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Rhodic soils are dark red, high in iron, and are common in parts of the Piedmont of North Carolina. (Original image courtesy of D. Lindbo, NCSU)
Original photo may be viewed at: www.flickr.com/photos/soilscience/5086320839/in/photolist...
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INSET: Coarse blocky soil structure with ped face coated with translocated clay. In this example; "many continuous prominent clay films on vertical faces of peds"
The Lloyd series consists of very deep, well drained, moderately permeable soils on uplands in the Southern Piedmont. The soils formed in residuum derived from intermediate and mafic, igneous and high-grade metamorphic rocks.
TAXONOMIC CLASS: Fine, kaolinitic, thermic Rhodic Kanhapludults
Most areas are cleared and used for cultivated crops or pasture. Principal crops are corn, small grain, hay and pasture grasses. Common trees in forested areas are loblolly pine, shortleaf pine, Virginia pine, northern red oak, southern red oak, white oak, post oak, hickory, and red maple. Understory plants include dogwood, winged elm, eastern hophornbeam, eastern redbud, eastern red cedar, and sassafras.
These soils are of large extent in the Southern Piedmont in North Carolina, South Carolina and Georgia, and possibly Alabama, and Virginia.
These soils were combined with Hiwassee in 1969. Hiwassee series was originally established on high stream terraces. This revision separates the soils formed in residuum as Lloyd on the basis of parent material and depth of Rhodic colors. Terrace Hiwassee soils are dominantly value 3 or less throughout. A proposal to amend the 1996 Keys to Soil Taxonomy involves changing the thickness of the part of the kandic horizon with value of 3 or less to include more soils in the Rhodic subgroup.
For a detailed description, visit:
soilseries.sc.egov.usda.gov/OSD_Docs/L/LLOYD.html
For acreage and geographic distribution, visit:
casoilresource.lawr.ucdavis.edu/see/#lloyd
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Clay films (argillans). The "shiny" or "waxy" appearance on the faces of the ped are clay coatings (clay films). Clay films area thin coating of oriented clay on the surface of a soil aggregate or lining pores or root channels. Synonyms: clay coating, clay skin, argillan, or ferriargillan (if stained by iron), or organoargillan (if stained by organic matter).
For more information about the major principles and practices needed for making and using soil surveys and for assembling and using related soils data (Soil Survey Manual), visit:
www.nrcs.usda.gov/resources/guides-and-instructions/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:
Photo Credit: Jeffrey Dubinsky
Copyright: DubinskyPhotography.com
May not be used for commercial or editorial purposes without the express consent of Dubinsky Photography.
Photo Credit: Jeffrey Dubinsky
Copyright: DubinskyPhotography.com
May not be used for commercial or editorial purposes without the express consent of Dubinsky Photography.
Photo Credit: Jeffrey Dubinsky
Copyright: DubinskyPhotography.com
May not be used for commercial or editorial purposes without the express consent of Dubinsky Photography.
A monolith, or vertical slice from topsoil down to subsoil, preserves a soil’s colors and layered horizons in position. Scientists make monoliths of the important soils in their region and use them in teaching. Step 1 In the field, scientists dig a pit about 6 feet deep, keeping one face a flat vertical plane.
www.emiratessoilmuseum.org/about
For more information about describing soils, visit:
www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052523...
For additional information about soil classification using Soil Taxonomy, visit:
Closeup of Bx horizon in Watson series colluvial soil (Typic Fragiudult). Note the fine "vertical streaks". (Original image and comments courtesy of Matthew C. Ricker, NC State University)
[cals.ncsu.edu/crop-and-soil-sciences/people/mcricker/]
The original photo may be viewed at:
www.flickr.com/photos/soilscience/49698009151/in/album-72...
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The Watson series consists of very deep, moderately well drained soils formed in pre-Wisconsin glacial till derived from sandstone, siltstone, and shale. Slopes range from 0 to 20 percent. Permeability is slow. Mean annual precipitation is 34 inches. Mean annual temperature is 52 degrees F.
TAXONOMIC CLASS: Fine-loamy, mixed, active, mesic Typic Fragiudults
The Btx typicallly has hue of 2.5YR through 7.5YR, is gravelly clay loam with gray (10YR 6/1) coating on faces of prisms. It has many coarse prominent light gray (10YR 7/2) mottles; weak very coarse prismatic structure parting to moderate medium blocky; very firm, brittle, sticky, plastic; common distinct clay films on faces of peds and in pores; many black manganese stains; 30 percent gravel; strongly acid; gradual wavy boundary.
