LOCATION PLOTT NC+GA SC TN VA
LBH-STE-AG; Rev. BPS
The Plott series consists of very deep, well drained, moderately permeable soils on cool, north- to east-facing or shaded ridges and side slopes in the Southern Blue Ridge mountains, MLRA 130B. These soils formed in residuum that is affected by soil creep in the upper part and weathered from felsic to mafic igneous and high-grade metamorphic rocks. Near the type location, the mean annual temperature is about 51 degrees F., and the mean annual precipitation is about 79 inches. Slope ranges from 8 to 95 percent.
TAXONOMIC CLASS: Fine-loamy, isotic, mesic Typic Humudepts
TYPICAL PEDON: Plott fine sandy loam, on a 55 percent north-facing mountain side slope at an elevation of 3,820 feet--forested. (Colors are for moist colors unless otherwise stated.)
Oi--0 to 1 inches; slightly decomposed deciduous leaves, twigs and roots.
A1--1 to 7 inches; very dark brown (10YR 2/2) fine sandy loam, dark grayish brown (10YR 4/2) dry; weak medium granular structure; very friable; many fine and coarse roots throughout; 1 percent gravel by volume; few fine flakes of mica; strongly acid; gradual wavy boundary.
A2--7 to 15 inches; very dark grayish brown (10YR 3/2) fine sandy loam; weak medium granular structure; very friable; many fine and coarse roots throughout; 3 percent gravel by volume; few fine flakes of mica; strongly acid; clear wavy boundary. (Combined thickness of the A subhorizons is 10 to 20 inches.)
Bw1--15 to 33 inches; dark yellowish brown (10YR 3/4) fine sandy loam; weak medium subangular blocky structure; very friable; common fine and medium roots; 4 percent gravel by volume; few fine flakes of mica; strongly acid; gradual wavy boundary.
Bw2--33 to 47 inches; dark yellowish brown (10YR 4/4) fine sandy loam; weak medium subangular blocky structure; very friable; common fine and medium roots; 4 percent gravel by volume; few fine flakes of mica; strongly acid; gradual wavy boundary. (Combined thickness of the Bw subhorizons is 10 to 36 inches.)
BC--47 to 63 inches; dark yellowish brown (10YR 4/6) gravelly fine sandy loam; weak medium subangular blocky structure; very friable; common fine roots; 26 percent gravel by volume; common fine flakes of mica; strongly acid.
TYPE LOCATION: Macon County, North Carolina; 300 feet southeast of Rock Gap along USFS logging road; then 75 feet south of road in woods; USGS Rainbow Springs topographic quadrangle; lat. 35 degrees 5 minutes 30 seconds N. and long. 83 degrees 31 minutes 17 seconds W., NAD 27.
RANGE IN CHARACTERISTICS: Solum thickness is 30 to more than 60 inches. Depth to bedrock is greater than 60 inches. Reaction ranges from extremely acid to moderately acid. Content of mica flakes is few or common. Content of rock fragments ranges up to 35 percent in the A and upper Bw horizons. Below 40 inches, rock fragment content may range up to 60 percent in the lower Bw horizon, and in the BC and C horizons. Fragments are of gravel, cobble, and stone size.
The A horizon has hue of 5YR to 10YR, value of 2 or 3, and chroma of 1 to 3. It is loam, fine sandy loam, sandy loam, or sandy clay loam in the fine-earth fraction.
Thin AB or BA horizons, where present, have hue of 7.5YR or 10YR, value of 3 or 4, and chroma of 2 to 4. Textures are the same as for the A horizon.
The Bw horizon has hue of 7.5YR or 10YR, value of 3 to 5 and chroma of 4 to 8. Mottles, if they occur, are in shades of red, yellow, or brown. Texture is loam, fine sandy loam, sandy loam or sandy clay loam in the fine-earth fraction.
The BC or CB horizons, where present, have hue of 7.5YR or 10YR, value of 4 to 6, and chroma of 3 to 8. They are loam, fine sandy loam, or sandy loam, in the fine-earth fraction.
The C horizon, where present, is variable in color, and is saprolite that has textures of fine sandy loam, sandy loam, loamy fine sand, loamy sand, or sand in the fine-earth fraction.
COMPETING SERIES: These are the
Tuckasegee series. Cheoah and Santeetlah soils formed in materials weathered from low-grade metasedimentary rocks such as phyllite and slate, and contain fragments of those rocks. Tuckasegee soils formed in colluvium and have C horizons of colluvial material rather than saprolite.
GEOGRAPHIC SETTING: Plott soils are on strongly sloping to very steep ridges and side slopes of the Southern Blue Ridge mountains, MLRA 130B. Elevation ranges from about 3,200 to 4,800 feet. These soils are on cool, north to east aspects or those slopes shaded by higher mountains. Slope is commonly between 30 to 80 percent but ranges from 8 to 95 percent. Plott soils formed in residuum, affected by soil creep in the upper part, weathered from felsic to mafic, igneous or high-grade metamorphic rocks such as granite, hornblende gneiss, mica gneiss, amphibolite, and high-grade metagraywacke. Mean annual temperature ranges from 46 to 57 degrees F., and mean annual precipitation ranges from about 50 to 80 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: In addition to the competing
Tuckasegee series, these include the
Wayah series. Burton, Craggey, and Wayah soils are in a frigid soil temperature class, and are at higher elevations. Additionally, Burton soils have lithic contact at depths of 20 to 40 inches, and Craggey soils have lithic contact at depths less than 20 inches. Chestnut and Edneyville soils have ochric epipedons and are on warmer and drier parts of the landscapes, typically on south to west aspects. Cullasaja, Haywood, Toecane, and Tusquitee soils formed in colluvium, have C horizons of colluvial material, and are in coves and on toe slopes at locally lower elevations. Porters soils have lithic contact at depths of 40 to 60 inches and have a thinner A horizons.
DRAINAGE AND PERMEABILITY: Well drained. Saturated hydraulic conductivity in the subsoil is moderately high, permeability is moderate; in the underlying material, saturated hydraulic conductivity is high, permeability is moderately rapid. Index surface runoff is medium or high.
USE AND VEGETATION: Most of this soil is in forest. The dominant forest type consists of northern red oak associated with black cherry, sugar maple, American beech, black oak, black birch, yellow birch, yellow-poplar, eastern hemlock, and black locust. In the drier, warmer part of the range, upland oaks, hickory, blackgum, red maple, and eastern white pine are associated. Flowering dogwood, mountain-laurel, silverbell, striped maple, serviceberry, rhododendron, red maple, blueberry, trillium, Solomons seal, and woodfern are common understory species. Approximately 20 percent of this soil is cleared and used for pasture, ornamentals, and Christmas trees.
DISTRIBUTION AND EXTENT: Southern Blue Ridge mountains, MLRA 130B of North Carolina, Georgia, South Carolina, Tennessee, and Virginia. The series is of large extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia
SERIES ESTABLISHED: Macon County, North Carolina; 1990. The name is from the Plott Balsam Mountain.
REMARKS: The Plott series was formerly included with the Porters series. However, the Porters series has hard bedrock at depths of 40 to 60 inches below the surface, and has an A horizon that is 6 to 10 inches thick.
The 1/97 revision placed Plott soils in a fine-loamy particle-size class. This series was formerly placed in a coarse-loamy particle-size class. Laboratory PSA (pipette method) and corresponding field texture estimates (feel method) indicate control section clay contents of generally 12 to 24 percent, with most pedons marginally coarse-loamy. Fine-loamy particle-size class placement is based on the presence of amorphous (non-crystalline) clay-size material associated with the relatively high organic matter content found in these soils. Although field estimates, laboratory measurements, and calculated values may vary, clay content in the particle-size control section is generally less than 25 percent. Although Plott soils may exhibit some of the characteristics of andic soil properties, they lack the volcanic glass found in soils of similar taxa in the Western United States.
Diagnostic horizons and features in this pedon are:
Umbric epipedon the mineral soil surface to 15 inches (A1 and A2 horizons)
Cambic horizon - 15 to 63 inches (Bw1, Bw2 and BC horizons)
Isotic mineralogy class - In more than one-half of the control section, a 1500 kPa water to clay ratio of 0.6 or more and a pH in NaF solution of more than 8.4.
ADDITIONAL DATA: Characterization data is available from the National Soil Survey Laboratory, Lincoln, NE for the following pedons: S85NC-113-021.
MLRA: 130B SIR(s): NC0219, NC0220 (STONY)
Revised: 10/92-LBH,STE,AG; 1/97-DHK, 12/97-DHK, 2/04-MKC
02/11-BPS: Taxonomic Classification -- 11th Keys, update competing and associated series, MLRA clarification
National Cooperative Soil Survey