Orthic Melanic Brunisol (O.MB)

Common horizon sequence: LF, Ah, Bm, Ck or C

These soils have the general properties specified for the Brunisolic order and the Melanic Brunisol great group. Characteristically, they have a forest mull Ah horizon with fine to medium granular structure and a brownish-colored Bm horizon with a chroma of 3 or more. The color of the B horizon normally fades with depth. Commonly the C horizon is calcareous.

Orthic Melanic Brunisols are identified by the following properties:

1. They have either an Ah horizon 10 cm thick or more or an Ap horizon at least 10 cm thick with a moist color value less than 4. The A horizon does not meet the requirements of a chernozemic A.
2. They have a pH (0.01 M CaCl₂) of 5.5 or more as specified for the great group.
3. They have a Bm horizon at least 5 cm thick.
4. They lack an eluvial horizon, Ae or Aej, at least 2 cm thick.
5. They lack mottles that indicate gleying as specified for Gleyed Melanic Brunisols.

Orthic Melanic Brunisols and all other subgroups of Brunisolic soils may have a lithic contact within 50 cm of the surface or have turbic or andic features. These features are separated taxonomically at the family (lithic, some andic) or series (turbic) levels, or as phases of any taxonomic level above the family.

Note: Diagnostic horizons are underlined.

List all known examples