Soil and natural vegetation play crucial roles in regulating life on Earth. Soils can be transported by running water, wind, or other erosion agents or may remain in their original position.
Soil
- Soil is a highly valuable natural resource, serving as a growth medium for plants, filtering water, and hosting millions of microorganisms. Comprising both mineral and organic matter, soil is susceptible to erosion from human activities, and its slow formation process renders it a non-renewable resource.
- Various soils exhibit distinct chemical properties, with acidity levels determining classifications—soils with lower lime content are termed acidic, while those with higher lime content are alkaline. When soil remains in its original position (in-situ), it undergoes modification influenced by climate, moisture supply, plant growth, and bacterial activity.
- In 2015, the United Nations declared it the International Year of the Soil to highlight its global significance. World Soil Day is observed annually on December 5th.
Structure and Composition of Soil
- Soil structure is determined by the arrangement of individual particles of sand, silt, and clay. When these particles assemble, they form aggregates, resembling larger particles in the soil.
- Soil character is expressed in terms of its aggregation or the binding properties of individual particles to form a secondary unit. Structure, affecting soil properties like porosity, has a significant impact on soil fertility.
- Soil texture and structure determine porosity and permeability. Sandy soil, with large particles, has decreased porosity and increased permeability, leading to higher water percolation and dryness.
- Loam soil, with a balanced mix of sand, silt, and clay, maintains permeability and porosity, making it highly fertile for agriculture.
Soil Texture
- Particle size characteristics include gravel (2 mm diameter), coarse sand (2 to 0.2 mm), fine sand (0.2 to 0.02 mm), silt (0.02 to 0.002 mm), and clay (< 0.002 mm).
Soil Acidity
- Acidity, measured on the pH scale (0 to 14), influences crop growth. A pH of around 6.5 is considered optimal. Lime-deficient soils are acidic, forming in high rainfall areas.
Soil Salinity and Alkalinity
- Saline/alkaline soils have top layers infused with efflorescences. Over-irrigation leads to salt percolation, while good drainage washes salts away. Poor drainage causes stagnant water with high salt concentration, leading to salt deposits.
- Sandy soils are prone to alkalinity, and loamy soils are susceptible to saline-alkalinity.
Factors Influencing Soil Formation
Some factors influencing soil formation are described below.
Parent Material
- These rocks from which soils are formed are called parent materials. Generally, the parent material determines the colouration, minera composition and texture of the soil.
- In some cases, the soil formed may or may not have the same physical properties of the parent rock. The surface rocks are exposed to the process of weathering.
- In this process, the rocks are converted into fine grains and provide a base for the soil formation.
- In Indian context, parent material is generally categorised into different types such as
- Ancient Crystalline and Metamorphic Rocks These red soils and red colour of the soils is due to the presence of iron oxides.
- Cuddapah and Vindhyan Rocks These Calcareous and argillaceous soils, as the rocks are ancient sedimentary rocks. These are devoid of metalliferous minerals.
- Gondwana Rocks It is less mature soils with low fertility, because the rocks are younger sedimentary rocks.
- Deccan Basalts These are regur or black soils because basalts are rich in titanium, magnetite, aluminium and magnesium giving the soil its dark colour.
Climate
- Hot summer and low rainfall develops black soil as is found in some parts of Tamil Nadu irrespective of the parent rock.
- In arid and semi-arid regions, evaporation always exceeds precipitation. There is little vegetation and the soils badly lack humus content.
- Hence, the soils are invariably of light colour. Here, the alkaline elements dissolved with water move from the lower layers to the upper layers by capillary action due to which the soil becomes more alkaline. Alkaline soil is rich in sodium. especially sodium carbonate.
Vegetation
- In latitudinal shifts, despite increased vegetation density from high to low latitudes, humus levels first rise and then decline.
- In high latitudes, low temperatures hinder organic matter decomposition, while in low latitudes, humus dissolves and leaches to lower layers.
- The roots and leaves of vegetation contribute to humus production, enhancing soil fertility and formation.
Terrestrial Topography
- Topography influences soil formation and erosion. Steep, rocky surfaces reduce soil-forming substance accumulation, resulting in thin soil layers, termed Residual soil. Contour bunding mitigates erosion in such areas.
- The Southern Indian plateau exhibits shallower soil due to heterogeneous relief, while deeper soil is found in river valleys and coastal deltaic areas.
Time
- Rock types affect soil formation time; porous rocks form faster than impervious or massive rocks.
Soil Fertility
- Fertile soil sustains plants with organic substances and clay minerals. Soil fertility is gauged by properties like colour, texture, consistency, porosity, mineral presence, moisture, and chemical processes. Soil horizons, visible in the field, classify soil based on these characteristics.
