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Soils Exam 1 Part 2
Flash cards for exam 1, part 2
51
Other
Undergraduate 2
02/06/2014

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Cards

Term
Hue
Definition
yellowness or redness
Term
Value
Definition
lightness or darkness
Term
Chroma
Definition
brightness
Term
Higher OM content =
Definition
darker soil
Term
Oxidized Fe3+ (ferric iron)
Definition
reds, yellows; well-drained
Term
Reduce Fe2+ (ferrous iron)
Definition
greys, blues; poorly drained
Term
Well Drained
Definition
30" or greater depth to grey or mottles
Term
Moderately Well Drained
Definition
18-30" depth to grey or mottles
Term
Somewhat Poorly Drained
Definition
10-18" (mostly brown) depth to grey or mottles
Term
Poorly Drained
Definition
10-18" (mostly grey) depth to grey or mottles
Term
Sand
Definition
  • 2-0.5 mm (usually quartz)
  • gritty feeling
  • large voids, rapid draining
Term
Silt
Definition
  • 0.05-0.002 mm (quartz or feldspar)
  • floury feel to soil
  • smaller pores (more numerous), retains water

 

Term
Clay
Definition
  • < 0.002 mm
  • large specific surface area
  • colloidal (stays suspended in water)
  • pores very small, water movement very slow
  • shaped like flakes or platelets
  • properties depend on type/amount
Term
Clay has a _____________ ribbon.
Definition
long
Term
Clay loam has a ______ ribbon.
Definition
medium
Term
Loam has a _______ ribbon.
Definition
short
Term
Silt has a ______ texture.
Definition
floury
Term
Aggregate (Ped)
Definition
arrangement of primary soil particles
Term
Spheroidal
Definition
characteristics of surface (A) horizons; subject to wide and rapid changes
Term
Plate-Like
Definition
Common in E-horizons, may occur in any part of the profile; often inherited from parent material of soil or caused by compaction
Term
Block-Like
Definition
Common in R horizons, particularly in humid regions; may occur in A horizons
Term
Prism-Like
Definition
Usually found in B horizons; most common in soils of arid and semi-arid regions
Term
Sand ________, _________ to transport
Definition
detaches easily, hard
Term
Clay is _______ to detach, _______ to transport
Definition
hard, easy
Term
Silt is ________ to detach, _______ to transport
Definition
easy, easy
Term
Biological Processes That Form Soil Aggregates
Definition
  • soil organisms (earthworms)
  • particle enmeshing by sticky network of roots (polysaccharides) and hyphae (Glomalin)
  • production of organic glues (not water soluble) by microorganisms
Term
Organic Matter
Definition
  • major agent in spheroidal formation and stabilization
  • carbon source for a, b, c & above
  • tillage
Term
Tillage
Definition
  • incorporates OM (short term)
  • increases OM oxidation (long term)
Term
Macropores
Definition
  • interped spaces
  • fast drainage
  • rapid gas exchange
  • biopore (created by living organisms)
Term
Micropores
Definition
  • intraped spaces
  • usually filled with water
Term
As pore space increases, _______ decreases
Definition
Db
Term
Finer silt loams, clay, clay loams =
Definition
lower Db
Term
Depth
Definition
As depth decreases, so does Db
Term
Less OM =
Definition
less aggregation
Term
Soil Crusting
Definition
  • due to aggregate dispersion (high salt content, rainfall action)
  • clogged pores by individual spore particles
  • poor seedling emergence
  • high runoff rates
Term
Gypsum (CaSO4)
Definition
  • promotes flocculation
  • prevents soil crusting
Term
Organic Polymers
Definition
similar to natural organics
Term
Soil Tilth Management Guidelines
Definition
  • minimize tillage
  • time traffic activities (soil should be dry as possible)
  • mulch soil surface
  • add OM
  • include sod crops
  • use cover crops or green manures
  • apply gypsum with or without organic polymers
Term
Soil Aeration Controls
Definition
  • rate of gas exchange within atmosphere
  • proportion of pore spaces filled with air
  • composition of the soil air
  • resulting oxidation/reduction potential
Term
O2 availability controlled by:
Definition
  • macroporosity
  • water content
  • O2 consumption
Term
Gaseous Content
Definition
  • Atmosphere - 21% O2, 0.035% CO2, >78% N
  • Soil Atmosphere - Same N, Lower O2, Higher CO2
Term
400 mV+
Definition
soil is aerobic
Term
320 mV-
Definition
soil is anaerobic
Term
Aerobic Conditions
Definition
C6H12O6 + 6O2 → 6CO2 + 6H2O
Term
Anaerobic Conditions
Definition
C6H12O6 → 3CH4 + 3CO2
Term
Well-Aerated Soil
Definition
Fe3+, Mn4+, NO3-, and SO42- predominate
Term
Poorly Drained/Poorly Aerated Soil
Definition
Fe2+, Mn2+, NH4+, and S2- predominate
Term
Wetlands
Definition
soils that are water-saturated near the surface fore prolonged periods when the soil temperature is high enough to result in anaerobic conditions
Term
Wetland Characteristics
Definition
  • wetland hydrology or water regime
  • hydric soils
  • hydrophytic plants
Term
Falcatative Anaerobic
Definition
399-329 mV
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