Chernozemic soils
Brown Chernozem (BC)
These are soils that occur in the most arid segment of the climatic range of Chernozemic soils and have brownish-colored A horizons. They are associated with xerophytic and mesophytic grass and forb vegetation. In virgin Brown Chernozems the upper part of the Ah horizon is commonly as light as or lighter in color value than the lower part of the Ah or the upper B horizon.
Brown Chernozems have chernozemic Ah or Ap horizons with color values darker than 3.5 moist and 4.5-5.5 dry. The chroma of the A horizon is usually higher than 1.5. The soil climate of this great group is typically cold, rarely mild, and is subarid to semiarid (see Chapter 14 on soil family).
Orthic Brown Chernozem (O.BC)
Common horizon sequence: Ah, Bm, Cca or Ck
The Orthic Brown Chernozem subgroup may be thought of as the central concept of Brown Chernozems. It encompasses the properties specified for the Chernozemic order and the Brown Chernozem great group. Orthic Brown Chernozems are well drained and their B horizons are usually brown with prismatic macrostructure. The prismatic peds are usually coarse in coarse-textured soils. With increasing clay content, the peds become smaller and have an increasing tendency to crush to fine blocky and granular aggregates. Thin clay coatings occur occasionally to commonly on ped surfaces in the B horizon. A light-colored horizon of carbonate accumulation usually occurs below the brownish B horizon.
Orthic Brown Chernozems are identified by the following properties:
- They have a Chernozemic A horizon with a color value darker than 3.5 moist and 4.5-5.5 dry.
- They have a B horizon (Bm, Btj, or Bt) at least 5 cm thick that contains no alkaline earth carbonates.
- They lack an Ae horizon at least 2 cm thick.
- They lack a Bnjtj horizon or a similar horizon characteristic of intergrades to the Solonetzic order.
- They lack evidence of gleying as indicated by faint to distinct mottling within 50 cm of the mineral surface.
Orthic Brown Chernozems and all other subgroups of Chernozemic soils may have any of the following features that are separated either at the family or series level taxonomically or as phases of any taxonomic level above the family: lithic, saline, and carbonated.
Rego Brown Chernozem (R.BC)
Common horizon sequence: Ah, C or Cca,or Ck
These soils have the general properties specified for the Chernozemic order and the Brown Chernozem great group. They differ from Orthic Brown Chernozems either in lacking a B horizon or in having a B horizon (Bm) less than 5 cm thick. Usually Rego Brown Chernozems have an AC profile. They may also have saline features.
Calcareous Brown Chernozem (CA.BC)
Common horizon sequence: Ah, Bmk, Cca or Ck
These soils have the general properties of the Chernozemic order and the Brown Chernozem great group. They differ from Orthic Brown Chernozems by having a B horizon from which primary alkaline earth carbonates have not been removed completely (Bmk). Otherwise, they have the general properties of Orthic Brown Chernozems.
Eluviated Brown Chernozem (E.BC)
Common horizon sequence: Ah, Ae, Btj or Bt, Cca or Ck
These soils have the general properties of the Chernozemic order and the Brown Chernozem great group. They differ from Orthic Brown Chernozems by having an eluvial horizon or horizons at least 2 cm thick (Ahe, Ae, Aej) usually underlain by a weakly to moderately developed illuvial Btj or Bt horizon. Commonly, the eluvial horizon is slightly to moderately acid. Two variations of this subgroup may be recognized.
One variation has pedons in which eluviation is indicated by light-colored, relic, macroprismatic structure below the Ah or Ap. The prismatic units break into coarse to medium platy peds that commonly have vesicular or tubular voids. This structure suggests the development of an eluvial horizon from a former prismatic B. The Bt or Btj horizon underlying the eluvial horizon usually has well-developed macroprismatic structure that breaks to blocky peds of lower color value and slightly higher chroma than the eluvial horizon.
