Gleysolic soils
Luvic Gleysol (LG)
Soils of this great group have the general properties specified for the Gleysolic order and a horizon of clay accumulation (Btg). They are similar to Luvisolic soils except that they have dull colors or prominent mottling, or both, which indicates strong gleying. They may have organic surface horizons and an Ah horizon. Luvic Gleysols occur commonly on poorly drained sites in association with Luvisolic soils and in depressions in areas of Black and Dark Gray Chernozemic soils.
Luvic Gleysols usually have an eluvial horizon (Ahe, Aeg) and a Btg horizon. A Btg horizon is defined based on an increase in silicate clay over that present in the A horizon. The presence of clay skins indicates illuvial clay. Colors and mottling as specified for the Gleysolic order indicate permanent or periodic reduction. Luvic Gleysols may have an organic surface horizon and an Ah horizon. In some cases the A horizon is very dark (value of 2) when moist, but its eluvial features are usually evident on drying. Such horizons generally have darker and lighter gray streaks and splotches, which are similar to the Ahe horizons of Dark Gray Chernozemic soils. Even if the eluvial horizon is dark, the Btg horizon is diagnostic of a Luvic Gleysol.
The great group is divided into six subgroups based on the kind and sequences of the horizons.
Vertic Luvic Gleysol (V.LG)
Common horizon sequence: LFH or O, Ah, Aeg, Bgf, Btg or Btgvj, Bntg or Bntgvj, Btgss or Cgss, Cg
These soils have the general properties specified for the Gleysolic order and the Luvic Gleysol great group. They may have any horizons in the upper solum common to other subgroups within the Luvic Gleysol great group. However, they differ from other subgroups by having properties indicative of intergrading to the Vertisolic order. Specifically, they have a slickenside horizon (Btgss or Cgss), the upper boundary of which occurs within 1 m of the mineral soil surface. They also may have a weak vertic horizon (Btgvj or Bntgvj).
Solonetzic Luvic Gleysol (SZ.LG)
Common horizon sequence: LFH or O, Ah, Aeg, Bntg, Cg
These soils have the general properties specified for the Gleysolic order and the Luvic Gleysol great group. They have, in addition, a solonetzic B horizon. They may have Ah or Ap horizons as specified for Humic Luvic Gleysols. These soils are commonly associated with saline parent materials.
Fragic Luvic Gleysol (FR.LG)
Common horizon sequence: LFH or O, Ah, Aeg, Btgx, or Btg and Bxg, Cg
These soils have the general properties specified for the Gleysolic order and the Luvic Gleysol great group. They have, in addition, a fragipan within or below the Btg horizon. They may also have a dark-colored Ah or Ap horizon, as specified for Humic Luvic Gleysols, or a Bgf or Btgf horizon, as specified for Fera Luvic Gleysols. They do not have a solonetzic B horizon; such horizons are not known to occur in association with a fragipan.
Humic Luvic Gleysol (HU.LG)
Common horizon sequence: LFH or O, Ah, Aeg, Btg, Cg
These soils have the general properties specified for the Gleysolic order and the Luvic Gleysol great group. They have, in addition, a mineral-organic surface horizon that meets the requirements of the Ah or Ap horizon of Humic Gleysols. Thus, the Ah horizon must be at least 10 cm thick and the Ap horizon must be at least 15 cm thick, contain at least 2% organic carbon, and have a darker color than the underlying horizon. Humic Luvic Gleysols have neither a solonetzic B horizon nor a fragipan, but they may have a Bgf horizon.
Fera Luvic Gleysol (FE.LG)
Common horizon sequence: LFH or O, Ah, Aeg, Btgf or Bfg and Btg, Cg
These soils have the general properties specified for the Gleysolic order and the Luvic Gleysol great group. They also have either a Bgf horizon at least 10 cm thick as well as a Btg horizon or a Btgf horizon. A Bgf or Btgf horizon contains accumulated hydrous iron oxide (dithionite extractable), which is thought to have been deposited as a result of the oxidation of ferrous iron. It usually has a high chroma and is commonly a horizon with a concentration of rusty mottles. Fera Luvic Gleysols lack all the following: an Ah or Ap horizon diagnostic of Humic Luvic Gleysols, a solonetzic B horizon, and a fragipan.
Orthic Luvic Gleysol (O.LG)
Common horizon sequence: LFH or O, Aeg, Btg, Cg
These soils have the general properties specified for the Gleysolic order and the Luvic Gleysol great group. Typically, they have a Btg horizon and organic or mineral-organic surface horizons overlying gleyed, eluvial horizons.
Orthic Luvic Gleysols are identified by the following properties:
- They have an eluvial horizon: Ahe, Ae, Aeg.
- They have a Btg horizon.
- They do not have an Ah or Ap horizon as defined for Humic Gleysols and Humic Luvic Gleysols.
- They have neither a solonetzic B horizon, nor a fragipan, nor a Bgf horizon at least 10 cm thick.
Humic Gleysol (HG)
Soils of this great group have a dark-colored A horizon in addition to the general properties of soils of the Gleysolic order. They occur commonly in poorly drained positions in association with some Chernozemic, Luvisolic, Podzolic, and Brunisolic soils. These soils may have organic surface horizons derived from grass and sedge, moss, or forest vegetation.
Humic Gleysols have no Bt horizon. They have either an Ah horizon at least 10 cm thick or a mixed surface horizon (Ap) at least 15 cm thick with all the following properties:
- It contains at least 2% organic carbon.
- It has a rubbed color value of 3.5 or less (moist), or 5.0 or less (dry).
- It has a color value (moist) at least 1.5 units lower than that of the next underlying horizon if the color value (moist) of that horizon is 4 or more, or one unit of color value lower than that of the underlying horizon if its color value is less than 4.
