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