Soil Profile and Horizons
- The vertical series of soil horizons from the surface to the parent rock is the soil profile. Profiles vary based on the parent rock’s location. Soil horizons, identified as O, A, E, B, C, represent different layers.
Organic Horizon
- Marked with the letter O, organic horizons lie above mineral horizons. Animal and bacterial activity influences soil content. O horizons are subdivided into O1 and O2.
- O1 contains decomposing organic matter.
- O2 consists of humus broken down beyond recognition.
Mineral Horizons
Some mineral horizons are as follows
A-Horizon
- The topsoil horizon primarily comprises minerals (sand, silt, and clay) along with significant organic matter.
- Predominantly found in grasslands and agricultural lands, this surface layer is crucial for plant growth.
E-Horizon
- A subsurface horizon subject to heavy leaching, resulting in a light color. Typically located between A and B horizons, it represents an older layer.
B-Horizon
- An accumulation of material from layers above, the B-horizon serves as a deposition site for minerals leached from A and E horizons.
- Functions as a zone of illuviation.
C-Horizon
- A subsurface horizon representing the least weathered layer, also known as saprolite. Composed of unconsolidated loose parent material.
- Acts as a zone of accumulation for soluble inorganic compounds percolating down from upper layers.
R-Horizon
- Unweathered parent material or parent rock, consisting of unbroken rock strata at the bottommost layer of the soil profile.
Soil Forming Processes
- Weathering: Breakdown and chemical changes of parent rocks in situ.
- Translocation: Material movement within the soil body.
- Eluviation: Downward transport of fine particles, especially clays and colloids, from the uppermost soil part.
- Illuviation: Accumulation of materials brought downward, typically from E-horizon to B-horizon.
- Decalcification: Leaching of calcium carbonate from the entire soil, usually in moist climates.
- Calcification: Occurs in dry regions where the soil accumulates significant amounts of soluble calcium carbonate and magnesium in the B-horizon.
- Salinization or Alkalization: Extreme evaporation leads to the accumulation of calcium or sodium salts on the soil surface due to capillary action from a water table.
- Desilication: Silica is more mobile than iron and aluminum oxides, resulting in desilicified soils known as ferralsols.
- Podzolization: Iron and aluminum oxides become more mobile, enriching the upper horizons with silica. Typically associated with coniferous and heathland vegetation.
- Gleying: Common in waterlogged or permanent water areas.
Stages in Soil Development
- Initial Stage: Unweathered parent material.
- Juvenile Stage: Weathering has commenced.
- Virile State: Weathered material with significant decomposition, increased clay content.
- Senile State: Decomposition in the final stage, most weathering has occurred.
- Final Stage: Soil development completed, weathered under prevailing conditions.
Classification of Soil
- Based on the global distribution of soils, various attempts have been made by soil taxonomists worldwide and global institutions.
- Russian pedologist V. Dokuchaev made the first soil classification attempt, and later, in 1938, CF Marbut of the United States Department of Agriculture (USDA) introduced the ‘USDA System.’
- The soil was broadly classified into three groups: Zonal soil, Intrazonal soil, and Azonal soil.
Azonal soils
- These soils are developed through the deposition process by erosion agents, consisting of fine rocky particles transported from distant regions. They are immature soils, lacking well-developed profiles, either due to insufficient time for full development or location on steep slopes hindering profile formation. Azonal soils are categorized into the following types:
- Alluvial Soil: Little or no profile development, found on active floodplains.
- Regosols: Composed of dry and loose dune sands or loess.
- Lithosols: Accumulations of imperfectly weathered rock fragments on steep slopes.
Intrazonal Soil
- Soils found within a climatic belt but different due to the dominance of local factors such as relief, parent material, climate, and vegetation. These soils are semi-mature and not continuous.
- Calcimorphic: Develop on limestone, e.g., Rendzina, Terra rossa, and Terarokes soils.
- Hydromorphic: Develop in water-abundant regions, e.g., Pit, Grasslands, Field, and Pleno solo soils.
- Halomorphic: Saline in nature due to high salt levels, found in dry regions, e.g., Saline, Solonetz, and Soloth soils.
Zonal Soil
- Zonal soils are formed at the site of their parent rocks, with the influence of parent rock and climate clearly visible. These mature soils have distinct profiles and clear horizons.
- Examples of zonal soils based on chemical compositions include Tundra soil in Arctic regions, Mediterranean soil in Mediterranean climates, red-yellow soil in deserts, and latosols in Equatorial climates.
Pedalfer
- These soils thrive in humid climates, from high-latitude coniferous forests to mid-latitude deciduous forests and tropical grasslands with an annual rainfall exceeding 63.5 cm.
