, peaty & marshy, and forest & mountain soils — with their properties, crops & spread. It closes with soil degradation (erosion, salinity, waterlogging, desertification) and conservation measures. With labelled diagrams, tables and PYQs + full model answers.

UPSC Prelims · Mains GS-I & GS-III Soil Types ~44 min read Conservation Very High Weight

1.Soil Formation & the Profile
2.Classification of Indian Soils
3.Alluvial Soil
4.Black (Regur) Soil
5.Red, Yellow & Laterite Soils
6.Arid, Saline & Other Soils
7.Soil Degradation & Erosion
8.Soil Conservation Measures
9.Soil Health & Governance
10.Significance & GS Synthesis
11.Current Affairs Link
12.Prelims PYQs
13.Mains PYQs + Model Answers
★15-Minute Revision Box

Conceptual Clarity — Why this Chapter Matters

Soil types, their crops & regions are dense Prelims fodder; soil degradation & conservation are heavy GS-III (agriculture/environment). Sort your prep three ways:

Definitional / static: soil-forming factors; profile horizons (O/A/B/C/R); each type's colour, texture, parent material, crops (alluvial → rice/wheat; black → cotton; laterite → cashew/tea).
Statement-elimination: khadar vs bangar, regur self-ploughing/moisture-retentive, laterite leaching, red-soil iron colour, saline/alkaline (usar/reh) reclamation.
Applied / synthesis (Mains GS-I & GS-III): soil erosion & desertification, salinity from over-irrigation, soil-health cards, conservation & the food-security link. Needs concept + example + judgement.

Territorial note: India's soils span the whole northern belt including the mountain soils of Jammu & Kashmir and Ladakh, which are Indian sovereign territory; the LoC and LAC are not settled international borders.

1. Soil Formation & the Profile

Soil is the loose surface layer of weathered rock & organic matter that supports plant life. Its formation (pedogenesis) is controlled by five factors, and it develops a layered profile.

Fig 14.1 — The soil profile: from the organic O-horizon & fertile A-topsoil down through the B-subsoil and weathered C-horizon to unweathered bedrock (R).

Five controllers: parent material (rock), climate (temperature & rainfall), relief (slope & drainage), organisms (vegetation & microbes), and time.
Horizons: O (organic litter), A (topsoil, humus + leaching), B (subsoil, accumulation), C (weathered parent rock), R (bedrock).
Residual vs transported: in-situ (residual) soils on the peninsula vs transported (alluvial/aeolian) soils of the plains & deserts.

Prelims lock: five soil-forming factors = parent material, climate, relief, organisms, time; profile horizons O–A–B–C–R (A = fertile topsoil).

2. Classification of Indian Soils

The ICAR (following USDA soil taxonomy) groups Indian soils into eight major types; older schemes used a colour/origin basis.

Major soil	Broadly where
Alluvial	Northern plains, coastal & deltaic tracts
Black (regur)	Deccan lava region (Maharashtra, MP, Gujarat)
Red & yellow	Peninsular crystalline uplands (TN, Karnataka, Odisha)
Laterite	High-rainfall summits (W. Ghats, NE, hilltops)
Arid / desert	NW (Rajasthan, S. Punjab)
Saline & alkaline	Arid tracts, over-irrigated & coastal areas
Peaty & marshy	Kerala (Kuttanad), Sundarbans, coastal wet spots
Forest & mountain	Himalaya & hill slopes

Concept: soils reflect their setting — alluvium in river plains, regur on basalt, red soil on crystalline rock, laterite where heavy rain leaches, desert soil where it is dry — a map of climate & parent rock.

3. Alluvial Soil

India's most widespread & agriculturally most important soil (~40% of area) — deposited by rivers across the northern plains, deltas & coasts.

Origin: transported & deposited by the Himalayan & peninsular rivers; renewed each flood.
Fertility: rich in potash & lime but often poor in nitrogen & humus; very productive with irrigation.
Khadar vs Bangar: khadar = new, fine, fertile floodplain alluvium; bangar = older, coarser, slightly higher terrace alluvium (with kankar/lime nodules).
Crops: rice, wheat, sugarcane, pulses, oilseeds — the food-bowl soil.

