LOCATION SOSTIEN LA+MSEstablished Series
TAXONOMIC CLASS: Fine, smectitic, nonacid, thermic Vertic Fluvaquents
TYPICAL PEDON: Sostien clay, on a 3 percent slope in hardwood woodland. (Colors are for moist soil unless otherwise
stated.)
A--0 to 4 inches; dark grayish brown (10YR 4/2) clay; common fine distinct dark brown and yellowish brown mottles; few fine
faint dark gray mottles; weak coarse subangular blocky structure; firm, plastic, sticky; common fine and medium roots; thin layer (1/4-inch) of very dark gray (10YR 3/1) clay on surface;
moderately alkaline; clear smooth boundary. (2 to 6 inches
thick)
Cg--4 to 65 inches; gray (10YR 5/1; 5Y 5/1) clay; many fine
and medium prominent strong brown (7.5YR 5/8) and dark brown
(7.5YR 4/4) mottles; common fine distinct yellowish brown (10YR
5/6) mottles; massive; very firm, very sticky, plastic; common
fine, medium, and coarse roots in upper part; many large clods and clayey soil fragments in varying shades of gray; thin
discontinuous bedding planes are evident in some clods; about 10 percent of the matrix is grayish brown (10YR 5/2) fine sandy loam that surrounds clods, lies in pockets, or is in vertical,
horizontal, and diagonal streaks; few fine and medium soft masses
of carbonates; moderately alkaline.
TYPE LOCATION: Concordia Parish, Louisiana; 3.5 miles west of the Old River Control Structure, Three Rivers Wildlife Management
Area, 1.5 miles west of levee on shell road, 0.8 mile south of
road, 300 feet south and 255 feet east of trail, unsectionized
area, T. 1 N., R. 8 E.
RANGE IN CHARACTERISTICS: Reaction ranges from slightly acid to moderately alkaline throughout. Cracks 1 to 3 centimeters wide develop to a depth of 50 to 60 centimeters in most years.
The A horizon has hue of 10YR, 2.5Y, or 5Y; value of 3 or 4, and chroma of 1 to 3. Texture is clay, silty clay, or silty clay
loam.
The Cg horizon has hue of 10YR, 2.5Y, or 5Y; value of 4 to 6, and chroma of 1 or 2. Mottles, where present, are in shades of brown. Some pedons have thin lenses or clods with hue of 5YR, value 4 or
5, and chroma 4 or 6. Texture is clay or silty clay. Few to
common pockets, streaks, or strata of sandy or loamy materials
occur throughout. Accumulations of calcium carbonate range from
none to common.
COMPETING SERIES: These are
Ambia and
Ijam series in the same
family and
Sharkey series. Ambia soils formed in undisturbed materials and are more acid throughout. Ijam soils are more
saline. Sharkey soils formed in undisturbed materials and have a cambic horizon.
GEOGRAPHIC SETTING: Sostien soils are on spoil banks adjacent to rivers and canals. Slopes range from 0 to 8 percent. The soils
are forming in thick, clayey sediments dredged from canals or
rivers or from land surfaces during construction of waterways. The climate is warm and humid. The mean annual temperature is about
66 degrees F., and the mean annual rainfall is about 59 inches
near the type location.
GEOGRAPHICALLY ASSOCIATED SOILS: These are mainly
Bruin,
Cocodrie,
Commerce,
Convent,
Crevasse, and the competing
Sharkey series. Bruin, Commerce, Convent, and Crevasse soils are on
nearby undisturbed areas and are loamy throughout. Cocodrie soils are developing in dredged materials and are coarse-silty.
DRAINAGE AND PERMEABILITY: Poorly drained; slow to medium runoff; very slow permeability. These soils are usually saturated
throughout during the winter and spring. Some areas of these
soils are subject to flooding.
USE AND VEGETATION: Most areas have reverted to woodland and are mainly for wildlife habitat. A few areas are used for pasture. Dominant tree species in wooded areas are sugarberry, black
willow, green ash, boxelder, and eastern cottonwood.
DISTRIBUTION AND EXTENT: Louisiana and possibly other states that have channel straightening and dredging operations. The series is
of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Concordia Parish, Louisiana; 1983.
REMARKS: The series name is derived from that of a local lake. These soils were formerly unclassified and included in the land
type, made land; or were classified and mapped at the Great Group Level; or were included with the Sharkey series.