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Anomalous Bright Loamy Soils: Newly Recognized Hydric Soils in the Mid Atlantic Coastal Plain

Anomalous Bright Loamy Soils: Newly Recognized Hydric Soils in the Mid Atlantic Coastal Plain. Martin C. Rabenhorst University of Maryland Dept. of Environmental Science and Technology College Park, MD. From FIHSUS.

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Anomalous Bright Loamy Soils: Newly Recognized Hydric Soils in the Mid Atlantic Coastal Plain

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  1. Anomalous Bright Loamy Soils: Newly Recognized Hydric Soils in the Mid Atlantic Coastal Plain Martin C. Rabenhorst University of Maryland Dept. of Environmental Science and Technology College Park, MD

  2. From FIHSUS • Hydric Soils: “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). • Nearly all hydric soils exhibit characteristic morphologies that result from repeated periods of saturation and/or inundation for more than a few days. This anaerobiosis promotes biogeochemical processes, such as • the accumulation of organic matter and • the reduction, translocation, and/or accumulation of iron and other reducible elements. • These processes result in characteristic morphologies …. making them particularly useful for identifying hydric soils.

  3. Typical “Hydric” Soil Organic matter accumulation Depletion of iron oxides from the matrix Segregation of iron oxides into prominent concentrations

  4. The Problem • Soils identified that meet saturation and reduction requirements for hydric soils • But they do not show the typical morphological features of hydric soils

  5. Not dominantly gray • Loamy in texture (loams and silt loams) Anomalous Bright Loamy Soils ABLS

  6. Anecdotal observations led to a research study • M.S. Thesis of Philip K. Zurheide • Under the guidance of the Mid-Atlantic Hydric Soils Committee

  7. Research hypotheses for the explanation of the ABLS phenomenon • Soils not saturated long enough • Oxyaquic conditions (saturated by not reducing) • Parent materials inherently resistant to color change (analogous to TF2 – red parent material) • Low lateral hydraulic gradient – sea level rise *

  8. F20. Anomalous Bright Loamy Soils. • For use in MLRA 149A of LRR S and MLRAs 153C and 153D of LRR T; for testing in MLRA 153B of LRR T. • Within 200 m (656 feet) of estuarine marshes or waters and within 1 m (3.28 feet) of mean high water, • a mineral layer at least 10 cm (4 inches) thick starting within 20 cm (8 inches) of the soil surface • with a matrix (60 percent or more of the volume) chroma of less than 5 and 10 percent or more distinct or prominent redox concentrations occurring as soft masses or pore linings and/or depletions. • User Notes: These soils are expected to occur on linear or convex landforms that are adjacent to estuarine marshes or waters.

  9. For use in MLRA 149A of LRR S and MLRAs 153C and 153D of LRR T

  10. for testing in MLRA 153B of LRR T

  11. Eastern Neck Island NWR 160 m • Within 200 m (656 feet) of estuarine marshes or waters and within 1 m (3.28 feet) of mean high water,

  12. A mineral layer at least 10 cm (4 inches) thick starting within 20 cm (8 inches) of the soil surface Can be overlain by any material

  13. matrix (60 percent or more of the volume) chroma of less than 5 (closer to 4 than to 6) 10 percent or more distinct or prominent redox concentrations occurring as soft masses or pore linings and/or depletions.

  14. A AE BE Bt1 Bt2 10YR 3/1 10YR 4/3 2.5Y 5/4 with 30% 10YR 5/6 concentrations 7.5YR 5/6 with 30% 10YR 5/8 concentrations 20% 2.5 6/4 and 10% 2.5Y 6/3 depletions Eastern Neck Island a layer at least 10 cm (4 inches) thick starting within 20 cm (8 inches) of the soil surface with a matrix chroma of less than 5 10 percent or more distinct or prominent redox concentrations and/or depletions

  15. A EA BE Bt1 10YR 3/1 10YR 4/3 1% 7.5YR 4/6 concentrations 2.5Y 6/4 matrix 5-10% 10YR 5/8; 10% 10YR 4/6 concentrations 25% 2.5Y 6/3 depletions EN low a layer at least 10 cm (4 inches) thick starting within 20 cm (8 inches) of the soil surface with a matrix chroma of less than 5 10 percent or more distinct or prominent redox concentrations and/or depletions

  16. A AE Bt1 Bt2 10YR 3.5/2 3% 7.5YR 3/3 concentrations 2.5Y 4/2.7 7% 7.5YR 3/3 concentrations 2.5Y 5/4 matrix 7% 7.5YR 4/6; 3% 7.5YR 3/4 concentrations 5% 2.5Y 5/3.2; 5% 2.5Y 6/2 depletions BW high a layer at least 10 cm (4 inches) thick starting within 20 cm (8 inches) of the soil surface with a matrix chroma of less than 5 10 percent or more distinct or prominent redox concentrations and/or depletions

  17. A AB BA Bt1 7.5YR 3/2 10YR 4/3 10% 7.5YR 4/6; 5% 5YR 3/4 concentrations 3% 2.5Y 4/2 depletions 2.5Y 5/4 35% 10YR 5/6; 3% 7.5YR 4/6 concentrations IOW high a layer at least 10 cm (4 inches) thick starting within 20 cm (8 inches) of the soil surface with a matrix chroma of less than 5 10 percent or more distinct or prominent redox concentrations and/or depletions

  18. A1 A2 AE EB Bt 7.5YR 2.5/1 3% 5YR 3/3 pore linings 7.5YR 2/2 10% 5YR 3/3 pore linings 2.5Y 3/3 15% 7.5YR 3/4 pore linings TH low a layer at least 10 cm (4 inches) thick starting within 20 cm (8 inches) of the soil surface with a matrix chroma of less than 5 10 percent or more distinct or prominent redox concentrations and/or depletions

  19. ABLS • An indicator now approved to accommodate these problem soils. • Should be kept in mind when examining low elevation soils on the coastal plain within 200 meters of tidal water or tidal marsh

  20. We would like to express appreciation to the following organizations who helped to support this work: • Maryland Department of the Environment • US Environmental Protection Agency • Maryland Agricultural Experiment Station • Mid-Atlantic Hydric Soil Committee

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