Plinthite: Exposed Plinthic horizon
Plinthite (Gr. plinthos, brick) is an iron-rich, humus-poor mixture of clay with quartz and other highly weathered minerals. It commonly occurs as reddish redox concentrations in a layer that has a polygonal (irregular), platy (lenticular), or reticulate (blocky) pattern. Plinthite irreversibly hardens upon exposure to repeated wetting and drying, especially if exposed to heat from the sun. Other morphologically similar iron-rich materials that do not progressively harden upon repeated wetting and drying are not considered plinthite.
Note the exposed soil surface in the center of the photo as compared to the freshly excavated area to the right. The area in the center has been exposed to the elements for an extended period of time and is essentially 100 percent cemented to a depth of 1 to 2 cm or more. The fresh cut area to the right exhibits a lesser degree of cementation, and a lower volume of cemented material. Cementation decreases with depth as you move from the surface into the soil. This is evidence of progressive cementation upon exposure to repeated wetting and drying. Upon examination of northern exposures along road banks versus southern exposures it was noted the surfaces were more than 90 percent cemented on southerly aspects and about 35 to 65 percent cemented of northern aspects.
A plinthic horizon contains a significant amount of plinthite. If the horizon constitutes a "continuous phase", zones that roots can enter are more than 10cm apart and plinthite makes up 50 percent or more of the volume of the horizon (proposed).
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 more information about a plinthic horizon, visit;
www.researchgate.net/publication/242649722_Rationale_for_...
or;
www.sciencedirect.com/science/article/pii/S00167061220043...
Plinthite: Exposed Plinthic horizon
Plinthite (Gr. plinthos, brick) is an iron-rich, humus-poor mixture of clay with quartz and other highly weathered minerals. It commonly occurs as reddish redox concentrations in a layer that has a polygonal (irregular), platy (lenticular), or reticulate (blocky) pattern. Plinthite irreversibly hardens upon exposure to repeated wetting and drying, especially if exposed to heat from the sun. Other morphologically similar iron-rich materials that do not progressively harden upon repeated wetting and drying are not considered plinthite.
Note the exposed soil surface in the center of the photo as compared to the freshly excavated area to the right. The area in the center has been exposed to the elements for an extended period of time and is essentially 100 percent cemented to a depth of 1 to 2 cm or more. The fresh cut area to the right exhibits a lesser degree of cementation, and a lower volume of cemented material. Cementation decreases with depth as you move from the surface into the soil. This is evidence of progressive cementation upon exposure to repeated wetting and drying. Upon examination of northern exposures along road banks versus southern exposures it was noted the surfaces were more than 90 percent cemented on southerly aspects and about 35 to 65 percent cemented of northern aspects.
A plinthic horizon contains a significant amount of plinthite. If the horizon constitutes a "continuous phase", zones that roots can enter are more than 10cm apart and plinthite makes up 50 percent or more of the volume of the horizon (proposed).
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 more information about a plinthic horizon, visit;
www.researchgate.net/publication/242649722_Rationale_for_...
or;
www.sciencedirect.com/science/article/pii/S00167061220043...