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126 Cards in this Set

  • Front
  • Back
What are 5 functions of soil?
Medium for plant growth, Regulator of water supplies, Waste recycling system, Habitat for soil organisms, Engineering medium
What are the consequences of the 1935 Dust Bowl?
Loss of topsoil, decline in food output, health issues, abandoned farms and refugees
What Act was established after the Dust Bowl? Why?
Soil Conservation Service (1935), because views of soil being 'indestructible' changed
Who said “The nation that destroys its soil destroys itself.”?
F. D. Roosevelt (1937)
Why has erosion has been less obvious in Illinois?
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
Soil = ?
What are the 3 Major Soil Components?
solids, liquids, gases
Soil Solids
inorganic minerals & organic matter (humus)
Primary minerals
formed by igneous rock)
Secondary minerals
formed by weathering
product of the decay of organic residues
Soil Water
soil solution composed of water, dissolved ions, molecules, & gases
Soil Atmosphere
contains similar gases as in atmosphere above the soil but often in very different proportions; higher CO2 & lower O2 than atmosphere
About 50% of soil is ______, 50% is _________
solids, voids
What are the 5 factors of soil formation?
CORPT: climate, organisms, relief, parent material, time
study of soil genesis, classification, morphology, mapping, & interception
smallest unit of a soil, about 1m hexagon, 1-2m deep
vertical exposure of soil showing horizons
nearly horizontal layer in soil formed by pedogenic processes
Soil Profile
morphology, chemical/biological/physical processes, vary with factors of formation, horizons, & diagnostic horizons
Zones of loss
leaching, eluviation
Zones of gain
O horizon
A horizon
surface mineral “topsoil”
E horizon
eluvial, leached
Bt horizon
illuvial, accumulation of weathering products, clay
BC horizon
transitional to C horizon
C horizon
slightly altered parent material
R horizon
What is the parent material of Alfisol and Mollisol?
4 soil components
Air, Water, Organic Matter, and Minerals
Soil Solids
Inorganic Minerals and Organic Matter
decay product of organic residues
Texture Class
relative % of soil separates by weight
massive or single grained
granular, platy, subangular blocky, angular blocky, prismatic, & columnar
produced by improper tillage wet soils, heavy equipment
produced by natural soil forming peds are produced by natural soil forming processes
Ideal soil has a balance of
macro and micro pores
retain water against the pull of gravity; contain the soil solution
drain free of water; contain the soil atmosphere
Soil Consistence
response of soil to applied force at various moisture content
4 basic soil properties
Color (HVC), Texture (Sand, Silt, Clay), Consistence (friable, firm, plastic), Structure (blocky, platy, crumbs)
material that formed from rock weathered in place
material that has been transported by some agent
material that is moved by water and deposited in fresh water lakes
material deposited on flood plains of active streams; usually stratified
Alluvial Fans
materials often deposited in fan shaped deposits in high energy environments at base of slopes
sediment carried by streams deposited in slower water
old abandoned floodplains
material moved by gravity and deposited at the base of steep slopes
sandy material deposited by wind
a mixture of rock material that has been ground into an assortment of different sized particles and moved by the action of glacial ice
alluvial material that was deposited by streams of glacial meltwaters
conical hill, sorted by water, often by filling cavities in a glacial ice sheet with sediment
serpentine ridge, meltwater flowing within/beneath glaciers and carrying sediment
closed depressions left as ice blocks in outwash or till melt
Outwash Plain
broad expanse of outwash, often downslope of a moraine
Till Plain/Ground Moraine
level plain of till from beneath the glacier
pile of till in a large cigar-shaped hill oriented with the direction of ice movement
Top 3 IL parent materials:
Loess 63%, Till 12% (Wisconsinan, Illinoian), Alluvium 10%
chemical bonding of water to cations and anions
reaction of water with a mineral resulting in the splitting of water into H+ & OH ions
higher plants and microorganisms produce a variety of organic compounds
water is an excellent solvent for polar species
Soil horizons are distinguished by (4):
color, organic matter content, texture, & structure
Master horizons can be subdivided into (4):
A1, A2, Bt1, Bt2
Limnic horizon (L)
used with Histosols, material deposited under water, plant tissues, diatoms, fish droppings, etc. includes diatomaceous earth (di), marl (ma), coprogenous earth (co)
Solum is in which horizons?
