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75 Cards in this Set
- Front
- Back
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List the five main functions of soil in an ecosystem...(*plus two extras)
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1. Medium for plant growth
2. Recycling of nutrients and organic matter 3. Controls the flow and purity of water 4. Habitat for soil organisms 5. Functions as a building material; Engineering medium *6. Modifier of the atmosphere *7. Information storage medium |
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What are the five master soil horizons?
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TOP-SOIL
O - pure organic matter; degree of decomp. A - mineral soil; high organic matter SUB-SURFACE E - site of eluviation/leaching B - site of illuviation/accumulation C - substratum; least weathered parent material *R - bedrock* |
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What are the four components of soil and their percent composition of each?
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Water ~ 20-30 %
Air ~ 20-30 % Minerals ~ 45 % Organic Matter ~ 5 % |
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What are the sub-horizons under master horizon O?
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i ~ identifiable; lightly decomposed
e ~ slightly identifiable; mod. decomposed a ~ unidentifiable; highly decomposed |
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Define: Solum
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Uppermost section of soil where there is biological activity.
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Define: Regolith
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Loose earth above solid rock
("can you stick a fork in it?") |
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Define: Parent material
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Chemically weathered material from which soil forms
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Define: Saprolite
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Regolith that has weathered in place from underlying bedrock
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What are the sub-horizons within master horizon A?
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p ~ plowed surface (agricultural soil)
b ~ buried surface |
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What are the sub-horizons within master horizon B?
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t ~ clays
g ~ gleying (iron depletion) k ~ carbonates (very dry) s ~ translocated sesquioxides h ~ humus w ~ weak B definition o ~ residual oxides (tropical soils) |
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What are the sub-horizons within master horizon C?
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r ~ saprolite (highly weathered bedrock)
k ~ carbonates |
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The type of mineral component in soil depends on what?
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The underlying bedrock
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While it makes up a small percentage of soil content, organic matter is....?
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- Hugely influential on soil properties
- Synthesized by soil microbes |
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What are the four main functions of organic matter in soil?
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1. Structure (soil glue!)
2. Water holding capacity 3. Nutrients for plants 4. Food/energy for soil organisms |
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The air in soil pores are high in ______ and low in ______.
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Carbon dioxide; Oxygen
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Soil is.......(3 things)
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1. 4-dimensional complex habitat
2. self-organizing body 3. living thing |
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What are the five factors of soil formation?
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*CLORPT*
[Active factors] 1. Climate/environment 2. Organisms [Passive factors] 3. Relief/topography 4. Parent material 5. Time |
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What are the two processes that create soil?
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1. Weathering of minerals (primary) to clay (secondary)
2. Accumulation of organic matter and decomposition to humus |
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What are the three major types of parent material?
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1. Rock
2. Sediment 3. Organic matter |
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What are the three major rock types and their properties?
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Igneous ~ cooled magma; faster cool = finer grain, slower cool = coarse grain
Sedimentary ~ decomposition of igneous rock, compaction of particles Metamorphic ~ fusion of rock sediments, but not fully fused |
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Fast forming rocks lead to........?
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Finer texture minerals and soils (i.e. clays and silts)
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Darker minerals generally.........?
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Fast weathering, yield more fertile soils
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What are the different "transported sediments" within Parent Material?
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[Mixed materials]
Glacial till/iceberg erratics ~ ice Colluvium ~ gravity [Sorted materials] Alluvium ~ moving water Lacustrine ~ lake water Marine ~ ocean Aeolian dust/loess ~ wind |
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What are the two parts of climate as a soil forming factor?
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- Temperature
- Effective precipitation |
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What are the four kinds of organisms as a soil forming factor?
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- Vegetation ~ roots, leaves
- Microbes ~ decomposition - Soil animals ~ pathways for subterranean movement - Humans ~ tillage, compaction, chemicals |
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What are the three factors of topography as a soil forming factor?
