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Indian Geography25 Essential Exam Concepts
Major Types of Soil Found in India: ICAR Classification GK
Soil represents the fundamental pedological interface sustaining India’s biological diversity, agricultural productivity, and national food security. The astonishing geomorphological variety of the subcontinent—spanning ancient Precambrian shields, young folded alpine mountains, volcanic flood basalts, and expansive depositional floodplains—has produced a diverse mosaic of soil orders. In 1953, the Indian Council of Agricultural Research (ICAR) established the All India Soil Survey Committee, which categorized the soils of India into eight primary scientific groups based on parent rock geology, climate, relief, vegetation, and chemical horizons, aligning these groupings with international USDA soil taxonomy orders.
The most extensive and economically dominant soil group is Alluvial Soil, blanketing approximately 40 to 43 percent of the country’s total geographical area across the Northern Plains and coastal river deltas. Transported and deposited by Himalayan and peninsular rivers, alluvial soils are rich in potash, phosphoric acid, and lime, but deficient in nitrogen and humus. They are divided into two distinct chronological types: older alluvium (Bangar), situated above flood levels and containing calcareous nodules known as kankar, and newer, fine-textured flood silt (Khadar), which is annually replenished by monsoon inundations. In peninsular India, the second prominent order is Black Soil, traditionally termed Regur or Black Cotton Soil, covering roughly 15 percent of the landmass across the volcanic Deccan Trap of Maharashtra, Gujarat, and Madhya Pradesh. Derived from the weathering of Cretaceous basalt, black soil is distinguished by its high clay content, exceptional moisture-retention capacity, and unique self-ploughing property, contracting and developing deep fissures during arid periods.
Covering extensive tracts across the eastern and southern peninsula is Red and Yellow Soil (occupying approximately 18.5 percent of India), developed over ancient crystalline metamorphic rocks under low-rainfall regimes. Its distinctive reddish hue derives from the wide diffusion of ferric oxides, transforming into yellow when hydrated. In contrast, Laterite Soil develops in tropical regions experiencing intense seasonal rains and high temperatures, where intense leaching dissolves silica and lime, leaving behind an acidic, porous subsoil rich in iron oxide and aluminum hydroxide, ideally suited for cashew, tea, coffee, and rubber plantations. The remaining groups include Arid/Desert Soils of western Rajasthan characterized by high kankar horizons, Saline/Alkaline Soils (known locally as Reh, Kallar, or Usar) created by poor canal drainage, Peaty/Marshy Soils (Kari) rich in undecomposed organic matter in coastal wetlands, and Mountain/Forest Soils across Himalayan slopes.
High-yield conceptual summaries for competitive exams and rapid revision.
The Indian Council of Agricultural Research (ICAR) officially classifies Indian soils into eight major groups based on genesis, color, composition, and location.
Alluvial soil is the most widespread soil order in India, covering approximately 40% to 43% of the nation's total geographical land area.
Alluvial soils are depositional (transported) soils laid down by the Indus, Ganga, and Brahmaputra river systems and coastal deltaic streams.
Bangar represents older alluvium located above annual floodplains, characterized by clayey texture and calcareous concentrations known as kankar.
Khadar represents newer, sandy-loam alluvium deposited annually on active floodplains, exhibiting higher natural fertility than Bangar.
Alluvial soils are generally rich in potash and lime, but severely deficient in nitrogen and organic humus.
Black soil (Regur) covers roughly 15% of India's area, dominating the Deccan Trap basalt region across Maharashtra, Gujarat, Madhya Pradesh, and Karnataka.
Black soil belongs to the Vertisols order in USDA soil taxonomy, characterized by high montmorillonite clay content and high cation exchange capacity.
Regur soil exhibits a unique "self-ploughing" characteristic: it swells and becomes sticky when wet, and develops deep, wide shrinkage cracks when dry.
Black soil is exceptionally moisture-retentive and provides the premier agricultural base for commercial cotton, sugarcane, pulses, and oilseeds.
Red and Yellow soils cover approximately 18.5% of India, developing on Archaean crystalline and metamorphic granites under low-rainfall conditions.
The red color of red soil is caused by the wide diffusion of iron (ferric oxides); it turns yellow when it occurs in a hydrated form.
Red soils are predominantly light, porous, and friable, but are deficient in nitrogen, phosphorus, and humus, requiring chemical fertilization.
Laterite soil is formed under tropical climatic conditions characterized by alternating wet and dry seasons and intense leaching (laterization).
Intense rainfall leaches out soluble silica and lime from laterite soil, leaving behind insoluble oxides of iron and aluminum (bauxite-like residues).
Laterite soils are acidic, poor in organic matter and calcium, but are extensively cultivated for cashew nuts, rubber, tea, and coffee with fertilizers.
Arid and Desert soils cover the hyper-arid tracts of western Rajasthan, northern Gujarat, and southern Punjab, classified under Aridisols.
Arid soils have high soluble salt content, low moisture, and a prominent subsurface kankar layer of calcium carbonate that impedes root penetration.
Saline and Alkaline soils (known regionally as Usar, Reh, Kallar, Rakar, and Chopan) contain high concentrations of sodium, potassium, and magnesium salts.
Saline soils develop in dry climates due to poor drainage, excessive canal over-irrigation (capillary water evaporation), and seawater ingress in coastal deltas.
Peaty and Marshy soils (locally termed Kari in Kerala) occur in heavy rainfall areas with high humidity, containing up to 40% to 50% undecomposed organic matter.
Forest and Mountain soils occupy steep Himalayan slopes, exhibiting high acidity and low humus in cold alpine zones, but fertile dark loam in river valleys.
The Central Soil Salinity Research Institute (CSSRI), located in Karnal, Haryana, conducts pioneering research on the reclamation of alkaline and saline soils.