Prelims lock: alluvial soil = most widespread (~40%); khadar (new, fertile) vs bangar (old, kankar); rich in potash/lime, poor in nitrogen/humus; grows rice & wheat.

4. Black (Regur) Soil

The black cotton soil (regur) of the Deccan lava country — formed by the weathering of basalt.

Parent rock: Deccan Trap basalt; found in Maharashtra, MP, Gujarat, parts of AP, Karnataka & TN.
Properties: clayey, moisture-retentive, rich in iron, lime, magnesia & alumina but poor in nitrogen, phosphorus & humus.
Self-ploughing: swells when wet & develops deep cracks when dry — "self-ploughing"; sticky when wet.
Crops: ideal for cotton, also sugarcane, jowar, wheat, citrus, oilseeds — good for dry farming.

Prelims lock: black/regur soil = weathered Deccan basalt; moisture-retentive & self-ploughing (cracks on drying); best for cotton; rich in lime/iron/magnesia, poor in N/P/humus.

5. Red, Yellow & Laterite Soils

The peninsular crystalline uplands & the high-rainfall summits give red/yellow & laterite soils respectively.

Red & yellow soil: forms on old crystalline & metamorphic rock (peninsula fringe — TN, Karnataka, AP, Chhattisgarh, Odisha, E MP); red from iron oxide (yellow when hydrated); porous, low in nitrogen/phosphorus/humus; needs fertiliser; grows millets, pulses, groundnut, potato.
Laterite soil: forms under high temperature & heavy seasonal rainfall (leaching of silica, enrichment of iron & aluminium) — W. Ghats summits, NE, Odisha, WB hills; acidic, low fertility (except with manuring); used for cashew, tea, coffee, rubber; hard laterite is cut as building brick.

Prelims lock: red soil = iron-oxide colour on crystalline rock; laterite = intense leaching under heavy rain (silica lost, Fe/Al left), acidic, grows cashew/tea/coffee & makes building brick.

6. Arid, Saline & Other Soils

The dry NW, the salt-affected tracts, and special wet/mountain settings give the remaining soil types.

Arid / desert soil: sandy, saline, low humus, high soluble salts & kankar; NW Rajasthan & S. Punjab; productive with irrigation (e.g., Indira Gandhi Canal).
Saline & alkaline soil: "usar/reh/kallar/thur" — excess salts from arid climate, over-irrigation & poor drainage; reclaimed with gypsum & drainage.
Peaty & marshy soil: heavy organic matter in waterlogged areas — Kerala's Kuttanad, Sundarbans, coastal Odisha/TN; often acidic & saline.
Forest & mountain soil: thin, immature, on Himalayan slopes; varies with altitude; good for tea, coffee, spices & orchards.

Prelims lock: desert soil = sandy/saline NW; saline-alkaline (usar/reh) reclaimed with gypsum + drainage; peaty = organic waterlogged (Kuttanad); mountain soil = thin Himalayan slope soil.

7. Soil Degradation & Erosion

Soil degradation — the decline of soil quality & productivity — threatens a large share of India's land.

Problem	Cause / where
Water erosion	Sheet, rill & gully erosion; ravines/badlands (Chambal)
Wind erosion	Arid NW; loose sandy soil blown away
Salinity / alkalinity	Over-irrigation without drainage (canal command areas)
Waterlogging	Poor drainage; rising water table
Desertification	Land degradation in dry areas (NW, rain-shadow)
Nutrient loss / acidification	Over-cultivation, leaching, imbalanced fertiliser

Ravines: the Chambal, Yamuna & Mahi badlands are severe gully-erosion landscapes.
Extent: a large share of India's land is degraded/undergoing desertification (ISRO/SAC Desertification Atlas). check for latest update or data

Erosion & food security: topsoil forms over centuries but erodes in a season; sheet, rill, gully & wind erosion silently cut yields — making conservation a food-security imperative. check for latest update or data

8. Soil Conservation Measures

Soil conservation combines agronomic, mechanical & biological methods to hold soil & restore fertility.

