Soils Exam 1
entisol
"baby soil" , not enough time has passed to form horizons which soil order is this
inceptisol
"toddler soil" grade about entisol, starting to see horizons, high base saturation which soil order is this
A
"top soil" is generally equivalent to which soil horizon which: B, E, C, A, D
base saturation
% of soil exchange sites occupied by bases ex: K, Mg, Ca, Na
field capacity
% of water remaining in the soil after the saturated (or satiated) soil has drained of gravitational water matric pot = (-)
redder
(Fe+3) iron (hematite) makes soil appear _____ - oxidized - dehydrated conditions
yellower
(Fe+3) iron +OH (geothite) make soil appear ____ - oxidized - hydrated conditions
parent material: Till what is the particle transport and degree of sorting
- Poorly sorted - coarse fragments randomly deposits as glacier moves
extrusive
- fine - faster cooling rate - small grain sizes
improving soil aeration
- improve peds (make more macropores with +Ca and OM) - Ca brings things together which makes more pores space - improve drainage - tillage (works in A horizon, below may be compacted)
parent material: Volcanic ash what is the particle transport and degree of sorting
- okay assortment - eruption - like glass - amorphous (no crystal structure)
general characteristics of soil to support plants
- support/ medium for growth - nutrients (recycling system for nutrients and organic waste) - water (supply) - habitat for organisms - modifier of the atmosphere
parent material: Eolian what is the particle transport and degree of sorting
- well sorted - No coarse - uniform small fragments
parent material: Alluvium what is the particle transport and degree of sorting
- well sorted - coarse fragments - high energy - small fragments - low energy
parent material: Glacial Outwash what is the particle transport and degree of sorting
- well sorted - coarse fragments - high energy - small fragments - low energy
parent material: Lacustrine what is the particle transport and degree of sorting
- well sorted - no coarse fragments
parent material: Colluvium what is the particle transport and degree of sorting
-poorly sorted -coarse fragments
clay particle
0.002 mm < plate like silicate clays, oxides (Fe, Al) has greater surface area more reactive more absorptive more plasticity
silt particle
0.05 - 0.002 mm spherical quartz, feldspars, micas
macroaggregate
0.25 - 5m
Db
1.33 Mg of solids and pore space would this classify as Db or Dp?
Dp
1.33 Mg solids (half), and half pore space would this classify as Db or Dp?
% air pores
100 - (Db/Dp *100) - (Pw *Db)
% pore space
100 - (Db/Dp x 100)
granite and basalt
2 examples of igneous rocks
sand particle
2-0.05mm spherical quartz and minor # of feldspars low plasticity low reactivity low absorptive capacity
microaggregate
2-250 nm (includes clay and OM)
soil monolith
2D - verticle section of the soil profile through all of its horizons and extending into the parent material. its extracted in the field and then mounted for displaying and teaching purposes
micropores
</= 0.08 mm ex: clay in soils
macropores
> 0.08 mm ex: granular structure
matric, gravity
A = clay B = sand what forces act in the A to move water: *water will build before moving into the next layer due to clays water holding abilities ** acts as a mechanical barrier to roots** what forces act in the B to move water:
gravity, matric
A = sand B = clay what forces act in the A to move water: what forces act in the B to move water:
soil solum
A and B horizon
greater porosity
A clay soil with strong fine granular structure is likely to have a ____ than a sandy soil which: greater porosity higher particle density lower porosity higher bulk density
angular blocky
A soil has A, B, C horizon. Structural types in the soil are granular, massive, and angular blocky. The structural type in the B horizon is likely to be ______ which: massive granular angular blocky no difference in probability among these structural types
41.3%
A soil has a Db of 1.55 gcm3 and a Dp of 2.64gcm3. what is the % pore space?
20%
A soil has a field mass of 27 grams and a dry mass of 22.5 grams. what is the Pw of this soil?
what are the 8 most abundant elements in the earths crust?
