1Which of the following terms refers to the study of soil as a natural body, focusing on its genesis, classification, and description?
A.Edaphology
B.Pedology
C.Petrology
D.Geology
Correct Answer: Pedology
Explanation:Pedology deals with the origin, classification, and description of soil as a natural body. Edaphology focuses on soil in relation to plant growth.
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2In the context of Edaphology, soil is primarily viewed as:
A.A natural body formed by weathering
B.A medium for plant growth
C.A geological deposit
D.A mixture of minerals only
Correct Answer: A medium for plant growth
Explanation:Edaphology is the study of soil from the standpoint of higher plants, viewing it primarily as a medium for plant growth.
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3Who is considered the 'Father of Modern Soil Science'?
A.Justus von Liebig
B.V.V. Dokuchaev
C.Hans Jenny
D.Charles Darwin
Correct Answer: V.V. Dokuchaev
Explanation:V.V. Dokuchaev is recognized as the founder of modern soil science for establishing that soil is a distinct natural body formed by specific environmental factors.
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4According to Hans Jenny (1941), the fundamental equation of soil formation is expressed as:
A.
B.
C.
D.
Correct Answer:
Explanation:The equation is , where is soil, is climate, is biosphere, is relief, is parent material, and is time.
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5Which of the following is classified as an active factor of soil formation?
A.Parent material
B.Relief (Topography)
C.Time
D.Climate
Correct Answer: Climate
Explanation:Climate and Biosphere (Organisms) are active factors because they supply the energy that acts upon the passive factors to form soil.
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6The vertical section of the soil through all its horizons and extending into the parent material is called:
A.Soil Solum
B.Soil Profile
C.Regolith
D.Pedon
Correct Answer: Soil Profile
Explanation:A soil profile is the vertical section of soil through all its horizons, from the surface down to the parent material.
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7The Solum consists of which soil horizons?
A.A and B horizons
B.A, B, and C horizons
C.O and A horizons only
D.B and C horizons
Correct Answer: A and B horizons
Explanation:The Solum represents the true soil, consisting of the A and B horizons, where soil formation processes are most active. It excludes the C horizon.
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8Which term describes the layer of unconsolidated material overlying the hard bedrock, generally including the A, B, and C horizons?
A.Solum
B.Regolith
C.Lithosphere
D.Ped
Correct Answer: Regolith
Explanation:Regolith is the layer of unconsolidated solid material covering the bedrock. In soil science terms, .
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9The master horizon dominated by organic material, often found in forests, is designated as:
A.A Horizon
B.B Horizon
C.O Horizon
D.E Horizon
Correct Answer: O Horizon
Explanation:The O Horizon is the organic horizon, composed mainly of organic matter such as decomposing leaves and twigs, typically found above the mineral soil.
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10Which master horizon is characterized by the eluviation (loss) of silicate clay, iron, or aluminum, often resulting in a bleached appearance?
A.A Horizon
B.B Horizon
C.E Horizon
D.C Horizon
Correct Answer: E Horizon
Explanation:The E Horizon (Eluvial) is the zone of maximum leaching or eluviation, where materials are washed out, leaving resistant minerals like quartz.
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11The B Horizon is primarily known as the zone of:
A.Eluviation
B.Illuviation
C.Organic accumulation
D.Parent material
Correct Answer: Illuviation
Explanation:The B Horizon is the zone of illuviation (accumulation), where materials washed down from the A and E horizons (clays, oxides, carbonates) accumulate.
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12Which chemical weathering process involves the reaction of minerals with water, where water dissociates into and ions?
A.Hydration
B.Hydrolysis
C.Carbonation
D.Oxidation
Correct Answer: Hydrolysis
Explanation:Hydrolysis is a double decomposition reaction involving water, where water splits into and , and the hydrogen ion replaces a cation in the mineral structure.
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13The transformation of Anhydrite () to Gypsum () is an example of which weathering process?
A.Hydrolysis
B.Hydration
C.Solution
D.Reduction
Correct Answer: Hydration
Explanation:Hydration involves the rigid attachment of water molecules to a mineral, as seen when Anhydrite absorbs water to become Gypsum.