Contour ploughing & bunding: ploughing/bunds along contours slow runoff on slopes.
Terracing: step terraces on hill slopes (NE, Himalaya) cut erosion.
Strip & cover cropping, crop rotation: keep soil covered & restore nutrients (legumes fix nitrogen).
Afforestation & shelter belts: tree lines check wind erosion in the arid NW.
Gully plugging & check dams: control ravine & gully erosion (Chambal).
Reclamation: gypsum for alkaline soil, drainage for waterlogging/salinity.

Prelims lock: contour bunding & terracing (slope erosion), shelter belts (wind erosion), gully plugging/check dams (ravines), gypsum + drainage (saline/alkaline reclamation).

9. Soil Health & Governance

Government programmes aim to monitor & restore soil health for sustainable farming.

Soil Health Card scheme: tests & advises farmers on nutrient status & balanced fertiliser use.
Watershed / IWMP & PMKSY: land & moisture conservation on a watershed basis.
National Mission for Sustainable Agriculture & organic/natural farming: restore soil organic carbon.
Desertification & UNCCD: India, party to the UNCCD, targets land-degradation neutrality; hosted UNCCD CoP14 (2019). check for latest update or data

Concept: soil governance has shifted from raising output alone to sustaining the resource — balanced fertiliser (Soil Health Cards), organic carbon, watershed treatment & land-degradation neutrality.

10. Significance & GS Synthesis

Soil ties agriculture, environment & livelihoods together — a GS-I resource base and a GS-III sustainability challenge.

Agricultural: soil type sets the crop map — alluvium (rice/wheat), regur (cotton), laterite (plantation).
Environmental: soil is a carbon store & water filter; degradation drives desertification & emissions.
Economic/social: soil health underpins farm incomes & food security for a billion-plus people.
Sustainability: balanced fertiliser, organic carbon, conservation & land-degradation neutrality (UNCCD).

GS synthesis: India's soils are its silent capital — matching crop to soil, checking erosion & salinity, and rebuilding organic carbon are the way to secure both food & climate goals.

11. Current Affairs & Contemporary Relevance (2024–2026)

Soils stay "current" through desertification data, Soil Health Cards, natural farming & land-degradation-neutrality targets — verify the latest status. check for latest update or data

11.1 Desertification & degradation

Desertification Atlas: ISRO/SAC data on the share of land undergoing degradation/desertification keeps soil loss topical. check for latest update or data

11.2 Soil health & natural farming

Soil Health Cards & natural farming: the push for balanced fertiliser, organic carbon & natural/organic farming targets soil restoration. check for latest update or data

11.3 Land-degradation neutrality

UNCCD & LDN: India's land-degradation-neutrality pledge and restoration targets link soil to global climate action. check for latest update or data

11.4 Why it matters

Development	Why it matters for UPSC
Desertification data	Land degradation (GS-III).
Soil Health Cards	Agriculture & inputs (GS-III).
Natural farming	Sustainable agriculture (GS-III).
LDN / UNCCD	Global commitments (GS-III).

Recurring exam hooks:

Soil types & crops · khadar/bangar · regur properties (evergreen Prelims).
Laterite & red-soil formation · conservation methods (favourite factual sets).
Soil erosion & desertification · salinity & soil health (evergreen Mains GS-III).

12. Prelims PYQs (exam-style, high-frequency themes)

Objective questions anchored to genuinely tested UPSC themes on India's soils. Each carries a worked rationale.

UPSC Prelims — exam-style

Q: The black cotton (regur) soil of India is formed by the weathering of:

(a) Granite & gneiss
(b) Deccan Trap basalt (lava)
(c) Sandstone
(d) Limestone

Answer: (b) Regur forms from weathered Deccan Trap basalt; it is clayey, moisture-retentive, self-ploughing and best for cotton.

UPSC Prelims — exam-style

Q: "Khadar" and "Bangar" are subdivisions of which soil?

(a) Alluvial soil
(b) Black soil
(c) Laterite soil
(d) Red soil

Answer: (a) Alluvial soil — khadar (new, fine, fertile floodplain alluvium) vs bangar (older, coarser terrace alluvium with kankar/lime nodules).

