Ch.3- Soils Flashcards
Soil - agricultural
surface layer of earth that is capable of supporting rooted plant life, where the lower limit coincides with lower limit of biological activity (usually only extends a few meters below the surface)
Soil - engineering
all unconsolidated earthy materials that overlie bedrock
What is one of the problems with the engineering definition of soil?
It is considered anything soft enough that you don’t need to blast, or things that you can easily shovel – this classifies weaker rocks, like shale, as soil
Regolith
entire mantle of loose, unconsolidated rock material of whatever origin that overlies coherent bedrock (organic or otherwise)
Residual soil
soil formed from weathered, but not eroded, from the bedrock.
Transported Soil
the product of erosion, broken and deposited elsewhere
What sedimentary features often mark transported soil?
Ripples/dunes
Types of Transported Soils (6)
- Alluvium
- Colluvium
- Aeolian Deposits
- Glacial Deposits
- Marine Deposits
- Lacustrine Deposits
Alluvium
transported by water
Colluvium
transported by gravity; often the product of a landslide
Aeolian Deposits
transported by wind
Marine Deposits
Deposited in a saltwater environment
Lacustrine Deposits
Deposited in a lake/freshwater environment
Pedon
The unit cell of a soil- the smallest volume that can be recognized as a soil individual
Characteristics of a Pedon (3)
- has 3 dimensions
- ranges from 1-10 sq.m
- roughly hexagonal in shape
Pedogenesis
Process of soil formation as the integral result of a combination of soil forming factors
Soil forming factors:
- Parent Material
- Time
- Climate
- Topography
- Vegetation
Soil is the product of ____ and ____
Erosion and Weathering
Soil Horizons
- O - organic topsoil
- A - topsoil, zone of leaching
- E - eluviation, incredibly leached
- B- subsoil, zone of accumulation
- C - unaltered material
- R - rock
What is the mnemonic for remembering soil orders?
Every
ANteater
GEnerally
INgests
Many
ALFalfas
SPORradically
And ,
VEry
Often,
ULTImately
Soil Orders:
-Entisol
-Andisol
-Gelisol
-Inceptisol
-Mollisol
-Alfisol
-Spodosol
-Aridisol
-Vertisol
-Oxisol
-Ultisol
Entisols
minimal soil profile development
recENT
Location: places with flooding; sand blowing in frequently; landslides
Andisols
develops on fresh volcanic ash, rich witb nutrients
ANDo, ANDesite
Locations: areas near active volcanoes (Ex. Hawaii)
Gelisol
minimal soil profile development, permafost regions – development paused due to freeze-thaw cycles
gELId- greek, cold
location: areas with permafrost
Inceptisols
well developed A-horizon, weak B-horizon; no strong boundary between the two
incEPTion- latin, beginning
Mollisols
thick, dark, highly organic A-horizon
MOLLIS- latin, soft
Location: under grasslands (E.g., Central US)
Alfisols
thin A-horizon over clay rich B-horizon, well developed E-horizon; loamy soil
pedALFer
Location: forests; humid, dry regions
Aridisols
thin A and B horizons with little organics, caliche in B or C horizons
arID
Locations: aridic moisture regimes
Caliche
an area of calcium carbonate formed in the soils of semiarid regions.
Histosols
Wet, organic-rich soils; thick O and A horizons
hIStos - greek, tissue
Location: wetlands and bogs
Vertisols
high clay content; shrinks an swells/w soil moisture variation; driven by wet-dry cycles, NOT freeze-thaw; no development of any horizons
Oxisols
highly weathered, red-B horizon from oxidized Fe; end product of mafic parent material soil formation
OXide
Location: Hawaii, Puerto Rico, US Virgin Islands
Ultisols
highly weathered, B-horizon enriched in clay and Al-oxides; end product of a felsic parent material soil formation
ULTimate
Location: warm and humid environments
Which soil order makes up a majority of continental crust?
Ultisols
Which soil order contains highly weathered, oxidized material?
Oxisols
In which areas are oxisols most commonly found?
Islands (Hawai’i, Puerto Rico, US Virgin Islands)
What soil order is most commonly found in areas with permafrost?
Gelisols
____ - ____ cycles inhibit the development of Gelisol.
freeze-thaw
____ - ____ cycles inhibit the development of horizons in Ventisols.
Wet-dry
Histosols are most commonly found in what areas?
Swamps/wetlands
Alfisols are most commonly found in (humid/arid) environments
Humid
Caliches are most commonly found in ….
Aridisols
____ are found under grass-lands in the central US and is extremely good for farming.
Mollisols
_____ are prized by farmers for its nutrient-dense material
Andisols
While they have a well developed A layer and a moderately developed B layer, _____ have no distinction between horizons
Inceptisols
Alfisols are often found in _____
forests
_____ have recent soil profile development
Entisols
Entisols are common in places where ________ or ______ often occur.
landslides; flooding
Spodisols are often found in…
cool and moist climates
____ are the end goal of mafic parent material soil formation
oxisols
____ are the end goal of felsic parent material soil formation
ultisols
