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Spodosols
By: Ross McHugh
Spodosols – General
Characteristics
Acid soils characterized by a subsurface accumulation
of humus that is complexed with Al, and Fe.
Typically form in coarse-textured parent material and
have light colored E horizon overlying a reddish brown
spodic horizon.
The process that forms these horizons is known as
podzolization.
General Characteristics cont.
Central concept of Spodosols is that of soils in which
amorphous mixtures of organic matter and aluminum,
with or without iron, have accumulated.
In undisturbed soils there is normally an overlying
eluvial horizon, generally gray to light gray in color,
that has the color of more of les uncoated quartz.
Most spodosols have little silicate clay. The particle size
class is mostly sandy, sandy-skeletal, coarse-loamy,
loamy, loamy-skeletal, or coarse-silty.
Spodosols in Minnesota
Spodosols are only found in Minnesota as the suborder
Orthods, which are forested soils with a sandy texture.
They are frequently found in small areas that are
downslope from a summit. Orthods are covered by
forests of aspen or pine and are rarely used for
agriculture because of their acid, droughty nature.
Locations and Area
Spodosols often occur under coniferous forests in cool
moist climates.
Globally, they occupy approximately 4% of the ice free
land area.
In the US they occupy approximately 3.5% of land area
Within Minnesota Spodosols, particularly the suborder
Orthods only occupy 122,000 acres or 0.2% of area.
Global Distribution
Percent of Land Area in
Spodosols
Minnesota Soil Suborders
- Shown on the map as the
Pink color. Not very
prevalent but can be seen in
patches throughout the
North Central and East
Region of Minnesota.
Diagnostic Horizons
Presence of a spodic diagnostic horizon, a subsurface
accumulation of soil organic matter with aluminum
and or iron sesquioxides.
Spodic horizon = an illuvial horizon containing active
amorpheous material and organic matter and Al with
or without Fe. Spodic horizons have the following
characteristics:
Suborders
Spodosols are divided into 5 suborders
Aquods
Gelods
Cryods
Humods
Orthods
Spodosols suborders