THE SOIL THAT WE CLASSIFY
"...Soil is the collective term used for the natural bodies, made up
of mineral and organic materials, that cover much of the earth's
surface, contain living matter and can support vegetation out of
doors, and have in places been changed by humanactivity. The
upper limit of soil is air or shallow water.
Its horizontal boundaries are where it grades to deep water or to
barren areas of rock or ice. The lower boundary that separates
soil from not-soil underneth is most difficult to define.
Soil consists of the horizons near the earth's surface which, in
contrast to the underlaying rock material, have been altered by
the interactions, over time between climate, relief, parent
material,s, and living organisms..." (Soil Survey Staff, 1996).
Epipedons | Subhorizons | FAO-UNESCO System | WRB System |