Agriculture Reference
In-Depth Information
Alfisol
Oi 0 - 5 cm; undecomposed organic material, mainly bark, twigs, and needles.
Oe 5 -10 cm; partially decomposed organic material like that of the horizon
above.
A 10 - 15 cm; dark gray (10YR 4/1) very stony loam, strong fine granular structure.
E 15 - 32.5 cm; pinkish gray (7.5YR 7/2) very stony very fine sandy loam, weak
thick platy to strong fine granular structure.
E/B 32.5 - 45 cm; mixed pinkish gray (7.5YR 7/2) very stony loam, weak fine
subangular structure.
Bt1 45 - 81 cm; brown (7.5YR 5/3) very stony clay, moderate fine subangular
blocky structure.
Bt2 81 - 91 cm; brown (7.5YR 5/3) very stony clay loam, weak medium
subangular blocky structure.
C 91 - 163 cm; brown (7.5 YR 5/4) extremely stony clay loam, massive.
Figure 1.1.
An example of an Alfisol; this is the Seitz soil series, which is the state soil of
Colorado (see Ref. 2).
horizons of varying texture, structure, color, bulk density, and other proper-
ties. Typically they are, as the name implies, horizontal, and are of varying
thickness. A pedon is the smallest unit that can be considered “a soil” and con-
sists of all horizons extending from the soil surface to the underlying geologic
strata. An area consisting of similar pedons is called a
polypedon
.
Soil features, texture, peds, profiles, and other properties and materials go
together in different ways to form different soils. Soil scientists in the United
