Oxisol and pseudo sand
Oxisols are typically 75 or more percent clay; however, both the structure and “feel” of Oxisols are deceptive. Upon first examination, they appear structureless and have the feel of a loamy texture. While some are loamy or even coarser textured, many have a fine or very-fine particle-size class, but the clay is aggregated in a strong grade of fine and very fine granular structure. To obtain a true “feel” of the texture, a wet sample must be worked for several minutes in the hands to break down the aggregates (or "pseudo sand").
Oxisols are an order in USDA soil taxonomy, best known for their occurrence in tropical rain forest, 15-25 degrees north and south of the Equator. They are classified as ferralsols in the World Reference Base for Soil Resources; some oxisols have been previously classified as laterite soils.
Oxisols are defined as soils containing at all depths no more than 10 percent weatherable minerals, and low cation exchange capacity, typical for soils formed on very old, stable landscapes. Oxisols are always a red or yellowish color, due to the high concentration of iron (III) and aluminum oxides and hydroxides. In addition, they also contain quartz and kaolin, plus small amounts of other clay minerals and organic matter.
For more information about soil classification using the WRB system, visit:
www.fao.org/3/i3794en/I3794en.pdf
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:
Oxisol and pseudo sand
Oxisols are typically 75 or more percent clay; however, both the structure and “feel” of Oxisols are deceptive. Upon first examination, they appear structureless and have the feel of a loamy texture. While some are loamy or even coarser textured, many have a fine or very-fine particle-size class, but the clay is aggregated in a strong grade of fine and very fine granular structure. To obtain a true “feel” of the texture, a wet sample must be worked for several minutes in the hands to break down the aggregates (or "pseudo sand").
Oxisols are an order in USDA soil taxonomy, best known for their occurrence in tropical rain forest, 15-25 degrees north and south of the Equator. They are classified as ferralsols in the World Reference Base for Soil Resources; some oxisols have been previously classified as laterite soils.
Oxisols are defined as soils containing at all depths no more than 10 percent weatherable minerals, and low cation exchange capacity, typical for soils formed on very old, stable landscapes. Oxisols are always a red or yellowish color, due to the high concentration of iron (III) and aluminum oxides and hydroxides. In addition, they also contain quartz and kaolin, plus small amounts of other clay minerals and organic matter.
For more information about soil classification using the WRB system, visit:
www.fao.org/3/i3794en/I3794en.pdf
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: