Indian Soils, Natural Vegetation & Land Degradation — Soil Types, Conservation, UNCCD & Land Use Change

Soil Formation — Factors & Processes

Soil is the thin layer of unconsolidated material on the earth's surface, formed through the weathering of parent rock and the decomposition of organic matter. The scientific study of soil formation (pedogenesis) was pioneered by V.V. Dokuchaev in Russia in the 1880s and later formalised by Hans Jenny in his 1941 book Factors of Soil Formation.

Jenny's Equation (CLORPT Model)

Hans Jenny expressed soil formation as a function of five interdependent factors:

S = f (cl, o, r, p, t)

Jenny left an ellipsis (...) in the equation to allow for additional factors discovered later (e.g., human activity).

Major Soil Types of India — ICAR Classification

The Indian Council of Agricultural Research (ICAR) classifies Indian soils into eight major groups. These groups reflect the diversity of parent material, climate, and topography across the subcontinent.

1. Alluvial Soil

• Coverage: ~15 lakh sq km (~45.6% of India's total land area) — the most extensive soil type
• Formation: Deposited by rivers of the Indus-Ganga-Brahmaputra system and peninsular rivers
• Distribution: Uttar Pradesh, Bihar, West Bengal, Punjab, Haryana, Assam, and deltaic regions of Mahanadi, Godavari, Krishna, and Kaveri
• Characteristics: Colour ranges from light grey to ash grey; texture varies from sandy loam to clayey; generally immature soils with poorly developed profiles
• Nutrient profile: Rich in potash and lime; deficient in nitrogen and phosphorus
• Suitable crops: Rice, wheat, sugarcane, maize, pulses, oilseeds

Khadar vs Bhangar:

2. Black Soil (Regur / Cotton Soil)

• Coverage: ~5.46 lakh sq km (~16.6% of India's geographical area)
• Formation: Derived from the weathering of Deccan Trap basalt (volcanic lava) of the Cretaceous period
• Distribution: Maharashtra (27% of all black soil), Madhya Pradesh (21.3%), Gujarat (11.5%), Karnataka (9.2%), Andhra Pradesh (7.1%), and parts of Chhattisgarh, Tamil Nadu, and Rajasthan
• Characteristics: Deep black to dark grey colour due to titaniferous magnetite and humus; high clay content (montmorillonite); develops wide cracks during the dry season (self-ploughing property); highly moisture-retentive
• Nutrient profile: Rich in iron, lime, aluminium, magnesium, and potassium; deficient in nitrogen, phosphorus, and organic matter
• Suitable crops: Cotton (hence "cotton soil"), soybean, sugarcane, wheat, jowar, tobacco, citrus fruits

3. Red and Yellow Soil

• Coverage: ~18.5% of India's total area
• Formation: Formed by weathering of ancient crystalline and metamorphic rocks (granite, gneiss) under low rainfall conditions; reddish colour due to diffusion of iron oxide (haematite); yellow colour when iron oxide occurs in hydrated form (limonite)
• Distribution: Tamil Nadu, Karnataka, Andhra Pradesh, Odisha, Jharkhand, Chhattisgarh, and parts of Madhya Pradesh and the north-eastern states
• Characteristics: Generally sandy to loamy texture; porous; friable; acidic in nature; thin topsoil with limited organic matter
• Nutrient profile: Deficient in nitrogen, phosphorus, and humus; contain adequate potash
• Suitable crops: Rice, millets, pulses, groundnut, potato, tobacco (with fertiliser application)

4. Laterite Soil

• Coverage: ~2.48 lakh sq km (~7.5% of India's area)
• Formation: Result of intense leaching under heavy rainfall and high temperature; silica and lime are washed away, leaving behind insoluble iron oxide and aluminium compounds
• Distribution: Western Ghats (Kerala, Karnataka, Goa), parts of Maharashtra, Odisha, Jharkhand, Assam, Meghalaya, and the Andaman and Nicobar Islands
• Characteristics: Brick-red to reddish-brown colour; hardens when exposed to air (used as building material — the word laterite comes from Latin later, meaning "brick"); highly acidic; poor water-holding capacity
• Nutrient profile: Deficient in nitrogen, phosphorus, potassium, lime, and organic matter
• Suitable crops: Tea, coffee, rubber, cashew, coconut (with heavy manuring); rice in low-lying areas

