Melanic Brunisol (MB)

These are Brunisolic soils having a dark-colored Ah horizon and a relatively high degree of base saturation as indicated by their pH. They occur typically under deciduous or mixed forest vegetation on materials of high base status in areas of boreal to mesic temperature class and humid moisture subclass, but they are not restricted to such environments. Many uncultivated Melanic Brunisols have a forest mull Ah horizon associated with the activity of soil fauna, especially earthworms.

Melanic Brunisols have an Ah horizon at least 10 cm in thickness or an Ap horizon 10 cm or more in thickness with a moist color value of less than 4, and either a Bm, Bfj, or Btj horizon at least 5 cm thick. The pH (0.01 M CaCl2) is 5.5 or more in some part or all of the uppermost 25 cm of the B horizon, or in some part or all of the B horizon and the underlying material either to a total depth of 25 cm or to a lithic contact above that depth. Melanic Brunisols may have L, F, and H horizons and Ae or Aej horizons, but they do not have solonetzic or Podzolic B horizons, or Bt horizons. The Ah horizons of some Melanic Brunisols have all of the properties diagnostic of a chernozemic A except the associated soil climate. If cultivated, these soils are classified as Melanic Brunisols if part of the Bm, Btj or Bfj horizon remains below the Ap and as Humic Regosols if the Ap includes all of the former B horizon.

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.

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Eluviated Melanic Brunisol (E.MB)

Common horizon sequence: LF, Ah, Ae or Aej, Bm or Btj, Ck or C

These soils have the general properties specified for soils of the Brunisolic order and the Melanic Brunisol great group. They differ from Orthic Melanic Brunisols by having an eluvial horizon, Ae or Aej, at least 2 cm thick. The underlying horizon may be a Btj with thin clay skins on some surfaces or, less commonly, a Bfj. Otherwise, they have the diagnostic properties of Orthic Melanic Brunisols.

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Gleyed Melanic Brunisol (GL.MB)

Common horizon sequence: LF, Ah, Bmgj, Cgj or Cg or Ckg

These soils have the general properties specified for soils of the Brunisolic order and the Melanic Brunisol great group. They differ from Orthic Melanic Brunisols by having faint to distinct mottles within 50 cm of the mineral surface, or distinct or prominent mottles at depths of 50-100 cm. Otherwise, they have the diagnostic properties of Orthic Melanic Brunisols.

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Gleyed Eluviated Melanic Brunisol (GLE.MB)

Common horizon sequence: LF, Ah, Ae or Aej, Bmgj or Btgj, Cgj or Cg or Ckg

These soils have the general properties specified for soils of the Brunisolic order and the Melanic Brunisol great group. They differ from Eluviated Melanic Brunisols by having mottles that indicate gleying. Gleyed Eluviated Melanic Brunisols have either an Ae or an Aej horizon at least 2 cm thick, and mottles as specified for Gleyed Melanic Brunisols.

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Note: Diagnostic horizons are underlined.