Slate Belt Soil Issues: Wetness

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Slate Belt Soil Issues Wetness Oxyaquic
Conditions

• Dave Lindbo, Soil Science, NCSU
• Mike Vepraskas, Soil Science, NCSU
• Joe Kleiss, Soil Science, NCSU
• Roy Vick Jr., USDA-NRCS
• John Kelley, USDA-NRCS

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Outline

• Soil Taxonomy - General
• Redoximorphic features
• Identifying oxyaquic conditions
• Application to Onsite Wastewater

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Review of Soil Taxonomy
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USDA-NRCS Soil Survey Manual and Soil Taxonomy

• Determination of water table by morphology is not
  defined saturation is defined
• Aquic conditions are defined
• Oxyaquic conditions are defined

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Aquic Conditions

• Pertaining to soils that are
• periodically or continuously
• saturated and reduced
• Identified by
• the presence of redoximorphic features
• measuring saturation and reduction

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Oxyaquic Conditions

• Pertaining to soils that are
• saturated but are not reduced and
• do not contain redoximorphic features
• Identified by
• measuring saturation

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Redoximorphic Features
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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

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Redox Transformations
Coating of Fe2O3
Remove Fe
Fe2
Gray Soil
Brown Soil Fe3
2e- 6H Fe2O3 ? 2Fe(II) 3H2O
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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

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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)

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Redox depletions (Fe depletions)
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Fe depletions
Fe depletion in ped interior
Fe depletion on ped face
Fe depletion on pore
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Concentrations and depletions
NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE
NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE
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Redox concentrations (Fe masses, Fe pore linings)
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Fe masses and Fe pore linings
Fe mass in matrix
Pore lining on root channel
Pore lining on Ped surface
Concretion
Nodule
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Fe pore linings
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Fe masses
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Reduction, oxidation and translocation
saturation
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Identifying Aquic Conditions
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Aquic Conditions - Suborder

• Ultisols
• Spodosols
• Inceptisols
• Entisols
• Alfisols

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Ultisols - Aquults

• Aquic condition within 20 of surface and
• Redox features in all horizons below Ap or 10 to
  16 from surface and
• within the upper 5 of the Bt
• 2 chroma matrix with concentrations or
• 1 chroma matrix or
• Concentrations with a matrix of 2.5Y or 5Y

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Spodosols - Aquods

• Histic epipedon or
• Redoximorphic features in the upper 20

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Inceptisols - Aquepts

• Histic epipedon or
• Directly below epipedon or with in 20
• 2 chroma matrix with concentrations or
• 1 chroma matrix

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Entisols - Aquents

• Aquic conditions with 20 in. of surface
• Texture loamy fine sand or finer with
• O chroma matrix or
• 1 chroma, 4 value matrix or
• 2 chroma and concentration
• Texture fine sand and coarser
• O chroma matrix or
• 1 chroma, 4 value matrix, 10YR or redder or
• 2 chroma and concentrations, 10YR or redder or
• 3 chroma and concentrations, 2.5Y or yellower or
• 1 chroma, 2.5Y or yellower or
• 5GY, 5G, 5BG, or 5B
• Permanent saturation and reduced matrix below 10
  in.

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Alfisols - Aqualfs

• Aquic condition within 20 of surface and
• Redoximorphic features in all horizons below Ap
  or 10 in. to 16 in. from surface and
• within the upper 5 inches of the Bt
• 2 chroma matrix with concentrations or
• 1 chroma matrix

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To Simplify

• Ultisols and Alfisols
• Redoximorphic features within 10 to 16 of
  surface
• 2 chroma matrix starting within 5 of top of Bt
• Inceptisols
• 2 chroma matrix starting within 20 of surface
• Spodosols
• Redoximorphic features starting within 20 of
  surface
• Entisols
• 3 chroma matrix starting within 20 of surface
• Permanent saturation below 10

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Aquic Conditions Great Group

• Ultisols
• Spodosols
• Inceptisols
• Entisols
• Alfisols

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Redox Concentration (Pore lining)
1. Plant root grows into soil
5. Reduced Fe moves away from decomposing
root Reduced Fe oxidizes, soil turns red
2. Root dies and starts to decompose
3. Water table rises
4. Bacteria continue to decompose root Oxygen
reduced Nitrate reduced Fe reduced and removed,
soil turns gray
6. Water drains from root channel
7. Root completely decomposed
8. Water table drops
Redox depletion
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To Simplify