The other variation has cumulic pedons in which the periodic deposition of transported soil materials modifies the normal horizon differentiation caused by leaching. These pedons have thick horizons of partly leached, accumulated materials overlying former A or transitional AB horizons. They are usually found on lower concave slopes where sediments are deposited from upslope. Commonly, such pedons can be recognized by their thick Ahe horizons.
Solonetzic Brown Chernozem (SZ.BC)
Common horizon sequence: Ah, Ae, Btnj or Btjnj, Csa or Ck
These soils have the general properties specified for the Chernozemic order and the Brown Chernozem great group. They differ from Orthic Brown Chernozems by having properties that indicate intergrading to the Solonetzic order. Specifically, they have a Bnj, Btjnj, or Btnj horizon and may have Ae, AB, and saline C horizons. The B horizon usually has prismatic structure and hard consistence. The prisms usually break to blocky secondary structural units having shiny, dark coatings. The eluvial horizon that is found in some Solonetzic Brown Chernozems may be similar to that described for the Eluviated Brown Chernozem subgroup. Solonetzic Brown Chernozems are usually associated with saline materials, and their B horizons usually have a higher proportion of exchangeable Na or Na and Mg than is characteristic of Orthic Brown Chernozems.
Vertic Brown Chernozem (V.BC)
Common horizon sequence: Ah or Ahk, Ae or Aej, Bm or Bmk, Btj or Bnjtj, Bvj, Bss or Bkss or Ckss, Ck
These soils have the general properties specified for the Chernozemic order and the Brown Chernozem great group. They may have any horizons in the upper solum common to other subgroups within the Brown Chernozem great group. However, they differ from other subgroups by having properties indicative of intergrading to the Vertisolic order. Specifically, they have a slickenside horizon (Bss, Bkss, or Ckss), the upper boundary of which occurs within 1 m of the mineral soil surface, and may have a weak vertic horizon (Bvj or BCvj).
Gleyed Brown Chernozem (GL.BC)
Common horizon sequence: Ah, Bmgj, Ckgj
These soils have the general properties specified for the Chernozemic order and the Brown Chernozem great group. They differ from Orthic Brown Chernozems by having faint to distinct mottles indicative of gleying within 50 cm of the mineral surface.
Gleyed Rego Brown Chernozem (GLR.BC)
Common horizon sequence: Ah,Ckgj
These soils have the general properties specified for the Chernozemic order and the Brown Chernozem great group. They differ from Rego Brown Chernozems by having mottles indicative of gleying. Gleyed Rego Brown Chernozems lack a distinct B horizon at least 5 cm thick and have faint to distinct mottles within 50 cm of the mineral surface.
Gleyed Calcareous Brown Chernozem (GLCA.BC)
Common horizon sequence: Ah, Bmkgj, Ckgj
These soils have the general properties specified for the Chernozemic order and the Brown Chernozem great group. They differ from Calcareous Brown Chernozems by having mottles indicative of gleying. Gleyed Calcareous Brown Chernozems have a Bmk horizon at least 5 cm thick and faint to distinct mottles within 50 cm of the mineral surface.
Gleyed Eluviated Brown Chernozem (GLE.BC)
Common horizon sequence: Ah, Aej, Btjgj or Btgj ,Ckgj
These soils have the general properties specified for the Chernozemic order and the Brown Chernozem great group. They differ from Eluviated Brown Chernozems by having mottles indicative of gleying. Gleyed Eluviated Brown Chernozems have an eluvial horizon and faint to distinct mottles within 50 cm of the mineral surface.
Gleyed Solonetzic Brown Chernozem (GLSZ.BC)
Common horizon sequence: Ah,Ae, Bnjtjgj, Csagj
These soils have the general properties specified for the Chernozemic order and the Brown Chernozem great group. They differ from Solonetzic Brown Chernozems by having mottles indicative of gleying. Gleyed Solonetzic Brown Chernozems have a Bnj or a Btnj horizon and faint to distinct mottles within 50 cm of the mineral surface.