Al, Fe, Ca, Na, K, Mg, O, Si
glacial till
An unsorted, transported parent material would most likely be identified as _____ which: loess lacustrine glacial till alluvium glacial outwash
Mg, Ca, Na, K
Bases in the soil include: which: Fe, Mg, Ca, Na Mg, Ca, Na, Si Mg, Ca, Na, Al Mg, Ca, Na, K
of the 8 most abundant elements in the earths crust, which are bases -Al -Fe -Ca -Na -K -Mg -O -Si
Ca, Mg, K, Na
Na and K
Effects of Cations: ___ and ___ push away - soils dry into hard clods making it difficult to till - low water penetration - puddles when wet
Mg and Ca
Effects of Cations: ___ and ____ soils are generally friable - easy to till water penetrates easily no puddling when wet
gray, blue, green
Fe+2 (reduced iron) makes soil appear _____
of the 8 most abundant elements in the earths crust, which are hydrous oxides of aluminum or iron
Fe, Al, O
false
Flocculation is the process by which certain chemicals in the soil stabilize large soil aggregates true or false
true
For any soil, bulk density is always lower than particle density true or false
quartz pebble
For what substance would particle density be equal to the bulk density which: organic soil a well aggregated surface soil a quartz pebble a wet soil a soil clod
rocks formed when molten magma solidifies
Igneous rock can best be characterized as ____ which: -rocks formed when molten magma solidifies -rocks found primarily near volcanoes -rocks containing both feldspars and micas - rocks containing both a mixture of primary & secondary minerals - rocks formed from the recrystallization of sedimentary materials
5
In a load of 10 cubic meters of topsoils, approximately how many cubic meters of the volume would be solid material which: 5 2.5 1 7.5 Not enough evidence
true
In aeolian settings, silt sized particles can travel greater distances than sand sized particles true or false
eolian
Loess belongs to what parent material
material B
Material A contains 15% Al2O3 and 3% CaCO3 on an elemental basis and material B contains 25% Al2O3 and 0.2% CaCO3. ______ is most likely the soil material, if the other material is the rock which: material B material A
calcite dolomite and gypsum
Name 2 minerals that are comparatively soluble in soil solution, making them easily weathered
true
No tillage = low soil temps tillage = high soil temps mulch + tillage = moderate soil temps mulch = protects soil water - helps with weed control and preventing erosion - helps keep soil temps lower but not too low - in the summer the mulch is cooler than the air - helps keep temps perfect for crops -- too low = no seed germination -- too high = no moisture in soil for seeds
true
OM increases = water field capacity increases (Om has alot of surface area) Om increases = increase in holding of hygroscopic water
granular
Percolation of water through a soil profile is dependent on a number of factors that included soil peds. Of aggregates listed, which would have the highest percolation rate? massive granular subangular blocky plate like water moves through each of these at the same rate
% water by volume
Pw * Db
particle density (Dp)
SOIL SOLIDS mass per particle per volume weight of solids/volume of soil *assume 2.65 when not given
of the 8 most abundant elements in the earths crust, which are made of silicon
Si, O
soil pedon
The smallest unit or volume of soil that contains all the soil horizons of a particular soil type - 3D
Aridisol
This soil order can be found from San Antonio westward and generally has little to no horizonation hint: little rain occurs - dry which: Aquasol Entisol Aridisol
Vertisol
This soil order has high shrink swell capacity and can form large cracks when dry which: Mollisol Vertisol Ultisol
silt loam
USING SOIL TEXTURE TRIANGLE if a soil is 20% clay and 20% sand, what is the soil texture?