5. Arid / Desert Soil

• Coverage: Found in arid and semi-arid regions (~7-8% of India's area)
• Formation: Formed under arid conditions with low rainfall (<25 cm) and high evaporation; mostly wind-deposited (aeolian)
• Distribution: Western Rajasthan (Thar Desert), parts of Gujarat (Kutch), southern Punjab, and southern Haryana
• Characteristics: Sandy to gravelly texture; light yellowish-brown to pale brown colour; low clay and organic content; high salt content (especially sodium); often develops a hard calcium-carbonate (kankar) layer at depth; porous with poor water-holding capacity
• Nutrient profile: Rich in phosphates and calcium carbonate; deficient in nitrogen and humus
• Suitable crops: Bajra, pulses, guar, cumin (with irrigation — canal irrigation from Indira Gandhi Canal has made parts of Rajasthan cultivable)

6. Saline and Alkaline Soil (Usar / Reh / Kallar)

• Coverage: ~6.73 million hectares
• Formation: Caused by capillary action bringing subsoil salts to the surface in arid and semi-arid areas; poor drainage and waterlogging exacerbate the problem
• Distribution: Parts of Rajasthan, Gujarat (Rann of Kutch), Punjab, Haryana, Uttar Pradesh, Bihar, and deltaic coastal areas
• Characteristics: White efflorescence (salt crust) on the surface; high pH (>8.5 for alkaline soils); poor structure; impervious to water
• Nutrient profile: Highly saline or sodic; toxic concentrations of sodium, magnesium, and calcium
• Reclamation: Application of gypsum for sodic soils, provision of proper drainage, leaching with fresh water, growing salt-tolerant crops (e.g., barley, rice)

7. Peaty and Marshy Soil

• Coverage: Limited extent
• Formation: Formed in areas with heavy rainfall and high humidity where organic matter accumulates faster than it decomposes; waterlogged conditions impede aeration
• Distribution: Kerala (Kuttanad below sea level), parts of coastal Odisha, Sundarbans of West Bengal, parts of north Bihar, and Almora (Uttarakhand)
• Characteristics: Dark brown to black colour; high organic/humus content (10-40%); highly acidic; heavy and poorly aerated
• Suitable crops: Rice (in reclaimed areas), paddy in Kuttanad

8. Forest and Mountain Soil

• Coverage: Found in hilly and mountainous regions
• Formation: Varies with altitude; generally formed from weathering of rocks in situ mixed with high organic content from forest litter
• Distribution: Himalayan region, Western and Eastern Ghats, peninsular hill regions
• Characteristics: Highly variable — acidic and rich in humus at higher altitudes; loamy and silty in valley floors; shallow and stony on steep slopes; colour varies from dark brown to reddish-brown
• Suitable crops: Tea, coffee, spices, temperate fruits (apple, walnut, pear), maize

Summary Table — Major Soil Types of India

Soil Degradation in India

India faces severe soil degradation. Based on ISRO's Desertification and Land Degradation Atlas of India (published August 2021):

India's total geographical area: 328.72 million hectares

Desertification (2018-19): 83.69 million ha (~25.5% of total land area)

Most Affected States

Rajasthan, Maharashtra, Gujarat, Karnataka, Ladakh, Jharkhand, Odisha, Madhya Pradesh, and Telangana together account for ~23.79% of the country's total degraded area.