Gleyed Vertic Brown Chernozem (GLV.BC)
Common horizon sequence: Ah or Ahk, Ae or Aej, Bmgj or Bmkgj, Btjgj or Bnjtjgj, Bgjvj, Bgjss or Bkgjss or Ckgjss, Ckgj or Ckg
These soils have the general properties specified for the Chernozemic order and the Brown Chernozem great group. They also have properties that indicate intergrading to the Vertisolic order. Specifically, they have a slickenside horizon (Bgjss, Bkgjss, or Ckgjss), the upper boundary of which occurs within 1 m of the mineral soil surface, and may have a weak vertic horizon (Bgjvj). They differ from Vertic Brown Chernozems by having faint to distinct mottles, indicative of gleying, within 50 cm of the mineral surface.
Dark Brown Chernozem (DBC)
These Chernozemic soils have A horizons somewhat darker in color than soils of the Brown Chernozem great group. Dark Brown Chernozems usually occur in association with native vegetation of mesophytic grasses and forbs in a semiarid climate. In virgin areas the Ah horizon is usually darkest at the surface and becomes progressively lighter in color with depth.
Dark Brown Chernozems have the characteristics specified for the Chernozemic order. The A horizon has a color value darker than 3.5 moist and 3.5-4.5 dry; the chroma is usually greater than 1.5 dry. The soil climate of this great group is typically cold, rarely mild, and semiarid.
Orthic Dark Brown Chernozem (O.DBC)
Common horizon sequence: Ah, Bm, Cca or Ck
The Orthic Dark Brown Chernozem subgroup may be thought of as the central concept of Dark Brown Chernozems. It encompasses the properties specified for the Chernozemic order and the Dark Brown Chernozem great group. Usually, Orthic Dark Brown Chernozems have brownish-colored, prismatic B horizons, and light-colored horizons of carbonate accumulation similar to those of Orthic Brown Chernozems.
Orthic Dark Brown Chernozems are identified by the following properties:
- They have a Chernozemic A horizon with a color value darker than 3.5 moist and between 3.5-4.5 dry.
- They have a B horizon (Bm, Btj, Bt) at least 5 cm thick that does not contain alkaline earth carbonates.
- They lack an Ae horizon at least 2 cm thick.
- They lack a Bnjtj horizon or a similar horizon characteristic of intergrades to the Solonetzic order.
- They lack evidence of gleying as indicated by faint to distinct mottling within 50 cm of the mineral surface.
Rego Dark Brown Chernozem (R.DBC)
Common horizon sequence: Ah, C, Cca or Ck
These soils have the general properties specified for the Chernozemic order and the Dark Brown Chernozem great group. They differ from Orthic Dark Brown Chernozems either in lacking a B horizon or in having a B horizon (Bm) less than 5 cm thick. Usually Rego Dark Brown Chernozems have an AC profile. They may also have saline features.
Calcareous Dark Brown Chernozem (CA.DBC)
Common horizon sequence: Ah, Bmk, Cca or Ck
These soils have the general properties specified for the Chernozemic order and the Dark Brown Chernozem great group. They differ from Orthic Dark Brown Chernozems by having a B horizon from which primary alkaline earth carbonates have not been removed completely (Bmk). Otherwise, they have the general properties of Orthic Dark Brown Chernozems.
Eluviated Dark Brown Chernozem (E.DBC)
Common horizon sequence: Ah, Ae, Btj or Bt, Cca, Ck
These soils have the general properties specified for the Chernozemic order and the Dark Brown Chernozem great group. They differ from Orthic Dark Brown Chernozems by having an eluvial horizon or horizons (Ahe, Ae, Aej) at least 2 cm thick usually underlain by a weakly to moderately developed illuvial Btj or Bt horizon. Two variations of this subgroup may be recognized. The first has an eluvial horizon developed in a former B horizon. The second has an eluvial horizon developing in an A horizon subject to periodic deposition of sediment. These variations are described in more detail for the Eluviated Brown Chernozem subgroup.
