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India Cluster268 Verified Questions
Soils of India: Alluvial, Black (Regur), Red & Laterite Soils GK Questions & Answers
The Indian Council of Agricultural Research (ICAR) classifies Indian soils into eight major orders based on pedogenic processes, parent rock material, and climatic weathering regimes. Alluvial soils constitute the largest soil group, covering over 40% of the total geographic area across the Indo-Gangetic-Brahmaputra plains and coastal deltas. They are divided into newer riverine alluvium (Khadar), characterized by high fertility and silty loam texture, and older elevated alluvium (Bhangar), containing calcareous nodules known as Kankar. Black soils, or Regur soils, dominate the Deccan lava plateau (Maharashtra, Madhya Pradesh, Gujarat) and originate from the weathering of basaltic rocks. Classified as Vertisols, they are rich in montmorillonite clay, displaying self-ploughing properties, high moisture retention, and suitability for cotton cultivation. Red and yellow soils (Alfisols/Ultisols) develop on Archean crystalline rocks under low rainfall conditions, deriving their color from ferric oxides. Laterite soils form in regions with high temperatures and heavy seasonal precipitation through intense leaching (desilication), leaving behind concentrations of iron and aluminum oxides that support plantation crops like tea, coffee, and cashew.
According to the USDA Soil Taxonomy classification mapped by NBSS&LUP, which soil order occupies the largest geographical area across India?
Verified Explanation
Inceptisols are weakly developed, young soils covering approximately 39.7% of India's total geographical area, making them the most widespread soil order. They occur extensively across the alluvial plains of northern India and deltaic river basins. Entisols (28%) and Alfisols (13.5%) follow Inceptisols in coverage.
Which soil order (under the USDA/ICAR Soil Taxonomy) represents the Black Cotton Soils (Regur) of the Deccan Trap region?
Verified Explanation
Black soils (Regur) correspond to the Vertisols order in soil taxonomy. They are rich in montmorillonite clay, giving them high moisture retention capacity, remarkable swelling when wet, and deep shrinkage cracks upon drying (self-ploughing property), making them ideal for rainfed cotton, soybean, and sugarcane cultivation.
Which micronutrient deficiency is most widespread across Indian agricultural soils, affecting over 35-40% of cultivable land according to ICAR soil health assessments?
Verified Explanation
Systematic soil health surveys by ICAR and the National Bureau of Soil Survey and Land Use Planning (NBSS&LUP) reveal that Zinc (Zn) deficiency is the single most prevalent micronutrient deficiency in Indian soils (affecting ~36.5% of soils), particularly in intensively cropped alluvial and calcareous soils under the rice-wheat cropping system.
Which unique physical property of Black Cotton Soil (Regur) causes it to develop deep fissures during dry summer months, leading to natural aeration?
Verified Explanation
Black soils have a high percentage of clay (montmorillonite group). They swell and become extremely sticky when wet and shrink drastically upon drying, forming wide, deep cracks. This shrinkage causes soil fragments to fall into cracks, resulting in a natural 'self-ploughing' effect that aerates the soil.
Which mineral amendment is widely applied to sodic and alkali soils in India to displace exchangeable sodium ions and restore soil structure?
Verified Explanation
Gypsum (hydrated calcium sulfate) is the standard soil amendment used to reclaim sodic (alkali) soils. The calcium ions (Ca2+) in gypsum replace the harmful exchangeable sodium ions (Na+) on clay particles, which are then leached out as soluble sodium sulfate, improving soil permeability and flocculation.
Under the USDA Soil Taxonomy adopted by the Indian Council of Agricultural Research (ICAR), which soil order covers the largest spatial area in India?
Verified Explanation
According to ICAR soil survey data, Inceptisols (young, weakly developed soils of alluvial plains and valleys) occupy the largest area in India (~39.4% or ~130 million hectares), followed by Entisols (~28.1%), Alfisols (~13.6%), and Vertisols (~8.5%).
Which type of soil in India develops through intense leaching (desilication) under conditions of high temperature and alternating wet and dry tropical seasons?
