soil science

The Father of Soil Science

VV. Dokuchaive

Define Soil as dynamic Natural Body with properties derived from the combined S=f(cl,o,r,p,t)

Jenny's Equation

The following are the functions of soil except:

provide food

Greek word of pedon means?

soil or earth?

This approach considers soil as natural body with a distinguishable origin (genesis)

pedological approach

greek word edaphos means?

soil or ground

Deals with the study of soils in relation to higher plants

edaphological approach

study of rocks concerned with composition, structure & origin

Petrology

refers to step 4 → compaction and cementation → from unconsolidated material (sediments) to consolidated (rock)

lithifications

collective term for step 1 to step 3 → weathering, transport, and deposition

sedimentary

granite outcrop is exposed at the surface. Over time, the rock develops cracks due to repeated heating during the day and cooling at night, but its mineral composition remains essentially unchanged. What type of weathering is dominant?

B. Physical weathering

Water enters a crack in a rock and freezes repeatedly. The crack becomes wider after several freeze-thaw cycles. Which explanation is BEST?

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Expanding ice exerts mechanical force on the rock

Which situation BEST distinguishes hydrolysis from hydration?

Hydrolysis changes mineral composition, while hydration involves water entering the mineral structure

Magnetite is converted into hematite through the addition of oxygen and loss of electrons. Which process is responsible?

Oxidation

A mineral gains electrons while oxygen is removed from it. Which chemical weathering process is being described?

Reduction

. A soil-forming environment has high temperature and abundant rainfall. Which combination would generally promote more intense chemical weathering and leaching?

High temperature + high precipitation

A soil profile contains a light-colored horizon where clay and Fe/Al oxides have been removed. Immediately below it is a horizon where these materials have accumulated. Which pair of processes is involved?

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Eluviation above and illuviation below

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A student remembers that the E horizon is where materials "EXIT." Which process should the student associate with this horizon?

Eluviation

Which horizon would most likely contain accumulated clay, organic matter, and Fe/Al compounds transported from horizons above?

B horizon

A soil has O, A, E, B, C, and R horizons. Which horizon represents the hard, unweathered bedrock?

R

Which statement BEST distinguishes the C and R horizons?

C is partially weathered parent material, while R is hard unweathered bedrock

Which sequence correctly represents the major soil horizons from the surface downward?

O → A → E → B → C → R

A soil scientist observes that soil horizons are becoming mixed because of animal burrowing. Which process is responsible?

Haploidization

Which process would MOST directly promote the differentiation of a soil into distinct horizons?

Horizonation

A farmer's field loses fine surface soil during heavy rainfall. Which general soil-forming process does this represent?

Removal

Soluble materials are washed out of the soil profile by percolating water. Which process is this?

Leaching

Which statement BEST distinguishes percolation from leaching?

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Percolation is downward water movement, while leaching involves soluble materials being carried by that water

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A light-colored mineral soil becomes darker after organic matter becomes mixed into it. Which process is occurring?

Melanization

Mineral particles are repeatedly added to the surface of a soil by wind and water. Which process BEST describes this addition?

Cumulization

Raw plant residues are transformed into stable humus. Which process is this?

Humification

Organic matter decomposes and releases inorganic mineral nutrients into the soil. Which process is this

Mineralization

Which sequence correctly represents Simonson's four general processes of soil formation?

Addition → removal → translocation → transformation

A soil accumulates calcium carbonate within a particular horizon. Which translocation process is most directly associated with this accumulation?

Calcification

A soil in a dry environment develops an accumulation of soluble salts such as chlorides and sulfates. Which process is occurring?

Salinization

A soil develops a high concentration of sodium ions on exchange sites. Which process is occurring?

Alkalization

A soil loses sodium ions and salts through leaching. Which process is occurring?

Dealkalization

A strongly weathered soil loses silica while Fe and Al oxides become concentrated. Which process is MOST likely?

Laterization

A soil experiences chemical migration of aluminum, iron, and/or organic matter, leaving silica concentrated in the eluviated layer. Which process is described?

Podzolization

A soil remains saturated with water for long periods. Oxygen becomes limited, iron is reduced, and bluish-gray colors develop. Which process is occurring?

Gleization

Which condition would MOST strongly favor gleization?

Waterlogged, oxygen-poor soil

Soil develops progressively brown, reddish-brown, and red colors due to increasing oxidation and hydration of iron compounds. Which processes are involved?

Braunification, rubification, and ferrugination

Fine clay particles are washed in suspension down cracks and other voids in the soil. Which process is this?

Lessivage

Which process specifically describes the movement of material INTO a portion of the soil profile?

Illuviation

Soil mixing caused by the shrinking and swelling of clay is called:

Argilliturbation

oil mixing caused by freezing and thawing of ground ice is called:

Cryoturbation

Soil mixing caused by animal activity such as burrowing is called:

Faunalturbation

Which hillslope position is generally most associated with rapid runoff and soil erosion?

Backslope

Sediments transported from upslope accumulate at a lower landscape position. Which factor of soil formation is MOST directly responsible for this difference?

Relief

Parent material transported and deposited by running water is called:

Alluvium

Which pairing is CORRECT?

Ice — glacial drift

Which igneous rock is most likely to have a fine-grained texture?

Basalt