rocks have more bases that soil does in soils, bases get withered away easily (Al and Fe remain in old soils)
When given the elemental composition of rock and a soil formed from it, distinguish between the two
valence state
Which of the following is not considered one of the five major factors influencing soil formation which: Topography Native parent materials climate living organisms valance state
clay
____ has the largest capillary movement out of the soil textures
Hardness
____ is a frequently used property for helping to distinguish among mineral in hand specimens which: texture consistence hardness structure
Calcite (CaCO3)
____ is the principle mineral in limestone which: gypsum quartz calcite feldspar silicate clay
feldspar
____ weathers to form silicate clay minerals which: feldspar hematite apatite quartz geothite
O
_____ horizon is above mineral surface of the soil
hard
_____ is word to describe the consistence of a soil which: malleable slick mushy packed hard
Db
_____ predicts total porosity
soil temperature
______ is important because it affects the rates of physical, chemical, and biological processes - too high or low microbes and plants may be affected because it limits the release of nutrients (4 deg C is biological 0) - winter soil is warmer than atmosphere - summer soil is cooler than atmosphere - ____ to high = dry soils and increase rate of reactions
high Db
__________ low porosity and soil compaction
well aerated
a __________ soil have movement of gases sufficient to meet biotic requirements
soil
a dynamic natural body composed of mineral and organic solids, gases, liquids, and living organisms which can serve as a medium for plant growth
soil
a dynamic natural body having properties due to the combined influences of climate and biota as modified by topography acting on parent material over time
less
a grainy surface has ___ water
soil horizon
a layer of soil that is generally parallel to the soil surface. it is differentiated based on properties and characteristics of layers adjacent to it what is this
clod
a lump or clump of soil is often referred to as a
prismatic
a soil researcher has determined that a soils profile includes an A and B horizon. Of the structures listed, which would be found in the B horizon? which: plate-like prismatic spheroidal All of the above
clay
a sticky, putty-like feel indicates a high percentage of which soil separate? which: none sand humus silt clay
soil profile
a vertical section of the soil through all its horizons and extending into the parent material. 2D what is this
Soil profile
a vertical section through a soil showing its succession of horizons and the underlying parent material
what kind of parent material is found in the pan-handle of texas
aeolian
secondary particles
aggregates or peds
plant available water
amount of water released between field capacity and permanent wilting point ____ = field capacity - PWP
phosphates
apatite belongs to what mineral group
mollisol
areas of grassland, lots of organic matter, dark soils, high base saturation which soil order is this
aridisol
areas where there isn't a lot of rain (arid regions) - can have horizons what type soil order is this
clay
at a given potential ___ soils hold more water and at a given moisture content the water is held more strongly than other soils silt next then sand is the lowest
soil water energy
based on differences in the energy level from one site or condition to another - dictates where water goes and the rate of movement in plants and soils - water moves from wetter to drier soils water moves from higher to lower energy sites
matric potential
baseline is pure, free water = 0 water with low energy (neg potential) is tightly bound with little ability to move adhesion to surfaces makes it difficult for water to move = low energy state - measure in bars
complexation/ chelation
binding of cations by organic anions K2[Si6Al2]Al4O20(OH)4 + 6C2O4H2 + 8H2O <-> 2K +8OJ +6C2O4Al+ 6Si(OH)4 (solid) + acid <- complexation -> solution * K would break off and become a nutrient
weathering of rocks
biochemical process in which there is destruction and synthesis - physical - biochemical
how is glacial till deposited in the environment
by ice
how is colluvium deposited in the environment
by movement of materials from upslope due to GRAVITY (sometimes water)
how is glacial outwash deposited in the environment
by water
how is alluvium deposited in the environment
by water - STREAMS and rivers
how is eolian deposited in the environment
by wind
true
carbonates like, calcite and dolomite are some what soluble true or false
true
clays hold more water but it is harder to get ahold of in sands, hold less water but its somewhat easier to get ahold of
active soil formation factors
climate and biota (animal and plant life)
intrusive
coarse grains - slow cooling rate - large grain sizes
What kind of parent material will you find in East Texas, along the coast
coastal plain sedimentation
subsoil
compact soil below the surface soil, generally poor in nutrients and OM, less fertile that surface soils, particularly weathered
has no effect on
compaction of soils ______ particle density and increase in bulk density which: has no effect on decreases increases
