Entisols

1

Spodosols Histosols Andisols Oxisols
Ultisols Gelisols Vertisols Aridisols
Entisols Inceptisols Mollisols Alfisols
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Gelisols
9 worldwide 7 US
Soils with permafrost or cryoturbation (mixing
from frost heaving) Cold or frozen much of the
year Can be organic or inorganic soils
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Entisols
A
16 Worldwide 12 US
C
Young, weakly developed soil Typically NO B
horizon (in some cases, can have a very
coarse-textured, poorly formed Bw) Typical
profiles C AC OC OAC Common on ridgetops,
recent deposits (rivers, beaches, ash), urban
areas
4
Inceptisols
10 Worldwide 9 US
Relatively young soils have B horizons More
developed than Entisols but less developed than
any other soil order (soil doesnt meet the
criteria of other orders)
5
Andisols
lt1 Worldwide 2 US
Developed from volcanic material A horizons that
are rich in Al-humic materials Secondary
minerals are predominately amorphous Range in
development from moderate to well-developed
6
Aridisols
12 Worldwide 9 US
Dry soils arid to semi-arid environments Typicall
y less plant growth, A horizon with less OM Can
have many types of B horizons, but Bks are
common
7
Mollisols
7 Worldwide 22 US
Have a mollic A horizon (gt50 Base Sat., with
good physical properties) Usually under
grasslands VERY fertile soils Profiles may be A
B_ C A C or even A E B_ C
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Alfisols
10 Worldwide 15 US
Has a Bt horizon Moderate Base Sat. (lt 50 and gt
35) Lower fertility than Mollisols, but still
excellent soil Common under deciduous forests,
grasslands A, E, Bt1, Bt2, C A, Bt1,
Bt2, BC
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Ultisols
9 Worldwide 10 US
Old, highly weathered soil, acidic Low Base Sat.
(lt 35) Has a Bt horizon Lower fertility than
Alfisols Common under forests Develop in wetter
temperate areas or tropical areas with lots of
leaching O, A, Bt1, Bt2, Bt3, C
10
Oxisols
8 Worldwide lt1 US
Most highly weathered, old soils Laterization
has an oxic B horizon Oxides prevalent, kaolinite
common A horizon low in organic matter Common in
tropical areas with high rainfall, stable
landscape
11
Spodosols
3 Worldwide 3 US
Has a Spodic horizon (Bs, Bhs) Illuvial
accumulation of Fe, Al, O.M. Usually has an E
horizon Acidic, lower fertility Found in cooler,
temperate regions, areas of high leaching,
coarse textured soil O, E, Bhs, Bs, C
12
Vertisols
2 Worldwide 2 US
High content of shrink/swell clay in the upper
1m of soil Montmorillonite Soil expands and
contracts Cracks open in dry season, material
falls in and cracks shut in wet seasonmixes
soil Subhumid to semi-arid areas Deep A horizon
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Histosols
1 Worldwide 1 US
Organic Soil (little mineral material) O
horizons Found in waterlogged areas of any type
of climate Wetlands When drained, can be
fertile but difficult to manage due to poor
physical properties Oa, Oe, Oi