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Soils Science 200 U of A
Exam 1 Information
55
Environmental Studies
Undergraduate 3
02/12/2014

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Term
Hue
Definition
Range from yellow to red in a soil.
Term
Value
Definition
Lightness or darkness of a soil
Term
Chroma
Definition
Intensity or brightness. Example: a chroma of 0 would be a neutral gray.
Term
Land Capability Classes
Definition
Used to manage soil usage. It can minimize soil erosion. The classes state what factors limit the usage of each area of land. There are 8 classes and 4 subclasses that show what that limiting factor is.
Term
Land Capability Classes I-VIII
Definition
Class I is the least limited, So a class I land will be the most useful for agriculture (prime agricultural land). Class VIII is the most limited, So a class 8 land is very susceptible to damage and will be reserved for soley plant and animal use.
Term
Land Capability Sub Classes
Definition
Sub-classes shows which each area of land is most susceptible to, and is added along with the class number. (e) erosion, (w) wetness, drainage, flooding, (s) root zone limitations, acidity, density, and shallowness, (c) climate limitations, short growing season. Example: 2e would be land that is slightly susceptible to erosion.
Term
Stoke's Law
Definition
V=kr^2 The velocity is proportional to the squared
k is a constant radius of each particle of soil. There is little
V=velocity variation in the density of soil particles.
r=radius of each particle
Term
Master Horizons: O horizon
Definition
Organic layers formed from fallen leaves and other plant and animal remains. They undergo varying transformations for this formation to occur. Referred to as the forest floor.
Term
A horizon:
Definition
Most eroded layer, lost some materials because of translocation. This horizon is dominated by mineral particles but have been darkened by water leaching organic materials from the surface layer down into the soil. AKA: topsoil, plow layer. Usually the layer that is plowed and brought up that helps plants grow the most.
Term
E horizon
Definition
Zone of maximum leaching or EEEluviation. of clay, Al Fe oxides. lighter than the A horizon above it, and lighter than the B horizon below it. Common in forests, never grasslands
Term
B horizon:
Definition
Subsoil horizon with much less organic matter. Composed of Iron, silicate clays, oxides, aluminum, gypsum, calcium carbonate. These materials accumulated from being washed down from the surface. Mostly formed by illuviation: Materials washing in from horizons above.
Term
C horizons
Definition
Plant roots and microorganisms extend below horizon B usually in humid regions. Chemical change in soil water occurs. Least weathered horizon of soil.
Term
Diagnostic Horizons: Epipedons
Definition
Diagnostic horizons that occur at the soil surface. The whole upper part of the soil that contains organic matter.
Term
Mollic Epipedon
Definition
Noted for its dark color. Accumulated organic matter,
Term
Umbric
Definition
Organic matter, dark color, but lower saturation than mollic
Term
Ochric epipedon
Definition
mineral horizon not as deep as mollic or umbric. lighter in color.
Term
Argillic Horizon
Definition
accumulation of silicate clays
Term
Kandic
Definition
Accumulation of Fe and Al oxides. But low acidic silicate clays.
Term
Oxic Horizon
Definition
highly weathered, high in Fe and Al oxides and low-activity silicate clays. Found in tropical areas.
Term
Spodic Horizon
Definition
illuvial horizon with colloidal organic matter and Al oxide. Forest soils. Cool humid climates
Term
Albic Horizon
Definition
light colored eluvial low in clay and oxides of Fe and Al.
Term
Illuviation
Definition
The movement of materials or materials being washed from an upper horizon layer to a lower one.Result of Eluvation, illuviation is an accumulation of those materials leached by the process of eluviation.
Term
Eluviation
Definition
Maximum leaching, or water seeping through the soil bringing down chemicals such as silicate clay, Al and Fe oxides.
Term
Soil Structure
Definition
The nature of the system of pores and channels in the soil. Determines the ability for the soil to hold and conduct the water and air necessary for sustaining life growing in it. Drainage; erosion susceptibility; air flow (aeration) gas transport.
Term
Peds
Definition
Dirt clods, used to determine structure. Such as... shape and size
Term
Alluvial Deposition
Definition
Water deposition: Water moving soil elsewhere. Causes some additions to the soil horizons. Example: alluvial fan: a deposit of sediment built up by a stream causing a fan shape in the soil.
Term
Colluvial Deposition
Definition
Down slope deposition. develops at the base of a hill slope from concentration surface runoff. Consisting of silt and bigger rock fragments. Avalanches, GRAVITY.
Term
Loess
Definition
Wind blown deposition, soil moved by wind.
Term
Particle Density
Definition
Does not change is an assumed value. Drainage aeration a microbial value.
Term
Bulk Density
Definition
Mass of Dry soil/ volume of the soil cylinder