Solum thickness ranges from 40 to 72 inches. Bedrock is usually below 60 inches. Depth to fragipan ranges from 18 to 32 inches. The fragipan is typically more than 30 inches thick.
For a detailed description, visit:
soilseries.sc.egov.usda.gov/OSD_Docs/W/WATSON.html
For acreage and geographic distribution, visit:
This is Wisconsin age colluvium over older colluvial deposits. At the contact around 130 cm a fragipan/fragic properties exist (Bx horizon). This soil corresponds to the Watson series.(Original image and comments courtesy of Matthew C. Ricker, NC State University)
[cals.ncsu.edu/crop-and-soil-sciences/people/mcricker/]
The original photo may be viewed at:
www.flickr.com/photos/soilscience/49698008736/in/album-72...
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INSET: Closeup of the Btx horizon showing gray vertical streaks common to prism faces in fragipan soils.
The Watson series consists of very deep, moderately well drained soils formed in pre-Wisconsin glacial till derived from sandstone, siltstone, and shale. Slopes range from 0 to 20 percent. Permeability is slow. Mean annual precipitation is 34 inches. Mean annual temperature is 52 degrees F.
TAXONOMIC CLASS: Fine-loamy, mixed, active, mesic Typic Fragiudults
DRAINAGE AND PERMEABILITY: Moderately well drained. Surface runoff is medium to slow and permeability is slow.
USE AND VEGETATION: Most of the soils are cleared and cultivated for hay, grain and other crops. Wooded areas are in mixed hardwoods.
DISTRIBUTION AND EXTENT: Glaciated portion of Ridge and Valley area in east central Pennsylvania. It is of moderate extent, with an estimated 25,000 acres.
For a detailed description, visit:
soilseries.sc.egov.usda.gov/OSD_Docs/W/WATSON.html
For acreage and geographic distribution, visit:
Photo Credit: Jeffrey Dubinsky
Copyright: DubinskyPhotography.com
May not be used for commercial or editorial purposes without the express consent of Dubinsky Photography.
Photo Credit: Jeffrey Dubinsky
Copyright: DubinskyPhotography.com
May not be used for commercial or editorial purposes without the express consent of Dubinsky Photography.
Photo Credit: Jeffrey Dubinsky
Copyright: DubinskyPhotography.com
May not be used for commercial or editorial purposes without the express consent of Dubinsky Photography.
Photo Credit: Jeffrey Dubinsky
Copyright: DubinskyPhotography.com
May not be used for commercial or editorial purposes without the express consent of Dubinsky Photography.
In Soil Taxonomy, a lamella is an illuvial soil horizon less than 7.5 cm thick that contains an accumulation of oriented silicate clay on or bridging sand and silt grains. Lamellae play an important role in the flux of water and nutrients, especially in coarse-textured soils and, therefore, on plant growth.
The significance of lamellae to soil classification is not in the single lamella but in the multiple number of lamellae, each with an overlying eluvial horizon in a single pedon. A single lamella may occur in a pedon, but more commonly there are several lamellae separated by eluvial horizons.
The movement upward of each lamella is not uniform throughout its extent. Consequently, lamellae are wavy rather than smooth, like the bedding planes from which they originated.
Another long--but very rewarding--day in the field. Landscape at the soil sample site (Guangdong Province, PRC; Rhodic Kandiudult PRC-03).
Slaking v. Disaggregation in soils with Fragic Soil Properties
a distinction without a difference???
As you view the video, note how the soil fragments on the top react to rapid wetting. They are blocky peds from the Btx horizon of a Cataula soil (fine, kaolinitic, thermic Oxyaquic Kanhapludult). The fragments on the bottom are platy peds from the same horizon. Samples were taken at a depth of about 50 to 100cm.
These soils align with the concept of a dual subgroup classification (Oxyaquic Fragic) if offered as an option in Soil Taxonomy. As currently written in the KEYS, the Oxyaquic subgroup takes higher priority than the Fragic subgroup. Cataula soils are mapped in association with Cecil soils. They commonly occur along shoulder slopes and toeslopes next to areas designated as Cecil.
They are very similar to Cecil soils but exhibit fragic soil properties in the subsoil (Btx horizons) ranging from 20 to 60 percent resulting in a transitory perched water table from 2 to 4 feet in winter and spring. The fragic soil properties are noticeable—dense, compact, brittle and root-restrictive. Excavation difficulty is high to very high even when moist. Matrix color indicates a very coarse, slightly reticulate mottle pattern. Cracks or zones that roots can enter are mostly less than 10 cm apart; therefore, failing the fragipan concept even though many pedons have more than 60 percent fragic soil properties.