Solonetzic Dark Brown Chernozem (SZ.DBC)
Common horizon sequence: Ah, Ae, Btnj or Btjnj, Csa or Ck
These soils have the general properties specified for the Chernozemic order and the Dark Brown Chernozem great group. They differ from Orthic Dark Brown Chernozems by having properties indicative of intergrading to the Solonetzic order. Specifically, they have a Bnj, Btjnj, or Btnj horizon and may have Ae, AB, and saline C horizons. The B horizon usually has prismatic structure with hard consistence. The prisms usually break to blocky secondary structural units having shiny, dark coatings. The eluvial horizon that occurs in some Solonetzic Dark Brown Chernozems may be similar to that described for the Eluviated Dark Brown Chernozem subgroup. Solonetzic Dark Brown Chernozems are usually associated with saline materials. Thus their B horizons usually have a higher proportion of exchangeable Na or Na and Mg than is characteristic of Orthic Dark Brown Chernozems.
Vertic Dark Brown Chernozem (V.DBC)
Common horizon sequence: Ah or Ahk, Ae or Aej, Bm or Bmk, Btj or Bnjtj, Bvj, Bss or Bkss or Ckss, Ck
These soils have the general properties specified for the Chernozemic order and the Dark Brown Chernozem great group. They may have any horizons in the upper solum common to other subgroups within the Dark Brown Chernozem great group. However, they differ from other subgroups by having properties indicative of intergrading to the Vertisolic order. Specifically, they have a slickenside horizon (Bss, Bkss or Ckss), the upper boundary of which occurs within 1 m of the mineral soil surface. As well, they may have a weak vertic horizon (Bvj or BCvj).
Gleyed Dark Brown Chernozem (GL.DBC)
Common horizon sequence: Ah, Bmgj, Cgj or Ckgj
These soils have the general properties specified for the Chernozemic order and the Dark Brown Chernozem great group. They differ from Orthic Dark Brown Chernozems by having faint to distinct mottles that indicate gleying within 50 cm of the mineral surface.
Gleyed Rego Dark Brown Chernozem (GLR.DBC)
Common horizon sequence: Ah, Ckgj
These soils have the general properties specified for the Chernozemic order and the Dark Brown Chernozem great group. They differ from Rego Dark Brown Chernozems by having mottles indicative of gleying. Gleyed Rego Dark Brown Chernozems lack a B horizon at least 5 cm thick and have faint to distinct mottles within 50 cm of the mineral surface.
Gleyed Calcareous Dark Brown Chernozem (GLCA.DBC)
Common horizon sequence: Ah, Bmkg, Ckgj
These soils have the general properties specified for the Chernozemic order and the Dark Brown Chernozem great group. They differ from Calcareous Dark Brown Chernozems by having mottles indicative of gleying. Gleyed Calcareous Dark Brown Chernozems have a Bmk horizon at least 5 cm thick and faint to distinct mottles within 50 cm of the mineral surface.
Gleyed Eluviated Dark Brown Chernozem (GLE.DBC)
Common horizon sequence: Ah, Aej, Btjgj, Cgj or Ckgj
These soils have the general properties specified for the Chernozemic order and the Dark Brown Chernozem great group. They differ from Eluviated Dark Brown Chernozems by having mottles indicative of gleying. Gleyed Eluviated Dark Brown Chernozems have an eluvial horizon and faint to distinct mottles within 50 cm of the mineral surface.
Gleyed Solonetzic Dark Brown Chernozem (GLSZ.DBC)
Common horizon sequence: Ah, Ae, Bnjtjgj, Ckgj, Csagj
These soils have the general properties specified for the Chernozemic order and the Dark Brown Chernozem great group. They differ from Solonetzic Dark Brown Chernozems by having mottles indicative of gleying. Gleyed Solonetzic Dark Brown Chernozems have a Bnj or a Btnj horizon and faint to distinct mottles within 50 cm of the mineral surface.