Volume of cylinder= V=(Pi*r^2)(Height)
Term
Particle Density
Definition
fixed value used to find porosity
Term
Porosity
Definition
Bulk density/ Particle density (fixed value) multiply by 100 then subtract from 100.
Term
Jenny Equation: 5 soil forming factors
Definition
1. Climate: Very important in determining the environment that the soil will be forming in. Affects the types of organic materials, such as which plants will grow. It affects amount of moisture, and which soil horizons will end up forming either because of aeration or leaching.
2. Organic material: (biota) dead plants and animals, and living. Animals prevent erosion and recycle material from under the soil to the top of the soil creating organic material.
3. Relief or topography: The way the landscape is shaped or sloped affects soil formation greatly, because depending on how it is shaped can cause water to flow down a slope creating a different soil structure than if it stayed at the bottom of a slope.
4. Parent Material: The parent material is the building block of every soil formed. The type of parent material depends on the location and also depends on the other four soil forming factors.
5. Time: Very important because the longer the parent material has had to break down the more developed all the soil horizons will be.
Term
Soil Taxonomy: Orders

SOIL ORDER 1
Definition
Gelisols: Soils with a lot of permafrost, found in the tundra. (Cryoturbation)
(Root: EL)
Term
ORDER 2: Histosol Root= ist
Definition
Histosols: Very high water capacity, more than 20 percent organic matter. Very rare. Many cations
Term
ORDER 3: Spodosols Root= Od(s)
Definition
Spodosols: Acid, sandy forest soils, highly leached giving andic properties. Light upper horizons to darker yellowish lower horizons.
Term
ORDER 4: ANDISOLS Root: Ands
Definition
Volcanic ash soils. Not as much development time. high water capacity. Easily tilled, low density. Organic matter accumulation.
Term
ORDER 5: Oxisols Root: OX
Definition
Most weathered soil order. Hot moist climates. tropical rain forest. deep oxic subsurface horizon Moderatley acidic clay, and high concentrations of Al and Fe
Term
Order 6: Vertisols: Root: ERT
Definition
Dark swelling and cracking clays. subhumid/semiarid environments. rainfall moistens cracks in clay and then it expands and hardens again. almost black in color most times.
Term
Order 7: Mollisols Root: OLL
Definition
Dark solft soils of grasslands. Calcium rich organic matter. granular or crumb surface horizon.
Term
Order 8: alfisols Root: ALF
Definition
Argillic (Clay bearing) or natric horizon, moderately leached. more weathered then most soils besides spodosols and ultisols and oxisols. Mediterranean climates. deciduous forests. Less acidic clay than Ultisols.
Term
Order 9: Ultisols Root: ULT
Definition
More highly weathered than alfisols, also argillic horizons, the only difference is ultisols have acidic clay and alfisols have less acidic clay.
Term
Order 10 :Ardisols Root: ID like arid
Definition
Dry soils. Arid environments. most abundant soil next to entisols. Water deficiency. Light colored top layer (epipedon). and little to no organic matter.
Term
Order 11: Entisols: Root: ENT
Definition
Recent soils: little to no development. no B horizon. Forms in shifting sand or on steep rocky slopes. or in recent alluvium (Water deposition).
Term
Order 12: inceptisols Root: ept
Definition
Has few diagnostic characteristics. ochric or umbric epipedon, cambic horizon.
Term
Sub-orders
Definition
Based on the root of the order. Entisols= order suborder=aquents
Term
Sub-orders
Definition
Based on the root of the order. Entisols= order suborder=aquents
Term
Great- group
Definition
more than 400 Examples: umbric, argillic (more clay) (, and natric....)
Term
Sub-group
Definition
more devisions of great group.... (Vermic Hapludolls ...)
Term
Families
Definition
Names are normally longer
example: Loamy sandy, mixed, active, cryic...
Term
Silt
Definition
.05-.002 cm particles spherical smoother than sand
Term
Sand
Definition
Larger particles 2mm-0.05mm in diameter spherical, more coarse than silt and clay.
Term
Clay
Definition
less than .002mm plate shaped, sticky texture. attracts cations. reacts with water causing shrinking and swelling
Term
Physical weathering:
Definition
Size and shape alterations intensity of weathering can help determine soil type
Term
Chemical weathering
Definition
Soil composition changes adding or loss of chemicals in the soil.
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