soils exam 111

whats the key difference between soil pore air and atmospheric air

soil pore air has less oxygen and more CO2 and Nitrogen due to microbial plant respiration

profile

vertical section of soil composed of multiple horizons from the ground to underlying rock

solum

O, A, and B horizons of soil layered above the parent material

regolith

loosely arranged material above bedrock including A,B, and C horizons

what are the names (letters) of all the soil horizons in order

O, A, E, B, C, R(ock)

what is found in the O horizon

Organic matter

what is found in the A horizon

surface horizon composed of minerals and organic matter, dark in color

What is found in the E horizon

subsurface horizon, light in color due to leaching eluviated material comprised of sand and silt (very little or no clay)

What is found in the B horizon

subsurface horizon, site of illuviation

What is found in the C horizon

parent material, this is the least weathered horizon

what materials is soil composed of

Minerals, Air, Water, Organic Matter

Saprolite

a soft, porous, and thoroughly decomposed rock formed by the in-place chemical weathering of parent bedrock, such as igneous, metamorphic, or sedimentary rocks

Eluviation

leaching - the removal of soil material in suspension from a layer or layers of soil - can also be defines as loss or removal of soil by water (process that makes E horizon happen)

illuviation

the deposition of soil material from an upper horizon to a lower horizon - materials flowing to lower horizons because of water moving through the soil (process that makes B horizon happen)

the B horizon will be larger in what age of soil (old/young)

older

residuum

weathering occurring from a stationary parent rock

colluvium

material transported by gravity

alluvium

material transported by water

loess

sediment deposit from eolian dust

eolian dust

sediment distributed by wind

Silicate primary minerals

Calcium Plagioclase, pyroxene, Olivine

where do extrusive igneous rocks originate from

what types of rock does it result in?

rapidly cooled volcanic activity

Basalt, small crystals finely textured

Where do intrusive igneous rocks originate from

what types of rock does it result in?

cools slowly within earths crust, forms granite, large crystals, coarse texture

Where do sedimentary rocks originate from

what types of rock does it result in?

product of weathered rock, calcite, limestone - these are the most common rocks you will find

where do metamorphic rocks originate from

what types of rock does it result in?

rocks transformed by high pressure and tectonic activity, limestone/marble: harder and more crystalline than sedimentary.

characteristics of basalt (texture, primary mineral, low or high in silicate, Fe or Si)

Fine texture, pyroxene (silicate), low silicate, iron, calcium and magnesium rich

characteristics of granite (texture, primary mineral, low or high in silicate, Fe or Si)

coarse texture, orthoclase (feldspar), high in silicate, silicon rich

what is plagioclase

a group of feldspar minerals containing aluminosilicates of calcium/sodium

what are some primary minerals in basalt

Ca-plagioclase
Olivine
Pyroxenes (aguite)

what are some primary minerals in granite

Biotite
Quartz
K-plagioclase

what do coarsly textured rocks weather into

sand

what do finely textured rocks weather into

clay

what is weathering

The disintegration of primary minerals and the reformation of some of those dissolved minerals into new secondary minerals.

physical weathering

the physical disintegration of rock materials into smaller sizes resulting in an increase in surface area

chemical weathering

the dissolution and/or alteration of primary
minerals and the reprecipitation into secondary minerals ( ie. clays)

surface area increases relative to ___

volume

what happens during a hydration weathering reaction

water molecules bind to a mineral

what happens during a hydrolysis weathering reaction

water molecules split into H+ and OH-
and H+ replaces the K+ from the mineral structure

what happens during a dissolution weathering reaction

water can dissolve minerals by hydrating the cation and anion and disassociating them

what happens during an acid reaction

acids accelerate weathering by increasing
H+ activity in water

increasing surface area increases…

chemical reactivity, biological activity, and water retention

what are some properties of clay

very high specific surface, high porosity, high water retention, surface charge (Negative for most [iron/aluminum based cays are the exception]), high chemical reactivity, high C sequestration, habitat for organisms

what happens during an oxidation-reduction reaction

minerals containing Fe, Mn, and S undergo
oxidation/reduction reactions in the soil

what happens during a complexation reaction

soil biological processes produce organic
acids (oxalic, citric, tartaric, fulvic, humic) which can form organic complexes (chelates) with metal cations (Al, Mn, Fe) removing them from the crystal structure.