Examples of color values of cultivated Humic Gleysols are as follows:
| Moist color value of Ap | ||
| Moist color value of underlying horizon |
The great group is divided into five subgroups based on the kind of horizons and their sequence.
Vertic Humic Gleysol (V.HG)
Common horizon sequence: LFH or O, Ah, Bg or Bgvj, Bgss or Cgss, Cg
These soils have the general properties specified for the Gleysolic order and the Humic Gleysol great group. They may have any horizons in the upper solum common to other subgroups within the Humic Gleysol great group. However, they differ from other subgroups by having properties indicative of intergrading to the Vertisolic order. Specifically, they have a slickenside horizon (Bgss or Cgss), the upper boundary of which occurs within 1 m of the mineral soil surface. They may also have a weak vertic horizon (Bgvj).
Solonetzic Humic Gleysol (SZ.HG)
Common horizon sequence: Ah, Bng, Cgsk
These soils have the general properties specified for the Gleysolic order and the Humic Gleysol great group. They also have a solonetzic B horizon and may have a Bgf horizon. Typically, they have saline parent materials.
Fera Humic Gleysol (FE.HG)
Common horizon sequence: LFH or O, Ah, Aeg, Bgf, Cg
These soils have the general properties specified for the Gleysolic order and the Humic Gleysol great group. They also have a Bgf horizon at least 10 cm thick and lack a solonetzic B horizon. The Bgf horizon contains accumulated hydrous iron oxide (dithionite extractable) thought to have been deposited as a result of the oxidation of ferrous iron. The Bgf horizon usually has many prominent mottles of high chroma.
Orthic Humic Gleysol (O.HG)
Common horizon sequence: LFH or O, Ah, Bg, Cg
These soils have the general properties specified for the Gleysolic order and the Humic Gleysol great group. Typically, they have a well-developed Ah horizon overlying gleyed B and C horizons. They may have organic surface horizons, an eluvial horizon, and a C horizon that does not have the dull colors and mottling that indicate gleying.
Orthic Humic Gleysols are identified by the following properties:
- They have an Ah horizon at least 10 cm thick as defined for the great group.
- They have a B horizon (Bg or Bgtj) at least 10 cm thick.
- They do not have any of the following: a Btg horizon, a solonetzic B horizon, or a Bgf horizon at least 10 cm thick.
Rego Humic Gleysol (R.HG)
Common horizon sequence: LFH or O, Ah, Cg
These soils have the general properties specified for the Gleysolic order and the Humic Gleysol great group. They differ from Orthic Humic Gleysols in that they lack a B horizon at least 10 cm thick. Typically, they have a well-developed Ah horizon overlying a gleyed C horizon.
Gleysol (G)
Soils of this great group have the general properties specified for soils of the Gleysolic order, but they lack a well-developed, mineral-organic surface horizon. They occur commonly in poorly drained positions in association with soils of several other orders.
Gleysols lack an Ah or Ap horizon as specified for Humic Gleysols. They also lack a Bt horizon. They may have either an Ah horizon thinner than 10 cm or an Ap horizon with one of the following properties:
- It contains less than 2% organic carbon.
- It has a rubbed color value greater than 3.5 (moist) or greater than 5.0 (dry).
- It shows 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).
These soils have a gleyed B or C horizon, and they may have an organic surface horizon.
The great group is divided into five subgroups based on the kind of horizons and their sequence.
Vertic Gleysol (V.G)
Common horizon sequence: LFH or O, Bg or Bgvj, Bgss or Cgss, Cg
These soils have the general properties specified for the Gleysolic order and the Gleysol great group. They may have any horizons in the upper solum common to other subgroups within the Gleysol great group. However, they differ from other subgroups by having properties indicative of intergrading to the Vertisolic order. Specifically, they have a slickenside horizon (Bgss or Cgss), the upper boundary of which occurs within 1 m of the mineral soil surface. They may also have a weak vertic horizon (Bgvj).
Solonetzic Gleysol (SZ.G)
Common horizon sequence: LFH or O, Aeg, Bng, Cgsk
These soils have the general properties specified for the Gleysolic order and the Gleysol great group. They also have a solonetzic B horizon and may have a Bgf horizon. Typically, they have saline parent materials.
Fera Gleysol (FE.G)
Common horizon sequence: LFH or O, Aeg, Bgf, Cg
These soils have the general properties specified for the Gleysolic order and the Gleysol great group. They also have a Bgf horizon at least 10 cm thick and lack a solonetzic B horizon. The Bgf horizon contains accumulated hydrous iron oxide (dithionite extractable), which is thought to have been deposited as a result of the oxidation of ferrous iron. The Bgf horizon usually has many prominent mottles of high chroma.
Orthic Gleysol (O.G)
Common horizon sequence: LFH or O, Bg, Cg
These soils have the general properties specified for the Gleysolic order and the Gleysol great group. Typically, they have strongly gleyed B and C horizons and may have organic surface horizons and an eluvial horizon. Orthic Gleysols are identified by the following properties:
- They have a B horizon (Bg or Btjg) at least 10 cm thick.
- They may have an Ah or Ap horizon as specified for the Gleysol great group.
- They have neither a Btg horizon, nor a solonetzic B horizon, nor a Bgf horizon at least 10 cm thick.
Rego Gleysol (R.G)
Common horizon sequence: LFH or O, Cg
These soils have the general properties specified for the Gleysolic order and the Gleysol great group. They differ from Orthic Gleysols in that they lack a B horizon at least 10 cm thick. They thus consist of a gleyed C horizon, with or without organic surface horizons, and a thin Ah or B horizon.
Note: Diagnostic horizons are underlined.