Albic Horizon - Soil Geography of the USA: A Diagnostic-Horizon Approach - page 77

Chapter 10
Albic Horizon

10.1 Introduction

The albic horizon is a bit unusual in that it is a diagnostic subsurface horizon that in
some soils, namely, the Spodosols, occurs at or near the mineral soil surface. The
albic horizon is defined as an eluvial horizon, 1 cm or more thick , that “generally
occurs below an A horizon but may be at the mineral soil surface” (Soil Survey
Staff 2010 , p. 9). An argillic, cambic, kandic, natric, or spodic horizon or a fragipan
generally occurs below the albic horizon. In bisequal soils, the albic horizon may lie
between a spodic horizon and either a fragipan or an argillic horizon, or it may be
between an argillic or kandic horizon and a fragipan. It may lie between a mollic
epipedon and an argillic or natric horizon or between a cambic horizon and an
argillic, kandic, or natric horizon or a fragipan. The albic horizon may separate
lamellae that together meet the requirements for an argillic horizon. However, these
lamellae are not considered to be part of the albic horizon.
The albic horizon contains soil materials with a color that is largely determined
by the color of primary sand and silt particles rather than by the color of their
coatings. This definition implies that clay and/or free iron oxides have been
removed from the materials or that the oxides have been segregated to such an
extent that the color of the materials is largely determined by the color of the
primary particles. The specific colors are a chroma of 2 or less; and either a color
value, moist, of 3 and a color value, dry, of 6 or more; or a color value, moist, of 4 or
more and a color value, dry, of 5 or more; or a chroma of 3 or less; and either a color
value, moist, of 6 or more; or a color value, dry, of 7 or more; or a chroma that is
controlled by the color of uncoated grains of silt or sand, hue of 5YR or redder, and
the color values above.
Relatively unaltered layers of light colored sand, volcanic ash, or other materials
deposited by wind or water are not considered albic materials, although they may