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14Which pedogenic process involves the migration of salts to the surface in arid climates due to evaporation?
A.Gleization
B.Podzolization
C.Salinization
D.Laterization
Correct Answer: Salinization
Explanation:Salinization is the accumulation of soluble salts (chlorides, sulfates) in the soil solum, typical in arid or semi-arid regions with high evaporation.
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15The process of Laterization is most common in which type of climate?
A.Cool and humid
B.Hot and humid (Tropical)
C.Cold and arid
D.Temperate
Correct Answer: Hot and humid (Tropical)
Explanation:Laterization occurs in hot, humid tropical climates, resulting in the removal of silica and the accumulation of Iron () and Aluminum () oxides.
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16Which specific pedogenic process results in the formation of a 'spodic' horizon rich in humus and iron/aluminum oxides, typically under coniferous forests?
A.Calcification
B.Podzolization
C.Gleization
D.Salinization
Correct Answer: Podzolization
Explanation:Podzolization is a process of acid leaching occurring under coniferous forests in cool climates, mobilizing iron and humus from the A/E horizons and depositing them in the B horizon.
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17The reduction of iron under anaerobic (waterlogged) conditions, leading to bluish-grey or greenish-grey soil colors, is called:
A.Rubefaction
B.Gleization
C.Laterization
D.Humification
Correct Answer: Gleization
Explanation:Gleization occurs in waterlogged soils where lack of oxygen leads to the reduction of Iron (), producing bluish-grey colors.
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18What is the primary role of the C Horizon?
A.It is the main zone of root growth.
B.It is the zone of organic matter accumulation.
C.It serves as the parent material from which the solum develops.
D.It is solid bedrock.
Correct Answer: It serves as the parent material from which the solum develops.
Explanation:The C Horizon consists of unconsolidated material that has undergone little pedogenic alteration and serves as the parent material for the soil above.
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19In the chemical weathering process of Carbonation, carbon dioxide reacts with water to form:
A.Sulfuric acid ()
B.Carbonic acid ()
C.Nitric acid ()
D.Hydrochloric acid ()
Correct Answer: Carbonic acid ()
Explanation:Carbonation involves . This weak acid accelerates the chemical weathering of minerals, particularly carbonates.
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20The removal of silica from soil, leading to a relative accumulation of sesquioxides ( and ), is known as:
A.Silication
B.Desilication
C.Calcification
D.Podzolization
Correct Answer: Desilication
Explanation:Desilication (or Ferrallitization) is the leaching of silica, common in tropical weathering, leaving behind iron and aluminum oxides.
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21Which of the following is considered a passive factor of soil formation?
A.Rainfall
B.Temperature
C.Microorganisms
D.Relief (Topography)
Correct Answer: Relief (Topography)
Explanation:Relief, Parent Material, and Time are passive factors. They represent the conditions or material on which the active factors (Climate and Biosphere) work.
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22A sequence of soils that differ only in their topography or relief is called a:
A.Lithosequence
B.Climosequence
C.Catena (Toposequence)
D.Chronosequence
Correct Answer: Catena (Toposequence)
Explanation:A Catena or Toposequence is a sequence of related soils that differ, one from the other, primarily because of topography.
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23The unconsolidated mineral or organic material on the immediate surface of the earth that serves as a natural medium for the growth of land plants is the definition of:
A.Rock
B.Soil
C.Mineral
D.Humus
Correct Answer: Soil
Explanation:This is the standard definition of Soil widely accepted in soil science, emphasizing its role as a medium for plant growth.
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24Which horizon is technically defined as the 'zone of maximum accumulation' of silicate clays, iron, aluminum oxides, or carbonates?
A.A Horizon
B.E Horizon
C.B Horizon
D.R Layer
Correct Answer: B Horizon
Explanation:The B Horizon is the illuvial horizon where materials leached from above accumulate.
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25In a soil profile, the R layer refers to:
A.The root zone
B.The regolith
C.Hard Bedrock
D.The organic layer
Correct Answer: Hard Bedrock
Explanation:The R layer represents hard, consolidated bedrock, such as granite, basalt, or limestone, located beneath the soil profile.
