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.
Note: Diagnostic horizons are underlined.