Ferro-Humic Podzol (FHP)
These soils have a dark-colored podzolic B horizon with a high content of organic C and an appreciable amount of extractable Fe and Al. They occur typically in the more humid part of the region of Podzolic soils under forest vegetation, or forest with heath or moss undercover. Under virgin conditions these soils usually have thick L, F, and H or O horizons; they may have an Ah horizon and usually have a light-colored Ae horizon. The podzolic B horizon is usually thick and dark reddish brown in the upper part and grades to lighter colors of higher chroma with depth. Typically the Bhf horizon is of higher chroma (commonly 2, 3, or 4) than the Bh horizon of Humic Podzols (commonly 1 or 2). The material below the podzolic B horizon may be cemented (duric), compact and brittle (fragipan), or friable.
Ferro-Humic Podzols have a Bhf horizon at least 10 cm thick and lack a Bh horizon at least 10 cm thick. The Bhf horizon contains 5% or more organic C and 0.6% or more pyrophosphate-extractable Fe+Al (0.4% for sands). It has a ratio of organic C to pyrophosphate-extractable Fe of less than 20, or has 0.3% or more pyrophosphate-extractable Fe, or both.
Ferro-Humic Podzols are generally both strongly acid and less than 50% base saturated (neutral salt). The pH-dependent CEC of the Bhf horizon is usually well above 8 cmol kg-1 and is commonly 25 cmol kg-1 or more. The Bhf horizon of these soils usually has a markedly silty feel when rubbed moist, which is presumably because of its high content of amorphous material.
Ferro-Humic Podzols are divided into ten subgroups based on the kind and sequence of horizons. Gleyed subgroups are not differentiated for those soils having a relatively impermeable subsoil horizon (placic, duric, fragic, Bt). A Gleyed Ortstein subgroup is included because some ortstein horizons are permeable to water and do not result in temporary gleying.
Orthic Ferro-Humic Podzol (O.FHP)
Common horizon sequence: LFH or O, Ae, Bhf, Bf, BC, C
These soils have the general properties specified for the Podzolic order and the Ferro-Humic Podzol great group. They are identified by the following properties:
- They have a Bhf horizon at least 10 cm thick.
- They do not have a Bh horizon at least 10 cm thick, an ortstein horizon at least 3 cm thick, a placic horizon, a duric horizon, a fragipan, a Bt horizon, an Ah horizon at least 10 cm thick, or evidence of gleying in the form of distinct or prominent mottling within 1 m of the surface.
Usually Orthic Ferro-Humic Podzols have L, F, and H or O horizons and an Ae horizon. Commonly they have a Bf horizon underlying the Bhf. Parts of the Bhf or Bf may be cemented but do not meet the requirements of an ortstein horizon.
Ortstein Ferro-Humic Podzol (OT.FHP)
Common horizon sequence: LFH or O, Ae, Bhf, Bhfc or Bfc, BC, C
These soils have the general properties specified for the Podzolic order and the Ferro-Humic Podzol great group. They differ from Orthic Ferro-Humic Podzols by having an ortstein horizon at least 3 cm thick. An ortstein horizon is a Bh, Bhf, or Bf horizon that is strongly cemented and occurs in at least one-third of the lateral extent of the pedon. The ortstein horizon in this subgroup is designated as Bhfc or Bfc depending upon its organic C content and is generally reddish brown to very dark reddish brown in color. Usually Ortstein Ferro-Humic Podzols have L, F, and H or O horizons and an Ae horizon. They may have one or more of placic, duric, Ah, or Bt horizons, a fragipan, or faint mottling.
Placic Ferro-Humic Podzol (P.FHP)
Common horizon sequence: LFH or O, Ae, Bhf, Bhfc or Bfc, Bf, BC, C
These soils have the general properties specified for the Podzolic order and the Ferro-Humic Podzol great group. They differ from Orthic Ferro-Humic Podzols by having a placic horizon within the control section. A placic horizon (Bhfc, Bfc, Bfgc) consists of a single thin layer (commonly 5 mm or less thick) or a series of thin layers that are irregular or involute, hard, impervious, often vitreous, and dark reddish brown to black. These thin horizons are apparently cemented by Fe-organic complexes, hydrated Fe oxides, or a mixture of Fe and Mn oxides. The placic horizon, or thin iron pan, may occur in any part of the B horizon and commonly extends into the BC horizon.
Placic Ferro-Humic Podzols usually have L, F, and H or O horizons and an Ae horizon. They do not have an ortstein horizon but may have a duric, Ah, or Bt horizon, or a fragipan. Evidence of gleying in the form of dull colors or mottling is commonly apparent especially above depressions in the placic horizon. These soils occur most commonly in coarse textured deposits in perhumid maritime climates.