igneous rock
cooling of magma
value
dark to light (soil) 2(dark) to 8(light) *influenced by OM more OM = darker
sedimentary rock
deposition of sediments and evaporation of water and then consolidation
residual parent material
develops in place from weathering of underlying rock
biochemical weathering of rocks
dissolution/decomposition of minerals results in synthesis of secondary minerals
A horizon
dominated by mineral particles but have been darkened by the accumulation of organic matter - top soil - less compacted - more sand and silt - smaller aggregates
percolation
downward movement of water through the soil profile - different based on pore sizes
osmotic potential
due to solutes in soil solution solutes = solids water around a solute has little freedom to move = lower energy potential *** only works if there is permeable barriers that bars the movement of solutes
chroma
dull to bright soil 0 (dull) to 8 (bright)
soil
dynamic natural body having properties due to the combined influences of climate and biota as modified by topography acting on parent material over time
soil consistence
ease which a soil can be reshaped or ruptured - depends on mositure -- dry, moist, wet ( plasticity, stickiness)
permeability
ease which gases, liquids, or plant roots penetrate or pass through the bulk mass of soil or layer of soil "how easily it can be moved through the soil"
parent material
effects on _______ _________ on soil properties are modified by the combination of influences of climate, biotic activities, topography, and time
flocculation
effects soil aggregates coming together - freeze/ thaw - physical activity - wetting / drying - roots/ animals - decaying OM / microbes - absorbed cations - tillage
stabilization
effects soil aggregates coming together as a group & cemented together - Organic glues (fungi) - Fe- Oxides - organic carbon - clay
TDR (Time-Domain Reflectometer)
electronic device gives indication of %water based on electric current - showing the flow of liquid helps determine matric potential
infiltration
entry of water into soil - only A horizon
low
fine textured soil = ______ Db than sand ex: clay and silt
Factors that influence soil aggregates:
flocculation and stabilization
metamorphic rock
from pre existing rock and high temp and pressure
hue
general spectral color of soil ex: 10Y 5YR
what happens to liquid movement when it encounters small pores that are dry ex: (top) sand loam/ clay (bottom)
gravity plays a role until it reaches the clay then capillary forces take over
Gravitational potential
gravity pulls water towards the center of the earth - higher in the profile = higher energy than lower in the profile gravity x height
aggregates or peds
group of soil particles that bind to eachother more strongly than other particles near
sulfates
gypsum belongs to what mineral group - relatively soluble
halides
halite and sylvite belong to what mineral group - very soluble
alfisol
horizons starting to form, located in areas with more rain, high-medium base saturation ex: pan handle which soil order is this
50%
how much of soil is solid material
dissolution
hydration of anions and cations until they dissociate ex: think of it as a salt CaSO4 + 2H2O + 2H2O <-> Ca SO4 + 4H2O (gypsum solid) <-> solution + water
6 biogeochemical weathering processes
hydration, hydrolysis, dissolution, acid reactions, oxidation-reduction, complexation/chelation
basic and fine
igneous rock - basalt is hint: formed extrusive acidic or basic fine or coarse
acidic and coarse
igneous rock- granite is hint: formed intrusive acidic or basic fine or coarse
slow and laterally
in a soil thats 2 meters deep, water will move _____ and _____ through a clay loam * capillary forces at work for the second blank
quickly
in a soil thats 2 meters deep, water will move _______ through sandy loam compared to clay loam
Gleysol
in a wetland area between the A and B horizon, might see an area that more red whats happening is the water table moves up and down, when it goes down oxidation occurs turning it red what soil order is this: hint its a german one
false
in general, colluvium would be better than sorted than alluvium true or false
how is lacustrine deposited in the environment
in lakes - silt and clay sized particles
20 to 30%
in soil, of the pore space how much is generally air? (same goes for water)
true
in the winter mulch acts as a blanket keeping the heat in winter : remember the time lag
hydration
intact water molecules bind to a mineral 5Fe2O3 +9H2O -> Fe10O14 + 9H2O (hematite +water = ferrihydrite +water)
the relationship between particle size and reactivity
largest particle = sand then silt smallest particle = clay surface area per volume increases as you move to smaller particles surface area, plasticity and reactivity all increase as size decreases sand and silt are spherical shape clay is plate like shape (even more surface area due to shape)
C horizon
least weathered
of the 8 most abundant elements in the earths crust: arrange them according to solubility over normal range of SOIL pH
least: -Ca, K, Na, Mg -O, Si -Al, Fe
true
limestone is a carbonate true or false
Fe, Ca, Mg, K
list 4 plant essential metallic elements that are most abundant in rock and minerals
thermal conductivity
