Soil Resources
Introduction
'Soil is India's MOST IMPORTANT natural resource. Agriculture DEPENDS on soil — and India is an AGRICULTURAL country. ICSE examiners test: TYPES of soil, their DISTRIBUTION, CHARACTERISTICS, and CONSERVATION. The question "Name the SOIL types found in India and describe their CHARACTERISTICS" appears in ALMOST EVERY ICSE Geography paper.'
Soil Formation Factors
| Factor | Role |
|---|---|
| Parent Rock | Determines MINERAL content |
| Climate | Temperature and rainfall affect RATE of formation |
| Relief | SLOPE affects drainage and erosion |
| Vegetation | ROOTS bind the soil — leaves DECOMPOSE to add humus |
| Time | Older soils are DEEPER and more DEVELOPED |
Major Soil Types of India
1. Alluvial Soil
| Aspect | Detail |
|---|---|
| Area | 45.6% of India's total area — MOST EXTENSIVE |
| Location | Northern Plains (Indus-Ganga-Brahmaputra), Coastal Plains, River VALLEYS |
| Formation | Deposited by RIVERS — ALLUVIUM (silt, clay, sand, gravel) |
| Characteristics | VERY FERTILE — rich in POTASH and LIME. Poor in NITROGEN |
| Crops | Rice, Wheat, Sugarcane, Jute, Cotton, Pulses |
| Divisions | KHADAR (new alluvium — MORE fertile) and BHANGAR (older alluvium — LESS fertile) |
2. Black Soil (Regur Soil)
| Aspect | Detail |
|---|---|
| Area | 16.6% of India — 5th largest |
| Location | MAHARASHTRA (most), Madhya Pradesh, Gujarat, Karnataka, Andhra |
| Formation | WEATHERING of LAVA rocks (Deccan Trap) |
| Characteristics | CLAYEY — retains MOISTURE. CRACKS in summer. Self-PLOUGHING. Rich in LIME, IRON, potash. Poor in PHOSPHORUS |
| Crops | COTTON (ideal), Sugarcane, Tobacco, Oilseeds |
| ICSE Note | 'Black soil is ALSO called REGUR or BLACK COTTON SOIL. It is the MOST SUITABLE for cotton cultivation.' |
3. Red and Yellow Soil
| Aspect | Detail |
|---|---|
| Area | 18.5% |
| Location | Eastern and southern parts of the Deccan Plateau — Tamil Nadu, Karnataka, Andhra, Odisha, Jharkhand |
| Formation | WEATHERING of ancient CRYSTALLINE rocks |
| Characteristics | RED colour due to IRON OXIDE. YELLOW when HYDRATED. SANDY-LOAM. Poor in LIME |
| Crops | Ragi, Groundnut, Tobacco, Millets, Potato |
4. Laterite Soil
| Aspect | Detail |
|---|---|
| Area | 8% |
| Location | HIGH rainfall areas — W. Ghats, Kerala, Karnataka, Meghalaya, Assam, Odisha |
| Formation | INTENSE LEACHING in high rainfall — soluble minerals WASHED away |
| Characteristics | RICH in IRON and ALUMINIUM. POOR in organic matter, nitrogen, lime. ACIDIC |
| Crops | TEA, Coffee, Rubber, Cashew (in well-managed areas). INFERTILE for food crops |
| ICSE Note | 'Laterite = Latin "LATER" (brick). It hardens when exposed to air — used as BUILDING material.' |
5. Arid / Desert Soil
| Aspect | Detail |
|---|---|
| Area | 4% |
| Location | THAR DESERT — Rajasthan, parts of Gujarat, Haryana |
| Formation | ARID conditions — low rainfall, high EVAPORATION |
| Characteristics | SANDY — low humus. SOLUBLE SALTS present. High pH (ALKALINE). LOW moisture |
| Crops | ONLY with IRRIGATION — Wheat, Cotton, Bajra |
| ICSE Note | 'These soils are INFERTILE but can be cultivated with IRRIGATION (Rajasthan Canal / Indira Gandhi Canal).' |
6. Forest / Mountain Soil
| Aspect | Detail |
|---|---|
| Location | HIMALAYAS, Western Ghats, Eastern Ghats |
| Characteristics | LOAMY — rich in HUMUS. HETEROGENEOUS (varies with altitude) |