Duric Ferro-Humic Podzol (DU.FHP)
Common horizon sequence: LFH or O, Ae, Bhf, BCc, C
These soils have the general properties specified for the Podzolic order and the Ferro-Humic Podzol great group. They differ from Orthic Ferro-Humic Podzols by having a duric horizon within the control section. A duric horizon is a strongly cemented horizon that does not satisfy the criteria of a podzolic B horizon. It usually has an abrupt upper boundary to an overlying podzolic B horizon and a diffuse lower boundary at least 50 cm below. Cementation is usually strongest near the upper boundary, which occurs commonly at a depth of 40-80 cm from the mineral surface. Usually the color of a duric horizon differs little from that of the parent material. As well the structure is usually massive or very coarse platy. Moist clods at least 3 cm thick usually cannot be broken in the hands. Air-dry clods of the material do not slake when immersed in water. Some duric horizons may meet the requirements of a Bt horizon (Btc).
Duric Ferro-Humic Podzols usually have L, F, and H or O horizons. They do not have an ortstein or a placic horizon but may have an Ah horizon and mottles that indicate gleying in some part of the control section. These soils occur most commonly in coastal southwestern British Columbia.
Fragic Ferro-Humic Podzol (FR.FHP)
Common horizon sequence: LFH or O, Ae, Bhf, Bf, BCx, C
These soils have the general properties specified for the Podzolic order and the Ferro-Humic Podzol great group. They differ from Orthic Ferro-Humic Podzols by having a fragipan within the control section. A fragipan (Bx or BCx) is a subsurface horizon of high bulk density that has firm and brittle consistence when moist and hard to extremely hard consistence when dry. Usually it is of medium texture. Commonly it has bleached fracture planes separating very coarse prismatic units and the secondary structure is platy. The fragipan is usually similar in color to the parent material, but it differs in structure and consistence and sometimes in bulk density. The upper boundary of a fragipan is usually either abrupt or clear, but the lower boundary is usually diffuse. It is often necessary to dig to about 3 m to expose clearly the material beneath the lower boundary of the fragipan. Air-dry clods of fragipans slake in water. A fragipan may have clay skins and meet the limits of a Bt horizon (Btx).
Fragic Ferro-Humic Podzols usually have L, F, and H or O horizons and an Ae horizon. They do not have ortstein, placic, or duric horizons but may have an Ah horizon and mottles that indicate gleying at some depth within the control section.
Luvisolic Ferro-Humic Podzol (LU.FHP)
Common horizon sequence: LFH or O, Ae, Bhf, Bf, Bt, C
These soils have the general properties specified for the Podzolic order and the Ferro-Humic Podzol great group. They differ from Orthic Ferro-Humic Podzols by having a Bt horizon of which the upper boundary is at a depth of more than 50 cm from the mineral surface. If the upper boundary of the Bt horizon is ≤50 cm from the surface the soil is classified in the Luvisolic order.
Luvisolic Ferro-Humic Podzols usually have L, F, and H or O horizons and an Ae horizon and they may have an Ah horizon. They do not have ortstein, placic, or duric horizons, or a fragipan but may have mottles that indicate gleying at some depth within the control section.
Sombric Ferro-Humic Podzol (SM.FHP)
Common horizon sequence: LFH or O, Ah, Ae, Bhf, Bf, BC, C
These soils have the general properties specified for the Podzolic order and the Ferro-Humic Podzol great group. They differ from Orthic Ferro-Humic Podzols by having an Ah horizon at least 10 cm thick.
Usually Sombric Ferro-Humic Podzols have L, F, and H or O horizons and may have an Ae horizon but do not have ortstein, placic, duric, or Bt horizons, a fragipan, or distinct or prominent mottles that indicate gleying.
Gleyed Ferro-Humic Podzol (GL.FHP)
Common horizon sequence: LFH or O, Aegj, Bhf, Bfgj, BCg, Cg
These soils have the general properties specified for the Podzolic order and the Ferro-Humic Podzol great group. They differ from Orthic Ferro-Humic Podzols by having distinct or prominent mottles that indicate gleying within 1 m of the surface. Usually they have thick L, F, and H or O horizons. They do not have ortstein, placic, duric, or Bt horizons, a fragipan, or an Ah horizon at least 10 cm thick.
Gleyed Ortstein Ferro-Humic Podzol (GLOT.FHP)
Common horizon sequence: LFH or O, Aegj, Bhf, Bhfc or Bfcg, BCg, Cg
These soils have the general properties specified for the Podzolic order and the Ferro-Humic Podzol great group. They differ from Ortstein Ferro-Humic Podzols by having distinct to prominent mottles that indicate gleying within 1 m of the surface. Usually they have thick L, F, and H or O horizons. They may have placic, duric, Ah, or Bt horizons, or a fragipan.
Gleyed Sombric Ferro-Humic Podzol (GLSM.FHP)
Common horizon sequence: LFH or O, Ah, Aegj, Bhf, Bfgj, BCgj, C
These soils have the general properties specified for the Podzolic order and the Ferro-Humic Podzol great group. They differ from Sombric Ferro-Humic Podzols by having distinct or prominent mottles that indicate gleying within 1 m of the surface. Usually they have thick L, F, and H or O horizons but do not have ortstein, placic, duric, or Bt horizons, or a fragipan.
Note: Diagnostic horizons are underlined.