Hydric soils are saturated long enough during the growing season to create and anaerobic (low oxygen) state in the soil horizon.

Anaerobic conditions create some distinguishing soil characteristics. The best way to study soil is to dig a hole 30 to 45 centimeters (12 to 18 inches) deep and use your senses to search for the following indicators:

1. sulfurous (rotten egg) smell
2. color: green, dark gray, brown, or black are good indications of wetland soil.
3. Water collecting in the hole, or soil that has a wet feel (sticks together in a ball or oozes between fingers).
4. Mottled coloring (red or black concentrations that result from mineral staining).
5. "Gleyed" soils (gray, blue-gray, green-gray colors, typical of hydric mineral soils).
6. Oxidized rhizopheres (mottling along plant rootlets in mineral soils resulting from excess oxygen escaping from plant roots, interacting with bacteria, and staining the surrounding soil with oxidized iron).