Gleyed Vertic Dark Brown Chernozem (GLV.DBC)
Common horizon sequence: Ah or Ahk ,Ae or Aej, Bmgj or Bmkgj, Btjgj or Bnjtjgj, Bgjvj, Bgjss or Bkgjss or Ckgjss, Ckgj or Ckg
These soils have the general properties specified for the Chernozemic order and the Dark Brown Chernozem great group. In addition they have properties indicative of intergrading to the Vertisolic order. Specifically, they have a slickenside horizon (Bgjss, Bkgjss or Ckgjss), the upper boundary of which occurs within 1 m of the mineral soil surface. As well, they may have a weak vertic horizon (Bgjvj). They differ from Vertic Dark Brown Chernozems by having faint to distinct mottles, indicative of gleying, within 50 cm of the mineral surface.
Black Chernozem (BLC)
These Chernozemic soils have A horizons darker in color and commonly thicker than soils of the Brown Chernozem and Dark Brown Chernozem great groups. Black Chernozems usually occur in association with a native vegetation of mesophytic grasses and forbs or with mixed grass, forb, and tree cover. Some Black Chernozems occur under alpine grass and shrub vegetation.
Black Chernozems have the characteristics specified for the order, and a Chernozemic A horizon with a color value darker than 3.5 moist and dry. The chroma of the Chernozemic A is usually 1.5 or less, dry. The soil climate of this great group is typically cold, rarely mild, and is subhumid.
Orthic Black Chernozem (O.BLC)
Common horizon sequence: Ah, Bm Cca or Ck
The Orthic Black Chernozem subgroup may be thought of as the central concept of Black Chernozems. It encompasses the properties specified for the Chernozemic order and the Black Chernozem great group. Usually Orthic Black Chernozems have brownish-colored, prismatic B horizons, and light-colored horizons of carbonate accumulation similar to those of Orthic Brown Chernozems.
Orthic Black Chernozems are identified by the following properties:
- They have a Chernozemic A horizon with a color value darker than 3.5 moist and dry.
- They have a B horizon (Bm, Btj, Bt) at least 5 cm thick that does not contain alkaline earth carbonates.
- They lack an eluvial horizon (Ahe, Ae, Aej) at least 2 cm thick.
- They lack a Bnjtj or similar horizon characteristic of intergrades to the Solonetzic order.
- They lack evidence of gleying as indicated by faint to distinct mottling within 50 cm of the mineral surface.
Rego Black Chernozem (R.BLC)
Common horizon sequence: Ah, Cca or Ck
These soils have the general properties specified for the Chernozemic order and the Black Chernozem great group. They differ from Orthic Black Chernozems either in lacking a B horizon or in having a B horizon (Bm) less than 5 cm thick. Usually Rego Black Chernozems have an AC profile. They may also have saline features.
Calcareous Black Chernozem (CA.BLC)
Common horizon sequence: Ah, Bmk, Cca or Ck
These soils have the general properties of the Chernozemic order and the Black Chernozem great group. They differ from Orthic Black Chernozems by having a B horizon from which primary alkaline earth carbonates have not been removed completely (Bmk). Otherwise they have the general properties of Orthic Black Chernozems.
Eluviated Black Chernozem (E.BLC)
Common horizon sequence: Ah, Ae, Btj, or Bt, Cca or Ck
These soils have the general properties of the Chernozemic order and the Black Chernozem great group. They differ from Orthic Black Chernozems by having an eluvial horizon or horizons at least 2 cm thick (Ahe, Ae, Aej) usually underlain by a weakly to moderately developed illuvial Btj or Bt horizon.
