LOCATION YORKTOWN AR+LA
Established Series
Rev. LBW:HVG
04/2015
YORKTOWN SERIES
The Yorktown series consists of very deep, very poorly drained, very slowly permeable soils that formed in clayey alluvium. These level to depressional soils are in back swamps, sloughs and abandon oxbows of the Arkansas River, Red River and their tributaries; MLRA 131. Slopes range form 0 to 1 percent. These soils are typically ponded with water, 6 inches to 5 feet deep, for 10 or more months in a normal year.
TAXONOMIC CLASS: Very-fine, smectitic, nonacid, thermic Vertic Epiaquepts
TYPICAL PEDON: Yorktown silty clay - baldcypress, water tupelo swamp. (Colors are for moist soil unless otherwise stated.)
0i--2 to 0 inches, dark brown (7.5YR 3/2) partially decomposed twigs, leaves, and roots; moderately acid; abrupt smooth boundary. (0 to 3 inches thick)
A--0 to 8 inches, gray (5Y 5/1) silty clay; weak coarse subangular blocky structure; firm, very sticky; many fine roots; few fine prominent dark brown (7.5YR 3/2) masses of iron-manganese accumulation in matrix; moderately acid; clear smooth boundary. (4 to 10 inches thick)
Bg1--8 to 24 inches, gray (5Y 5/1) clay; moderate coarse blocky structure; very firm, very sticky; common fine roots; many medium prominent yellowish red (5YR 5/8) masses of iron accumulation; common fine prominent black (10YR 2/1) masses of manganese accumulation in matrix; moderately acid; clear smooth boundary. (10 to 17 inches thick)
Bg2--24 to 35 inches, dark gray (5Y 4/1) clay; moderate medium and coarse blocky structure; very firm, very sticky; few medium roots; common fine and medium prominent yellowish red (5YR 4/6) masses of iron accumulation in matrix; common fine prominent black (10YR 2/1) masses of manganese accumulation in matrix; moderately acid; clear smooth boundary. (10 to 15 inches thick)
Bg3--35 to 42 inches, greenish gray (5BG 5/1) clay; weak coarse blocky structure; very firm, very sticky; few medium roots; many coarse prominent strong brown (7.5YR 5/6) and few coarse prominent yellowish red (5YR 5/8) masses of iron accumulation in matrix; common fine prominent black (10YR 2/1) masses of manganese accumulation in matrix; moderately acid; abrupt smooth boundary. (6 to 20 inches thick)
Bw--42 to 60 inches, reddish brown (5YR 4/4) clay; strong medium blocky structure parting to strong fine blocky structure; very firm, very sticky; common fine pressure faces; greenish gray (5BG 5/1) fillings in root channels; common fine prominent gray (10YR 6/1) iron depletions in matrix; many fine Fe-Mn concretions; slightly alkaline.
TYPE LOCATION: Lincoln County, Arkansas; about 5 miles north of Star City on Highway 81 and 2 1/2 miles east-northeast of Yorktown along an unimproved road; 75 feet northwest from edge of a delineated area in NE1/4SW1/4NW1/4sec. 14, T. 8 S., R. 7 W.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 50 to 80 inches. Depth to the Bw horizon ranges from 40 to 60 inches but typically is 40 to 50 inches. The A and Bg horizons range from moderately acid to neutral. The Bw horizon is mildly or moderately alkaline. Some pedons have Bw horizons that are
calcareous and contain few to many, fine to coarse, carbonate concretions. The average clay content of the 10- to 40-inch control section is 60 to 85 percent.
The A horizon has hue of 10YR, 2.5Y or 5Y, value of 4 to 6, and chroma of 1 or 2, or is Neutral, with value of 4 to 6. Masses of iron and /or manganese accumulation are in shades of red, brown or black. Texture is silty clay or clay.
The Bg1 and Bg2 horizons hve hue of 10YR or 5Y, value of 4 to 6, and chroma of 1, or is Neutral with value of 4 to 6. Prominent masses of iron and/or manganese accumulation are in shades of red, brown or black. Texture is clay
The Bg3 horizon has hue of 10YR, 5Y, 5G, or 5BG, value of 4 to 6, and chroma of 1, or is Neutral, with value of 4 to 6. Prominent masses of iron and/or manganese accumulation are in shades of red, brown or black. Masses of iron-manganese accumulations decrease with depth.Texture is clay
The Bw horizon has hue of 5YR or 2.5YR, value of 3 to 5, and chroma of 3 to 6. Prominent iron depletions are in shades of gray. The iron depletions generally decrease in number with depth. The Bw horizon has moderate or strong blocky structure with few to many, fine pressure faces.
Some pedons may have a 2BC or 2C horizon with colors and textures similar to the Bw horizon.
COMPETING SERIES: These are no other series in this family.
GEOGRAPHIC SETTING: Yorktown soils are in low, ponded back swamps, sloughs, oxbows and abandoned channels of the Arkansas and Red Rivers and their tributaries. Slopes range from 0 to 1 percent. These soils are ponded at least 10 months of most years with from 6 inches to 5 feet of water. Near the type
location, the average annual temperature is 65 degrees F. and average annual precipitation is 51 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Desha,
Hebert,
Perry,
Portland and
Rilla series. All of which are on higher landscape positions Hebert and Rilla soils have coarser textures within the control section.
DRAINAGE AND PERMEABILITY: Very poorly drained; very slow permeability.
USE AND VEGETATION: Practically all of these soils are used for wildlife habitat and occasionally for timber production. The vegetation is dominantly baldcypress, water tupelo, and buttonbush.
DISTRIBUTION AND EXTENT: Backswamps, sloughs, oxbows and abandon channels on flood plains of the Arkansas and Red Rivers and their tributaries in Arkansas, Louisiana, and possibly Texas; MLRA 131. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: TEMPLE, TEXAS
SERIES ESTABLISHED: Faulkner County, Arkansas; 1975.
REMARKS: These soils have a very high shrink-swell potential but do not crack because they are wet most of the time. The Yorktown series was formerly considered as part of the water areas of shallow lakes and clayey swamps. The series would have been classified in the Alluvial great soil group
ADDITIONAL DATA: Organic carbon analysis by the University of Arkansas Soil Characterization Laboratory on one pedon is as follows:
0-8 inches -- 2.15%
8-24 inches -- 1.40%
24-35 inches -- 1.45%
35-42 inches -- 0.65%
42-60 inches -- 0.55%
National Cooperative Soil Survey
U.S.A.