looking at the way heat moves through the soil * think of them as atoms compact dry soil = good at transferring heat to surrounding particles - loses heat more easily (high K) loose soil = good thermal insulator (low K)
Soil Om
low in sand (high OM turnover rate) high in clay (clay protects OM (aerobic condition))
satiated
macro and micropores are filled with water matric potential = 0
saturated
macropores are filled with water matric potential = 0
regolith
made up of A to C horizons, the C horizon isnt really effected by climate/biota
solum
made up of only A and B horizons, is acted on by climate and biota
high Dp
magnetite and garnet have a __________ of 3.0g cm3
clay
make ups of particles: more secondary silicate minerals other secondary minerals little quartz some primary silicate minerals little to no primary minerals
sand
make ups of particles: mostly quartz some primary silicate minerals little secondary minerals
silt
make ups of particles: some primary minerals some secondary silicate minerals some other secondary minerals good amount of quartz
white
makes soil appear _____ uncoated quartz, calcite, gypsum, soluble salts
true
matric potential and tension are the same: to remove water it requires work mp = negative tension = positive
lateral
mechanical impedence: clay pan or compacted are or water table limits root growth cause root to go down and then to the side
thickening
mechanical impedence: root can still get through thickens before passing through the dense layer
corkscrew
mechanical impedence: root cant go anywhere else so it curls into or around itself
contortion
mechanical impedence: root grows lateral and then finds a place to go down through the dense layer
the disintegration of rocks due to differential expansion of minerals
mechanical weathering processes result in ____ which: -the hydrolysis of minerals through frost action -the oxidation of iron & manganese compounds -the decomposition of primary minerals -the disintegration of rocks due to differential expansion of minerals
sedimentary rock, limestone
metamorphic rock: marble is made up of
sedimentary rock, shale turns to phylitte which turns into ____
metamorphic rock: schist is made up of
sedimentary rock, shale
metamorphic rock: slate is made up of
biochemical weathering of rocks
microbes in plants are making acids and breaking down/ weathering rock plays the biggest role at the end of it all
mottled
mixed color due to oxidation and reduction described by the amount, size, contrast, and color - cause by high water table
% water (Pw)
moist soil weight / dry soil weight * 100
water and air
moist surface soils contain approximately equal parts by volume of _____ which: water & air OM & air mineral & organic matter mineral matter & water solids % air
stickiness
moisture content at which the soil adheres to the fingers and thumb - nonsticky - slightly sticky - sticky - very sticky * wet the soil (more clay = more stick)
Permanent Wilting Point (PWP)
moisture content of the soil at which plants wilt and fail to regain turgor overnight matric pot = (-) as plants loose water they wilt during the day, at night they recover the lost soil
plasticity
moldability of soil - non plastic - slightly plastic - plastic - very plastic * lots of sand little clay = lack of moldability
B horizon
more clay than the ___ horizon because it likes to travel
A horizon
more sand than the other horizons
capillarity
movement of water due to forces (adhesion and cohesion) h = 0.15 / radius - smaller radius = more water can be pulled up - larger radius = harder to pull more water up can be vertical and horizontal
Quartz
name 3 primary silicate minerals that are resistant to weathering and dominates the sand and silt fractions of most soils
Water holding capacity
not enough water, plants will die ex: want a soil with clay over sand
10%
of just the soil solids, what percent is OM?
true
of the incoming solar radiation: - some reflected by cloud and some is scattered by particles in atmosphere - some is absorbed by atmosphere (half makes it the the ground) what made it the the surface - only small % of the heat is absorbed by the soil during the DAY at NIGHT - soil loses heat
muck (sapric)
organic deposits: ____ : little fiber remain due to decomposition
peat (fibric)
organic deposits: ____ allows plant fibers to be identified
O
organic layer of soil is which horizon
organic deposits
organic material that accumulates in wet areas or really cold areas places where plant growth exceeds that rate of residual decomposition due to the lack of O2
oxidation reduction
oxidation : loss of e reduction : gain of e *end product are things we see in older soils 3MgFeSiO4 + 2H2O <-> H4Mg3Si2O9 + SiO2 + 3FeO (olivine solid) -> serpentine solid + solution + Fe(2) oxide ferrous iron ((hydrolysis) 4FeO + O2 + 2H2O <-> 4FeOOH (Fe(II) oxide ferrous iron) = goethite Fe(III) oxyhydroxide ferrous iron ferric iron (( -> oxidation )) (( <- hydrolysis))
which mineral group is most resistant to weathering
oxides made of Fe and Al - geothite - hematite - gibbsite
passive soil forming factor
parent material
five soil forming factors
parent material climate biota topography time
lacustrine
parent material deposited in lakes
true
