Key to the reference soil groups of the wrb for soil resources (WRB 2006)

organized as

Key to the reference soil groups of the WRB for soil resources (WRB 2006)

Soil Group

Keys & properties

Examples

having organic soil material, either

1. 10 cm or more thick starting at the soil surface and immediately overlying ice, continuous rock, or fragmental materials, the interstices of which are filled with organic soil material; or

2. cumulatively within 100 cm of the soil surface either 60 cm or more thick if 75% (by volume) or more of the material consists of moss fibres or 40 cm or more thick in other materials and starting within 40 cm of the soil surface.

ANTHROSOLS

1. either a hortic, irragric, plaggic or terric h. 50 cm or more thick; or

2. an anthraquic h. and an underlying hydragric h. with a combined thickness of 50 cm or more.

TECHNOSOLS

1. 20% (by volume, by weighted average) or more artefacts in the upper 100 cm from the soil surface or to continuous rock or a cemented or indurated layer, whichever is shallower; or

2. a continuous, very slowly permeable to impermeable, constructed geomembrane of any thickness starting within 100 cm of the soil surface; or

3. technic hard rock starting within 5 cm of the soil surface and covering 95% or more of the horizontal extent of the soil.

CRYOSOLS
CR

1. a cryic h. starting within 100 cm of the soil surface; or

2. a cryic h. starting within 200 cm of the soil surface and evidence of cryoturbation in some layer within 100 cm of the soil.

LEPTOSOLS

1. one of the following:

a. limitation of depth by continuous rock within 25 cm of the soil surface; or

b. less than 20% (by volume) fine earth averaged over a depth of 75 cm from the soil surface or to continuous rock, whichever is shallower; and

2. no calcic, gypsic or spodic h..

Leptosol hyperskeletic

VERTISOLS

1. a vertic h. starting within 100 cm of the soil surface; and

2. after the upper 20 cm have been mixed, 30 percent or more clay between the soil surface and the vertic h. throughout; and

3. cracks which open and close periodically.

FLUVISOLS

1. fluvic soil material starting within 25 cm of the soil surface or starting immediately below a plough layer of any depth and continuing to a depth of 50 cm or more; and

2. no layers with andic or vitric properties with a combined thickness of 30 cm or more within 100 cm of the soil surface and starting within 25 cm of the soil surface.

Fluvisol salic

Fluvisol haplic arenic

SOLONETZ

having a natric h. starting within 100 cm of the soil surface.

Solonetz gypsic

Btn surface

SOLONCHAKS SC

1. a salic h. starting within 50 cm of the soil surface; and

2. no thionic h. starting within 50 cm of the soil surface.

GLEYSOLS

1. within 50 cm of the mineral soil surface in some parts reducing conditions and in half or more of the soil volume a gleyic colour pattern; and

2. no layers with andic or vitric properties with a combined thickness of either

a. 30 cm or more within 100 cm of the soil surface and starting within 25 cm of the soil surface; or

b. 60% or more of the entire thickness of the soil when continuous rock or a cemented or indurated layer is starting between 25 and 50 cm from the soil surface.

ANDOSOLS

1. one or more layer with andic or vitric properties with a combined thickness of either

a. 30 cm or more within 100 cm of the soil surface and starting within 25 cm of the soil surface; or

b. 60% or more of the entire thickness of the soil when continuous rock or a cemented or indurated layer is starting between 25 and 50 cm from the soil surface; and

2. no argic, ferralic, petroplinthic, pisoplinthic, plinthic or spodic h. (unless buried deeper than 50 cm)

Andosol

PODZOLS

having a spodic h. starting within 200 cm of the mineral soil surface.

Podzol haplic

Podzol umbric

PLINTHOSOLS PT

either

1. a plinthic, petroplinthic or pisoplinthic h. starting within 50 cm of the soil surface; or

2. a plinthic h. starting within 100 cm of the soil surface and, directly above, a layer 10 cm or more thick, that has in some parts reducing conditions for some time during the year and in half or more of the soil volume, single or in combination

a. a stagnic colour pattern; or

b. an albic h..

NITISOLS

1. a nitic h. starting within 100 cm of the soil surface; and

2. gradual to diffuse horizon boundaries between the soil surface and the nitic h.; and

3. no ferric, petroplinthic, pisoplinthic, plinthic or vertic h. starting within 100 cm of the soil surface.; and

4. no gleyic or stagnic colour pattern starting within 100 cm of the soil surface.

Nitisol haplic

FERRALSOLS

1. having a ferralic h. starting within 150 cm of the soil surface; and

2. no argic h. that has, in the upper 30 cm, 10% or more water-dispensible clay unless the upper 30 cm of the argic h. has one or both of the following:

a. geric properties; or

b. 1.4% or more organic carbon

PLANOSOLS

1. an abrupt textural change within 100 cm of the soil surface and, directly above or below, a layer 5 cm or more thick, that has in some parts reducing conditions for some time during the year and in half or more of the soil volume, single or in combination

a. a stagnic colour pattern; or

b. an albic h. ; and

no albeluvic tonguing starting within 100 cm of the soil surface.

