An Introduction to Hydric Soils and Hydric Soil Terminology • Based on deliberations of: The National Technical Committee for Hydric Soils (NTCHS). A word about the NTCHS • The National Technical Committee for Hydric Soils is a committee with the following representation: – Seven representatives from the various universities. – Five representatives from the USDA, Natural Resources Conservation Service (NRCS). – One representatives from each the following federal agencies: USDA, Forest Service, US Army Corps of Engineering, EPA, US Fish and Wildlife Service, and Bureau of Land Management. • The NTCHS make all decisions concerning hydric soils. Decision are by majority vote. The only agency bound by NTCHS decisions is NRCS. • By relying heavily on the scientific and technical communities for its membership, most NTCHS decisions are quite sound. Wetlands Wetlands • In most cases (previous slide) there are three technical criteria that must be met before an area can be called a wetland: Wetland Hydrology, Wetland Vegetation, and Hydric Soils. • Throughout this lecture and all remaining lectures we are not going to concern ourselves with Wetland Hydrology and Wetland Vegetation. We are going to concentrate our efforts on learning about Hydric Soils. Hydric Soil Topics • Hydric Soil Definition • Hydric Soil Lists • Hydric Soil Indicators • Hydric Soil – The definition provides up the basis for this lecture, the hydric soil lists are for off-site (office use), and the indicators provide us the best method of field identifying and delineating hydric soils. The ultimate goal of this lecture series is for you to fully understand hydric soils. Hydric Soil Definition • A soil that formed under conditions of saturation, flooding, or ponding long enough during the growing season to develop anaerobic conditions in the upper part (Federal Register. July 13, 1994). • The definition sets the stage for this and future lectures and parts of the definition will be referenced often. – “that formed under” means that there are such things as drained hydric soils; that the presence of ditches do not alter the status of a hydric soil. – “saturation, flooding, and ponding” tells us there are three conditions for wetness. These 3 conditions of wetness are utilized differently. – “during the growing season” will be applied differently for different applications. – “develop anaerobic conditions” tell us that a hydric soil need not be reduced but only lack oxygen. – “in the upper part” is vague enough to allow interpretations that vary from region to region and from climate to climate. • This definition has many different forms in the 1 1/2 decades prior to 1994; the NTCHS does not anticipate changing this (1994) version. Special consideration: Flooded and Ponded Soils • The NTCHS has deliberated that a soil that is frequently flooded or ponded for long or very long duration (longer than 7 days) during the growing season is a Hydric Soil. • However; Anaerobic conditions (as defined in the Hydric Soil Technical Standard) must exist also. • This (meaning inundation)) provides us the first method of identifying a hydric soil (there will be two others). • This method of identifying a hydric soil requires use of “during the growing season” data. Growing Season • Growing Season: The portion of the year when soil temperatures are above biologic zero 5 degrees C (41 degrees F) at 50 cm (19.7"). The following growing season months are assumed for each of the actual mean annual soil temperatures and soil temperature regimes of Soil Taxonomy: • No Permafrost and – 22 0 C or higher Isohyperthermic: January-December – 22 0 C or Higher Hyperthermic: February-December – 15 to 22 0 C Isothermic: January-December – 15 to 22 0 C Thermic: February-October – 8 to 15 0 C Isomesic: January-December – 8 to 15 0 C Mesic: March-October – Lower than 8 0 C Frigid: May-September – Lower than 8 0 C Isofrigid: May-September – Soil Taxonomy Requirements Cryic: May -August • Permafrost and – -10 0 C or lower Hypergelic: July-August – -4 to -10 0 C Pergelic: July-August – +1 to -4 0 C Subgelic: July-August Hydric Soil List: Most hydric soil lists are created by a soil scientist based on local experience and knowledge. Clay County, Florida _____________________________________________________________________________________________ | | | | Map symbol and | Component |Percent | Landform | Hydric map unit name | | of map | | rating | | unit | | _______________________________|_______________________|________|_________________|________ 8: | | | | Sapelo fine sand |Sapelo, hydric | 20 | Flats | Yes |Rutlege | 3 | Depressions | Yes |Albany | 10 | Knolls | No |Sapalo, nonhydric | 67 | Flatwoods | No 9: | | | | Leon fine sand |Leon, hydric | 10 | Flats | Yes |Lynn Haven | 3 | Flats | Yes |Sapelo, hydric | 3 | Flats | Yes |Leon, nonhydric | 70 | Flatwoods | No |Sapelo, nonhydric | 14 | Flatwoods | No 11: | | | | Allanton and Rutlege mucky fine |Allanton | 45 | Depressions | Yes sands, depressional | | | | |Rutlege | 35 | Depressions | Yes |Surrency | 5 | Depressions | Yes |Sapelo, hydric | 5 | Flats | Yes |Leon, nonhydric | 10 | Flatwoods | No 12: | | | | Surrency fine sand, depressional|Surrency | 80 | Depressions | Yes |Leon, hydric | 3 | Flats | Yes |Meggett | 3 | Flats | Yes |Rutlege | 3 | Depressions | Yes |Santee | 2 | Flood plains | Yes |Plummer | 9 | Flatwoods | No 13: | | | | Meggett fine sandy loam |Meggett | 85 | Flats | Yes |Goldhead, nonhydric | 15 | Flatwoods | No 17: | | | | Plummer fine sand |Plummer, hydric | 20 | Flats | Yes |Pelham, nonhydric | 15 | Flatwoods | No |Plummer, nonhydric | 65 | Flatwoods | No 19: | | | | Osier fine sand |Osier, hydric | 15 | Flats | Yes |Rutlege | 2 | Depressions | Yes |Osier, nonhydric | 65 | Flatwoods | No |Albany | 10 | Knolls | No |Hurricane | 8 | Knolls | No 20: | | | | Scranton fine sand |Scranton, hydric | 15 | Flats | Yes |Leon, hydric | 3 | Flats | Yes |Rutlege | 2 | Depressions | Yes |Scranton | 68 | Flatwoods | No |Ridgewood | 5 | Knolls | No |Ona, nonhydric | 3 | Flatwoods | No Inherent Problems with Hydric Soil Lists • There is a problem with hydric soil lists which may confuse users (Hurt and Carlisle. 1997). – The presence of a soil on a hydric soil list does not mean that the soil is in fact hydric. This is only an interpretive rating. Just as is the case with all interpretations based on information in a published soil survey or other sources of estimated soil properties, hydric soil interpretations are confirmed by on-site investigations. • Hydric soil indicators (Hurt and Vasilas. 2006) provides us a method of on-site confirmation of the presence or absence of a hydric soil. Hydric Soil Indicators • Field Indicators of Hydric Soils in the US (Vasilas, et.al. 2006) has been approved as the sole source document for hydric soil identification and delineation by the NRCS, US Army COE, EPA, and US Fish and Wildlife Service. It has also been approved as the sole source document for hydric soil identification and delineation by the State of Florida (DEP and Water Management Districts). The beauty of the hydric soil indicators is that they provide us a method to prove or disproved the presence of a hydric soil based on something felt, seen, or smelled and not estimated or guessed. Indicators are based on biogeochemical processes that occur when a soil is saturated or inundated. Biogeochemical Processes • Biogeochemical processes are processes that alter soil due to the interaction of its chemical composition and the animal and plant life it supports. • Hydric soil indicators are based on several biogeochemical processes (Vepraskas. 1994) that occur when soils are saturated or inundated (this subject will be covered thoroughly in the lecture of redoximorphic features). – Iron – Carbon – Carbon and Iron – Carbon and/or Iron – Carbon and Iron/Manganese – Iron/Manganese – Sulfur – Algae • The processes and the hydric soil indicator that result from the processes are reviewed in the next few slides. The indicators will be covered in depth during a later lecture. Ignore their being referenced for now; you may need to refer back after the next lecture. Iron • Twelve indicators are based on iron reduction, transformation, and differential accumulation: – A13, A14, A15, S4, S5, F2, F3, F8, F9, F18, F19 and F20. Carbon • Nineteen indicators are based on carbon accumulation and differential decomposition: – A1, A2, A3, A5, A6, A7, A8, A9, A10, S1, S2, S3, S7, S8, S9, F1, F11, F13, and F17. Carbon and Iron • Four indicators are based on carbon accumulation and differential decomposition and iron reduction, translocation, and differential accumulation: – A11, A12, F6, and F7. Carbon and/or Iron • One indicator is based on carbon accumulation and differential decomposition and/or iron reduction, translocation, and differential accumulation: – S6. Carbon and Iron/Manganese • One indicator is based on carbon accumulation and differential decomposition and iron/manganese reduction, translocation, and differential accumulation: – F16. Iron/Manganese • One indicator is based on iron/manganese reduction, transformation, and differential accumulation: – F12. Sulfur • One indicator is based on sulfur reduction: – A4. Algae • One indicator is based on precipitation of calcium carbonate by algae: – F10. Where do we begin our observations? • To determine whether an indicator is present or not it is critical to know where to begin looking. To determine whether a hydric soil indicator is present we would begin our observation of the soil in the photo to the