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- Relief ~ steep/flat
- Aspect ~ direction of face (N,W,E,S) - Elevation ~ linked to temp/organisms |
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Define: Krotovina
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Tunnels created by various soil organisms that allow for movement of water
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Define: Bioturbation
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Organisms naturally moving and tilling the soil.
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List the various parts of a landscape from summit down to floodplain....(5 total)
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Summit
Shoulder Backslope Toeslope Floodplain |
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With a 10 degree temperature increase, there is.......?
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a doubling in biological activity (as well as increased pedogenesis)
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The main effect of time as a soil forming factor is.....?
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Soil horizonation/ maturation
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What are some factors that retard soil development? (7)
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- Low rainfall/relative humidity
- Parent materials mostly quartz - High clay content - High water table - Steep slopes - Cold temperature - Presence of toxins |
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What are the four processes that affect soil development (add examples)?
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Additions: rain, organic matter, capillary movement
Losses: runoff, leaching Translocations: organic matter, clay, iron Transformations: organic matter to humus, primary minerals to clay |
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What are the six types of chemical weathering?
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[Acid/base]
1. Hydration ~ addition of water 2. Hydrolysis ~ breakup of water, H+ acts as acid for weathering 3. Carbonation ~ formation of carbonic acid 4. Complexation ~ organic acids interact with metal ions; chelation [Redox] 5. Oxidation-Reduction ~ exchanged of electrons [All leading to....] 6. Dissolution |
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What is the main key to weathering (chemical and physical)?
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Water (effective precipitation)
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Describe the current USDA soil classification system...
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- Each part of the name tells you something about the soil.
- Used since 1965 - Based on soil properties than can be measured/observed: color, moisture, structure, etc. |
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Define: Pedon
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The fundamental unit of soil classification (1-10 sq. meter area to a depth of 3-4 meters)
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Define: Polypedon
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Contiguous group of similar pedons
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Define: Soil series
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Group of polypedons with similar charactistics
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What are the six categories of general soil classification?
(*Taxonomy) |
Order
Suborder Great group Subgroup Family Series |
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Level of description:
One word, formative element, ending in -sol |
Order (i.e. Andisol)
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Level of description:
2 parts, tells something about properties, contains the order |
Suborder (i.e. Cryand)
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Level of description:
3 parts, adds more info, contains order and suborder |
Great group (i.e. Duricryand)
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Level of description:
2 words, adds more info, contains great group, suborder, and order |
Subgroup (i.e. Aquic Duricryand)
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Level of description:
5-6 words, more info about soil, longest chain |
Family (i.e. Medical-skeletal amorphic Aquic Duricryand)
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Level of description:
Single name with no real scientific information |
Series (i.e. "Grousehilll")
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Explain "genetic" vs. "diagnostic" labels...
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Genetic: based on observational data; initial guess as how it should be identified
Diagnostic: based on specific lab data (texture/chemical) **Diagnostic labels help classify the soil taxonomically** |
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What six soil orders are considered the less developed or "young" soils?
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Entisol
Inceptisol Gelisol Histosol Andisol Aridisol |
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What six soil orders are considered the more developed or "mature" soils?
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Vertisol
Mollisol Ultisol Alfisol Spodosol Oxisol |
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Which two soil orders are a pair that develop in tropic conditions and under extreme weathering?
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Ultisol
Oxisol |
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Which two soil orders are paired as being the youngest soils?
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Entisol
Inceptisol |
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Which two soil orders are paired as being the most fertile and productive?
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Mollisol
Alfisol |
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Which two soil orders are known for having Albic horizons (E horizons; zone of depletion/elluviation)?