Verified Explanation
Laterite soils (from Latin 'later' meaning brick) form in tropical regions characterized by high temperatures and alternating heavy monsoon rainfall and dry spells. Heavy rainfall leaches silica and lime downward (desilication), leaving behind a surface layer concentrated with insoluble iron and aluminium oxides.
Which distinct soil problem, locally termed 'Kallar', 'Reh', or 'Usar' in Punjab, Haryana, and western Uttar Pradesh, is aggravated by excessive canal irrigation and poor drainage?
Verified Explanation
In the canal-irrigated tracts of the Green Revolution belt (Punjab, Haryana, western UP), intensive flood irrigation without proper sub-surface drainage causes the water table to rise. Capillary action brings dissolved sodium, calcium, and magnesium salts to the surface, creating an infertile white efflorescence known as Reh, Kallar, or Usar.
9ID: GK-GEOG-00481
easyAgriculture & Cropping Patterns
Which soil type, also known as 'Regur soil', is most suitable for cultivating cotton in India?
Verified Explanation
Black soil (Regur soil), formed by weathering of Deccan trap basaltic lava, has high clay content and moisture retention, making it ideal for cotton cultivation.
10ID: GK-GEOG-00542
easyAgriculture & Cropping Patterns
Black soil (Regur soil), formed primarily from volcanic basaltic lava, is most ideal for the cultivation of which cash crop?
Verified Explanation
Black soil (Regur) has high clay content and moisture retention capacity, making it exceptionally suited for cotton cultivation in the Deccan Trap region.
11ID: GK-GEOG-00595
easyAgriculture & Cropping Patterns
Which soil type, also known as 'Regur soil', is characteristically rich in clay, highly moisture-retentive, and most ideal for cotton cultivation in the Deccan Trap?
Verified Explanation
Black soil (Regur) is formed by weathering of basaltic lava of the Deccan Trap, possessing high clay content and moisture retention, making it ideal for cotton farming.
12ID: GK-GEOG-00630
mediumAgriculture & Cropping Patterns
Which soil type is formed as a result of intense tropical weathering and leaching under alternating wet and dry monsoonal regimes, rich in iron oxide and bauxite?
Verified Explanation
Laterite soil (from Latin 'later' meaning brick) develops through heavy leaching of silica and alkali in high-rainfall tropical areas, leaving behind iron oxides and aluminium.
Which expanding 2:1 lattice clay mineral is primarily responsible for the swelling-shrinking behavior, deep dry cracking, and 'self-ploughing' nature of Black Cotton Soils (Vertisols)?
Verified Explanation
Black soils (Vertisols) are dominated by the smectite group clay mineral Montmorillonite (a 2:1 expanding layer lattice mineral). When wet, it expands significantly and becomes sticky; upon drying, it contracts intensely, developing wide and deep cracks. This cracking causes soil materials to fall into the fissures, creating a natural self-mixing or 'self-ploughing' process.
The pedogenic process of laterization on upland plateaus in humid tropical India involves which primary geochemical mechanism?
Verified Explanation
Laterite soils develop under conditions of high temperature and alternating wet and dry seasons. Heavy tropical rainfall causes intense leaching of silica and soluble bases (desilication), leaving behind an insoluble residue rich in iron oxides and aluminum oxides known as sesquioxides, giving the soil its characteristic red-brown color and acidic reaction.
Highly saline and sodic soils formed in the canal-irrigated arid tracts of Punjab, Haryana, and Uttar Pradesh (locally called Reh or Usar) are reclaimed agriculturally by adding which chemical amendment?
Verified Explanation
Sodic (alkaline) soils have high exchangeable sodium percentages that destroy soil structure. Applying Gypsum (calcium sulfate dihydrate) replaces exchangeable sodium ions on soil clay colloids with calcium ions. The displaced sodium forms soluble sodium sulfate, which is then removed via leaching and drainage.
Under the Planning Commission's agro-climatic regional planning framework, how many broad Agro-Climatic Zones was the Indian territory delineated into?