Solonetzic Black Chernozem (SZ.BLC)
Common horizon sequence: Ah, Ae, Btnj, or Btjnj, Cs or Ck
These soils have the general properties specified for the Chernozemic order and the Black Chernozem great group. They differ from Orthic Black Chernozems by having properties indicative of intergrading to the Solonetzic order. Specifically, they have a Bnj, Btjnj, or Btnj horizon and may have Ae, AB, and saline C horizons. The B horizon usually has prismatic structure and hard consistence. The prisms usually break to blocky secondary structural units with shiny, dark coatings. The eluvial horizon that occurs in some Solonetzic Black Chernozems may be similar to that described for the Eluviated Black Chernozem subgroup. Solonetzic Black Chernozems are usually associated with saline materials. Thus, their B horizons usually have a higher proportion of exchangeable Na or Na and Mg than is characteristic of Orthic Black Chernozems.
Vertic Black Chernozem (V.BLC)
Common horizon sequence: Ah or Ahk, Ae or Aej, Bm or Bmk, Btj or Bnjtj, Bvj, Bss or Bkss or Ckss, Ck
These soils have the general properties specified for the Chernozemic order and the Black Chernozem great group. They may have any horizons in the upper solum common to other subgroups within the Black Chernozem great group. However, they differ from other subgroups by having properties indicative of intergrading to the Vertisolic order. Specifically, they have a slickenside horizon (Bss, Bkss or Ckss), the upper boundary of which occurs within 1 m of the mineral soil surface. As well, they may have a weak Vertic horizon (Bvj or BCvj).
Gleyed Black Chernozem (GL.BLC)
Common horizon sequence: Ah, Bmgj, Ckgj
These soils have the general properties specified for the Chernozemic order and the Black Chernozem great group. They differ from Orthic Black Chernozems by having faint to distinct mottles indicative of gleying within 50 cm of the mineral surface.
Gleyed Rego Black Chernozem (GLR.BLC)
Common horizon sequence: Ah, Ckgj
These soils have the general properties specified for the Chernozemic order and the Black Chernozem great group. They differ from Rego Black Chernozems by having mottles indicative of gleying. Gleyed Rego Black Chernozems lack a B horizon at least 5 cm thick and have faint to distinct mottles within 50 cm of the mineral surface.
Gleyed Calcareous Black Chernozem (GLCA.BLC)
Common horizon sequence: Ah, Bmkgj, Ckgj
These soils have the general properties specified for the Chernozemic order and the Black Chernozem great group. They differ from Calcareous Black Chernozems by having mottles indicative of gleying. Gleyed Calcareous Black Chernozems have a Bmk horizon at least 5 cm thick and faint to distinct mottles within 50 cm of the mineral surface.
Gleyed Eluviated Black Chernozem (GLE.BLC)
Common horizon sequence: Ah, Aej, Btjgj,Ckgj
These soils have the general properties specified for the Chernozemic order and the Black Chernozem great group. They differ from Eluviated Black Chernozems by having mottles indicative of gleying. Gleyed Eluviated Black Chernozems have an eluvial horizon and faint to distinct mottles within 50 cm of the mineral surface.
Gleyed Solonetzic Black Chernozem (GLSZ.BLC)
Common horizon sequence: Ah, Ae, Bnjtjgj, Ckgj, Csgj
These soils have the general properties specified for the Chernozemic order and the Black Chernozem great group. They differ from Solonetzic Black Chernozems by having mottles indicative of gleying. Gleyed Solonetzic Black Chernozems have a Bnj or a Btnj horizon and faint to distinct mottling within 50 cm of the mineral surface.
Gleyed Vertic Black Chernozem (GLV.BLC)
Common horizon sequence: Ah or Ahk, Ae or Aej, Bmgj or Bmkgj, Btjgj or Bnjtjgj, Bgjvj, Bgjss or Bkgjss or Ckgjss, Ckgj or Ckg
These soils have the general properties specified for the Chernozemic order and the Black Chernozem great group. They also have properties indicative of intergrading to the Vertisolic order. Specifically, they have a slickenside horizon (Bgjss, Bkgjss or Ckgjss), the upper boundary of which occurs within 1 m of the mineral soil surface. They may have a weak vertic horizon (Bgjvj). As well, they differ from Vertic Black Chernozems by having faint to distinct mottles, indicative of gleying, within 50 cm of the mineral surface.