In March 1982 the series was revised to change the classification from Typic Fragiudults to Typic Hapludults. The November 1998 OSD revision changed the classification to Oxyaquic Kanhapludults.
Distinguishing Slaking from Disaggregation
Disaggregation is the general process by which soil aggregates break down when submerged in water. Within this process, two distinct behaviors can be observed: slaking and sloughing.
Slaking is a rapid, dynamic form of disaggregation, most often associated with fragic soil properties—horizons that are compact: dense, brittle, and root-restrictive. When air-dried aggregates from these soils are submerged, water infiltrates internal pores, creating pressure that causes the aggregates to “pop” as they fragment. A 50–75 mm ped may collapse completely within 5–10 minutes, reflecting the restrictive porosity and rigidity of soils that exhibit fragic soil properties.
Sloughing, by contrast, is a slow, uniform breakdown. Aggregates gradually soften and weaken as water infiltrates and cohesive forces diminish. Collapse occurs over several minutes to hours, without the sudden fragmentation typical of slaking.
Distinguishing between slaking and sloughing is more than a matter of terminology—it provides a practical diagnostic tool for recognizing fragic soil properties and identifying fragipans, aiding soil classification and correlation.
Soil profile of Cw—Crowley silt loam, 0 to 1 percent slopes from St. Landry Parish, Louisiana. (Photo provided by Brandon Waltman, Assistant State Soil Scientist, Louisiana.) The site was sampled as part of a Dynamic Soil Properties Study: MLRA 150A - Dynamic Soil Properties Compare Cropland vs Pastureland for Crowley silt loam.
The Crowley Series consists of very deep, somewhat poorly drained, very slowly permeable soils that formed in clayey fluviomarine deposits of the Pleistocene age. (This pedon formed in clayey fluviomarine deposits derived from igneous, metamorphic and sedimentary rock.) These nearly level to very gently sloping soils occur on flat coastal plains terraces. Slope is dominantly less than 1 percent but ranges to 3 percent.
TAXONOMIC CLASS: Fine, smectitic, thermic Typic Albaqualfs
Detailed Soil Description (soil health sample in rice). Describers Name: LA & TX staff :
E—0 to 13 centimeters (0.0 to 5.1 inches); brown (10YR 5/3) silt loam; moderate medium subangular blocky parts to weak fine granular structure; 2.0 very fine roots throughout and 1.0 fine roots throughout; 2.0 very fine pores; 15 percent fine yellowish brown (10YR 5/8), moist, masses of oxidized iron in matrix; fragments; abrupt smooth boundary.; moist when described; observed in pit, large or quarry
Btg1—13 to 27 centimeters (5.1 to 10.6 inches); dark grayish brown (10YR 4/2) silt loam; moderate medium subangular blocky structure; 1.0 very fine roots throughout; 2.0 very fine pores; 10 percent medium strong brown (7.5YR 5/8), moist, masses of oxidized iron in matrix and 30 percent medium black (10YR 2/1), moist, manganese masses in matrix; fragments; abrupt smooth boundary.; moist when described; observed in pit, large or quarry
Btg2—27 to 51 centimeters (10.6 to 20.1 inches); light brownish gray (10YR 6/2) silt loam; moderate medium subangular blocky structure; 1.0 very fine roots throughout; 1 percent fine black (10YR 2/1), moist, manganese masses in matrix and 15 percent fine strong brown (7.5YR 5/8), moist, masses of oxidized iron in matrix; fragments; abrupt smooth boundary.; moist when described; observed in pit, large or quarry
Btg3—51 to 79 centimeters (20.1 to 31.1 inches); grayish brown (10YR 5/2) silty clay; moderate medium prismatic parts to moderate medium subangular blocky structure; 1.0 very fine roots throughout; 1 percent medium black (10YR 2/1), moist, manganese masses in matrix and 35 percent coarse red (2.5YR 4/8), moist, masses of oxidized iron in matrix; fragments; abrupt smooth boundary.; moist when described; observed in pit, large or quarry
Btg4—79 to 108 centimeters (31.1 to 42.5 inches); light brownish gray (10YR 6/2) silty clay loam; moderate medium subangular blocky structure; 1.0 very fine roots throughout; 10 percent fine black (10YR 2/1), moist, manganese masses in matrix and 40 percent coarse yellowish brown (10YR 5/8), moist, masses of oxidized iron in matrix; fragments; abrupt smooth boundary.; moist when described; observed in auger, bucket
Btg5—108 to 175 centimeters (42.5 to 68.9 inches); light brownish gray (10YR 6/2) silty clay loam; moderate medium subangular blocky structure; 1 percent fine black (10YR 2/1), moist, manganese masses in matrix and 30 percent coarse yellowish brown (10YR 5/8), moist, masses of oxidized iron in matrix; fragments; abrupt smooth boundary.; moist when described; observed in auger, bucket
Bt—175 to 200 centimeters (68.9 to 78.7 inches); light yellowish brown (10YR 6/4) clay; moderate medium subangular blocky structure; and 1 percent fine very dark grayish brown (10YR 3/2), moist, manganese masses in matrix and 3 percent medium yellowish red (5YR 5/8), moist, masses of oxidized iron in matrix and 25 percent medium reddish yellow (7.5YR 6/6), moist, masses of oxidized iron in matrix and 30 percent coarse light brownish gray (10YR 6/2), moist, iron depletions in matrix; fragments.; moist when described; observed in auger, bucket.