Types of Soil Degradation

Notable Degradation Hotspots

• Chambal Ravines (MP, UP, Rajasthan): Severe gully erosion has created extensive badlands
• Shivalik foothills: Sheet and rill erosion due to deforestation
• Western Rajasthan: Wind erosion affects 56% of degraded land in the region
• Sundarbans: Coastal erosion and saline water intrusion

UNCCD — UN Convention to Combat Desertification

Land Degradation Neutrality (LDN)

LDN is a global target within UNCCD's framework for 2030 (aligned with SDG 15.3):

• Definition: "A state whereby the amount and quality of land resources necessary to support ecosystem functions and services and enhance food security remains stable or increases within specified temporal and spatial scales and ecosystems"
• India's LDN target: India committed to restoring 26 million hectares of degraded land by 2030 (pledged at COP 14 in 2019)
• Challenge: Current degradation rate exceeds restoration rate

Soil Conservation Measures

Soil conservation involves practices that prevent soil loss and maintain soil fertility. Key methods employed in India include:

Mechanical / Engineering Methods

Biological / Agronomic Methods

Soil Health Card Scheme

PMKSY and Watershed Development

Pradhan Mantri Krishi Sinchayee Yojana (PMKSY)

Launched in 2015, PMKSY has four components -- one dedicated to watershed management:

Watershed Development Component (WDC-PMKSY):

Integrated Watershed Management -- Key Steps

1. Identification of degraded watershed
2. Treatment works -- land treatment (bunding, terracing) and drainage line treatment (check dams, gully plugging)
3. Vegetative treatment -- plantation, grass seeding
4. Groundwater management -- farm ponds, recharge structures
5. Livelihood integration -- SHGs, livelihoods for landless

Organic Farming and Soil Health

National Mission for Sustainable Agriculture (NMSA)

• Focus: Climate-resilient agriculture; soil health management; resource conservation
• Components: Soil health management, rain-fed area development, climate change adaptation
• Paramparagat Krishi Vikas Yojana (PKVY): Organic farming clusters under NMSA
• Zero Budget Natural Farming (ZBNF): PM's promotion; Andhra Pradesh leading practitioner

Soil Organic Carbon (SOC)

• Indian soils are generally low in organic carbon (most soils <0.5% OC vs ideal >1%)
• Building SOC through compost, green manure, crop residue management is essential
• SOC is also a carbon sink -- improving soils contributes to climate change mitigation

Champion and Seth Classification of Indian Forests (1968)

H.G. Champion and S.K. Seth published A Revised Survey of the Forest Types of India in 1968, classifying India's forests into 6 major groups and 16 type groups (further subdivided into 221 sub-types). This remains the standard reference for Indian forestry.

The 6 Major Groups and 16 Type Groups

Forest Cover in India — ISFR 2023

The India State of Forest Report (ISFR) 2023 is the 18th edition published by the Forest Survey of India (FSI). Key findings:

Forest Cover Summary

Forest Cover by Density Class

Change from ISFR 2021

• Total forest and tree cover increased by 1,445 sq km (forest cover +156 sq km; tree cover +1,289 sq km)
• Scrub decreased from 46,539 sq km to 43,623 sq km

Top States by Forest Cover (Area-wise)

States/UTs with Highest Forest Cover (% of Geographic Area)

Mangrove Cover (ISFR 2023)

India's mangrove cover constitutes 0.15% of the total geographical area. The Sundarbans (West Bengal) accounts for the largest share.

Natural Vegetation and Rainfall Correlation

The type of natural vegetation in India is primarily determined by the amount and distribution of rainfall, along with temperature and altitude.

India's Biogeographic Zones

In 1988, Rodgers and Panwar of the Wildlife Institute of India (WII) proposed a biogeographic classification of India into 10 biogeographic zones and 27 biogeographic provinces for wildlife conservation planning.

Biosphere Reserves of India

India has 18 notified Biosphere Reserves, of which 13 have been recognised by UNESCO under the Man and the Biosphere (MAB) Programme's World Network of Biosphere Reserves (WNBR).

Key facts for UPSC:

• Nilgiri (1986) was India's first biosphere reserve; Nilgiri (2000) was the first UNESCO-recognised BR from India
• Kachchh (Great Rann) is the largest BR; Dibru-Saikhowa is the smallest
• Cold Desert became India's 13th UNESCO biosphere reserve in 2025
• Panna is the third BR in Madhya Pradesh to receive UNESCO recognition (after Pachmarhi and Achanakmar-Amarkantak)

