🌍 Class 11 Geography – Chapter 6
Soil (मृदा)
🌱 Soil (मिट्टी) :-
- Soil is a valuable natural resource 🌏 and the most important part of the earth's crust.
- It is the upper surface layer of the earth, formed by a climatic and biochemical process by mixing:
- Broken rock particles 🪨
- Rotten parts of vegetation 🌿
🌀 Soil Formation (मृदा निर्माण प्रक्रिया) :-
Soil formation is a complex process influenced by many factors:
- Parent Material (अभिभावक पदार्थ)
- Soil originates from rocks.
- Breaking of rocks → soil formation.
- Relief (भूप्रकृति)
- Steep slope → fast water flow → less soil formation.
- Gentle slope → more deposition → thick soil layer.
- Climate (जलवायु)
- Temperature 🌡️ + Rainfall 🌧️ → different soil types.
- Natural Vegetation (वनस्पति)
- Vegetation growth helps soil formation & development.
- Time (समय)
- Thousands of years are required to form a thin soil layer.
🏞️ Types of Soil in India (भारत में मृदा के प्रकार) :-
- Alluvial Soil (जलोढ़ मिट्टी)
- Found in North Indian plains & river valleys.
- Formed by river-borne sediments.
- Most fertile soil 🌾
- High in Potash, low in Phosphorus.
- Color → Light Gray to Ash Gray.
- Found in Ganga–Brahmaputra Plains.
- Black Soil (काली मिट्टी)
- Origin: Volcanic Lava 🌋
- Known as Regur Soil / Cotton Soil.
- Rich in Lime, Iron, Magnesium, Alumina.
- Lacks Phosphorus, Nitrogen, Organic matter.
- Found in Deccan Plateau, Maharashtra, Gujarat, Andhra Pradesh, Tamil Nadu.
- Becomes sticky when wet.
- Red & Yellow Soil (लाल/पीली मिट्टी)
- Color → Red (iron oxide), Yellow (hydrated).
- Low fertility, poor in Nitrogen & Phosphoric acid.
- Found in Odisha, Chhattisgarh, Middle Ganga Plains.
- Fine-grained → fertile | Coarse-grained → infertile.
- Laterite Soil (लेटराइट मिट्टी)
- Word from Latin “Later” = Brick 🧱
- Found in High temperature & heavy rainfall areas.
- Formed by Leaching process (dry & wet seasonal changes).
- Not very fertile ❌
- Found in West Coast Hills, Tamil Nadu, Andhra Pradesh, Orissa, Assam, Rajmahal Hills.
- Used for brick making.
- Dry Soil (शुष्क मिट्टी)
- Color → Red to Brownish.
- Sandy & Saline.
- High Salt content (Salt extracted by evaporation).
- Low Moisture & Humus.
- Found in Western Rajasthan desert areas.
- Pebble layers limit water seepage → irrigation maintains moisture.
🌱 Soil (मिट्टी) – Saline Soil, Degradation, Erosion & Conservation
🧂 Saline Soil (खारी मिट्टी)
- Found in arid (शुष्क) & semi-arid (अर्ध-शुष्क) regions and waterlogged areas.
- Structure → Sandy to Loamy (रेतीली से दोमट).
- Also called Barren Soils (अनुपजाऊ मिट्टी).
- Contain excess sodium, potassium, magnesium → vegetation cannot grow.
- Dry climate + poor drainage → increases salt content.
- Example: Rann of Kutch → monsoon winds bring salt particles, deposited as a crust.
- In delta regions, seawater filling encourages saline soil formation.
- Even fertile alluvial soils are turning saline due to over-irrigation & Green Revolution practices.
⚠️ Soil Degradation (मिट्टी का ह्रास)
- Decline in soil fertility (उपजाऊ शक्ति).
- Nutrient level decreases, depth reduces due to erosion & misuse.
- Main factor behind depletion of soil resources in India.
🌪️ Soil Erosion (मृदा अपरदन)
- Destruction of soil cover due to natural & human causes.
Types of Soil Erosion:
- Wind-borne Erosion (पवन अपरदन): Occurs in arid & semi-arid regions.
- Water-borne Erosion (जल अपरदन): Common in hilly slopes.
- Sheet/Layer Erosion (परत अपरदन): Removal of top soil after heavy rains.
- Gully/Drainage Erosion (नाली अपरदन): Formation of deep gullies by running water. Example – Chambal Ravines.
🚫 Causes of Soil Erosion (कारण)
- Deforestation (वनों की कटाई) 🌳
- Over-irrigation (अधिक सिंचाई) 💧
- Excessive chemical fertilizers (अत्यधिक उर्वरक)
- Faulty farming practices (गलत कृषि पद्धति) 🚜
- Overgrazing (अत्यधिक चराई) 🐄
✅ Measures to Prevent Soil Erosion (निवारण उपाय)
- Tree Plantation (वृक्षारोपण) 🌲
- Contour Plowing (समोच्च रेखा पर हल चलाना)
- Controlled Grazing (नियंत्रित चराई)
- Limited Irrigation (सीमित सिंचाई)
- Proper fertilizer use
- Scientific farming practices
🛡️ Soil Conservation (मृदा संरक्षण)
- Meaning: Prevention of erosion & maintaining fertility.
Major Measures:
- Avoid cultivation on 15–25% slope gradient.
- Terrace Farming (पहाड़ी सीढ़ीदार खेती).
- Crop Rotation (फसल चक्र / सस्यावर्तन).
- Plantation of trees, shrubs & grasses.
- Contour Plowing & Weeding → slows water flow.
- Controlled Pastoralism → reduce grazing pressure.
- Right agricultural methods → sustainable soil use.
📌 Exam Tip:
- Short notes on Saline Soil, Soil Erosion types, and Soil Conservation measures are frequently asked in 3–5 marks questions.