- Red and yellow pedalfer soils are prevalent in low latitudes with high temperatures and abundant rainfall, but bacterial activity leads to humus depletion, making the soil infertile without fertilizers. Pedalfer includes various soil types such as Podzol.
Podzol
- Developed through podzolization in regions with precipitation surpassing evapotranspiration, Podzols are sandy soils found in cooler climates like the Tundra region, hosting coniferous forests. These acidic soils lack earthworms and bacterial presence, presenting challenges for agriculture.
Grey Podzol
- Situated in the Taiga coniferous region of the sub-Arctic climatic zone, Grey Podzol is acidic (pH = 4) due to slow organic matter decomposition. Unfit for agriculture, the A-horizon exhibits a bleached grey appearance, while the B-horizon features illuviation, hard clayey pan, and brown nodules.
Grey-Brown Podzol
- Found in mid-latitude deciduous forest regions, Grey-Brown Podzol is rich in humus. Fertile with manure, fertilizers, and crop rotation, it supports dairy and mixed farming practices.
Red-Yellow Podzol
- Developed through podzolization and laterization in sub-tropical climates with high rainfall, Red-Yellow Podzol is devoid of humus due to pronounced bacterial activity. Responsive to fertilizers, it promotes high crop yields.
Red Podzol or Terra Rossa
- Found in Mediterranean regions, Red Podzol has a red appearance due to Ferrous Oxide (Fe2O3) and lime presence. Lacking humus, it is deeply weathered, with low fertility but potential productivity under scientific use.
Prairie Soil
- Combining characteristics of Chernozem and grey-brown podzol, Prairie Soil is brown-black due to humus, fertile, and found in wet temperate tall grass regions like the Prairie region of the USA, Pampas of South America, Pustaz of Hungary, and Downs of Australia.
Laterite Soil
- Formed in tropical wet climates with high temperatures and abundant rainfall, Laterite Soil undergoes leaching-dominant laterization. Rich in aluminum and iron oxides, it features crust formation, nodular concretions, and induration. Unsuitable for agriculture, it hosts hard wood trees and thorny shrubs in regions like the Zaire Basin and Amazon Basin.
- Developed through podzolization in cold-humid climate regions with coniferous forests, Podzol Soil is well-suited for these environmental conditions.
Tundra Soil
- Developed by gleyization in the Tundra climate region, Tundra Soil experiences extremely low temperatures, leading to water-filled conditions from snowmelt.
- Microorganism activity decreases, and oxygen levels are low due to these frigid temperatures.
- The slow decomposition of organic matter results in its accumulation, while minimal physical and chemical changes in the rocky structure hinder complete soil development. Lichen and mosses dominate the main vegetation in this environment.
Pedocals
- Formed through calcification in semi-arid and dry climates, Pedocals witness alkaline elements moving upward through capillary action, elevating soil alkalinity. As aridity increases, vegetation density decreases, reducing humus content. Types of Pedocals include Brown Earth, Chernozem Soil, Chestnut Brown, Sierozems, and Red Desert Soil.
Brown Earth
- Moderately or well-drained, Brown Earth soils are found where precipitation exceeds potential evapotranspiration. Mainly present in the UK and other warm temperate climates, these soils are reasonably fertile, with particles moving downward through the soil.
Chernozem Soil
- The most fertile soil, Chernozem requires minimal fertilizers and irrigation. Abundant lime is present in its lower layers. Found in the Steppe region, it maintains a balance between calcification and leaching, with high organic matter decomposition and humus content, earning it the name “Black Earth soil.”
Chestnut Brown
- Dark brown soil in drier Chernozem regions, Chestnut Brown contains less humus than Chernozem. Lighter in color, it forms CaCO3 nodules in the B-horizon. Red chestnut and red-brown soil are found in semi-arid parts of the Savanna region.
Sierozems
- Basic soil (pH>8) in hot desert mid-latitudes, Sierozems have lime deposition over the upper layer, with poor horizonization and low humus content.
Red Desert Soil
- Found in hot deserts with low rainfall, high temperature, and high evaporation rates, Red Desert Soil is characterized by lime deposition near the surface and a lack of humus. Productivity depends on nitrogen content and irrigation availability.
USDA Soil Classification
- In 1960, the Soil Survey Department of the Soil Conservation Service of the United States introduced the Comprehensive Soil Classification Scheme (CSCS), dividing global soils into 12 classes based on cross-sectional features.
