Soil color (ped exterior versus ped interior)
Soils are often dominated by two main coloring agents: organic matter and iron minerals. Often we see colors of red, yellow, brown, orange, etc. in a soil profile. All of these colors are created by different forms of iron minerals present on the soil particles. 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 (lithochromic mottles) and chemical reactions in the soil (redixomorphic features--mottles that form as a result of saturated conditions in the soil). 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 example, most of the naturally occuring iron has been stripped from the ped face leaving a neutral gray color as a result of redoximorphic processes.
Alfisols (SOIL TAXONOMY; JA.1. a or c.) Even though the ped interior does not have a predominately gray interior color, it is considered aquic if 50 percent or more redox depletions with chroma of 1 or less are on faces of peds or chroma of 2 or less with redox concentrations in the matrix.
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...
Soil color (ped exterior versus ped interior)
Soils are often dominated by two main coloring agents: organic matter and iron minerals. Often we see colors of red, yellow, brown, orange, etc. in a soil profile. All of these colors are created by different forms of iron minerals present on the soil particles. 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 (lithochromic mottles) and chemical reactions in the soil (redixomorphic features--mottles that form as a result of saturated conditions in the soil). 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 example, most of the naturally occuring iron has been stripped from the ped face leaving a neutral gray color as a result of redoximorphic processes.
Alfisols (SOIL TAXONOMY; JA.1. a or c.) Even though the ped interior does not have a predominately gray interior color, it is considered aquic if 50 percent or more redox depletions with chroma of 1 or less are on faces of peds or chroma of 2 or less with redox concentrations in the matrix.
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...