UPSC Prelims — exam-style

Q: Laterite soil is formed mainly by:

(a) Wind deposition
(b) Intense leaching under high temperature and heavy rainfall
(c) River deposition
(d) Glacial action

Answer: (b) Laterite forms where heavy seasonal rain & high heat leach out silica, leaving iron & aluminium; it is acidic, grows cashew/tea/coffee & is cut as brick.

UPSC Prelims — exam-style

Q: The most widespread soil in India by area is:

(a) Alluvial soil
(b) Black soil
(c) Red soil
(d) Laterite soil

Answer: (a) Alluvial soil covers ~40% of India (the northern plains, deltas & coasts) and is agriculturally the most important.

UPSC Prelims — exam-style

Q: The red colour of red soils is chiefly due to the presence of:

(a) Humus
(b) Iron oxides
(c) Lime
(d) Aluminium

Answer: (b) Iron oxides give red soils their colour (yellow when hydrated); they form on old crystalline/metamorphic rock in the peninsula.

UPSC Prelims — exam-style

Q: Alkaline (usar/reh) soils are best reclaimed by applying:

(a) Gypsum and improving drainage
(b) Lime only
(c) Nitrogen fertiliser
(d) Sand

Answer: (a) Gypsum (calcium sulphate) plus drainage leaches out excess sodium salts, reclaiming saline/alkaline "usar/reh" soils.

UPSC Prelims — exam-style

Q: The Chambal ravines are an example of:

(a) Wind erosion
(b) Gully (water) erosion / badlands
(c) Salinity
(d) Waterlogging

Answer: (b) The Chambal (and Yamuna/Mahi) ravines are severe gully-erosion badlands, controlled by gully plugging & check dams.

UPSC Prelims — exam-style

Q: Which soil is best suited to cotton cultivation?

(a) Laterite
(b) Black (regur)
(c) Desert
(d) Peaty

Answer: (b) The moisture-retentive black (regur) soil of the Deccan is ideal for cotton — hence "black cotton soil".

Prelims — anticipated themes

Likely: soil-forming factors & profile · alluvial (khadar/bangar) · regur (basalt, cotton, self-ploughing) · red vs laterite formation · desert & saline/alkaline reclamation · erosion types & ravines · conservation methods · Soil Health Card. check for latest update or data

13. Mains PYQs + Model Answers

Genuine UPSC GS-I/GS-III themes on India's soils, degradation and conservation. Each carries a full answer skeleton — Introduction → body → Conclusion.

UPSC Mains GS-I — style 15 marks · 250 words

Q: Describe the major soil types of India and relate them to their characteristic crops.

Model Answer

Introduction: India's soils, shaped by parent rock & climate, form a mosaic that fixes its crop geography.
Alluvial: most widespread & fertile — rice, wheat, sugarcane in the northern plains.
Black (regur): moisture-retentive basalt soil — cotton, jowar, oilseeds in the Deccan.
Red & laterite: crystalline & leached uplands — millets/pulses (red), cashew/tea/coffee (laterite).
Conclusion: matching crop to soil is the foundation of India's agricultural regions.

UPSC Mains GS-III — style 15 marks · 250 words

Q: Soil erosion is a serious threat to Indian agriculture. Examine its causes and conservation measures.

Model Answer

Introduction: topsoil takes centuries to form but erodes in a season — erosion silently cuts India's yields.
Causes: deforestation, over-grazing, faulty ploughing, slope cultivation, heavy monsoon runoff & wind in the arid NW.
Types: sheet, rill, gully (ravines) & wind erosion.
Conservation: contour bunding, terracing, strip & cover cropping, shelter belts, gully plugging/check dams, afforestation, watershed treatment.
Conclusion: conserving soil is a food-security imperative needing agronomic, mechanical & biological methods together.

UPSC Mains GS-III — style 15 marks · 250 words

Q: Discuss soil salinity and desertification in India and measures to combat land degradation.