Dark Gray Chernozem (DGC)
These soils have Chernozemic A horizons with characteristics indicative of eluviation associated with soils developed under forest vegetation. Dark Gray Chernozems usually occur under mixed native vegetation of trees, shrubs, forbs, and grasses in forest-grassland transition zones in areas of cold, subhumid soil climate. Virgin Dark Gray Chernozems usually have leaf mats (L-H horizons) overlying Ah or Ahe horizons. The peds of the A horizons may have dark-colored surfaces, but the crushed peds usually have gray or brownish colors of higher value or chroma. A "salt and pepper" effect, light gray spots, or bands on a darker matrix may be observable in the A horizons, which tend to have platy structure.
Dark Gray Chernozems have the characteristics specified for the order. Virgin soils have a Chernozemic A horizon with a color value darker than 3.5 moist and 4.5 dry. An Ap horizon 10 cm thick must have a color value darker than 3.5 moist and 5 dry. The chroma of the A horizon is usually 1.5 or less, dry. Dark Gray Chernozems may have a light-colored Ae horizon 5 cm or less thick provided that the mixed surface horizon (Ap) meets the requirements specified for the great group. Similar soils having a distinct Ae horizon thicker than 5 cm below the Chernozemic A horizon and a Bt horizon are classified as Dark Gray Luvisols.
Orthic Dark Gray Chernozem (O.DGC)
Common horizon sequence: Ahe, Ae, Bm or Btj or Bt, Cca or Ck
The Orthic Dark Gray Chernozem subgroup may be thought of as the central concept of Dark Gray Chernozems. It encompasses the properties specified for the Chernozemic order and the Dark Gray Chernozem great group. Usually Orthic Dark Gray Chernozems have brownish-colored, prismatic B horizons that commonly meet the requirements of a Bt horizon.
Orthic Dark Gray Chernozems are identified by the following properties:
- They have a Chernozemic A horizon with a color value darker than 3.5 moist and 3.5-4.5 dry for virgin soils (3.5-5 dry for Ap).
- They have a B horizon (Bm, Btj, Bt) at least 5 cm thick that does not contain alkaline earth carbonates.
- They lack an Ae horizon more than 5 cm thick.
- They lack a Bnjtj horizon or a similar horizon characteristic of intergrades to the Solonetzic order.
- They lack evidence of gleying as indicated by faint to distinct mottling within 50 cm of the mineral surface.
Rego Dark Gray Chernozem (R.DGC)
Common horizon sequence: Ah or Ahe, Cca or Ck
These soils have the general properties specified for the Chernozemic order and the Dark Gray Chernozem great group. They differ from Orthic Dark Gray Chernozems either in lacking a B horizon or in having a B horizon (Bm) less than 5 cm thick. Usually Rego Dark Gray Chernozems have an AC profile. They may also have saline features.
Calcareous Dark Gray Chernozem (CA.DGC)
Common horizon sequence: Ah, Ahe, Bmk, Cca or Ck
These soils have the general properties of the Chernozemic order and the Dark Gray Chernozem great group. They differ from Orthic Dark Gray Chernozems by having a B horizon from which primary alkaline earth carbonates have not been removed completely (Bmk). Otherwise they have the general properties of Orthic Dark Gray Chernozems.