World Distribution of Soil
| Soil Types | Land Area (%) | Distribution |
| Alfisols | 10% | Moist zones with high Al and Fe content, less fertile and low humus |
| Andisols | 1.0% | Dominance of short-range order minerals or Al-humus complexes, high phosphorus retention, water capacity, and cation exchange capacity |
| Gelisols | RON | Freezing presence of permafrost, features associated with broken horizons and organic material incorporation |
| Aridisols | 12% | Desert zones with salty and carbonate minerals, low water and humus content |
| Histosols | 1.0% | High organic matter content, absence of permafrost, formed in various environments except arid |
| Entisols | 16% | Dominance of mineral soil materials, absence of distinct pedogenic horizons, found in any climate and vegetation |
| Vertisols | 2.0% | High clay content, pronounced volume changes with moisture, cracks opening and closing periodically |
| Oxisols | 28.0% | Extreme weathering of minerals, low clay fraction activity, loamy or clayey texture, rich in Fe and Al oxides |
| Spodosols | 4.0% | B-horizon accumulation of black or reddish materials with high cation exchange capacity, found in cold, moist climates like Taiga region |
| Ultisols | 8.0% | Markers of clay translocation and intensive leaching, found in equatorial, tropical, and subtropical regions with red, yellow, and brown colors |
| Mollisols | 7.0% | Dark brown to black surface horizons, extensive in steppes of Europe, Asia, North and South America, similar to Chernozem soil, most fertile with large humus content |
Methods of Soil Conservation
- No-Tillage Farming: Cultivating crops without removing existing plant cover and previous crop residues. Shallow ploughing is done only to the minimum depth required for quick germination, leaving crop residues and ground litter to protect the soil.
- Contour Cropping: Ploughing and planting along the contours of the land to reduce water runoff and soil erosion.
- Strip Cropping: Alternating strips of close-growing plants (e.g., grass or clover) with regular crops (e.g., corn, cotton, and potatoes) to slow water runoff. When combined with contour cropping, it can reduce soil erosion by up to 75%.
- Terracing: Creating flat, step-like terraces on steep slopes to reduce water runoff.
- Crop Rotation and Cover Crops: Periodically planting fields with close-growing secondary crops to minimize soil erosion. Dense cover plants are used when no primary crop is being grown.
- Gully Reclamation: Seeding gullies with quick-growing plants and using check dams of manure and straw to reduce erosion.
- Windbreaks (Shelter Belts): Planting rows of shrubs and trees along windward edges of croplands to reduce soil loss from wind. Replanting trees on unused cropland.
- Not Planting Marginal Land: Focusing on raising crop yields on good land to reduce pressure on marginal land.
- Land Classification and Zoning: Classifying land based on suitability for cultivation and using zoning and controls to prevent loss of good cropland and planting on marginal land.
Agroforestry:
- Agroforestry: An integrated approach combining agricultural and forestry technologies to create diverse, productive, and sustainable land use systems. It contributes to soil conservation and ecological health.
Soil Degradation and Erosion
- Soil degradation is the decline in soil condition due to improper use or poor management, often for agricultural, industrial, or urban purposes. It’s a serious environmental problem.
- Soil erosion involves the top layer (topsoil) being eroded, affecting the fertile material crucial for life. The rate of erosion depends on factors like soil composition, vegetation, and the intensity of wind and rain.
- Accelerated erosion, caused by human activities like farming, construction, logging, and mining, disrupts the natural balance between rainfall and runoff.
Natural Vegetation
- Natural vegetation refers to plant communities that have grown without human aid and remain undisturbed for an extended period (virgin vegetation). It includes tall trees, shrubs, grasses, bushes, and flowering plants in a given environment, classified into forests, grasslands, and deserts.
Forest Vegetation
- This can be further classified based on climate, temperature, and regions found worldwide:
- Tundra Vegetation: Vast lowlands along Arctic oceanic shores with frozen ground for most of the year. The tundra climate has very low annual mean temperatures, dropping to -40°C to -50°C below freezing in winter, with milder summers.
- The tundra, lacking trees, is characterized by mosses, lichens, sedges, and other low-level vegetation. Key animals in this region include polar bears, caribou, musk-ox, and reindeer.
- This vegetation is primarily found north of the Arctic Circle in the Northern Hemisphere, extending to the north of Asia, Canada, and Europe. It encompasses the coastal strip of Greenland, the barren grounds of Northern Canada and Alaska, and the Arctic seaboard of Eurasia.
Arctic Tundra
- Arctic Tundra encircles the North Pole in the Northern Hemisphere, extending south to the coniferous forests of the taiga. Known for cold, desert-like conditions, it has a growing season ranging from 50 to 60 days.
- The average winter temperature is -34 to -6°C, while the average summer temperature is 3-12°C, sustaining life in this biome.
- Permafrost, a layer of permanently frozen subsoil mostly consisting of gravel and finer material, is present. When water saturates the upper surface, bogs and ponds may form, supporting plant life. The vegetation in Arctic Tundra has no deep root systems, but various plants, including low shrubs, sedges, reindeer mosses, liverworts, and grasses (around 1,700 species), adapt to resist the cold climate. Fauna includes herbivorous and carnivorous mammals, migratory birds, insects, and fish.
