LOCATION OVERCUP AR
Established Series
Rev. LBW:DF:CH
10/2018
OVERCUP SERIES
The Overcup series consists very deep, poorly drained, very slowly permeable soils that formed in alluvium. These soils are on terraces in the Western Lowlands of east Arkansas. Slopes range from 0 to 3 percent. Mean annual air temperature is about 61 degrees F and the mean annual precipitation is about 47 inches.
TAXONOMIC CLASS: Fine, smectitic, thermic Vertic Albaqualfs
TYPICAL PEDON: Overcup silt loam, on a 1 percent slopes in an idle field. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 4 inches; dark grayish brown (10YR 4/2) silt loam; weak medium and coarse subangular blocky structure; firm; common fine and very fine roots; common fine and very fine pores; common fine distinct yellowish brown (10YR 5/8) iron accumulations; few fine distinct light brownish gray (10YR 6/2) iron depletions; many fine and medium soft round iron-manganese nodules; strongly acid; abrupt smooth boundary. (3 to 7 inches thick)
Eg--4 to 8 inches; light gray (10YR 7/1) silt loam; weak coarse subangular blocky structure; firm; few fine and very fine roots; common fine and very fine pores; common medium distinct yellowish brown (10YR 5/6) iron accumulations; many fine and medium soft round iron-manganese nodules; strongly acid; clear wavy boundary. (3 to 7 inches thick)
Btg1--8 to 22 inches; grayish brown (2.5Y 5/2) silty clay; moderate fine angular blocky structure; firm; plastic and sticky; few fine and very fine roots; common fine and very fine pores; many faint clay films on faces of peds and lining pores; few slickensides that do not intersect; light gray (10YR 7/1) clay depletions along old vertical cracks; few medium distinct strong brown (7.5YR 5/6) iron accumulations in matrix and around old root channels; common fine and medium soft round iron-manganese nodules; very strongly acid; gradual wavy boundary.
Btg2--22 to 44 inches; dark grayish brown (2.5Y 4/2) silty clay; moderate fine angular blocky structure; firm; plastic and sticky; few fine and very fine roots; common fine and very fine pores; many distinct clay films on faces of peds and lining pores; few slickensides that do not intersect; few fine distinct dark yellowish brown (10YR 4/6) iron accumulations; common fine and medium soft round iron-manganese nodules; very strongly acid; gradual smooth boundary.
Btg3--44 to 61 inches; grayish brown (2.5Y 5/2) silty clay; moderate fine angular blocky structure; firm; slightly sticky and slightly plastic; few fine and very fine roots; common fine and very fine pores; many faint clay films on faces of peds and lining pores; few medium distinct dark yellowish brown (10YR 4/6) iron accumulations; few fine distinct light gray iron depletions; common fine and medium soft round iron-manganese masses; few medium prominent black (10YR 2/1) manganese accumulations on faces of peds; very strongly acid; gradual smooth boundary. (Combined thickness of the Btg horizon ranges from 44 to 60 inches.)
BCg--61 to 72 inches; light brownish gray (2.5Y 6/2) silty clay loam; moderate medium subangular blocky structure; firm; common fine and very fine pores; common medium distinct dark yellowish brown (10YR 4/4) iron accumulations; common fine and medium soft round iron-manganese nodules; many medium prominent black (10YR 2/1) manganese accumulations on faces of peds; strongly acid. (0 to 15 inches thick.)
TYPE LOCATION: Woodruff County, Arkansas; NW1/4NE1/4SE1/4 sec. 13, T. 8 N., R. 2 W.
RANGE IN CHARACTERISTICS: Solum thickness is more than 60 inches. The boundary between the ochric epipedon and the argillic horizon is abrupt or clear and the depth to the abrupt texture change ranges from 6 to 14 inches. The content of exchangeable sodium increases with depth and ranges from 5 to 15 percent in the lower part of the solum.
The A or Ap horizon has hue of 10YR, value of 4 or 5, and chroma of 2 or 3. Reaction is typically strongly acid or moderately acid but ranges to slightly alkaline due to the addition of alkaline irrigation water. Iron accumulations and depletions are in shades of gray or brown. Texture is silt loam.