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26Which basic pedogenic process involves the movement of soil material from one horizon to another within the same profile?
A.Additions
B.Losses
C.Translocation
D.Transformation
Correct Answer: Translocation
Explanation:Translocation is the movement of organic or mineral matter from one horizon to another (e.g., eluviation and illuviation).
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27The decomposition of complex organic compounds into simpler mineral forms (inorganic) is known as:
A.Humification
B.Mineralization
C.Immobilization
D.Chelation
Correct Answer: Mineralization
Explanation:Mineralization is the conversion of organic compounds into inorganic (mineral) forms, releasing nutrients like nitrogen and phosphorus for plant use.
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28Which weathering mechanism is primarily physical?
A.Hydrolysis
B.Exfoliation
C.Carbonation
D.Oxidation
Correct Answer: Exfoliation
Explanation:Exfoliation (peeling away of rock layers) is a physical weathering process caused by temperature changes or pressure release. The others are chemical.
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29The accumulation of Calcium Carbonate () in the soil profile, common in arid and semi-arid regions, is called:
A.Decalcification
B.Calcification
C.Podzolization
D.Gleization
Correct Answer: Calcification
Explanation:Calcification is the process where calcium carbonate accumulates in the B horizon due to limited rainfall preventing its complete leaching.
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30Which soil component typically constitutes approximately 45% of the total soil volume in an ideal loam soil?
A.Organic Matter
B.Soil Water
C.Soil Air
D.Mineral Matter
Correct Answer: Mineral Matter
Explanation:An ideal soil volume composition is roughly: 45% Mineral Matter, 5% Organic Matter, 25% Water, and 25% Air.
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31The accumulation of sodium ions () on the exchange complex of the clay, often leading to soil dispersion, is known as:
A.Calcification
B.Alkalization (Solonization)
C.Dealkalization
D.Podzolization
Correct Answer: Alkalization (Solonization)
Explanation:Alkalization or Solonization involves the accumulation of sodium ions, which raises the pH and causes dispersion of soil colloids.
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32The 'A' Horizon is often referred to as the:
A.Subsoil
B.Parent material
C.Topsoil
D.Bedrock
Correct Answer: Topsoil
Explanation:The A Horizon is commonly called the topsoil. It is the surface mineral layer, usually darker due to organic matter.
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33A Lithosequence is a group of soils having different properties primarily due to differences in:
A.Time
B.Parent Material
C.Climate
D.Vegetation
Correct Answer: Parent Material
Explanation:A Lithosequence varies based on the lithology (rock type) of the Parent Material, while other factors remain constant.
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34The reaction (rusting) represents which chemical weathering process?
A.Reduction
B.Hydrolysis
C.Oxidation
D.Hydration
Correct Answer: Oxidation
Explanation:Oxidation involves the loss of electrons. In weathering, iron () often oxidizes to in the presence of oxygen, indicated by a reddish color.
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35The process of mixing the soil, often by soil fauna like earthworms or by shrinking and swelling of clays, is called:
A.Pedoturbation
B.Eluviation
C.Leaching
D.Humification
Correct Answer: Pedoturbation
Explanation:Pedoturbation refers to the mixing or churning of the soil (bioturbation by animals, cryoturbation by frost, etc.).
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36Which horizon is designated as the transition layer that is more like A than B?
A.AB Horizon
B.BA Horizon
C.BC Horizon
D.E Horizon
Correct Answer: AB Horizon
Explanation:Transitional horizons are named with two capital letters. AB indicates a transition between A and B, but more like A. (If it were more like B, it would be BA).
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37The conversion of raw organic residues into complex, relatively stable organic substances (humus) is called:
A.Mineralization
B.Humification
C.Gleization
D.Weathering
Correct Answer: Humification
Explanation:Humification is the process of transforming organic matter into humus, a stable and complex organic material.
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38Which of the following is NOT a form of physical weathering?
A.Freeze-thaw cycles
B.Abrasion by water/wind
C.Dissolution
D.Thermal expansion
Correct Answer: Dissolution
Explanation:Dissolution is a form of chemical weathering where minerals dissolve in water. The others are physical/mechanical processes.
