LOCATION PORTERS NC+GA SC TN VA
The Porters series consists of 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, affected by soil creep in the upper part, that has weathered from felsic to mafic, high-grade metamorphic and igneous rocks such as granite, gneiss, hornblende gneiss, mica gneiss, and amphibolite. Near the type location, the mean annual air temperature is about 52 degrees F., and the mean annual precipitation is about 52 inches. Slope ranges from 2 to 95 percent.
TAXONOMIC CLASS: Fine-loamy, isotic, mesic Humic Dystrudepts
TYPICAL PEDON: Porters loam--pasture. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 7 inches; very dark grayish brown (10YR 3/2) loam; moderate fine and medium granular structure; very friable; many fine roots; few fine mica flakes; slightly acid; gradual smooth boundary. (7 to 10 inches thick)
BA--7 to 10 inches; brown (10YR 4/3) loam; weak fine and medium subangular blocky structure; friable; few mica flakes; few medium gneiss and quartz fragments; moderately acid; gradual smooth boundary. (0 to 6 inches thick)
Bw--10 to 22 inches; brown (7.5YR 4/4) loam; weak medium subangular blocky structure; friable; few fine mica flakes; few medium fragments of quartz and partly weathered rock; slightly acid; gradual smooth boundary. (10 to 30 inches thick)
BC--22 to 28 inches; brown (7.5YR 4/4) loam; very weak medium and coarse subangular blocky structure; friable; common medium fragments of quartz and partly weathered rock; few fine mica flakes; slightly acid; diffuse wavy boundary. (0 to 16 inches thick)
C--28 to 42 inches; mottled brown (10YR 4/3) and grayish brown (10YR 5/2) sandy loam; gneiss saprolite with quartz, weathered feldspar, hornblende, mica and other minerals; massive; friable; slightly acid; grades into hard rock.
R--42 inches; dark colored gneiss bedrock.
TYPE LOCATION: Alleghany County, North Carolina; 5 miles northeast of Laurel Springs; 1 mile south of Prathers Creek Church; 300 yards east of County Road 1149.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 20 to 50 inches. Depth to hard bedrock is 40 to 60 inches. Reaction is very strongly to slightly acid. Content of rock fragments commonly ranges from 0 to 15 percent by may range up to 35 percent. Fragments are of gravel, cobble, and stone size. Flakes of mica range from few to common.
The A or Ap horizon has hue of 7.5YR or 10YR, value of 2 or 3, and chroma of 1 to 4. Thin A2 or AB horizons are present in some pedons. They have hue of 7.5YR or 10YR, value of 3 or 4, and chroma of 2 to 4. Texture is fine sandy loam, sandy loam, loam, and sandy clay loam in the fine earth fraction.
The BA horizon, where present, has hue of 7.5YR or 10YR, value of 4 or 5, and chroma of 3 to 6. It is fine sandy loam, sandy loam, loam, or sandy clay loam in the fine earth fraction.
The Bw horizon has hue of 7.5YR or 10YR, value of 4 to 6, and chroma of 3 to 8. Texture is fine sandy loam, sandy loam, loam, or sandy clay loam in the fine earth fraction.
The BC horizon has hue of 7.5YR or 10YR, value of 4 to 6, and chroma of 3 to 8. Mottles in shades of brown, yellow, or gray range from none to common. Texture is fine sandy loam, sandy loam, loam, or sandy clay loam in the fine earth fraction.
The C horizon is saprolite that is variable in color. It is commonly multicolored or mottled, but in the upper part it may be similar in color to the BC horizon. Texture is fine sandy loam, sandy loam, loam, loamy sand, or loamy fine sand in the fine earth fraction.
Some pedons have a thin Cr horizon of soft, weathered bedrock below 40 inches that grades into hard bedrock within depths of 40 to 60 inches.
The R horizon is hard felsic to mafic, high-grade metamorphic or igneous rock such as granite, gneiss, hornblende gneiss, mica gneiss, schist, and amphibolite.
COMPETING SERIES: These are the
Whiteoak series. Crossnore and Jeffrey soils formed in residuum and Whiteoak in colluvium derived from low-grade metamorphic rock such as metasandstone and contain fragments of those rocks. In addition, Crossnore soils have soft bedrock at depths of 20 to 40 inches. Jeffrey and Unaka soils have hard bedrock at depths of 20 to 40 inches. Porters soils have bedrock at depths of 40 to 60 inches. Tusquitee soils formed in colluvium and are greater than 72 inches to bedrock. Whiteoak soils have Bw horizons with clay content ranging from 18 to 29 percent.
