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126 Cards in this Set
- Front
- Back
What are 5 functions of soil?
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Medium for plant growth, Regulator of water supplies, Waste recycling system, Habitat for soil organisms, Engineering medium
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What are the consequences of the 1935 Dust Bowl?
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Loss of topsoil, decline in food output, health issues, abandoned farms and refugees
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What Act was established after the Dust Bowl? Why?
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Soil Conservation Service (1935), because views of soil being 'indestructible' changed
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Who said “The nation that destroys its soil destroys itself.”?
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F. D. Roosevelt (1937)
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Why has erosion has been less obvious in Illinois?
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damage done by water, not wind, years of intensive tillage converted soils to sediments, now dredged from the Illinois River in the Mud to Parks project
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Soil = ?
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Pedoshpere
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What are the 3 Major Soil Components?
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solids, liquids, gases
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Soil Solids
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inorganic minerals & organic matter (humus)
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Primary minerals
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formed by igneous rock)
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Secondary minerals
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formed by weathering
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Humus
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product of the decay of organic residues
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Soil Water
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soil solution composed of water, dissolved ions, molecules, & gases
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Soil Atmosphere
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contains similar gases as in atmosphere above the soil but often in very different proportions; higher CO2 & lower O2 than atmosphere
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About 50% of soil is ______, 50% is _________
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solids, voids
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What are the 5 factors of soil formation?
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CORPT: climate, organisms, relief, parent material, time
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Pedology
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study of soil genesis, classification, morphology, mapping, & interception
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Pedon
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smallest unit of a soil, about 1m hexagon, 1-2m deep
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Profile
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vertical exposure of soil showing horizons
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Horizons
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nearly horizontal layer in soil formed by pedogenic processes
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Soil Profile
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morphology, chemical/biological/physical processes, vary with factors of formation, horizons, & diagnostic horizons
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Zones of loss
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leaching, eluviation
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Zones of gain
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illuviation
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O horizon
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organic
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A horizon
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surface mineral “topsoil”
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E horizon
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eluvial, leached
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Bt horizon
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illuvial, accumulation of weathering products, clay
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BC horizon
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transitional to C horizon
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C horizon
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slightly altered parent material
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R horizon
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bedrock
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What is the parent material of Alfisol and Mollisol?
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loess
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4 soil components
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Air, Water, Organic Matter, and Minerals
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Soil Solids
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Inorganic Minerals and Organic Matter
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humus
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decay product of organic residues
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Texture Class
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relative % of soil separates by weight
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Structureless
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massive or single grained
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Structured
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granular, platy, subangular blocky, angular blocky, prismatic, & columnar
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Clods
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produced by improper tillage wet soils, heavy equipment
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Peds
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produced by natural soil forming peds are produced by natural soil forming processes
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Ideal soil has a balance of
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macro and micro pores
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Micropores
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retain water against the pull of gravity; contain the soil solution
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Macropores
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drain free of water; contain the soil atmosphere
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Soil Consistence
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response of soil to applied force at various moisture content
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4 basic soil properties
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Color (HVC), Texture (Sand, Silt, Clay), Consistence (friable, firm, plastic), Structure (blocky, platy, crumbs)
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Residuum
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material that formed from rock weathered in place
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Transported
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material that has been transported by some agent
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Lacustrine
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material that is moved by water and deposited in fresh water lakes
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Alluvium
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material deposited on flood plains of active streams; usually stratified
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Alluvial Fans
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materials often deposited in fan shaped deposits in high energy environments at base of slopes
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Deltas
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sediment carried by streams deposited in slower water
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Terraces
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old abandoned floodplains
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Colluvium
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material moved by gravity and deposited at the base of steep slopes
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Eolian
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sandy material deposited by wind
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Till
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a mixture of rock material that has been ground into an assortment of different sized particles and moved by the action of glacial ice
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Outwash
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alluvial material that was deposited by streams of glacial meltwaters
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Kames
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conical hill, sorted by water, often by filling cavities in a glacial ice sheet with sediment
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Eskers
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serpentine ridge, meltwater flowing within/beneath glaciers and carrying sediment
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Kettles
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closed depressions left as ice blocks in outwash or till melt
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Outwash Plain
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broad expanse of outwash, often downslope of a moraine
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Till Plain/Ground Moraine
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level plain of till from beneath the glacier
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Drumlin
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pile of till in a large cigar-shaped hill oriented with the direction of ice movement
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Top 3 IL parent materials:
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Loess 63%, Till 12% (Wisconsinan, Illinoian), Alluvium 10%
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Hydration
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chemical bonding of water to cations and anions
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Hydrolysis
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reaction of water with a mineral resulting in the splitting of water into H+ & OH ions
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Complexation
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higher plants and microorganisms produce a variety of organic compounds
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Dissolution
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water is an excellent solvent for polar species
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Soil horizons are distinguished by (4):
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color, organic matter content, texture, & structure
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Master horizons can be subdivided into (4):
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A1, A2, Bt1, Bt2
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Limnic horizon (L)
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used with Histosols, material deposited under water, plant tissues, diatoms, fish droppings, etc. includes diatomaceous earth (di), marl (ma), coprogenous earth (co)
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Solum is in which horizons?