what are the names of the minerals that are most susceptible to weathering

olivine, pyroxene, Ca-plagioclaise

what are the names of the minerals that are the least susceptible to weathering

K-feldspar, quartz, muscovite

what type of weathering turns parent material into clay

chemical weathering

what is desilication

the process where soluble silica is dissolved from silicate minerals by rain and other water, and then transported away from the soil or rock, leading to the enrichment of iron (Fe) and aluminum (Al) oxides and the formation of highly weathered soils

What degree of soil development do goethite, limonite, and hemetite have

12

What degree of soil development do gibbsite and allophane have

11

What degree of soil development do kaolinite and halloysite have

10

What degree of soil development do montmorillonites have

9

What are some primary parent rocks

basalt, granite

what are some secondary clay minerals

Aluminosilicate Clays!
Smectite (Ca-montmorillonite)
Kaolinite (AlSi)
Imogolite (AlSi)
Halloysite (AlSi)
Allophane (AlSi)

what are some secondary oxide minerals

Goethite (Fe)
Hematite (Fe)
Gibbsite (Al)
Ferrihydrite (Fe)

What are some secondary crystalline minerals

Smectite (Ca-montmorillonite)
Kaolinite (AlSi)
Halloysite (AlSi)
Goethite (Fe)
Hematite (Fe)
Gibbsite (Al)

what are some secondary amorphous minerals

Allophane (AlSi)
Ferrihydrite (Fe)
Imogolite (AlSi)

What does ClORPT stand for

Climate, organisms, Relief (topography), Parent Material, Time

What are the four soil forming processes

Additions, transformations, losses, translocations

what are the two components that influence climate

temperature and precipitation

Which soil horizon is typically the largest in a tropical climate

B horizon

What factors influence topography/relief

Elevation, Slope, Depressions, Drainage, Aspects(temp and rainfall)

Whats an addition

organic matter, water, eolian, alluvial and
colluvial sediments

whats a transformation

alteration of soil constituents,
chemical weathering, OM decomposition, redox chemistry (Fe3+ to Fe2+)

whats a loss

leaching, erosion, gas exchange

whats a translocation

movement of soil materials
(dissolved and mineral) between horizons

pedon

a fundamental unit of soils

soil series

a group of polypedons all with similar characteristics

Entisol

a recent soil - weak development with only A and C horizon, fertility depends on parent material

inceptisols

minimal horizon development - only evident horizon is the B horizon

often occurs on steep slopes or alluvial settings

Andisols

Formed from volcanic ash - low density and high organic matter - high water holding capacity

minerology dominated by allophane, imogolite, and ferrihydrite.

Gelisols

permafrost!

Histisols

organic soil with low profile development - low bulk density and high water colding capacity

Folists

a unique type of histosols because they are formed in recent lava flows and are enriched in organic matter

Aridisols

Dry soils or soils characterized by water deficiency through most of the year.

Vertisols

Shrink and swell - high smectite count, fertile with poor physical properties - dark color from Mn oxides - Calcium rich parent material

Mollisols

soft and rich, very fertile with organic matter in top horizon- developed from grasslands

Alfisols

halfway between ultisol and mollisol - developed in moist deciduous forest landscape (think minecraft) moderately leached, semi-fertile, neutral/acidic

Ultisols

leached soil, acidic, low fertility, enriched in aluminum and iron oxide, low activity clay, highly weathered

Spodisols

highly weathered, cooler climate, coniferous forest, infertile, albic->spodic horizon - elluvial (doesn't always have an albic horizon) translocation of organic matter and aluminum iron oxides

Oxisols

highly weathered, humid tropics, high ph, low fertility, deep B horizon, strong P fixation (deficient in phosphorous)

Anthropic epipedon

similar to mollic, but enriched in nutrients due long-term cultivation

Folistic epipedon

thin organic layer saturated foer less than 30 cumulative days in a year

Histic

20-60 cm thick organic material overlying mineral soil, peat or muck layer
with low BD.

Melanic

black organic rich > 30 cm thick developed from volcanic ash, light and fluffy.

Mollic

mineral surface layer with dark color characteristic of high organic matter content (> 0.6% OC > 25 cm thick, BS > 50%) common to grassland soils.

Ochric

pale in color, a mineral horizon that is either too pale, too thin, or too low in OM to be mollic or umbric.

Plaggen

black horizon developed from long-term manure additions

Umbric

same as mollic except BS < 50%, common occurs in areas with high rainfall and where PM low in Ca/Mg.

Albic

light colored eluvial horizons

argillic

subsurface accumulation of silicate clays.

Calcic

accumulation of carbonates.

Cambic

evidence of physical and chemical alteration