Verified Explanation
In 1988, the Planning Commission divided India into 15 broad Agro-Climatic Zones (14 for the mainland and 1 for the Islands) based on physiography, climate, soil types, and water availability. The National Agricultural Research Project (NARP) under ICAR subsequently delineated 127 sub-zones for micro-level agricultural planning.
Which Indian state consistently holds the highest share in the total production of Soyabean in India?
Verified Explanation
Madhya Pradesh is widely known as the 'Soya State' of India, leading the country in soybean acreage and production (competing closely with Maharashtra), supported by the extensive black soil tracts of the Malwa plateau and Narmada valley.
The 'System of Rice Intensification' (SRI), adopted in several Indian states, primarily benefits paddy cultivation by which mechanism?
Verified Explanation
The System of Rice Intensification (SRI) is an agro-ecological methodology that involves transplanting young single seedlings at wider spacing, maintaining moist but unflooded soil conditions (alternate wetting and drying), and active soil aeration. This cuts irrigation water usage by 25-50% and seed requirement by up to 90% while boosting yield.
Under the agro-ecological classification of India developed by NBSS&LUP-ICAR, how many distinct Agro-Ecological Regions (AERs) have been delineated across the country?
Verified Explanation
The National Bureau of Soil Survey and Land Use Planning (NBSS&LUP) of ICAR delineated India into 20 Agro-Ecological Regions (AERs) and 60 Agro-Ecological Sub-regions based on physiography, soils, bio-climate, and length of growing period (LGP). Note that the Planning Commission had previously classified India into 15 Agro-Climatic Zones.
The distinctive reddish hue of Red Soils across the peninsular plateau of India is primarily due to the wide diffusion of what chemical constituent?
Verified Explanation
Red soils develop on Archean crystalline igneous and metamorphic rocks (granites and gneisses) in areas of low rainfall. Their reddish color is caused by the wide diffusion of ferric oxide (iron) in the soil matrix. When hydrated, these soils take on a yellowish appearance.
Which of the following agronomic practices is an essential operational component of the System of Rice Intensification (SRI)?
Verified Explanation
The System of Rice Intensification (SRI) is an agro-ecological methodology that involves transplanting very young (8-12 days old) single seedlings per hill in a wide grid (e.g. 25x25 cm), keeping the soil moist through Alternate Wetting and Drying (AWD) rather than continuous flooding, which saves up to 40% water and promotes deeper root growth.
22ID: GK-AGRI-00008
easyKharif, Rabi & Cash Crop Patterns
Which soil type, also known as 'Regur soil', is considered most suitable for the commercial cultivation of Cotton in India?
Verified Explanation
Black soil (or Regur / Black Cotton Soil) is rich in clayey material and retains moisture exceptionally well, making it ideal for cotton farming across the Deccan lava plateau.
23ID: GK-AGRI-00043
hardAgricultural Revolutions & ICAR Institutes
The Central Soil Salinity Research Institute (CSSRI), internationally recognized for pioneering gypsum reclamation of sodic/alkali soils, is located in which city?
Verified Explanation
ICAR-Central Soil Salinity Research Institute (CSSRI) was established in 1969 at Karnal, Haryana, to address the reclamation and management of salt-affected soils in India.
24ID: GK-AGRI-00047
easyRural Credit, NABARD & Agro-Schemes
The Soil Health Card Scheme was launched on 19 February 2015 from Suratgarh in Rajasthan with which official slogan?
Verified Explanation
Prime Minister Narendra Modi launched the Soil Health Card Scheme on 19 February 2015 from Suratgarh, Rajasthan, under the motto 'Swasth Dhara, Khet Haraa' (Healthy Earth, Green Farm).
25ID: GK-AGRI-00122
hardAgricultural Revolutions & ICAR Institutes
The National Bureau of Soil Survey and Land Use Planning (ICAR-NBSS&LUP), which creates digitized soil resource mapping and land capability maps of India, is headquartered in which city?
Verified Explanation
ICAR-NBSS&LUP is headquartered in Nagpur, Maharashtra, dedicated to soil resource survey, land evaluation, and agro-ecological zone mapping across the country.