Key Government Programmes for Forest & Soil Conservation

1. National Afforestation Programme (NAP)

• Objective: Promote afforestation and eco-restoration of degraded forests through people's participation via Joint Forest Management Committees (JFMCs)
• Structure: Three-tier institutional model -- State Forest Development Agency (SFDA), Forest Development Agency (FDA), and JFMCs at village level
• Funding: 60:40 Centre-State sharing (90:10 for NE and hilly states)

2. National Mission for a Green India (Green India Mission / GIM)

• Launched: 2014, as one of the eight missions under the National Action Plan on Climate Change (NAPCC)
• Target: Increase forest and tree cover on 5 million hectares (Mha) of forest/non-forest lands, and improve quality of forest cover on another 5 Mha
• Revised roadmap: Implementation over 2021-2030
• Expenditure: Rs 624.71 crore released to 18 states between 2019-20 and 2023-24

3. Compensatory Afforestation Fund (CAMPA)

• Legal basis: Compensatory Afforestation Fund Act, 2016
• Purpose: Compensate loss of forest cover due to diversion of forest land for developmental projects (under Forest Conservation Act, 1980)
• Scale: Rs 55,394.16 crore released to States/UTs in the last five years under CAMPA funds

4. Joint Forest Management (JFM)

• Introduced: 1990 (Government of India circular)
• Concept: Partnership between the State Forest Department and local communities for the protection and management of degraded forests
• Structure: Village-level JFMCs with representation of women and marginalised communities
• Benefit-sharing: Communities share in the timber and non-timber forest produce

5. Other Notable Initiatives

Important for UPSC

Prelims focus areas:

• ICAR classification of soils and their characteristics (especially nutrient deficiencies)
• Bhangar vs Khadar distinction
• Champion and Seth classification -- 6 major groups, 16 type groups
• ISFR 2023 data -- total forest cover, top states, density classes, mangrove cover
• All 18 biosphere reserves -- states, year of notification, UNESCO status
• Rodgers and Panwar biogeographic zones (10 zones, 27 provinces)
• ISRO land degradation figure (97.85 mha or 29.7%)
• UNCCD secretariat (Bonn), COP 14 location (Greater Noida, 2019)
• India's LDN target (26 million ha by 2030)
• Soil Health Card launch date (19 February 2015), number of parameters (12)
• PMKSY watershed component

Mains answer themes:

• Linkage between soil degradation and food security; measures for soil health (Soil Health Card scheme)
• India's land degradation crisis -- causes, extent, and the role of watershed management
• India's commitment to Land Degradation Neutrality by 2030 -- assess challenges and progress
• Role of community participation in forest conservation (JFM, Van Panchayats)
• Forest rights and tribals -- Forest Rights Act, 2006 vs Forest Conservation Act, 1980
• Biosphere reserves as a model for balancing conservation and livelihoods
• Climate change and shifting vegetation zones -- northward migration of species, shrinking alpine ecosystems

Common Prelims traps:

• Tropical dry deciduous (not moist deciduous) is the largest forest type in India
• Alluvial soil is deficient in nitrogen and phosphorus, not potash
• Black soil is self-ploughing (cracks in summer) -- a frequently tested characteristic
• Laterite soil hardens on exposure to air -- the word comes from Latin later (brick)
• Cold Desert BR (Himachal Pradesh) became the 13th UNESCO biosphere reserve from India in 2025

Mnemonics:

• Soil types: "All Black Rocks Look Desert-hot" (Alluvial, Black, Red, Laterite, Desert, Mountain)
• CLORPT factors: "Climate-Life-Organic matter-Relief-Parent material-Time"
• Black soil crops: "Cotton Wheat Sorghum Tobacco" (CWST)
• ISRO degradation: "97.85 million hectares = 29.7% of India"

Vocabulary

Laterite

• Pronunciation: /ˈlætəraɪt/
• Definition: A reddish, iron-rich soil formed in tropical and subtropical regions through intense leaching that removes silica and enriches the residual material with iron and aluminium oxides.
• Origin: From Latin later ("brick") + -ite (mineral suffix), coined because the soil hardens like brick when exposed to air.