The Eg horizon has hue of 10YR, value of 5 to 7, and chroma of 1 or 2. Iron accumulations and depletions are in shades of brown or gray. Reaction is typically very strongly acid to moderately acid but ranges to slightly alkaline due to the addition of alkaline irrigation water. Texture is silt loam.
The Btg horizon has hue of 10YR or 2.5Y, value of 5 or 6, and chroma of 1 or 2. Iron and manganese accumulations and depletions are in shades of brown, red or gray. Reaction ranges from slightly acid to very strongly acid. Texture is silty clay or clay.
The BCg horizon has hue of 10YR or 2.5Y, value of 5 or 6, and chroma of 1 or 2. Iron and manganese accumulations and depletions are in shades of gray, yellow and brown. Reaction ranges from strongly acid to moderately alkaline. Texture is silty clay loam or silty clay.
The Cg horizon, where present, has hue of 10YR or 2.5Y, value of 5 or 6, and chroma of 1 or 2. Iron and manganese accumulation and depletions are in shades of gray, yellow or brown. Texture is silty clay loam or silt loam. Reaction ranges from strongly acid to moderately alkaline.
COMPETING SERIES: These include the
Anacoco,
Edna,
Herty,
Lufkin,
Mabank,
Oakhurst, and
Zulch series in the same family. Anacoco soils have 40 to 60 inch sola and are somewhat poorly drained. Edna soils have higher ph in the argillic horizon and are somewhat poorly drained. Herty soils have 40 to 60 inch sola, contain gypsum, barite and other salts in the lower part of the Bt horizon and are somewhat poorly drained. Lufkin soils have base saturation of 80 to 100 percent throughout the argillic horizon and are somewhat poorly drained. Mabank soils contain cemented carbonate concretions, gypsum crystals, have values of 4 or less in the upper part of the argillic and are somewhat poorly drained. Oakhurst soils have sola 40 to 60 inches thick and are somewhat poorly drained. Zulch soils have 30 to 40 inch sola, have values of 3 or less in the upper argillic horizon and are somewhat poorly drained.
GEOGRAPHIC SETTING: Overcup soils are on level to nearly level slightly convex slopes on braided stream terraces in the Western Lowlands of eastern Arkansas; MLRA 131. Slopes are typically 0 to 1 percent, but range to 3 percent. Overcup soils formed in alluvial sediments deposited by the Mississippi River or its ancestors. Near the type location, the average annual air temperature is about 61 degrees, and the mean annual precipitation is about 47 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Bonn,
Foley
Grubbs and
Jackport soils. The Bonn and Foley soils occur on slightly lower landscapes, have fine-silty control sections and natric horizons. Grubbs soils occur on short escarpments to old abandon channels, have mixed mineralogy and are
somewhat poorly drained.
Jackport soils are on slightly higher landscapes, have very-fine control sections and do not have an abrupt texture change.
DRAINAGE AND PERMEABILITY: Overcup soils are poorly drained and runoff is slow. Permeability is very slow. A seasonally high water table is within 12 inches of the soil surface from December through April most years.
USE AND VEGETATION: Most of the acreage is cleared and in cultivated crops. Soybeans, grain sorghum, and rice are the crops. A few small tracts of hardwood timber remain. The native vegetation was mixed hardwood forests.
DISTRIBUTION AND EXTENT: MLRA 131. The Western Lowlands of Arkansas and southeast Missouri. The series is of moderate extent.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: AUBURN, ALABAMA
SERIES ESTABLISHED: Greene County, Arkansas, 10/1995.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - surface to 8 inches (Ap and E horizons.)
Albic horizon - zone from 4 to 8 inches (E horizon)
Abrupt texture change - contact between the albic horizonand the underlying argillic horizon.
Argillic horizon horizon - zone from 8 to 64 inches. (Btg horizon)
Additional Data: Characterization of the typical pedon by the University of Arkansas Soil Characterization Laboratory. Pedon number S89AR-147-08.
National Cooperative Soil Survey
U.S.A.