| ICSE Note | 'Found in FORESTED areas. Rich in organic matter but may be THIN on steep slopes.' |
Comparison Table — Major Soil Types
| Soil Type | Colour | Fertility | Suitable Crops | Major States |
|---|---|---|---|---|
| ALLUVIAL | Light grey to DARK | VERY high | Rice, Wheat, Sugarcane | Punjab, UP, Bihar, WB |
| BLACK | DARK black to grey | HIGH (with moisture) | COTTON, Sugarcane | Maharashtra, Gujarat, MP |
| RED & YELLOW | Red/Brown/Yellow | LOW-MODERATE | Ragi, Groundnut | Tamil Nadu, Karnataka |
| LATERITE | Red/Brown | LOW (without fertiliser) | TEA, Coffee | Kerala, Meghalaya |
| ARID | Sandy/Brown | LOW | Barley, Bajra | Rajasthan |
Soil Erosion
| Type | Description | Cause |
|---|---|---|
| GULLY Erosion | DEEP channels — BADLANDS (Chambal Valley) | WATER flows in channels |
| SHEET Erosion | THIN layer REMOVED evenly | RUNNING water |
| WIND Erosion | Topsoil BLOWN away | STRONG winds (Rajasthan) |
| RILL Erosion | SMALL channels — can become GULLIES | Surface RUNOFF |
Causes of Soil Erosion
- DEFORESTATION — trees protect soil
- OVERGRAZING — animals remove vegetation cover
- SHIFTING CULTIVATION (Jhum) — leaves soil exposed
- FLOODS — wash away topsoil
- INDISCRIMINATE farming — monoculture depletes nutrients
Soil Conservation Methods
| Method | Description |
|---|---|
| CONTOUR PLOUGHING | Ploughing along the contour lines — REDUCES runoff |
| TERRACE FARMING | Steps on slopes — Himalayas, Western Ghats |
| STRIP CROPPING | Alternate strips of CROPS + GRASS — reduces WIND erosion |
| SHELTER BELTS | Lines of TREES — block wind in DESERTS |
| AFFORESTATION | Plant TREES — roots bind the soil |
| COVER CROPS | Plant CROPS between seasons — soil NOT left BARE |
| CHECK DAMS | Small DAMS to slow WATER flow in gullies |
Common Mistakes in ICSE Answers
| Mistake | Correction |
|---|---|
| Calling alluvial soil 'black soil' | Alluvial = river deposits. Black = lava origin |
| Confusing RED and YELLOW soil with LATERITE | Red = crystalline rock. Laterite = LEACHED |
| Ignoring KHADAR and BHANGAR | Know the DIFFERENCE — Khadar = NEW, more fertile |
| Forgetting LATERITE hardens | Laterite = building material when dried |
ICSE Exam Focus — Marks Blueprint
| Question Type | Marks | Frequency |
|---|---|---|
| Types of soil in India — characteristics | 6-8 | Always |
| Black soil — formation, properties, crops | 4-6 | Always |
| Alluvial soil — divisions (Khadar/Bhangar) | 4-6 | Very High |
| Soil erosion — types and causes | 4-6 | Very High |
| Soil conservation methods | 4-6 | Very High |
Self-Test
-
Alluvial Soil: Where is alluvial soil found in India? Why is it FERTILE? Differentiate between KHADAR and BHANGAR.
-
Black Soil: Describe the CHARACTERISTICS of black soil. Why is it SUITABLE for cotton cultivation?
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Laterite Soil: What is LATERITE SOIL? How does it FORM? Why is it INFERTILE for food crops?
-
Erosion: What is GULLY EROSION? Name ONE area in India where it is SEVERE.
-
Conservation: Explain ANY THREE methods of soil conservation.
-
Comparison: Compare ALLUVIAL and BLACK soil on: (a) Colour, (b) Chemical properties, (c) Crops grown.
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Arid Soil: Where is arid soil found? What are its LIMITATIONS? How can it be made CULTIVABLE?