Photo Credit: Jeffrey Dubinsky
Copyright: DubinskyPhotography.com
May not be used for commercial or editorial purposes without the express consent of Dubinsky Photography.
Masses of secondary calcium carbonate (white bodies below a depth of about 60 cm) in the calcic horizon of an Aridisol.
Masses are non-cemented concentrations that commonly cannot be removed from the soil as a discrete unit. Masses may consist of, but are not limited to, calcium carbonate, fine crystals of gypsum or soluble salts, or iron and manganese oxides. In most cases, masses form in place.
A horizontal view (looking down) of a fragipan from a soil (a Fragiudalf) in Tennessee. The horizon has prismatic structure with gray seams between prisms and reddish redoximorphic features, mostly within the prisms. This view allows the structure and color patterns of the horizon to be easily observed. The exposed area is approximately 30 by 40 cm.
A horizontal view of each horizon is useful. This exposes structural units that otherwise may not be readily observable from the vertical pit face. Patterns of color within structural units, variations of particle size from the outside to the inside of structural units, and the pattern in which roots penetrate structural units are commonly seen more clearly in a horizontal section.
These blocks (excluding the bricks) were cut from a surrounding exposed ironstone layer that occurs in the upper 2 meters of the soil. While driving through the area several structures (fence walls or out buildings) were observed using blocks cut from ironstone exposed along roads or streams.
Photo Credit: Jeffrey Dubinsky
Copyright: DubinskyPhotography.com
May not be used for commercial or editorial purposes without the express consent of Dubinsky Photography.
Muscovite is the most common form of mica. Its name is derived from "Muscovy Glass", which describes thick sheets of transparent mica that were once used as a glass substitute in Russia. Because of Muscovite's abundance, its presence is usually lacking in collections except for it being an accessory mineral to other minerals. However, there are certain interesting formations and colors which are very aesthetic, and those forms are well-represented in collections. Muscovite can come in enormous crystal groupings that can weigh several hundred pounds. Thin sheets can be peeled off as layers, and the thinner a layer is peeled the greater its transparency becomes.
Except for large and resistant specimens, Muscovite is very hard to clean because if washed it will absorb water internally and start to break apart. The best way to wash Muscovite and other Micas is with a dry electric toothbrush.
credit: Lishka Arata
Hicks Mountain Ranch RMN surveys in February 2023
Point Blue staff: Sophie Noda, Ryan DiGaudio, Lishka Arata
This gull was in obvious distress, by the time the last crew member left the island, the bird had died.
Photo Credit: Jeffrey Dubinsky
Copyright: DubinskyPhotography.com
May not be used for commercial or editorial purposes without the express consent of Dubinsky Photography.
Soil profile (of a Torriorthent in the United Arab Emirates) showing rock structure as fine to coarse stratifications throughout. The upper
60 cm is recent eolian sand. The lower part consists of old alluvial deposits interspersed with eolian strata. Scale is in cm. (Photo courtesy of Dr. Craig Ditzler)
The epipedon (Gr. epi, over, upon, and pedon, soil) is a horizon that forms at or near the surface and in which most of the rock structure has been destroyed. It is darkened by organic matter or shows evidence of eluviation, or both. Rock structure includes fine stratification (less than 5 mm) in unconsolidated sediments (eolian, alluvial, lacustrine, or marine) as well as saprolite derived from consolidated rocks in which the unweathered minerals and pseudomorphs of weathered minerals retain their relative positions to each other. An epipedon is not the same as an A horizon. It may include part or all of an illuvial B horizon if the darkening by organic matter extends from the soil surface into or through the B horizon.