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39In the soil profile, a subscript 'p' (e.g., ) indicates:
A.Accumulation of clay
B.Plowing or other disturbance
C.Gleying
D.Soft bedrock
Correct Answer: Plowing or other disturbance
Explanation:The subscript p (as in Ap) denotes a horizon that has been plowed or disturbed by cultivation.
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40Which factor of soil formation is most responsible for the accumulation of organic matter in the soil?
A.Relief
B.Parent Material
C.Biosphere (Vegetation/Organisms)
D.Time
Correct Answer: Biosphere (Vegetation/Organisms)
Explanation:The Biosphere (specifically vegetation) provides the raw organic material, which accumulates and decomposes to form soil organic matter.
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41A Chronosequence refers to soils that share all factors of formation except for:
A.Climate
B.Time
C.Relief
D.Parent Material
Correct Answer: Time
Explanation:A Chronosequence studies the effect of Time on soil development, assuming climate, organisms, relief, and parent material are constant.
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42Which pedogenic process involves the complete removal of Calcium Carbonate () from the soil profile?
A.Calcification
B.Decalcification
C.Salinization
D.Gleization
Correct Answer: Decalcification
Explanation:Decalcification is the removal of calcium carbonate or calcium ions from the soil by leaching, usually occurring in humid regions.
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43In the context of soil phases, the 'Soil Solution' refers to:
A.The solid mineral phase
B.The liquid phase containing dissolved ions
C.The gaseous phase
D.The organic matter
Correct Answer: The liquid phase containing dissolved ions
Explanation:The Soil Solution is the liquid phase of the soil, consisting of water and dissolved nutrients/salts, crucial for plant uptake.
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44The subscript 't' (e.g., ) in a soil profile description indicates an accumulation of:
A.Silicate Clay
B.Carbonates
C.Organic Matter
D.Sesquioxides
Correct Answer: Silicate Clay
Explanation:The symbol t indicates an accumulation of silicate clay (Argillic horizon), formed by illuviation.
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45Granite weathering to form sandy soils is primarily an influence of which soil formation factor?
A.Parent Material
B.Climate
C.Relief
D.Biosphere
Correct Answer: Parent Material
Explanation:Granite is a coarse-grained rock rich in quartz. Its weathering naturally produces sandy soils, demonstrating the influence of Parent Material.
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46The downward movement of water through the soil, carrying dissolved or suspended material, is best described as:
A.Runoff
B.Percolation/Leaching
C.Evaporation
D.Capillarity
Correct Answer: Percolation/Leaching
Explanation:Leaching (driven by percolation) is the removal of soluble materials from the soil by water moving downwards.
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47Which horizon typically has the highest biological activity?
A.A Horizon
B.B Horizon
C.C Horizon
D.E Horizon
Correct Answer: A Horizon
Explanation:The A Horizon (topsoil) contains the most organic matter and roots, supporting the highest population of microorganisms and soil fauna.
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48The breaking down of rocks into smaller fragments without changing their chemical composition is called:
A.Chemical Weathering
B.Physical (Mechanical) Weathering
C.Biological Weathering
D.Decomposition
Correct Answer: Physical (Mechanical) Weathering
Explanation:Physical Weathering (disintegration) reduces particle size (increase in surface area) without altering the chemical makeup of the minerals.
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49In the pedogenic process of Gleization, the dominant element undergoing chemical reduction is:
A.Calcium ()
B.Iron ()
C.Silicon ()
D.Potassium ()
Correct Answer: Iron ()
Explanation:Iron is the primary coloring agent. Under anaerobic conditions, ferric iron (, red/yellow) reduces to ferrous iron (, mobile/grey), characterizing gleization.
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50Which of the following represents the correct order of master horizons from the surface downward in a well-developed forest soil?
A.O - A - E - B - C - R
B.A - O - B - E - C - R
C.R - C - B - A - O
D.O - B - A - E - C - R
Correct Answer: O - A - E - B - C - R
Explanation:The standard sequence is O (organic), A (topsoil), E (eluvial), B (illuvial/subsoil), C (parent material), and R (bedrock).
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