O, A, E, Bt
Regolith is in which horizons?
O, A, E, Bt, C
Transition Horizons
dominated by the properties of one master horizon, but with some properties of another master horizon
Subordinate Distinction p
Subordinate Distinction g
Subordinate Distinction t
illuvial concentration of silicate clays
Subordinate Distinction b
buried genetic
Subordinate Distinction n
sodium accumulation
Subordinate Distinction w
weakly developed B horizon
Subordinate Distinction x
Soil Surveys
Predict soil conditions in certain areas and interprets them for practical uses
ave. level of management
optimum management
Base & Benchmark soils in IL
Drummer sicl, Elburn sil, Flanagan sil, Ipava sil, Sable sicl
Soil Taxonomic Classification
soils are classified based on the presence or absence of diagnostic horizons and major differences in soil forming factors or properties
Mollic Epipedon
mineral (A) horizon that is dark, thick, rich (high in bases), soft
Histic Epipedon
organic horizon (O) of a mineral soil
Umbric Epipedon
mineral horizon (A) that is thick enough, dark enough to be a mollic epipedon but having low base saturation
Ochric Epipedon
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
strongly developed E horizon, lighter in color & lower in clay than horizons above/below
clay (Bt), important in Illinois
exchangeable Na (Bn)
(Bw or Bg) Slight development
Entisols (ents)
Young soil formed in recent deposits, alluvium,
colluvium etc., no diagnostic horizons
Inceptisols (epts)
has the most coarse fragments
Mollisols (olls)
pPrairie soil, thick, dark mollic epipedon
Alfisols (alfs)
soils that do not have a mollic epipedon but have an argillic horizon with greater than 35% base saturation
Spodosols (ods)
formed under acid, chelating vegetation,
albic E and spodic B horizon
Ultisols (ults):
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
Oxisols (Bo)
soils that have an oxic horizon (Bo) no argillic or natric horizon, highly weathered; Old soils formed in hot, wet climates
Histosols (ists)
have most organic matter
Vertisols (erts)
soils which contain 30% or more swelling type clay (smectites) to ≥ 50 cm, and when dry have cracks open at the surface
Aridisols (ids)
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
Andisols (ands)
volcanic soils with andic properties &high content of volcanic ash & glass
Gelisols (els)
young permafrost and frost churning soils with little development; poor drainage, gleyed colors
Levels of classification:
Order, suborder, great group, subgroup, family, series
Given oven dry weight and sample
volume, calculate bulk density
BD = Ms (mass of oven-dry solids) / Vt (volume solids + volume pores)
Given bulk density and assuming
particle density calculate porosity
PS (pore space) = (1 - BD/ PD) (where PD is particle density)
.Given the porosity and assuming
particle density calculate bulk density
BD = 1 - (PS)(PD)
What is an "ideal soil"?
~50% pores, ~ 50% solids. ~45% minerals, 5% humus by volume
What is the "soil taxonomy order"?
order, suborder, great group, subgroup, family, series
Particle sizes in decreasing order? (4):
course fragments (>2mm), sand (2-.05mm), silt (.05-.002mm), clay (<.002mm)
Generally, soils have higher ________ and lower ______ than atmosphere above the soil
CO2, O2
Which element needed by plants is not gotten from the air or water?
What is the most common parent material that most Illinois soils are formed in?
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?
What glacier went the furthest south?
Why (primary reason) are the soils in west central Illinois more productive (higher crop yields)?
loess is thicker
Residual parent materials are best described as:
materials formed by weathering of rocks and minerals in place
Sandstone is a ____________ rock.
The maximum soil development occurs in which master horizon (color change, soil structure)
for a given soil profile?
What subscript means an illuvial concentration of clay?
What subscript means evidence of a buried soils?
The reaction: [ Fe3+ + e- > Fe2+] is an example of:
The reaction: [ mica + H2O → K+ + OH- + acid clay ] is an example of
Granite is an example of a(n):
igneous rock
What soil order which churns, has surface cracks when dry, and swells when wet?
The mesic temperature regime in North America was originally linked to the distribution of which crop?