📑 Topics on this page (Jump to Topic):
📌 1. Major Soil Types
| Soil | Region / formation | Properties & crops |
|---|---|---|
| Alluvial — most widespread (≈ 40%) | Northern plains, deltas; river deposits | Rich in potash & lime, poor in nitrogen & phosphorus; wheat, rice, sugarcane |
| Black / Regur | Deccan Trap (Maharashtra, MP, Gujarat); from weathered basalt | Highest moisture retention, cracks when dry ("self-ploughing"); rich in iron, lime, magnesium; cotton ("black cotton soil") |
| Red & Yellow | TN, Karnataka, Odisha, Chhattisgarh; from granite-gneiss | Red colour from ferric oxide; yellow when hydrated; pulses, millets, groundnut |
| Laterite | High temperature + heavy rain: Western Ghats, Kerala, Meghalaya, Odisha | Formed by leaching; acidic; rich in iron-aluminium; used as bricks; tea, coffee, cashew |
| Arid / Desert | Western Rajasthan | Sandy, saline, low humus; kankar layer below; millets with irrigation |
| Saline / Alkaline — "reh, kallar, usar" | W. Gujarat, Sundarbans, over-irrigated Punjab-Haryana | High sodium-magnesium; remedy — gypsum |
| Peaty / Marshy | Kerala, Sundarbans, Odisha coast | High organic matter (40–50%), acidic |
| Mountain / Forest | Himalayas, Western Ghats | Rich in humus, acidic; tea, coffee, spices, fruits |
- Study of soil = Pedology. Classification — ICAR (8 types). Area order: alluvial > red > black.
- Soil pH: lime corrects acidic soil, gypsum corrects alkaline soil.
📌 2. Soil Erosion & Conservation
- Types: sheet erosion, gully erosion — Chambal ravines, wind erosion (Rajasthan).
- Conservation: contour ploughing, terrace farming on slopes, strip cropping, shelter belts (tree rows against wind), afforestation, check dams, crop rotation.
- Soil Health Card scheme — 2015 (launched at Suratgarh, Rajasthan); World Soil Day — 5 December.
- Jhum (shifting cultivation, NE) also increases erosion.
⚠️ Exam Traps:
- Black soil retains the most moisture; laterite is an acidic soil formed by leaching.
- Red colour is from ferric oxide (iron); alluvial soil lacks nitrogen.
- Alkaline soil → gypsum; acidic → lime.
📌 3. Practice MCQs
📝 Practice MCQs (prepared by SF Prep — not PYQs)
Q1. Which soil covers the largest area in India? Practice
Correct answer: (B)
Alluvial soil covers ≈ 40%, mainly in the northern plains.
Alluvial soil covers ≈ 40%, mainly in the northern plains.
Q2. Which soil is best suited for cotton? Practice
Correct answer: (C)
Black soil retains moisture; called "black cotton soil".
Black soil retains moisture; called "black cotton soil".
Q3. Black soil is formed by the weathering of — Practice
Correct answer: (D)
From the basaltic lava of the Deccan Trap.
From the basaltic lava of the Deccan Trap.
Q4. The red colour of red soil is due to — Practice
Correct answer: (A)
Diffused iron oxide gives the red colour.
Diffused iron oxide gives the red colour.
Q5. Which soil forms by leaching in areas of high temperature and heavy rain? Practice
Correct answer: (B)
Silica is leached away, leaving iron and aluminium.
Silica is leached away, leaving iron and aluminium.
Q6. Laterite soil is especially suited for — Practice
Correct answer: (C)
Cashew, tea, coffee grow on laterite in Kerala, Karnataka, Goa.
Cashew, tea, coffee grow on laterite in Kerala, Karnataka, Goa.
Q7. Alluvial soil is generally deficient in — Practice
Correct answer: (D)
Alluvial soil is rich in potash but poor in nitrogen and phosphorus.
Alluvial soil is rich in potash but poor in nitrogen and phosphorus.
Q8. Which is added to reclaim alkaline (usar) soil? Practice
Correct answer: (A)
Gypsum replaces sodium and reduces alkalinity.
Gypsum replaces sodium and reduces alkalinity.
Q9. What is used to correct acidic soil? Practice
Correct answer: (B)
Lime (CaCO₃) neutralises acidity.
Lime (CaCO₃) neutralises acidity.
Q10. Which soil is "self-ploughing" due to deep cracks when dry? Practice
Correct answer: (C)
Black soil swells and shrinks, aerating itself.
Black soil swells and shrinks, aerating itself.
Q11. The science of soils is called — Practice
Correct answer: (D)
Pedology = soils; petrology = rocks.
Pedology = soils; petrology = rocks.
Q12. The Chambal ravines are an example of — Practice
Correct answer: (A)
Running water cuts deep channels forming ravines.
Running water cuts deep channels forming ravines.
Q13. The most effective way to check erosion on hill slopes is — Practice
Correct answer: (B)
Terraces slow down run-off.
Terraces slow down run-off.
Q14. Rows of trees planted to check wind erosion are called — Practice
Correct answer: (C)
Shelter belts reduce wind speed.
Shelter belts reduce wind speed.
Q15. World Soil Day is observed on — Practice
Correct answer: (D)
5 December (FAO); 22 April is Earth Day, 5 June Environment Day.
5 December (FAO); 22 April is Earth Day, 5 June Environment Day.
Q16. The main feature of peaty soil is — Practice
Correct answer: (A)
Heavy rain and waterlogging give up to 40–50% organic matter.
Heavy rain and waterlogging give up to 40–50% organic matter.
Q17. When hydrated, red soil appears — Practice
Correct answer: (B)
Hydrated iron oxide gives a yellow colour.
Hydrated iron oxide gives a yellow colour.
Q18. Which body classified Indian soils into 8 types? Practice
Correct answer: (C)
The Indian Council of Agricultural Research (ICAR).
The Indian Council of Agricultural Research (ICAR).
Q19. The Soil Health Card scheme was launched at — Practice
Correct answer: (D)
On 19 Feb 2015 at Suratgarh, Rajasthan.
On 19 Feb 2015 at Suratgarh, Rajasthan.
Q20. Which soil problem has grown in over-irrigated Punjab-Haryana? Practice
Correct answer: (A)
Waterlogging brings salts up by capillary action.
Waterlogging brings salts up by capillary action.