plants have to exert the most energy to get water from clays (increase clay content = more neg matric potential) in loams they dont require as much energy to get water in sands they require the least amount of energy to get water
water
polar - reason it sticks to things - reason it has a high specific heat - connect to each other through H bonds
properties of water
polar h bonds cohesion adhesion
major components of a typical, moist surface soil
pore space (40 - 60%) - air (20-30%) - water (20-30%) soil solids (50%) - mineral (45%) - OM (5%)
what happens to liquid movement when it encounters large pores that are dry ex: clay loam (top) / sand (bottom)
pores have to be filled before water will make its way down
negative matric potiential
positive or negative matric potential water is absorbed so tightly to the particle its not a liquid any more the amount of work to be applied is so high = negative potential to remove the water (if is it easy to remove the water/ free water = 0)
acid reactions
presence of acids accelerates weathering processes with increase H ion activity in water CO2 + H2O <-> H2CO3 (carbonic weak acid) H2CO3 + CaCO3 <-> Ca + 2HCO3 (carbonic acid) + (calcite acid) = solution
what soil properties affect infiltration rates
rain events (slow rain = good infiltration) (lots of rain = flows over land with some infiltration) previous soil moisture
soil consistency
resistance to penetration by an object - measure of how much resistance is there when you try to penetrate the soil
physical weathering of rocks
results in the reduction of grain size ex: freeze, thaw ex: temperature, moisture, abrasion by wind/ice/water, animal and plant root pressures
importance of O2 in soil
root respiration aerobic respiration to decompose OM oxidation reactions (think about Fe) - roots get wet they will die due to lack of O2
drainage rate
sand = high clay = low (water likes to stick to clay due to the charge)
compactability
sand = large pores, when wet it compacts but doesnt stay clay = really plastic
eolian
sand dunes are an example of deposition of which parent material
leaching potential
sand has large pores to higher potential clay has smaller pores so lower potential
what kind of parent material is found in the northern part of texas near the pan handle
sandstone, siltstone, shales
gravity
saturated flow: movement of water when the soill is saturated or satiated - all pores are filled - movement via _____ and small capillarity
calcite and dolomine
sedimentary rock: limestone is made of ______ and ______
quartz
sedimentary rock: sandstone is made of
silicate clay minerals
sedmentary rock: shale is made of
hydrostatic potential
seen ONLY in saturated zones below the water table
volcanic ash particle sizes
silt and sand
clay
smallest of the particles, hard to see even under a microscope
diffusion
soil aeration: movement due to differences in partial pressures (more common) ex: CO2 wants to move from high concentration (soil) to low concentration (atmosphere) same goes for O2 but from atmosphere to soil
mass flow
soil aeration: movement due to differential total pressures (rare)
soft soil consistence
soil consistence crumble under slight force
hard soil consistence
soil consistence: can be compressed in hand
time
soil is finite during the human lifetime because it takes thousands of years to form. which soil forming factor is this
false
soil is interfaced with lithosphere through gases emissions and energy transfer true or false
ultisol
soil is no longer fertile, red in color, low base saturation which soil order is this
soil consistency
soil resistance to penetration by an object is the definition of
bulk density (Db)
soil soilds and pore space mass of total soil per volume weight of dry soil/ volume of soil * how compacted the soil might be *
parent material
soils is a dynamic natural body having properties due to the combined effects and biotic activity as modified by relief acting on _____ over time which: parent material pedon profile solum regolith
transported parent material
soils moved from location and deposited in another ex: colluvial, alluvial, coastal/marine sedimentation, glacial ice/melt waters, aeolian, lacustrine, volcanic ash
plate like
structure: - A and E horizon *mainly E
Prism-like (Columnar)
structure: - never want in a soil - soils have Na caps Na disperses soil particles creating gaps letting smaller particles fall through and water - B horizon - puddling of water due to gathering
prism like (prismatic)
structure: - striations occur - B horizon - length > width - they have clay, if there isnt enough clay it can form subangular blocky
grade
structure: 0, weak, moderate, strong how well it stays together when passed from hand to hand
spheriodal
structure: EXCLUSIVELY A ONLY - space between peds - water/ air movement = good - OM acts as a glue
angular blocky
structure: common in B horizon higher amounts of clay humid regions sharper edges
Spheriodal
structure: granular and crumb belong to ____ ped
structure less conditions
structure: massive: lots of clay makes a big clump -soils are important - low permeability once pores are full puddles form
structure less
structure: nothing is going on, all single grains
subangular blocky