Solonetzic Dark Gray Chernozem (SZ.DGC)
Common horizon sequence: Ahe, Ae, Bnjtj, Cs or Ck
These soils have the general properties specified for the Chernozemic order and the Dark Gray Chernozem great group. They differ from Orthic Dark Gray Chernozems by having properties indicative of intergrading to the Solonetzic order. Specifically, they have either a Bnj, Bnjtj, or Btnj horizon, and they may have Ae, AB, and saline C horizons. The Ae horizon, if present, is not more than 5 cm thick. The B horizon usually has prismatic structure and hard consistence, and the prisms usually break to blocky secondary structural units with shiny, dark coatings. Solonetzic Dark Gray Chernozems are usually associated with saline materials. Thus, their B horizons usually have a higher proportion of exchangeable Na or Na and Mg than is characteristic of Orthic Dark Gray Chernozems.
Vertic Dark Gray Chernozem (V.DGC)
Common horizon sequence: Ah or Ahk, Ae or Aej, Bm or Bmk, Btj or Bnjtj, Bvj, Bss or Bkss or Ckss Ck
These soils have the general properties specified for the Chernozemic order and the Dark Gray Chernozem great group. Theymay have any horizons in the upper solum common to other subgroups within the Dark Gray Chernozem great group. However, they differ from other subgroups by having properties indicative of intergrading to the Vertisolic order. Specifically, they have a slickenside horizon (Bss, Bkss or Ckss), the upper boundary of which occurs within 1 m of the mineral soil surface. As well, they may have a weak vertic horizon (Bvj or BCvj).
Gleyed Dark Gray Chernozem (GL.DGC)
Common horizon sequence: Ahe, Bmgj, Ckgj
These soils have the general properties specified for the Chernozemic order and the Dark Gray Chernozem great group. They differ from Orthic Dark Gray Chernozems by having faint to distinct mottles indicative of gleying within 50 cm of the mineral surface.
Gleyed Rego Dark Gray Chernozem (GLR.DGC)
Common horizon sequence: Ahe, Ckgj
These soils have the general properties specified for the Chernozemic order and the Dark Gray Chernozem great group. They differ from Rego Dark Gray Chernozems by having mottles indicative of gleying. Gleyed Rego Dark Gray Chernozems lack a B horizon at least 5 cm thick and have faint to distinct mottles within 50 cm of the mineral surface.
Gleyed Calcareous Dark Gray Chernozem (GLCA.DGC)
Common horizon sequence: Ahe, Bmkgj, Ckgj
These soils have the general properties specified for the Chernozemic order and the Dark Gray Chernozem great group. They differ from Calcareous Dark Gray Chernozems by having mottles indicative of gleying. Gleyed Calcareous Dark Gray Chernozems have a Bmk horizon at least 5 cm thick and faint to distinct mottles within 50 cm of the mineral surface.
Gleyed Solonetzic Dark Gray Chernozem (GLSZ.DGC)
Common horizon sequence: Ahe, Ae, Bnjtjgj, Ckgj, Csgj
These soils have the general properties specified for the Chernozemic order and the Dark Gray Chernozem great group. They differ from Solonetzic Dark Gray Chernozems by having mottles indicative of gleying. Gleyed Solonetzic Dark Gray Chernozems have a Bnj or a Btnj horizon and faint to distinct mottles within 50 cm of the mineral surface.
Gleyed Vertic Dark Gray Chernozem (GLV.DGC)
Common horizon sequence: Ah or Ahk, Ae or Aej, Bmgj or Bmkgj, Btjgj or Bnjtjgj, Bgjvj, Bgjss or Bkgjss or Ckgjss, Ckgj or Ckg
These soils have the general properties specified for the Chernozemic order and the Dark Gray Chernozem great group. They also have properties indicative of intergrading to the Vertisolic order. Specifically, they have a slickenside horizon (Bgjss, Bkgjss or Ckgjss), the upper boundary of which occurs within 1 m of the mineral soil surface. As well, they may have a weak vertic horizon (Bgjvj). They differ from Vertic Dark Gray Chernozems by having faint to distinct mottles, indicative of gleying, within 50 cm of the mineral surface.
Note: Diagnostic horizons are underlined.