• Ultisols and Alfisols
• 2 chroma redoximorphic depletions within 10 to
  20 of top of Bt or,
• 2 chroma redoximorphic depletions within 30 of
  surface
• Inceptisols
• 2 chroma redoximorphic depletions within 30 of
  surface
• Spodosols
• 2 chroma redoximorphic depletions within 30 of
  surface
• Entisols
• 2 chroma redoximorphic depletions within 40 of
  surface

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So how does this help?
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Identifying Oxyaquic Conditions
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What is the definition of oxyaquic conditions?

• Soils that are saturated but are not reduced, and
• Soils that do not contain redoximorphic features

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How do you know if you have oxyaquic conditions?

• You measure saturation

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Determining oxyaquic conditions

• In Ultisols, Spodosols, Inceptisols, Entisols,
  and Alfisols
• Can not have aquic conditions
• Saturation for in normal years above 40 for
• 20 consecutive days or
• 30 cumulative days

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This sounds too hardis there another way?
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Redox Transformations
Coating of Fe2O3
Remove Fe
Fe2
Gray Soil
Brown Soil Fe3
2e- 6H Fe2O3 ? 2Fe(II) 3H2O
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Redox concentrations
WT 4
4 chroma depletion
Oxyaquic Zone
WT 3
3 chroma depletion
WT 2
WT 1
lt 2 chroma depletion
Aquic Zone
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Oxyaquic examples
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3 and 4 chroma depletions concentrations
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Landscape where oxyaquic may be found
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Additional Notes

• What to look for to determine wetness

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Depletions and concentrations some root bark
may look like concentrations
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Look for evidence of redox reaction throughout
the profile
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Fe pore linings and masses
3 chroma depletions
2 chroma depletions
2 chroma matrix
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Fe masses
3 chroma depletions
2 chroma depletions
2 chroma matrix
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Fe pore linings and masses
A1
A2
C1
Depletion?
C2
Oxidation of mineral grains
C3
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3 chroma matrix
2 chroma depletions and concentrations
2 chroma matrix
Depletions and concentrations
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Relict Features
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Relict features

• Occur when soil colors are not in equilibrium
  with the soil conditions
• Colors generally take years to form
• Colors can be in error due to
• a change in hydrology (draining or flooding)
• addition of soil material (fill)
• both can result in an estimation of higher or
  lower ESHW

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Relict Features

• How do you know a feature is relict?
• Look at multiple profiles especially with fill
• Site history
• Monitoring

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Is this a poorly-drained soil?
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The previous profile is located at the edge of
this quarry.
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Is this soil wet?
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Drainage must be maintained in order for any
feature to be truly relict
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Formation of a relict feature
Clay film
Fe depletion formed next to channel where root
grew
Root dies and depletion stops forming. It can
be covered by clay that may be Fe-rich
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Relic Feature???
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Formation of a relict feature
Clay film
Fe concentration formed next to channel where
root grew
Root dies and concentration stops forming. It
can be covered by gray clay or organic material
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This pore lining is not forming
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Relict Feature?
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Cautionary Note

• Data to prove this is limited
• Always look at landscape
• Is the evidence of a change in hydrology?
• Drainage ditches is there an outlet?
• Incised stream
• Look at vegetation
• Upland?
• Wetland?

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Lithochromic Features
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Lithochromic Features

• Colors or structures inherited from the parent
  material
• Flood plains-can be grayer or redder than actual
  site conditions would suggest
• Saprolite-rock controlled structure vs soil
  structure

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Even gray parent materials may show redox
depletions and concentration
Concentrations
Depletions
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Red colors from parent material hard to reduce
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Low chroma colors from minerals in parent
material not reduction
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Low chroma colors from minerals in parent
material not reduction
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Flood plain soil where Mn may slow Fe
transformations
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Redox depletion
Lithochromic mottle
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Morphology
Concentrations
3 Chroma
lt 2 Chroma
NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE
NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE
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Clayey
Coarse-loamy
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Sandy
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6
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Coarse-loamy
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Sandy
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10
6
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6
10
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20
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Stallings
Wet-Foreston
Foreston