GEOGRAPHIC SETTING: Porters soils are on cool, north- to east-facing or shaded strongly sloping to very steep ridges and side slopes of the Southern Appalachian Mountains. Elevation ranges from about 2,600 feet to 4,800 feet. Slopes are generally between 30 and 95 percent but range from 2 to 95 percent. Porters soils formed in residuum, affected by soil creep in the upper part, weathered from felsic to mafic, high-grade metamorphic or igneous rocks such as granite, gneiss, hornblende gneiss, mica gneiss, and amphibolite. Mean annual temperature is 52 degrees F., and mean annual precipitation is 52 inches near the type location.
GEOGRAPHICALLY ASSOCIATED SOILS: In addition to the competing
Unaka series, these are
Wayah series. Burton, Craggey, and Wayah soils are in a frigid family and are at higher elevations. In addition, Burton is moderately deep and Craggey is shallow to bedrock. Cashiers soils are in a micaceous family and are in the same landscape position as Porters soils. Chandler, Chestnut and Edneyville soils have lighter colored or thinner ochric epipedons and are on warmer and drier parts of the landscapes, typically on south to west aspects. Chandler and Watauga soils are in a micaceous family. Cowee, Evard, Saluda, and Watauga soils have an argillic horizon and are at locally lower elevations or on warmer slopes, typically south to west aspects. Cullasaja, Haywood, Saunook, Toecane, Tuckasegee, and Tusquitee soils formed in colluvium, are very deep, have C horizons of colluvial material, and are in coves and on toe slopes at locally lower elevations. Plott soils are very deep to bedrock and have an umbric epipedon 10 to 20 inches thick. Trimont soils have an argillic horizon, are in a fine-loamy family, and are at locally lower elevations on cool aspect slopes. Unaka soils are in the same landscape position as Porters soil.
DRAINAGE AND PERMEABILITY: Well drained, moderate permeability. Runoff class is medium on strongly sloping or moderately steep slopes, and high on steeper slopes. Runoff is much lower where forest litter has little or no disturbance.
USE AND VEGETATION: Most areas are in forest consisting of a dominant forest type of northern red oak with hickory, sugar maple, yellow-poplar, black locust, hemlock, and eastern white pine as associated. On dry sites or the higher elevations upland oaks, hickory, blackgum, red maple, yellow birch, black birch, and pitch pine are associated. Flowering dogwood, mountain laurel, and rhododendron are the dominant understory species. Approximately 20 percent of the soil is cleared and used for pasture, hay, corn, truck crops, burley tobacco and Christmas trees.
DISTRIBUTION AND EXTENT: The Southern Blue Ridge mountains of Georgia, North Carolina, South Carolina, eastern Tennessee, and Virginia. The series is extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia
SERIES ESTABLISHED: Bedford County, Virginia; 1901.
REMARKS: Porters soils were formerly classified as Gray-Brown Podzolic soils intergrading to Lithosols. The 9/89 revision restricts depth to bedrock to 40 to 60 inches. The Plott series was previously included with Porters soils. Plott soils are deeper than 60 inches to bedrock and have an umbric epipedon 10 to 20 inches thick.
The 1/97 revision placed Porters soils in a fine-loamy family. This series was formerly placed in a coarse-loamy family. 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. However, chemical lab data indicate that sufficient amorphous, clay-sized materials occur in the particle-size control section to place this soil in a fine-loamy family. Average clay contents are generally less than 25 percent.
Additionally, textures were also modified in the range in characteristics for horizons within the solum.
This latest revision places Porters soils in an isotic mineralogy class. Using the 7th Edition of Keys to Soil Taxonomy (1996), Porters soils would classify as fine-loamy, isotic, mesic Andic Dystrochrepts. However, a proposal has been made to add an acid oxalate-extractable silicon requirement to Andic subgroups, which would exclude Balsam soils, which lack volcanic glass.
Diagnostic horizons and features in this pedon are:
Ochric epipedon - 0 to 7 inches (Ap horizon)
Umbric Dystrochrept feature - Moist value of 3 in the 0 to 7 inch Ap horizon.
Cambic horizon - 10 to 28 inches (Bw and BC horizons)
Lithic contact - hard bedrock at a depth of 42 inches.
Isotic mineralogy class - within the PSCS the soil generally has high amorphous materials (high pH-dependent charge) and a high moisture retention (at 1500 kPa) to clay ratio.
Properties that would place the soil in an Andic subgroup--a horizon or horizons with total thickness of 7 inches (18 cm) or more within 30 inches (75 cm) of the mineral soil surface with a fine-earth bulk density of 1.0 g/cm3 or less (at 33 kPa water retention) and ammonium oxalate extractable aluminum plus 1/2 iron percentages totaling more than 1.0.
Revised: 10/92-DLN,HJB,AG; 1/97-DHK, 12/97-DHK
01-2011 Classification -- 11th Keys, update competing series, MLRA clarification -- BPS
National Cooperative Soil Survey