Humus

• Pronunciation: /ˈhjuːməs/
• Definition: The dark, organic component of soil formed by the decomposition of plant and animal matter by soil microorganisms, which improves soil fertility and water retention.
• Origin: From Latin humus ("earth, soil"), from Proto-Indo-European *dʰǵʰom- ("earth"), akin to Greek chamai ("on the ground") and Sanskrit kṣam- ("earth").

Leaching

• Pronunciation: /ˈliːtʃɪŋ/
• Definition: The process by which soluble minerals and nutrients are washed out of the upper soil layers by percolating rainwater, leaving behind insoluble residues.
• Origin: From Middle English leche ("leachate, sluggish stream"), from Old English *lǣce ("muddy stream"), from Proto-Germanic *lēkijō ("a leak, drain, flow").

Key Terms

Biosphere Reserve

• Pronunciation: /ˈbaɪəsfɪər rɪˈzɜːrv/
• Definition: An area designated under UNESCO's Man and the Biosphere (MAB) Programme that combines nature conservation with sustainable human development, structured into three concentric zones -- a legally protected core zone (no human activity), a buffer zone (limited research and education activities), and a transition zone (sustainable resource use by local communities). India has 18 notified Biosphere Reserves covering 91,425 sq km, of which 13 have been recognised under UNESCO's World Network of Biosphere Reserves (WNBR).
• Context: "Biosphere" from German Biosphäre, coined by geologist Eduard Suess in 1875, from Greek bios ("life") + sphaira ("sphere"); "reserve" from Latin reservāre ("to keep back"). The MAB Programme was launched by UNESCO in 1971. India's first biosphere reserve was Nilgiri (notified 1986, UNESCO recognition 2000). The largest is Kachchh (Great Rann, Gujarat, notified 2008), and the smallest is Dibru-Saikhowa (Assam, notified 1997). Cold Desert Biosphere Reserve (Himachal Pradesh) became India's 13th UNESCO-recognised BR in September 2025, featuring the trans-Himalayan cold desert ecosystem with snow leopard and ibex.
• UPSC Relevance: GS1 Geography and GS3 Environment. Prelims regularly tests all 18 biosphere reserves -- states, year of notification, and UNESCO recognition status. Key facts to memorise: Nilgiri was first (1986), Kachchh is largest, Dibru-Saikhowa is smallest, Panna (MP) received UNESCO recognition in 2020, Cold Desert became 13th UNESCO BR in 2025. Mains asks about biosphere reserves as a model for balancing conservation with livelihoods, why the three-zone structure works better than strict exclusionary conservation, and how BRs differ from national parks and wildlife sanctuaries.

Champion and Seth Classification

• Pronunciation: /ˈtʃæmpiən ənd sɛθ ˌklæsɪfɪˈkeɪʃən/
• Definition: The standard classification of Indian forests published by H.G. Champion and S.K. Seth in their 1968 work A Revised Survey of the Forest Types of India, dividing India's forests into 6 major groups (Tropical Moist, Tropical Dry, Montane Subtropical, Montane Temperate, Sub-Alpine, and Alpine), 16 type groups, and over 200 sub-types based on climate, physiognomy, species composition, phenology, topography, soil factors, and altitude. It remains the standard reference framework for Indian forestry used by the Forest Survey of India.
• Context: The original classification was first prepared by H.G. Champion alone in 1936 and subsequently revised with S.K. Seth in 1968 using temperature and rainfall data as the primary classification criteria. While many forest types have since changed in composition and extent due to anthropogenic and natural factors, the Champion and Seth framework has not been officially replaced. The largest forest type under this classification is tropical dry deciduous forest (~38.2% of India's forest area), found in regions receiving 70-100 cm rainfall with a 4-6 month dry season.
• UPSC Relevance: GS1 Geography and GS3 Environment. Prelims tests the 6 major groups and 16 type groups, and which is the largest forest type -- tropical dry deciduous, NOT moist deciduous (a classic trap that catches many aspirants). Mains expects correlation between rainfall zones and forest types (>200 cm = evergreen, 100-200 cm = moist deciduous, 70-100 cm = dry deciduous, <70 cm = thorn), and the linkage between this classification and ISFR 2023 data on forest cover. For high-scoring answers, mention that the classification needs updating given climate change-driven shifts in vegetation zones.