Illustrated Guide to Soil Taxonomy (p. 3-6)
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. The horizon in which plinthite occurs commonly has 2.5 percent (by mass) or more citrate dithionite extractable iron in the fine-earth fraction and a ratio between acid oxalate extractable Fe and citrate-dithionite extractable Fe of less than 0.10.
For more information about describing soils, visit:
www.nrcs.usda.gov/resources/guides-and-instructions/field...
For additional information about soil classification using Soil Taxonomy, visit:
www.nrcs.usda.gov/resources/guides-and-instructions/keys-...
For more information about a plinthic horizon, visit;
www.researchgate.net/publication/242649722_Rationale_for_...
or:
www.sciencedirect.com/science/article/pii/S00167061220043...
For more information about Slake Tests, visit:
www.nrcs.usda.gov/sites/default/files/2023-01/SSIR51.pdf
Soil Survey Field and Laboratory Methods Manual; Soil Survey Investigations Report No. 51, Version 2; Issued 2014 (pp. 148-157)
3.7 Soil Stability, Dispersion, and Slaking
3.7.5 Slaking (Disaggregation) for Identification and Semiquantification of Cemented Materials
John Kelley and Michael A. Wilson, United States Department of Agriculture, Natural Resources Conservation
Service, Soil Survey Staff
Photo Credit: Jeffrey Dubinsky
Copyright: DubinskyPhotography.com
May not be used for commercial or editorial purposes without the express consent of Dubinsky Photography.
Soil profile of Cw—Crowley silt loam, 0 to 1 percent slopes from Vermillion Parish, Louisiana. (Photo provided by Brandon Waltman, Assistant State Soil Scientist, Louisiana.) The site was sampled as part of a Dynamic Soil Properties Study: MLRA 150A - Dynamic Soil Properties Compare Cropland vs Pastureland for Crowley silt loam.
The Crowley Series consists of very deep, somewhat poorly drained, very slowly permeable soils that formed in clayey fluviomarine deposits of the Pleistocene age. (This pedon formed in clayey fluviomarine deposits derived from igneous, metamorphic and sedimentary rock.) These nearly level to very gently sloping soils occur on flat coastal plains terraces. Slope is dominantly less than 1 percent but ranges to 3 percent.
TAXONOMIC CLASS: Fine, smectitic, thermic Typic Albaqualfs
Detailed Soil Description (soil health sample). Describers Name: Mitch Mouton, Mike Lindsey, Gavin Faulk,
Brandon Waltman:
Ap—0 to 11 centimeters (0.0 to 4.3 inches); grayish brown (10YR 5/2) silt loam; weak fine granular structure; very friable; 3.0 very fine roots throughout and 1.0 medium roots throughout and 3.0 fine roots throughout; 1 percent fine faint yellowish red (5YR 4/6), moist, masses of oxidized iron lining pores; fragments.; moist when described; observed in pit,
large or quarry
E—11 to 21 centimeters (4.3 to 8.3 inches); light brownish gray (10YR 6/2) silty clay; weak fine subangular blocky parts to weak fine granular structure; very firm; 2.0 fine roots throughout; 5 percent prominent light gray (10YR 7/2), moist, silt coats on all faces of peds; 20 percent fine strong brown (7.5YR 5/6), moist, masses of oxidized iron lining pores; fragments.; moist when described; observed in pit, large or quarry
BE—21 to 31 centimeters (8.3 to 12.2 inches); brown (7.5YR 5/2) clay; weak medium subangular blocky parts to weak fine subangular blocky structure; very firm; 0.5 very fine roots throughout and 1.0 fine roots throughout; 5 percent fine brown (7.5YR 4/4), moist, iron-manganese masses in matrix and 10 percent fine black (10YR 2/1), moist, manganese masses in matrix; fragments.; moist when described; observed in pit, large or quarry
Btg1—31 to 64 centimeters (12.2 to 25.2 inches); brown (7.5YR 4/2) clay; weak coarse prismatic parts to moderate fine subangular blocky structure; very firm; 0.5 fine roots throughout; 2 percent medium black (7.5YR 2/1), moist, manganese masses and 15 percent medium red (2.5YR 4/8), moist, masses of oxidized iron in matrix; fragments.; moist when described; observed in auger, bucket
Btg2—64 to 109 centimeters (25.2 to 42.9 inches); gray (7.5YR 5/1) clay; weak coarse prismatic parts to moderate fine subangular blocky structure; very firm; 0.5 very fine roots throughout; 2 percent medium black (10YR 2/1), moist, manganese masses and 25 percent medium strong brown (7.5YR 5/6), moist, masses of oxidized iron in matrix; fragments.; moist when described; observed in auger, bucket
