Vertisol (V)
These are soils that generally occur in the most arid portion of the climatic range of Vertisolic soils. They are primarily associated with a native vegetation of xerophytic and mesophytic grasses and forbs. They have both a vertic and a slickenside horizon as specified for the Vertisolic order. Except for the poorly drained members, they also have brownish-colored A horizons (dry color value of 3.5 or lighter, chroma usually greater than 1.5 dry, and organic C usually 3% or less) similar to associated Chernozemic soils. However, they differ from Chernozemic soils in that it is often difficult to separate the A horizon from the rest of the solum based on color alone, and the Ah horizon is massive and hard when dry. They also lack other horizons, in the upper solum, common to Chernozemic or other soils.
The poorly drained members occur commonly in depressional positions associated with better-drained Vertisolic soils. Besides the presence of both a slickenside and a vertic horizon, they have the general characteristics specified for the Gleysolic order. As well, under native conditions they lack a mineral-organic surface (Ah) horizon 10 cm or more in thickness. If cultivated the Ap horizon has one of the following properties:
- Less than 2% organic C.
- A rubbed color value greater than 3.5 (moist) or greater than 5.0 (dry).
- Little contrast in color value with the underlying layer (a difference of less than 1.5 units, if the value of the underlying layer is 4 or more, or a difference of less than 1 unit, if that value is less than 4).
Orthic Vertisol (O.V)
Common horizon sequence: Ah, Bv or Bvk, Bss or Bssk or Ckss, Ck
These soils have the general properties specified for the Vertisolic order and those members of the Vertisol great group other than the poorly drained members. They have a vertic horizon (Bv or Bvk) and a slickenside horizon (ss), the upper boundary of which occurs within 1 m of the mineral surface. The slickenside horizon may be confined to the B horizon (Bss or Bssk), may form part of the C horizon (Ckss), or may form part of both.
Orthic Vertisols, and all other subgroups of Vertisolic soils, may have saline features. These features are separated taxonomically at the series level, or as a phase of any taxonomic level above the family.
Gleyed Vertisol (GL.V)
Common horizon sequence: Ah, Bvgj or Bvkgj, Bssgj or Bsskgj or Ckssgj, Ckgj or Ckg
These soils have the general properties specified for the Vertisolic order and those members of the Vertisol great group other than the poorly drained members. They differ from Orthic Vertisols by having faint to distinct mottles that indicate gleying within 50 cm of the mineral surface.
Gleysolic Vertisol (GLC.V)
Common horizon sequence: LFH or O, Bvg, Bssg or Cgss, Cg
These soils have the general properties specified for the Vertisolic order and the poorly drained members of the Vertisol great group. They differ from Orthic and Gleyed Vertisols mainly by having, within 50 cm of the surface, either colors that indicate poor drainage and periodic reduction (diagnostic of the Gleysolic order) or prominent mottles that indicate gleying, or both.
Note: Diagnostic horizons are underlined.