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Redoximorphic Features and Hydric Soils NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY.

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Presentation on theme: "Redoximorphic Features and Hydric Soils NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY."— Presentation transcript:

1 Redoximorphic Features and Hydric Soils NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE

2 Redoximorphic Features  Formed by changes in redox conditions in saturated soil  Reduction and oxidation of C, Fe, Mn, and S compounds  Translocation of C, Fe, Mn, and S compounds NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE

3 Redox Transformations Coating of Fe 2 O 3 Remove Fe Brown Soil Fe 3+ Fe 2+ Gray Soil 2e - + 6H + + Fe 2 O 3  2Fe(II) + 3H 2 O NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE

4 Redox features are like M&Ms =

5 In order to form features: must have anaerobic conditions (reduced and saturated) must have Fe and/or Mn (electron acceptor) must have microbes (bugs) must have carbon (food for the bugs) NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE

6 Redoximorphic Features Redox concentrations – zone where Fe - Mn oxides have accumulated Redox depletions – zone where of Fe – Mn oxide have been stripped out Reduced matrix – low chroma matrix that changes color when exposed to air

7 Redox depletions (Fe depletions) NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE

8 Fe depletions Fe depletion on ped face Fe depletion on pore Fe depletion in ped interior NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE

9 Fe depletions NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE

10 Concentrations and depletions NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE

11 Redox concentrations (Fe masses, Fe pore linings) NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE

12 Fe masses and Fe pore linings Pore lining on root channel Pore lining on Ped surface Nodule Fe mass in matrix Concretion NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE

13 Fe pore linings NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE

14 Fe masses NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE

15 Reduction, oxidation and translocation = saturation NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE

16 1. Plant root grows into soil 2. Root dies and starts to decompose 3. Water table rises 5. Reduced Fe moves away from decomposing root Reduced Fe oxidizes, soil turns red 7. Root completely decomposed 6. Water drains from root channel 8. Water table drops Redox depletion Redox Concentration (Pore lining) NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE

17 Lithochromic mottle Redox depletion

18 Concepts of Wetlands, Hydric Soils, and Wetland Hydrology

19 What is a wetland?

20 Wetland Definition (as defined by FSA Manual and COE 1987 Manual) has wetland hydrology has a predominance of hydrophytic vegetation the presence of hydric soil

21 Wetland hydrology occurs when: the water table is at or near the surface (12 inches) and, present for at least 5 percent (consecutive) of the growing season.

22 Month Depth (in.) Determining Wetland Hydrology

23 Determining the Growing Season Use NRCS County Soil Survey for beginning and end dates Determine number of days in season Multiply by 0.05 Usually between 12 and 14 days in this region

24 Definition of Hydric Soil A hydric soil is 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

25 Field Indicators of Hydric Soils Field indicators of hydric soils are designed for on-site identification of hydric soils

26 Field Indicators of Hydric Soils in the United States Version 5.01

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