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O, A, E, Bt
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Regolith is in which horizons?
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O, A, E, Bt, C
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Transition Horizons
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dominated by the properties of one master horizon, but with some properties of another master horizon
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Subordinate Distinction p
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plowed
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Subordinate Distinction g
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gleyed
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Subordinate Distinction t
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illuvial concentration of silicate clays
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Subordinate Distinction b
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buried genetic
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Subordinate Distinction n
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sodium accumulation
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Subordinate Distinction w
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weakly developed B horizon
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Subordinate Distinction x
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fragipan
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Soil Surveys
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Predict soil conditions in certain areas and interprets them for practical uses
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B810
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ave. level of management
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B811
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optimum management
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Base & Benchmark soils in IL
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Drummer sicl, Elburn sil, Flanagan sil, Ipava sil, Sable sicl
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Soil Taxonomic Classification
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soils are classified based on the presence or absence of diagnostic horizons and major differences in soil forming factors or properties
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Mollic Epipedon
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mineral (A) horizon that is dark, thick, rich (high in bases), soft
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Histic Epipedon
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organic horizon (O) of a mineral soil
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Umbric Epipedon
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mineral horizon (A) that is thick enough, dark enough to be a mollic epipedon but having low base saturation
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Ochric Epipedon
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mineral horizon (A) that is too thin, too light in color, or too little organic matter to be a mollic or umbric or histic epipedon, the default epipedon
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Albic
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strongly developed E horizon, lighter in color & lower in clay than horizons above/below
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Argillic
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clay (Bt), important in Illinois
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Natric
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exchangeable Na (Bn)
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Cambic
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(Bw or Bg) Slight development
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Entisols (ents)
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Young soil formed in recent deposits, alluvium,
colluvium etc., no diagnostic horizons |
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Inceptisols (epts)
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has the most coarse fragments
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Mollisols (olls)
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pPrairie soil, thick, dark mollic epipedon
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Alfisols (alfs)
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soils that do not have a mollic epipedon but have an argillic horizon with greater than 35% base saturation
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Spodosols (ods)
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formed under acid, chelating vegetation,
albic E and spodic B horizon |
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Ultisols (ults):
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soils without a mollic epipedon in a mesic or warmer temperature regime that have an argillic or kandic horizon with less than 35% base saturation
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Oxisols (Bo)
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soils that have an oxic horizon (Bo) no argillic or natric horizon, highly weathered; Old soils formed in hot, wet climates
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Histosols (ists)
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have most organic matter
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Vertisols (erts)
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soils which contain 30% or more swelling type clay (smectites) to ≥ 50 cm, and when dry have cracks open at the surface
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Aridisols (ids)
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soils that occur in an aridic moisture regime, climates that are dry enough to restrict normal soil development, evaporation exceeds precipitation; formed in volcanic deposits, shows ash
layers |
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Andisols (ands)
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volcanic soils with andic properties &high content of volcanic ash & glass
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Gelisols (els)
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young permafrost and frost churning soils with little development; poor drainage, gleyed colors
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Levels of classification:
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Order, suborder, great group, subgroup, family, series
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Given oven dry weight and sample
volume, calculate bulk density |
BD = Ms (mass of oven-dry solids) / Vt (volume solids + volume pores)
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Given bulk density and assuming
particle density calculate porosity |
PS (pore space) = (1 - BD/ PD) (where PD is particle density)
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.Given the porosity and assuming
particle density calculate bulk density |
BD = 1 - (PS)(PD)
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What is an "ideal soil"?
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~50% pores, ~ 50% solids. ~45% minerals, 5% humus by volume
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What is the "soil taxonomy order"?
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order, suborder, great group, subgroup, family, series
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Particle sizes in decreasing order? (4):
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course fragments (>2mm), sand (2-.05mm), silt (.05-.002mm), clay (<.002mm)
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Generally, soils have higher ________ and lower ______ than atmosphere above the soil
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CO2, O2
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Which element needed by plants is not gotten from the air or water?
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calcium
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What is the most common parent material that most Illinois soils are formed in?
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Loess
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Which glacial feature best describes a serpentine ridge with sand and gravel that was formed by a stream flowing through a crack in the glacial ice?
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esker
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What glacier went the furthest south?
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Illinoian
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Why (primary reason) are the soils in west central Illinois more productive (higher crop yields)?
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loess is thicker
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Residual parent materials are best described as:
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materials formed by weathering of rocks and minerals in place
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Sandstone is a ____________ rock.
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sedimentary
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The maximum soil development occurs in which master horizon (color change, soil structure)
for a given soil profile? |
B
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What subscript means an illuvial concentration of clay?
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t
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What subscript means evidence of a buried soils?
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b
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The reaction: [ Fe3+ + e- > Fe2+] is an example of:
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reduction
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The reaction: [ mica + H2O → K+ + OH- + acid clay ] is an example of
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hydrolysis
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Granite is an example of a(n):
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igneous rock
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What soil order which churns, has surface cracks when dry, and swells when wet?
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vertisols
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The mesic temperature regime in North America was originally linked to the distribution of which crop?
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corn
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