structure: rounded edges - humid regions - A, E, B horizons - B = little to moderate clay content
blocky
structure: subangular and angular belong to which ped
size or class
structure: very fine, fine, medium, coarse, very coarse the more coarse the decrease in ability to hold nutrients
false
subsoil is roughly equivalent to the O horizon true or false
B horizon
subsoil; silicate clays, iron, and aluminium oxides, gypsum, calcium carbonate - plant roots - more clay - more compacted - larger aggregates - LESS OM
true
surface soil heats up and cools down during the summer - greater differences in temperature the deeper you go there is "lag time" it takes a while for the heat to make its way down there and it loses energy along the way - less differences in temperature
more porous
surface soils are more _____ than subsoils which: lighter in color more compact more porous more dense more clayey
soil structure
the arrangement of sand, silt, clay, and OM in soils plays a large role in how air and water flow through a system
soil
the collection of natural bodies occupying parts of the Earths surface that is capable of supporting plant growth and that has properties resulting from the integrated effects of climate and living organisms acting upon parent material, as conditioned by topography over periods of time
texture
the distribution of sand, silt, and clay particles determines a soils which: structure texture suture tester
Calcite (CaCO3)
the mineral is the most soluble and easily weathered in wet climate which: Calcite Quartz Hematite Feldspar apatite
matrix color
the most common color of the soil horizon in mottled soils is called
biochemical + physical
the order in which rocks are weathered is: which: physical -> biochemical biochemical + physical biochemical -> physical
silt and sand
the percentages of which soil components represent the MINIMUM information necessary to determine the textural class of a soil? which: sand, silt, clay sand and silt clay, water & air clay and OM gravel and sand
hydrolysis
the reaction below is an example of ______ 2HAISi3O8 + 11h2o <--> Al2O3 + 6H4SiO4 which: acid reaction hydration hydrolysis dissolution
feldspar
the silicate mineral is prone to weathering due to bases which: feldspar quartz goethite gibbsite calcite
pedon
the smallest volume that can be called a soil is ... hint: 3D
surface & subsurface soil
the solum consist of ____ which: surface & subsurface soil surface soil only A, B, & C horizons
true
the state soil of Texas is Houston black and is a Vertisol true or false
medium
the structural size of a horizon having a moderate, medium columnar structure is ____ which: moderate moderate, medium columnar moderate, medium columnar medium
0.002
the upper limit in equivalent spherical diameter for clay particles, according to the USDA system, is ____ mm which: 0.2 0.02 2 0.0002 0.002
transported and residual
there are 2 broad classifications of parent materials what are they
preferential flow paths
these are 2 types of : open to surface closed to surface - capillarity forces - gravity takes over ones its under ground * water wants to take the path of least resistance = open to surface
aggregates
these are types of ______ : granular prismatic subangular blocky platy
clay
this describes what particle : high water holding capacity poor aeration very slow drainage rate high to medium soil OM high compactability less(unless cracked) leaching potential
sand
this describes what particle : low water holding capacity good aeration high drainage rate low soil OM low compactability high leaching potential
A
this horizon: - less compacted (lower Db) - more sand and silt - smaller aggregates - darker due to OM
B
this horizon: - more compacted (higher Db) - more clay - larger aggregates - less OM
transported
this is an example of what kind of parent material: bring sand home with you from the beach
residual
this is an example of what kind of parent material: limestone isnt going to move, stuff is going to build and form soils on top of it or dead OM in swamps - creates Histosol - gets layered on top of one another
sand
this particle can be seen with the naked eye
silt
this particle size is similar to flour, cant be seen without a microscope
osmotic potential
this potential has little influence on the movement of water in soils but it does affect plant- soil water relationships ex: water wants to move from the root -> out due to there being more negative charges outside of the root
vertisol
this soil has lots of clay, found in areas with few trees, shrink-swell clays. particularly fertile- hangs on to & absorbs plant nutrients ex: SA which soil order is this
true
true or false Al and Fe are a small portion of rock but a larger portion of the soil large ratio: ex: 1.87, 3.42
true
true or false Dp > Db usually
true
true or false K and Ca are being lost from the soil small ratio: ex: 0.21, 0.14
true
true or false a soil to rock ratio that is larger than 1, something is being gained from the soil
true
true or false always have to mention moist or dry when writing soil color
false - reduction
true or false blue in soil - oxidation occuring
true
true or false clay hold more water due to reactive surfaces Om holds more water due to increase surface area
true