Planosol solodic calcic

STAGNOSOLS

1. within 50 cm of the mineral soil surface in some parts reducing conditions for some time during the year and in half or more of the soil volume, single or in combination,

a. a stagnic colour pattern; or

b. an albic h.; and

2. no albeluvic tonguing starting within 100 cm of the soil surface.

Luvic umbric Stagnosol

CHERNOZEMS

1. a mollic h. with a moist chroma of 2 or less to a depth of 20 cm or more, or having this chroma directly below any plough layer that is 20 cm or more deep; and

2. a calcic h., or concentrations of secondary carbonates starting within 50 cm below the lower limit of the mollic h. and, if present, above a cemented or indurated layer; and

3. a base saturation (by 1 M NH₄OAc) of 50% or more from the soil surface to the clacic h. or the concentrations of secondary carbonates throughout.

Chernozem haplic

Chernozem voronic

KASTANOZEMS

1. a mollic h.; and

2. a calcic h., or concentrations of secondary carbonates starting within 50 cm below the lower limit of the mollic h. and, if present, above a cemented or indurated layer; and

3. a base saturation (by 1 M NH₄OAc) of 50% or more from the soil surface to the calcic h. or the concentrations of secondary carbonates throughout.

Kastanozem haplic

Kastanozem calcic

Kastanozem arable

PHAEOZEMS

1. a mollic h.; and

2. a base saturation (by 1 M NH₄OAc) of 50 percent or more throughout to a depth of 100 cm or more from the soil surface or to continuous rock or a cemented or indurated layer, whichever is shallower.

GYPSISOLS

1. a petrogypsic h. starting within 100 cm of the soil surface; or

2. a gypsic h. starting within 100 cm of the soil surface and no argic h. unless the argic h. is permeated with gypsum or calcium carbonate.

Gypsisol petric

DURISOLS

having a petroduric or duric h. starting within 100 cm of the soil surface.

Durisol

CALCISOLS

1. a petrocalcic h. starting within 100 cm of the surface; or

2. a calcic h. starting within 100 cm of the soil surface and

a. a calcareous matrix between 50 cm from the soil surface and the calcic h. thoughout if the calcic h. starts below 50 cm; and

b. no argic h. unless the argic h. is permeated with calcium carbonate.

ALBELUVISOLS AB

having an argic h. starting within 100 cm of the soil surface with albeluvic tonguing at its upper boundary.

Albeluvisol arable

ALISOLS

1. an argic h., which has a cation exchange capacity (by 1 M NH₄OAc) of 24 cmol_c kg^-1 clay or more throughout or to a depth of 50 cm below its upper limit, whichever is shallower, either starting within 100 cm of the soil surface, or within 200 cm of the soil surface, if the argic h. is overlain by loamy sand or coarser textures throughout; and

2. a base saturation (by 1 M NH₄OAc) of less than 50% in the major part between 50 and 100 cm.

ACRISOLS

1. an argic h., which has a cation exchange capacity (by 1 M NH₄OAc) of less than 24 cmol_c kg^-1 clay in some part to a maximum depth of 50 cm below its upper limit, either starting within 100 cm of the soil surface, or within 200 cm of the soil surface if the argic h. is overlain by loamy sand or coarser textures throughout, and

2. a base saturation (by 1 M NH₄OAc) of less than 50% in the major part between 50 and 100 cm.

Acrisol umbric

LUVISOLS

having an argic h. with a cation exchange capacity (by 1 M NH₄OAc) of 24 cmol_c kg^-1 clay or more throughout or to a depth of 50 cm below its upper limit, whichever is shallower, either starting within 100 cm of the soil surface or within 200 cm of the soil surface if the argic h. is overlain by loamy sand or coarser textures throughout.

Luvisol haplic

Luvisol albic

Luvisol arable

LIXISOLS

having an argic h., either starting within 100 cm of the soil surface or within 200 cm from the soil surface if the argic h. is overlain by loamy sand or coarser textures throughout.

UMBRISOLS UM

having an umbric or mollic h.

ARENOSOLS

1. a weighted average texture of loamy sand or coarser, if cumulative layers of finer texture are less than 15 cm thick, either to a depth of 100 cm from the soil surface or to a petroplinthic, pisoplinthic, plinthic or salic h. starting between 50 and 100 cm from the soil surface; and

2. less than 40% (by volume) of gravels or coarser fragments in all layers within 100 cm of the soil surface or to a petroplinthic, pisoplinthic, plinthic or salic h. starting between 50 and 100 cm from the soil surface; and

3. no fragic, irragic, hortic, plaggic or terric h.; and

4. no layers with andic or vitric properties with a combined thickness of 15 cm.

CAMBISOLS

1. a cambic h. starting within 50 cm of the soil surface and having its base 25 cm or more below the soil surface or 15 cm or more below any plough layer; or

2. an anthraquic, hortic, hydragric, irragric, plaggic or terric h.; or

3. a fragic, petroplinthic, pisoplinthic, plinthic, salic or vertic h. starting within 100 cm of the soil surface; or

4. one or more layers with andic or vitric properties with a combined thickness of 15 cm or more within 100 cm of the soil surface.

Cambisol haplic

Cambisol arable

REGOSOLS

Other soils

h. = horizon

Prepared 2012 by Yakov Kuzyakov

The most soil photos were done by Yakov Kuzyakov and can be used without limitations.