Btg3—109 to 140 centimeters (42.9 to 55.1 inches); gray (2.5Y 6/1) silty clay; moderate coarse prismatic parts to moderate fine subangular blocky structure; firm; 0.5 very fine roots throughout; 1 percent fine black (10YR 2/1), moist, manganese masses in matrix and 40 percent medium yellowish brown (10YR 5/6), moist, masses of oxidized iron in matrix; fragments.; moist when described; observed in auger, bucket
Btg4—140 to 205 centimeters (55.1 to 80.7 inches); gray (10YR 6/1) silty clay; moderate coarse prismatic parts to moderate fine subangular blocky structure; firm; 25 percent prominent gray (10YR 5/1), moist, silt coats; 5 percent medium black (10YR 2/1), moist, manganese masses in matrix and 30 percent coarse yellowish brown (10YR 5/8), moist, masses of oxidized iron in matrix; fragments.; moist when described; observed in auger, bucket.
A shallow soil pit with a face that has been cleaned and prepared for describing the soil profile. This soil (a Fibristel in Alaska) has been dug to the depth of permafrost (about 40 cm).
In order to observe a pedon fully, including soil structure (size and kind), horizon boundary topography, and short-range variability in horizon thickness, a pit exposing a vertical face approximately 1 meter across to an appropriate depth ) is adequate for most soils. Excavations associated with roads, railways, gravel pits, and other soil disturbances provide easy access for studying soils. Old exposures, however, must be used cautiously. In these areas, the soils can dry out or freeze and thaw from both the surface and the sides. In addition, the soil structure may be more pronounced than is typical, salts may have accumulated near the edges of exposures or been removed by seepage, plinthite may have irreversibly hardened to ironstone, or other changes may have taken place.
This soil in New York City formed in human-transported material with human artifacts in the profile, such as brick, glass, and metal. The surface layer is an anthropic epipedon. The anthropic epipedon is a thick horizon that formed in human-altered or human-transported material. The key feature is that it formed as the result of intentional human alteration (but not simply by the common agricultural practices of plowing and amending the soil with fertilizers). Its landscape setting (such as a raised surface due to filling) and/or presence of human artifacts are key characteristics.
Illustrated Guide to Soil Taxonomy (p. 3-8)
A section of the Btv horizon of a Dothan soil from South Carolina. Slake test indicated 41 percent by volume cemented plinthite.
An AI evaluation based on color separation indicated the darker, reddish-brown areas including transitional areas (plinthite) made up 40 percent of the surface area. Further testing may indicate AI as a tool to roughly identify plinthite (or other feature) content (percent by volume).
www.flickr.com/photos/jakelley/51835813168/in/album-72157...
Slaking is defined as a process that results in breakdown of soil aggregates (aggregate disintegration) to a finer aggregate size >2µm. Studies have established that slaking results from stress on the soil aggregate (shock of wetting) created from differential swelling, heat release from wetting, entrapped air, and mechanical action of moving water. The degree or rate of slaking in noncemented, in-situ soil materials is influenced by organic matter, clay content, clay mineralogy, Fe and Al oxides, carbonates, salinity of soil and water, and moisture content of the soil prior to wetting (i.e., antecedent water content).
Slake tests measures the stability of soil when exposed to rapid wetting. You can learn more about slake tests on-line at:
www.nrcs.usda.gov/sites/default/files/2023-01/SSIR51.pdf
Soil Survey Field and Laboratory Methods Manual; Soil Survey Investigations Report No. 51, Version 2; Issued 2014 (pp. 148-157)
3.7 Soil Stability, Dispersion, and Slaking
3.7.5 Slaking (Disaggregation) for Identification and Semiquantification of Cemented Materials
John Kelley and Michael A. Wilson, United States Department of Agriculture, Natural Resources Conservation
Service, Soil Survey Staff