We focused
on the terminology and philosophy of the soil horizon nomenclature system.
Master horizons (upper case letters) are used to identify horizons subjected
to major processes (organic matter addition, weathering, or no weathering
for example).
Most soils, and
soil horizons, are dominated by minerals, but the system contains names for
the rarer peat soils and organic layers on soil surfaces.Most master horizons
are modified with one or more lower case terms that provide more specific
information about soil formation processes. In many soils, there is a gradual
trend from one major horizon to another, creating the need to combine master
horizon symbols to indicate horizons containing properties of more than one
master horizon.
The subtle rules
(established by USDA) for adding horizon symbols will be introduced by example
during the semester and in ESPM 122.