Model Answer

Introduction: a large share of India's land is degraded — by salinity in canal-command areas & desertification in dry zones.
Salinity/alkalinity: over-irrigation without drainage raises the water table & brings salts up (usar/reh).
Desertification: land degradation in arid/semi-arid tracts from over-use, deforestation & climate stress.
Measures: gypsum & drainage, efficient irrigation, shelter belts, watershed & afforestation, UNCCD land-degradation neutrality.
Conclusion: combating degradation protects both food security & the climate.

UPSC Mains GS-III — style 15 marks · 250 words

Q: How does soil health affect agricultural sustainability? Evaluate India's soil-health initiatives.

Model Answer

Introduction: soil organic carbon & nutrient balance underpin long-term yields — degraded soil means falling productivity.
Problems: imbalanced (urea-heavy) fertiliser, low organic carbon, micronutrient deficiency, erosion & salinity.
Initiatives: Soil Health Card scheme, natural/organic farming, PMKSY watershed, balanced-fertiliser & nano-urea push.
Gaps: uneven uptake, testing capacity, need for behaviour change & incentives.
Conclusion: restoring soil health through balanced inputs & organic carbon is central to sustainable agriculture.

UPSC Mains GS-I — style 10 marks · 150 words

Q: Explain how climate and parent rock control the distribution of Indian soils.

Model Answer

Introduction: soil is a product of parent rock modified by climate — both shape India's soil map.
Parent rock: basalt → black regur; crystalline rock → red soil; river deposits → alluvium.
Climate: heavy rain & heat → leached laterite; aridity → sandy desert & saline soil.
Conclusion: India's soils faithfully mirror the interplay of rock & climate across its regions.

Mains — anticipated themes

Likely: soil types & crops · soil erosion & conservation · salinity & desertification · soil health & sustainability · climate/parent-rock control. check for latest update or data

15-Minute Revision Box

Must-Remember Facts — Soils of India

Formation:

5 factors: parent rock, climate, relief, organisms, time
Profile: O–A–B–C–R (A = fertile topsoil)

Major soils & crops:

Alluvial (~40%, most fertile): rice/wheat; khadar vs bangar
Black/regur (basalt, self-ploughing): cotton
Red (iron oxide, crystalline): millets/pulses
Laterite (leached, acidic): cashew/tea/coffee, brick

Other soils:

Desert (sandy, saline NW)
Saline/alkaline (usar/reh) — gypsum + drainage
Peaty (Kuttanad); mountain (Himalaya)

Nutrient notes:

Alluvial: rich potash/lime, poor N/humus
Regur: rich lime/iron/magnesia, poor N/P/humus

Degradation:

Water (sheet/rill/gully — Chambal ravines)
Wind (arid NW); salinity; waterlogging; desertification

Conservation:

Contour bunding, terracing
Shelter belts, gully plugging/check dams
Gypsum + drainage; watershed; Soil Health Card

Highest-frequency themes: soil types & crops · khadar/bangar · regur & laterite formation · erosion & conservation. One logic: soil mirrors rock + climate; match crop to soil, check erosion & salinity, rebuild organic carbon.

Soil	Crop
Alluvial	Rice/wheat
Black/regur	Cotton
Red	Millets/pulses
Laterite	Cashew/tea

Soil	Rock
Regur	Basalt
Red	Crystalline
Alluvial	River deposit

Topic 14: Soils of India

On this page

Conceptual Clarity — Why this Chapter Matters

1. Soil Formation & the Profile

2. Classification of Indian Soils

3. Alluvial Soil

4. Black (Regur) Soil

5. Red, Yellow & Laterite Soils

6. Arid, Saline & Other Soils

7. Soil Degradation & Erosion

8. Soil Conservation Measures

9. Soil Health & Governance

10. Significance & GS Synthesis

11. Current Affairs & Contemporary Relevance (2024–2026)

11.1 Desertification & degradation

11.2 Soil health & natural farming

11.3 Land-degradation neutrality

11.4 Why it matters

12. Prelims PYQs (exam-style, high-frequency themes)

13. Mains PYQs + Model Answers

Model Answer

Model Answer

Model Answer

Model Answer

Model Answer

15-Minute Revision Box

Must-Remember Facts — Soils of India