- Plants are short and grouped to resist cold temperatures, adapting to photosynthesis at low temperatures and low light intensities. The growing seasons are short due to the harsh conditions.
- Animals in the Arctic Tundra are adapted to handle long, cold winters and quickly breed and raise young in the summer when food is more abundant. Reptiles and amphibians are scarce due to extreme cold temperatures.
Alpine Tundra
- Unlike the Arctic tundra, the soil in the Alpine Tundra is well-drained.
- Plants in the Alpine Tundra are similar to Arctic ones, including tussock grasses, dwarf trees, small-leafed shrubs, and heaths.
- Animals in the Alpine Tundra are also well-adapted, such as mammals like pikas, marmots, mountain goats, sheep, elk, birds like grouse-like birds, and insects like springtails, beetles, grasshoppers, and butterflies.
Taiga (Coniferous) Vegetation
- Taiga experiences the lowest annual average temperatures after the tundra and has permanent ice caps.
- Found only in the Northern Hemisphere due to its vast East-West extent, it is absent in the Southern Hemisphere.
- Located just below the Arctic Circle, taiga has annual precipitation ranging from 38 cm to 63 cm, dominated by evergreen coniferous forests. Conifers, adapted to low moisture, are prevalent in this sub-Arctic climate.
- In Siberia, you’ll find the largest single band of coniferous forest, providing abundant softwood resources. Unlike equatorial rainforests, coniferous forests boast a lower density and more uniform appearance, with trees growing straight and tall. The majority of conifers are evergreen, lacking an annual replacement of new leaves.
- This vast coniferous forest stretches from 50° N to 70° N across Central Canada, parts of Scandinavian Europe, and much of Central and Southern Russia. It blends with the Arctic tundra around the Arctic Circle, resulting in a ‘sub-Arctic climate’ with characteristics of both maritime and continental climates.
Equatorial Vegetation
- Equatorial Vegetation thrives in lush tropical rainforests due to high temperatures and abundant rainfall. In the Amazon lowlands, the forest is so dense it’s referred to as selvas. Unlike temperate regions, the growing season here lasts all year, and seeding, flowering, fruiting, and decay occur without a seasonal pattern.
- This vegetation is dominated by maritime tropical air masses and receives maximum insolation from the Sun, resulting in a rich flora and fauna, including species like rosewood, mahogany, and ebony.
- Equatorial Vegetation is primarily found between 5° N and 10° S of the Equator, with major regions in the Amazon, Congo, Malaysia, and the East Indies lowlands.
Deciduous Vegetation
- Deciduous Vegetation can be classified as temperate and tropical deciduous. Temperate Deciduous Forests consist mainly of trees that shed their leaves during the cold season. Common species include oak, elm, ash, birch, beech, and poplar.
- These forests have a longer growing season, more intense light, and receive a moderate amount of precipitation (50 cm to 150 cm per year). Soils are podzolic and fairly deep.
- Tropical Deciduous Forests, also known as monsoon forests, are found along the Equator between the Tropic of Cancer and Tropic of Capricorn, as well as in humid subtropical regions. These forests, different from tropical deciduous rainforests, experience a long dry season, leading most trees to shed their leaves due to stress. Valuable timber like teak, sal, acacia, and eucalyptus is obtained from these forests.
- Between 10°N and 30°S, the most developed mangrove vegetation is found in regions such as India, Burma, Thailand, Laos, Cambodia, parts of South China, Northern Australia, and Vietnam.
Mangrove vegetation
- Mangrove vegetation comprises broad-leaved trees, ranging from 10 to 40 feet tall, flourishing in muddy creeks and tidal estuaries. These ecosystems, situated in the transition zone between land and sea, exemplify an ecotone.
- Thriving in warm saline waters, mangroves are confined to tropical and sub-tropical coastal areas. They offer habitat for a diverse range of terrestrial and marine organisms due to their unique position at the meeting point of terrestrial and marine ecosystems, leading to higher species diversity.
- Worldwide, mangroves are distributed between latitudes 25°N and 25°S, encompassing approximately 15.9 million hectares of mangrove forests in tropical oceans. They are prevalent along the Atlantic coast from Florida to Argentina, extending to Africa’s Western and Eastern coasts, India, Myanmar, Southeast Asia, New Zealand, and Australia.
There are three main types of mangroves:
- Red Mangroves: Known for their hardiness, growing along coastlines.
- Black Mangroves: Identified by their dark bark, growing at slightly higher elevations with more exposed roots for increased oxygen access.
- White Mangroves: Growing at higher elevations without aerial roots.