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Alfisols
Spodosols |
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Explain: Entisols
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- Newly developed soil
- Very little horizonation - Exist in areas where their parent material hasn't reacted to soil-forming factors (i.e. high heat, high moisture, etc.) |
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Explain: Inceptisols
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- Young soil
- Weak horizon development - Presence of Bw horizon (i.e. Cambic) - Found in most climatic and physiographic conditions, like Entisols |
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Explain: Andisols
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- Formed on volcanic ash and cinder deposits
- Found near volcano source or downwind from the volcano - Aluminum-Humus complexes - Light, fluffy soil; easily tilled, yet high water capacity and resistant to water erosion - High fertility |
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Explain: Gelisols
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- Permafrost and cryoturbation (frost churning)
- Broken/convoluted horizons - Infertile |
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Explain: Histosols
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- Organic soils
- Peat; comprised of partially decomposed, fibrous remains of plant tissues - Wet, boggy, marsh climates |
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Explain: Aridisols
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- Dry soils
- Water deficiency; no available water - Light in color; low fertility |
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Explain: Vertisols
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- High clay content; shrink-swell
- Subhumid to semiarid environments - Slickensides develop as the clay swells around once open cracks (Bss) |
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Explain: Mollisols
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- Dark, soft, fertile soils
- Found in grasslands - Has Mollic epipedon |
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Explain: Alfisol
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- Moderately leached (E horizon)
- Cool-hot humid climates - Deciduous forests - Argillic (Bt) horizon - Albic (E) horizon |
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Explain: Ultisols
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- Highly leached
- Tropical climates - Highly weathered, High oxides - Less weathered than Oxisol |
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Explain: Spodosols
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- Sandy, forest soils
- Acid parent materials - Albic (E) horizon - Moist, wet (subtropic) conditions |
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Explain: Oxisols
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- Most highly weathered
- Tropic conditions ~ hot and wet - Highly leached |
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SUB-ORDERS:
List the 6 moisture regimes from WET to DRY... |
Aquic - saturated for extended period
Udic - not dry more than 90 days Ustic - dry 90 to 180 days Aridic - wet less than 90 days Xeric - dry summer, wet winter Torric - dry and hot |
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SUB-ORDERS:
List the 7 temperature regimes from COLD to HOT... |
Pergelic
Cryic Frigid Mesic Thermic Hyperthermic Iso- (frigid, mesic, thermic, hyperthermic) |
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SUB-ORDERS:
List 5 key features as suborders... |
Fluv- fluvial; from river
Psamm- sandy Alb- albic horizon; leached Arg- argillic horizon (Bt); clayed Orth- "true definition"; "Orthod" = spodosol |
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List the 5 naturally-occuring diagnostic surface horizons, as well as the 2 human-caused horizons...
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Natural:
Mollic - high base sat. (Mollisol); grassland Umbric - low base sat. (Alfisol); less fert. than Mol. Ochric - low base sat.; light/infertile; less organic matter Melanic - volcanic materials (Andisols); light/fluffy Histic - peat bog; all vegetative (>20% OM) Human: Anthropic - mollic-like; added P+; human-modified for agriculture (therefore Ap) Plaggen - manure and pottery shards added over years |
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List the 6 diagnostic subsurface horizons and their qualities...
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Albic: light color; elluviation (E); low in clay/oxides
Cambic: weakly developed (Bw) Spodic: illuviated with accumulations of O.M. and oxides Agrillic: subsurface accumulation of silicate clays (Bt) Oxic: weathered, high Fe/Al oxides Calcic: carbonates, often chalk like (Bk) |
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What are the distinctions for each (used as suborder, great group, or subgroup)?
- Agri - Psamm - Calc - Cry - Dur - Fluv - Hapl - Torr - Hum |
Agri: clay (Bt)
Calc: carbonates (Bk) Dur: hard Hapl: "meets minimum requirements" Hum: humic materials Psamm: sand Cry: frozen Fluv: fluvial materials Torr: dry |
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What are the three general types of subgroup distinctions?
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Intergrades
Extragrades Central concept |
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How are Families differentiated?
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Particle size, mineralogy, fertility, temperature class
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Oregon has every soil order except what two?
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Oxisols and Gelisols
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What is the size differentiation for:
Sand, Silt, and Clay? |
Sand is >0.05mm
Silt is 0.05mm to 0.002mm Clay is <0.002mm |
