Epipedon

An epipedon is diagnostic surface horzon in Soil Taxonomy

The general rule of thumb is to determine the properties after mixing the soil to a depth of 18 cm. An absolute exception to this 'rule of thumb' is soil structure, and it is never to be homogenized or mixed.

Mollic

Umbric

Like Mollic except the percent base saturation is less than 50%.

Ochric

Epipedon that does not meet the requirements of the other epipedons.

None

If the epipedon is stripped there is none.

Histic

Epipedon of organic soil material 20 to 40 cm thick, unless composed of sphagnum fibers, then 20 to 60 cm thick. May consist of mineral soil material if plowed.

Folistic

Epipedon of organic soil material saturated less than 30 days, ≥ 15cm thick, unless composed of sphagnum fibers then ≥ 20 cm.

Anthropic

Epipedon like mollic except for P2O5 content and duration of available moisture.

Melanic

Epipedon with andic soil properties, > 30 cm thick within 30 cm of the soil surface, value/chroma < 2/2 moist, > 4% OC and average > 6% OC, melanic index < 1.70.

Plaggen

Epipedon of human-induced horizon from manuring and spading.