Grasslands Vegetation
- Grasslands, covering around 20% of the Earth’s land surface, are known by various names worldwide. These ecosystems exist in areas with distinct hot and dry, as well as warm and rainy seasons. Grasslands are grass-dominated and occur in both tropical and temperate regions, where conditions are insufficient to support tree growth.
Temperature Grasslands
- Temperate grasslands, characterized by woody or negligible growth, are found in the mid-latitudes of North America and Eurasia, away from Mediterranean regions and in the interiors of continents.
- They are extensive, entirely continental in the Northern Hemisphere, known as Steppes in Eurasia, Prairies in North America, and Pampas in Argentina and Uruguay.
Tropical grasslands
- Tropical grasslands, commonly referred to as Savannas, form a complex ecosystem with scattered medium-sized trees in grasslands, ranging from woodland to grassland. These ecosystems offer a blend of open, park-like appearance and significant biodiversity.
- In Savanna woodland, trees are spaced widely apart due to insufficient soil moisture during the dry season, preventing a full tree cover. The African Savanna boasts diverse large grazing mammals, accompanied by a variety of predators such as lions, leopards, cheetahs, hyenas, and jackals. Elephants, the largest animals in the savanna and adjacent woodland, are notable residents.
- For instance, deciduous acacias shed leaves during the cool, dry season to limit water loss through transpiration. Many trees in the region are umbrella-shaped, exposing only a narrow edge to strong winds. Situated on either side of the Equator between 5° and 20° latitude, it represents a transitional climate between Equatorial forests and semi-arid/sub-tropical humid climates.
- Notable regions with a Savanna climate include the Llanos of Orinoco valley, Campos of Brazil, hilly areas of Central America, Southern Zaire, and other Savanna climate zones.
Desert Vegetation:
- Deserts, characterized by high temperatures and low rainfall, favor plant growth due to moisture lag and excessive heat. Despite arid conditions, deserts host vegetation like grass, scrub, and herbs. The vegetation in hot and mid-latitude deserts is Xerophytic or drought-resistant scrub.
- Major hot deserts worldwide, situated between latitudes 15°-30° N and S, include the Sahara desert, great Australian desert, Arabian desert, Iranian desert, Thar desert, Kalahari, and Namib deserts.
Social Forestry:
- Social forestry involves the management and protection of forests, afforestation on degraded land, contributing to environmental, social, and rural development. It is a community-based initiative with massive plantation efforts through Panchayat/village assemblies, engaging farmers, village workers, government, private bodies, etc., under Joint Venture Programme (JVP).
- Agri Silviculture System: In this system, agricultural crops and forest tree species are cultivated on the same piece of land simultaneously, like the cultivation of teak and onions.
- Silvo Pastoral System: This system involves the cultivation of silvicultural tree species in combination with pastoral grass, such as growing teak and berseem grass for fodder purposes.
- Agri Silvo Pastoral System This integrated system combines agricultural crops, silvicultural tree species, and grasses on the same piece of land during a specific period.
Prelims Facts
- Conservation of soil is the process in w -Soil is conserved from harm (BPSC (Pre) 1994)
- The formal development of Terrarossa takes place in that part of land which consists of -Limestone (BPSC (Pre) 1994)
- Soil Leaching is a major problem in which region? -In tropical rain forests (UPPSC (Pre) 1998)
- A Halophytes is a salt tolerant plant that grows in -Saline soil (MPPSC (Pre) 2014)
- Which factors adds nitrogen to the soil -Excretion of Urea by animals and death of vegetation (LAS (Pre) 2013
- Contour bunding is a method of soil conservation used in Marginal, sloping and Hilly land (IAS (Pre) 2013]
- The correct group of abiotic components that helps in moisture ? the formation of soil Rains, temperature variation and acid rains (MPSC (Pre) 2017
- Which soil needs little irrigation as it retains soil – Black soil (UPPSC (Pre) 2010)
- The term “Soil Texture’ refers to the -arrangement of soil particles (MPSC (Pre) 2016]
- In soil formation process, the material transported and deposited by water is -Alluvium (MPSC (Pre) 2016)
- Laterite soils are formed under the conditions of -High temperature and rainfall [Tripura PSC (Pre) 2011)
- To which group does the black cotton soil of India belong -Chernozem [Nagaland PSC (Pre) 2014]
- Vertisol soils that contains clay minerals is also called- Regur (MPSC (Pre) 2016, 2017)
- Relative percentage of sand, silt and clay is a soil is known as -Soil texture (MPSC (Pre) 2017)
- The ‘sandy loam’ soil is favourable for the growth of which crop -Nachani or Ragi crop (RAS/RTS (Pre) 2005]
- Deficiency of iron is common in which type of soils Calcareous soils (MPPSC (Pre) 2012)
- What soil particles are present in loamy soils? -Sand, Clay and Silt [BPSC (Pre) 2011]
- Good loamy soils contains about what percent of silt? -30-50% (MPSC (Pre) 2014]
- The total pore space in sandy soil is – More than clay (MPSC (Pre) 2016]
- existence in Biodiversity forms the basis for human which way (APSC Soil formation (Pre) 2011
- Which type of forest covers highest percentage of forest Temperate Coniferous forest [APSC (Pre) 2016 area in the world?
