Spodosols

Spodosols (from Greek spodos, "wood ash") are acid soils characterized by a subsurface accumulation of humus that is complexed with Al and Fe. These photogenic soils typically form in coarse-textured parent material and have a light-colored E horizon overlying a reddish-brown spodic horizon. The process that forms these horizons is known as podzolization. Many Spodosols support forest. Because they are naturally infertile, they require additions of lime in order to be productive agriculturally. They are divided into five suborders: Aquods, Gelods, Cryods, Humods and Orthods.

Spodosols often occur under coniferous forest in cool, moist climates. Globally, they occupy approximately 4% of the ice-free land area. In the U.S., they occupy approximately 3.5% of the land area.

Spodosols layers of soil
Spodosols have either: (1) an albic horizon (light-colored, leached) and a spodic horizon (accumulation of Fe- and Al-humus complexes); or (2) a plow layer (Ap) consisting of at least 85% spodic materials (USDA-NRCS)

Aquods

Poorly drained Spodosols with a water table at or near the surface for much of the year 

Gelods, Cryods

Gelods — Spodosols of very cold climates (mean annual soil temperature <0°C); Cryods — Spodosols of cold climates

Orthods

common Spodosols that don’t meet requirements of other suborders

Egg-cup Spodosol (New Zealand)

A specific type of Podzolized soil found in New Zealand, particularly associated with kauri forests.