Redox concentrations (RMFs): soil ped (L) and shovel slice (R)
Redoximorphic features (RMFs) consist of color patterns in a soil that are caused by loss (depletion) or gain (concentration) of pigment compared to the matrix color, formed by oxidation/reduction of iron and/or manganese coupled with their removal, translocation, or accrual; or a soil matrix color controlled by the presence of iron.
The composition and responsible formation processes for a soil color or color pattern must be known or inferred before it can be described as an RMF.
This is an example of a depleted matrix with Fe concentrations along an old root channel. A depleted matrix refers to the volume of a soil horizon or subhorizon in which the processes of reduction and translocation have removed or transformed iron, creating colors of low chroma and high value.
Once the soil is saturated, Fe in solution moves downward and laterally. As the soil dries, the Fe accumulates along the pore wall forming pore linings. The linings are zones of accumulation that may be either coatings on a ped or pore surface or impregnations of the matrix adjacent to the pore or ped. Over time, the Fe concentrations thicken, and cementation may occur.
For more information about describing and sampling soils, visit:
www.nrcs.usda.gov/resources/guides-and-instructions/field...
or Chapter 3 of the Soil Survey manual:
www.nrcs.usda.gov/sites/default/files/2022-09/The-Soil-Su...
For additional information on "How to Use the Field Book for Describing and Sampling Soils" (video reference), visit:
www.youtube.com/watch?v=e_hQaXV7MpM
For additional information about soil classification using USDA-NRCS Soil Taxonomy, visit:
www.nrcs.usda.gov/resources/guides-and-instructions/keys-...
or;
www.nrcs.usda.gov/resources/guides-and-instructions/soil-...
For more information about Hydric Soils and their Field Indicators, visit:
www.nrcs.usda.gov/resources/guides-and-instructions/field...
Redox concentrations (RMFs): soil ped (L) and shovel slice (R)
Redoximorphic features (RMFs) consist of color patterns in a soil that are caused by loss (depletion) or gain (concentration) of pigment compared to the matrix color, formed by oxidation/reduction of iron and/or manganese coupled with their removal, translocation, or accrual; or a soil matrix color controlled by the presence of iron.
The composition and responsible formation processes for a soil color or color pattern must be known or inferred before it can be described as an RMF.
This is an example of a depleted matrix with Fe concentrations along an old root channel. A depleted matrix refers to the volume of a soil horizon or subhorizon in which the processes of reduction and translocation have removed or transformed iron, creating colors of low chroma and high value.
Once the soil is saturated, Fe in solution moves downward and laterally. As the soil dries, the Fe accumulates along the pore wall forming pore linings. The linings are zones of accumulation that may be either coatings on a ped or pore surface or impregnations of the matrix adjacent to the pore or ped. Over time, the Fe concentrations thicken, and cementation may occur.
For more information about describing and sampling soils, visit:
www.nrcs.usda.gov/resources/guides-and-instructions/field...
or Chapter 3 of the Soil Survey manual:
www.nrcs.usda.gov/sites/default/files/2022-09/The-Soil-Su...
For additional information on "How to Use the Field Book for Describing and Sampling Soils" (video reference), visit:
www.youtube.com/watch?v=e_hQaXV7MpM
For additional information about soil classification using USDA-NRCS Soil Taxonomy, visit:
www.nrcs.usda.gov/resources/guides-and-instructions/keys-...
or;
www.nrcs.usda.gov/resources/guides-and-instructions/soil-...
For more information about Hydric Soils and their Field Indicators, visit:
www.nrcs.usda.gov/resources/guides-and-instructions/field...