- belme the commercially important group of trees belongs to the Oak, Poplar and Maple (APSC (Pre) 2011
- Amazon forest is home of which animals -Macaws, Toucans and Black Skimmen (MPPSC (Pre) 2012
- What do you mean by the term ‘Alfalfa’? -A kind of Grass (MPPSC (Pre) 2011
- Which type of temperature grasslands are found in – Steppes (UPPSC (Pre ) 2010
- Pampas, Veld and Downs are examples of Temperature Grasslands [UPPSC (Pre) 2011
- The Neem tree (Azadirachta India) is an Tropical dry evergreen tree [WBCS (Pre) 2012
- Pampas grassland is mainly located in Argentina (UPPSC (Mains) 2012
- The Savannas are most widespread in which continent Africa (UPPSC (Mains) 2012
- Which country has a constitutional provision for maintaining 70% of its Geographical area under forest -Bhutan (UPPSC (Mains) 2016
- Which type of forests are found near the equator? -Tropical forest (IAS (Pre)2007
- The Evergreen rainforests are found in Brazil [UKPSC (Pre) 2002
- Dense forest ton the Earth are mostly found in which are – Nearby Equator (BPSC (Pre) 1996
- Which basin is noted for extensive tropical rain forests – Congo Basin (UPPSC (Pre)1996
- Dalbergia Species is associated with the productiond -Rosewood [IAS (Pre)2007
UPSC NCERT Practice Questions
1. Which of the following is concerned with soil? UPPSC (Pre) 2018
(a) Edaphic
(b) Climatic
(c) Biotic
(d) Topography
2. Relative percentage of sand, silt and clay in a soil is known as MPSC (Pre) 2017
(a) soil structure
(b) soil texture
(c) soil porocity
(d) soil density
3. Choose the correct answer from the following. MPSC (Pre) 2017
1. In clay, soil water and air movement is restricted.
2. Water holding capacity of clay soil is high.
Codes
(a) Only 1
(b) Only 2
(c) Both 1 and 2
(d) None of these
4. Match List I and List Il and select the correct answer by using the codes given below the lists.
| List I (Soils) | List II (Climate Regions) |
| A. Podzol | 1. Temperate cold steppe |
| B. Chernozem | 2. Cold temperate |
| C. Spodosols | 3. Hot and humid |
| D. Laterite | 4. Humid cold temperate |
Codes
(a) 2 1 4 3
(b) 3 4 2 1
(c) 2 3 4 1
(d) 4 1 3 2
5. In soil formation process, the material transported and deposited by water is MPSC (Pre) 2016
1. Colluvium
3. Alluvium
2. Lacustrine
4. Till
Codes
(a) Only 1
(b) 1 and 2
(c) Only 3
(d) Only 4
6. Choose the correct group of abiotic components, that helps in the formation of soil. MPSC (Pre) 2017
(a) Rain, temperature, fauna and chemicals.
(b) Acid rain, temperature, flora and animals.
(c) Rains, temperature variation and acid rains.
(d) Animals, insects, bacteria and microorganism.
7. Parent rock, climate, relief, flora and fauna and time are the factors of soil formation. Relate the following factors with the activities they perform by matching the following.
| List I | List II |
| A. Parent rock | 1. Thickness of soil profile |
| B. Flora and Fauna | 2. Colour, texture, permeability |
| C. Climate | 3. Rate of humus formation |
| D. Time | 4. Rate of weathering |
Codes
(a) 3 2 1 4
(b) 2 3 4 1
(c) 4 1 2 3
(d) 4 3 1 2
8. Alluvial soils vary in nature from sandy loam to clay. They are generally
(a) poor in potash and rich in phosphorus.
(b) poor in both potash and phosphorus.
(c) rich in both potash and phosphorus.
(d) rich in potash and poor in phosphorus.
9. Identify the type of soil on the basis of the given characteristics.
1. They are rich in lime, iron, magnesia and alumina.
2. They are generally clayey, deep and impermeable.
3. They are mainly found in Maharashtra, Madhya Pradesh and Gujarat.
Select the correct answer by using the codes given below.
