Redoximorphic features: Subsoil with redoximorphic features from a hydric soil formed in lower coastal plain marine sediments
Although dark red and distinct, the red redox concentrations in this image are not considered plinthite. Unlike plinthite, they did not have a firm or firmer rupture resistance, could not be removed as a discrete body, and did not exhibit progressive hardening in the surrounding exposed road cuts and stream banks.
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 (2+). 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.
Redoximorphic concentrations, redoximorphic depletions, reduced matrices, and other features indicating the chemical reduction and oxidation of iron and manganese compounds resulting from saturation.
Redox concentrations – Zones of apparent accumulation of Fe-Mn oxides in soils.
Redox depletions – Zones of low chroma (2 or less) where Fe-Mn oxides alone or both Fe-Mn oxides and clay have been stripped out of the soil.
The difference between mottles and redoximorphic features. Historically, the term “mottles” has been used to identify differences in color patterns in a soil profile. Those color difference can be a result of something inherent in the parent material that formed the soil, the movement of organisms (worm channels), deposition of heterogenous materials (alluvial deposits), and chemical reactions in the soil (reduction/oxidation) to name just a few.
Because of the wide range of origins for the existence of mottling, soil scientists decided to coin a new term to specifically capture mottles that formed as a result of saturated conditions in the soil. That term is “redoximorphic features”. The word redoximorphic stems from “redox” which is short for reduction and oxidation and “morphic” which is short for “morphology”, which is the study of how things form, in this case soils. So the term literally means the formation of reduction and oxidation features. Therefore, a redoximorphic feature is a type of mottle that specifically identifies features created as a result of saturated conditions in the soil.
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...
Redoximorphic features: Subsoil with redoximorphic features from a hydric soil formed in lower coastal plain marine sediments
Although dark red and distinct, the red redox concentrations in this image are not considered plinthite. Unlike plinthite, they did not have a firm or firmer rupture resistance, could not be removed as a discrete body, and did not exhibit progressive hardening in the surrounding exposed road cuts and stream banks.
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 (2+). 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.
Redoximorphic concentrations, redoximorphic depletions, reduced matrices, and other features indicating the chemical reduction and oxidation of iron and manganese compounds resulting from saturation.
Redox concentrations – Zones of apparent accumulation of Fe-Mn oxides in soils.
Redox depletions – Zones of low chroma (2 or less) where Fe-Mn oxides alone or both Fe-Mn oxides and clay have been stripped out of the soil.
The difference between mottles and redoximorphic features. Historically, the term “mottles” has been used to identify differences in color patterns in a soil profile. Those color difference can be a result of something inherent in the parent material that formed the soil, the movement of organisms (worm channels), deposition of heterogenous materials (alluvial deposits), and chemical reactions in the soil (reduction/oxidation) to name just a few.
Because of the wide range of origins for the existence of mottling, soil scientists decided to coin a new term to specifically capture mottles that formed as a result of saturated conditions in the soil. That term is “redoximorphic features”. The word redoximorphic stems from “redox” which is short for reduction and oxidation and “morphic” which is short for “morphology”, which is the study of how things form, in this case soils. So the term literally means the formation of reduction and oxidation features. Therefore, a redoximorphic feature is a type of mottle that specifically identifies features created as a result of saturated conditions in the soil.
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...