Hydric Soils

There were three criteria used to label a given profile as 'Hydric',
(1) Was the soil legally defined as hydric;
(2) Did the position of the soil in the taxonomy indicate that it was hydric; and
(3) Did the scientific oversight staff adjust the determination based on the above criteria along with more specific criteria.

The first criterion was tested by checking the soil name against the listing provided by the Florida Department of Environmental Regulation (F.D.E.P.) in attach6.pdf. This document lists soil names which have determined to be “hydric” soils.    They are:

Ariaquolls
Bakersville
Bessie
Bohicket
Brighton
Brookman
Buccaneer
Ceia
Chobee
Copeland
Croatan
Dania
Dasher
Delray
Denaud
Dirego
Dorovan
Durbin
Everglades
Favoretta
Fellowship
Floridana
Gator
Gentry
Handsboro
Harbeson
Hicoria
Homosassa
Hontoon
Humaquepts
Islamorada
Istokpoga
Johnston
Kaliga
Kenner
Keylargo
Kingsland
Lauderhill
Manatee
Martel
Maurepas
McKee
Micco
Montverde
Nittaw
Ocoee
Okeechobee
Okeelanta
Oklawaha
Pahokee
Pamlico
Peckish
Pellicer
Pickney
Placid
Pocomoke
Popash
Portsmouth
Riomar
Rutlege
Samsula
Sanibel
Santee
Sellers
Shenks
Stockade
Tamiami
Tavernier
Terra
Tidewater
Timbalier
Tisonia
Tomoka
Torhunta
Torry
Turnbull
Umbraqualfs
Weekiwachee
Wulfert

The second criterion was tested by using the taxonomy of the soil to characterize it as hydric or non-hydric. A three-dimensional matrix of 68 great groups by 35 suborders by 13 orders was drawn up and the 30940 cells were either scored as hydric or non-hydric using NRCS’s methodology for their SSURGO hydric soil determination (SSURGO Manual, Appendix B, p 12). We concluded that a soil would be hydric using the following rules:

  • All histosols, except folists
  • Soils in the aquic suborder
  • Soils in the albolls suborder
  • Soils in the Salorthids great group

Other rules (i.e. using aquic, pell, pachic and cumulic subgroups) were mentioned in SSURGO’s criteria but did not apply to our samples.

The taxonomy of any given soil can be separated into great group, suborder and order and the appropriate cell in the matrix can therefore be located. As an example, the soil haplosaprists would result in haplo- (great group), -sapr- (suborder) and –ist (order). If that cell was scored as 'Hydric', then the soil would be so labeled.

Using these criteria, the data were tagged  as hydric (H) or non-hydric (N), using the two criteria described above. The results are expressed as a two-character field assigned to the XML tag HYDRICRATIONALE. The first position refers to the soil name criterion and the second position refers to the taxomony criterion. Thus:
NN = nonhydric for both criteria;
HH = Hydric for both criteria;
NH = the soil name was not found in the FDEP list but the taxonomy indicated that the soil was hydric; and
HN = the soil name was in the FDEP list but the taxonomy indicated otherwise.

The overall status of a soil was coded into the XML field HYDRICSTATUS. If a soil was found to be hydric on either criterion, e.g., an 'H' appeared in either position in the HYDRICRATIONALE field, then HYDRICSTATUS was set to 'Hydric'. If  HYDRICRATIONALE field was set to 'NN', then HYDRICSTATUS field was set to 'Nonhydric'.

The determination by taxonmy should be considered only as a first approximation and can be reversed by the scientific oversight staff when additional criteria are applied. As an example, a profile in Alachua County (S01_047) consisted of Myakka Sand and has a taxonomy of Aeric Alaquods. The cell [Al][aqu][ods] is scored as hydric but the long-term water table was indicated to be at 30cm (by indirect means), thus making this profile 'Nonhydric'.