retain water at field capacity longer than other soil horizons. Knowledge of the soil horizons in
combination with the Hydra Probes accuracy will allow the user to construct a more complete
picture of the movement of water in the soil. The horizons that exist near the surface can be 6 to
40 cm in thickness. In general, with increasing depth, the clay content increases, the organic
mater decreases and the base saturation increases. Soil horizons can be identified by color,
texture, structure, pH and the visible appearance of clay films.
More information about soil horizons is provided by the USDA National Resource Conservation
Service at
http://soils.usda.gov/education/resources/k_12/lessons/profile/
More information about the soil horizons in your area can be found by in a soil survey. A soil
survey for your area can be found at
http://soildatamart.nrcs.usda.gov/
Soil
Horizon
Property
O
Decaying plants on or near surface
A
Top Soil, Organic Rich
B
Subsoil, Most Diverse Horizon and the Horizon with the most sub
classifications
E
Leached Horizon (light in color)
C
Weathered/aged parent material
Table 3.3 Basic description of soil horizons.
Figure 3.7 Soil Horizons.
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