true or false deep soil = pulls more water up shallow soil = pulls less water up in example: the bottom of the tray where the water is being added has high energy the soil has low energy
true
true or false greatest to least porosity crumb granular subangular blocky angular blocky prismatic plate like structureless (massive)
true
true or false iron in soil - oxidation occuring
true
true or false lots of OM = low Dp Dp = 0.9 - 1.4 gcm3 OM makes it light and fluffy
true
true or false low fertility due to : low CEC (cation exchange capacity) low OM leaching (low water holding capacity) WHC sand soils are basically neutral, due to these things
true
true or false soil temp depends on the amount of heat energy absorbed - light soil = less than darker soils lots of water in soils = longer to heat little water = fast heat - sunlight can evaporate the water but it wont have enough energy to heat the soil
false- they do
true or false texture Om and structure DONT influence field capacity
true
true or false the more OM present in aggregates the greater ability the ped will hold shape when wetted
true
true or false the parent material, alluvium, is deposited in the coastal plains and is an example of coastal/ marine sedimentation
gravity
true or false water moves by capillary action (matric potential) EXCEPT when large pores are full then ______ takes over
true
true or false structure description: - grade, size, structure type ex: weak, coarse, subangular blocky
true
true or false soil texture greatly influences PWP
true
true or false weatherability of silicates: order olivine pyroxenes amphiboles Fe-mica feldspars Al-mica (clays) Quartz
Regolith
unconsolidated debris overlaying hard unweathered rock
capillarity
unsaturated flow: movement of water in soil when some of the pores (large) do not contain water - movement of water via ______
surface soil
uppermost loose layer, has OM, completely unweathered, dark brown color
enchanted rock is made of what kind of parent material - its located in south, central texas
volcanic
true
water has a high specific heat dry soil has a low specific heat when a soil is wet it doesnt heat or cool down quickly soil will maintain a higher temp when moist (wet soils store more heat during the fall months) wet soils require more energy to heat during the spring
hygroscopic water
water held so tightly that its considered "non-liquid" - will not move via capillary action once PWP is reached water is held so tightly to particle it is unable to be reached by plant
gravitational water
water in the largest pores will move due to gravity
hydrolysis
water molecules split into H and OH components H = replaces cation in mineral structure (water disappears) KAlSi3O8 + H2O -> HAlSi3O8 + K OH (solid) = solids + solution
high(0) to low(-)
water movement due to matric potential: from _____ to _____ potential
true
water moves from sites of high matric potential to low OR (low tension sites to high tension sites) true or false
adhesion
water sticking to a surface ex: solute in solution (NaCl)
surface tension
water wants to stick together which creates _____ reason bugs can float on water
cohesion
water wants to sticking to another water molecule
most
weatherability of silicates: basic or mafic minerals are _____ weatherable
least
weatherability of silicates: acidic or siliceous minerals are ____ weatherable
feldspars, amphiboles, pyroxenes, and micas
what are the 3 primary minerals that weather to form clay in soils
climate and biota
what are the active soil forming factors
air, water, minerals, OM
what are the four components of soil
parent material
what are the passive soil forming factors
any material of glacial origin
what is glacial drift
topography
what is the modifying factor when soil is forming?
limestone
what is the parent material for san antonio
volcanic
what kind of parent material is found in the western part of texas
Vertisol
what kind of soil order is considered a "shrink-swell clay"
OM and mineral matter
what makes up soil solid material
loose soil consistence
what soil consistence: cant break/ rupture easily
subsurface flow
when water hits a clay pan it cant get through so it flows under the surface what is this called
structure
when you read "arrangement" think of sand silt and clay
texture
when you read "distribution" think of sand silt and clay
true
when you remove whole trees you can expect warmer soil temps there when you leave the stems : less warm when you remove stems and soil is compacted = coolest trees act as mulch layer in a way
Blackland Prairie region of Texas
where is Houston Black soil found
A
which horizon is typically the darkest
B
which is greater? Both are 1 cubic meter A = 1.33Mg (solids and pore space) B = 1.33Mg (solids) which makes up half, the other half is pore space.
all of the above
which of the following are functions of soil? Medium for plant growth Regulates water flow Habitat for soil organisms Recycler of raw materials Modifier of the atmosphere engineering medium All of the Above
10
which of the following pH values represents the most alkaline condition which: 10 7.0 6.0 5.0
true
wilting coefficient (PWP) increases as texture becomes finer
eolian (loess)
wind carried silt size particles - can be a factor of glaciation