(a) Laterite soil
(b) Red and yellow soil
(c) Saline soil
(d) Black soil
10. The formal development of Terra Rossa takes place in that part of land which consists of? BPSC (Pre) 1994
(a) Limestone
(b) Cynite
(c) Granite
(d) Sandstone
11. Which of the following adds/add nitrogen to the soil? IAS (Pre) 2013
1. Excretion of urea by animals
2. Burning of coal by man
3. Death of vegetation
Select the correct answer by using the codes given below.
(a) Only 1
(b) 2 and 3
(c) 1 and 3
(d) All of these
12. Which one of the following statements) is/are correct? MISC (re 2015, UPPSC (Mains) 2015
1. Laterite soils are typical soils of monsoon climate.
2. Laterite soils are rich in iron, aluminium, potash and lime.
Codes
(a) Only 1
(b) Only 2
(c) Both 1 and 2
(d) Neither 1 nor 2
13. Which of the following statement/statements are correct about laterite soils? HPSC (Pre) 2022
1. These soils develop in the areas with high temperature and low rainfall.
2. These soils are rich in organic matter, nitrogen, phosphate and calcium.
3. These soils are widely cut as bricks for use in house construction.
4. These soils have mainly developed in the higher areas of the peninsular plateau.
Codes
(a) 1 and 2
(b) 3 and 4
c) 1, 2 and 3
(d) 2, 3 and 4
14. Which one of the following with regard to Aridisol, one of the soil orders, is not correct?
(a) Lack of water for plants during most part of the year
(b) High organic matter
(c) Large accumulation of carbonates at depth
(d) Absence of deep wide cracks
15. Contour bunding is a method of soil conservation used in IAS (Pre) 2013
(a) desert margins, liable to strong wind action.
b) low flat plains, close to stream courses, liable to
flooding.
(c) scrublands, liable to spread to weed growth.
(d) None of the above
16. Leaf litter decomposes faster surface any othe biome and as a result the soil surface is often almost bare. Apart from trees, the vegetation is largely composed of plant forms that reach up into the canopy vicariously, by on ting the troo or growing as epiphytes, rooted on the upper branches of trees’. This is the most likely description of
(a) coniferous forest
(b) dry deciduous forest
(c) mangrove forest
(d) tropical rainforest
17 The vegetation of Savanna consists of grassland with scattered small trees, but extensive areas have no trees. The forest development in such areas is generally kept in check by one or more a combination of some conditions. UPPSC (Pre) 2014
Which of the following are such conditions?
1. Burrowing animals and termites
2. Fire
3. Grazing-Herbivores
4. Seasonal rainfall
5. Soil properties
Codes
(a) 1 and 2
(b)4 and 5
(c) 2, 3 and 4
(d) 1, 3 and 5
18. Which one of the following pair (s) is/are not correctly matched? UPPSC (Mains) 20%
(a) Downs : Tropical grassland
(b) Steppes : Temperate grassland
(c) Selvas : Tropical forest
(d) Taiga : Temperate forest
Know Right Answer
1 (a)
2 (b)
3 (c)
4 (a)
5 (c)
6 (c)
7 (b)
8 (d)
9 (d)
10 (a)
11 (c)
12 (a)
13 (b)
14 (b)
15 (d)
16 (d)
17 (c)
18 (a)
Frequently Asked Questions (FAQs)
Q1: Why are NCERT notes essential for UPSC preparation in Geography – Soils and Natural Vegetation?
A1: NCERT notes in Geography – Soils and Natural Vegetation provide a strong foundation for UPSC preparation. They cover the fundamental concepts and principles, ensuring a comprehensive understanding of soil types, their distribution, and the correlation with natural vegetation. UPSC often draws questions from basic concepts, and NCERT notes serve as a reliable source to build a solid knowledge base.
Q2: How do Soils and Natural Vegetation play a crucial role in the UPSC exam syllabus?
A2: Soils and Natural Vegetation form an integral part of the UPSC exam syllabus as they connect various aspects of geography, ecology, and environment. Questions related to soil characteristics, their impact on agriculture, and the influence of natural vegetation on regional ecosystems are commonly asked. A thorough understanding of these topics, as provided in NCERT notes, helps candidates in tackling both conceptual and applied questions in the examination.
Q3: How can UPSC aspirants effectively use NCERT notes on Soils and Natural Vegetation for exam preparation?
A3: UPSC aspirants can maximize the utility of NCERT notes by adopting a structured study approach. Begin by thoroughly reading and understanding the basic concepts outlined in the NCERT texts. Supplement this with additional reference materials and current affairs to stay updated on contemporary issues related to soils and vegetation. Practice solving previous years’ question papers and engage in answer writing to enhance analytical and writing skills. Integrating NCERT notes into a comprehensive study strategy ensures a holistic preparation for the Geography section of the UPSC exam.
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