LOCATION POCOLA OKEstablished Series
TAXONOMIC CLASS: Fine, mixed, active, thermic Vertic Epiaqualfs
TYPICAL PEDON: Pocola silt loam, in pasture.
(Colors are for moist soil unless otherwise
stated.)
Ap--0 to 8 inches; dark grayish brown (10YR 4/2) silt loam, light brownish gray (10YR 6/2) dry; weak fine granular structure; hard, friable; slightly acid; clear smooth boundary. (4 to 9
inches thick)
B21tg--8 to 13 inches; dark grayish brown (10YR 4/2) silty
clay loam, light brownish gray (10YR 6/2) dry; common fine faint
gray and yellowish brown mottles; weak fine subangular blocky structure; hard, friable; nearly continuous clay films on faces of peds; strongly acid; clear smooth boundary. (0 to 8 inches thick)
B22tg--13 to 25 inches; very dark grayish brown (10YR 3/2)
silty clay, grayish brown (10YR 5/2) dry; common fine distinct
gray and common fine prominent red mottles; weak fine blocky structure; very hard, very firm; nearly continuous clay films on faces of peds; few fine black and yellowish brown concretions; strongly acid; gradual smooth boundary. (12 to 31 inches thick)
B23tg--25 to 57 inches; very dark grayish brown (10YR 3/2)
silty clay, grayish brown (10YR 5/2) dry; few fine distinct gray mottles; weak fine blocky structure; very hard, very firm; nearly continuous clay films on faces of peds; few fine yellowish brown
and black concretions; slightly acid; diffuse smooth boundary.
(19 to 39 inches thick)
B3--57 to 67 inches; dark brown (10YR 3/3) silty clay, brown (10YR 5/3) dry; gray coatings on few faces of peds; weak fine
blocky structure; very hard, very firm; nearly continuous clay
films on faces of peds; common fine black concretions; moderately alkaline; gradual smooth boundary. (0 to 20 inches thick)
C--67 to 81 inches; dark reddish brown (5YR 3/4) silty clay, reddish brown (5YR 5/4) dry; gray coatings on few faces of peds; massive; very hard, very firm; common fine black concretions; few fine calcium carbonate concretions; calcareous; moderately
alkaline.
TYPE LOCATION: LeFlore County, Oklahoma; about three miles
southeast of Spiro, Oklahoma; 700 feet north and 1,600 feet east
of the southwest corner of section 32, T. 9 N., R 26 E.
RANGE IN CHARACTERISTICS: Solum thickness is 50 to more than 60 inches.
The A horizon is very dark grayish brown (10YR 3/2), dark grayish brown (10YR 4/2), or dark brown (10YR 4/3). It is loam, silt
loam, clay loam, or silty clay loam and ranges from strongly acid
to slightly acid.
The B21t horizon is dark gray (10YR 4/1), gray (10YR 5/1), very
dark grayish brown (10YR 3/2), or dark grayish brown (10YR 4/2)
and has gray and brown mottles. It is silty clay loam or clay
loam and clay content ranges from 27 to 35 percent. The B21t
horizon ranges from strongly acid to slightly acid. Some pedons
lack the silty clay loam or clay loam B21t horizons.
The B22t and B23t horizons are very dark gray (10YR 3/1), dark
gray (10YR 4/1), gray (10YR 5/1, 6/1), light gray (10YR 7/1), very dark grayish brown (10YR 3/2), or dark grayish brown (10YR 4/2)
and have gray, red, or brown mottles. They are clay or silty clay and the clay content ranges from 40 to 60 percent. They range
from strongly acid to moderately alkaline but noncalcareous.
The B3 horizon is reddish brown (5YR 4/3, 4/4) or dark brown
(7.5YR 4/4; 10YR 4/3, 3/3). It is clay or silty clay. It is moderately alkaline and usually calcareous with calcium carbonate concretions.
The C horizon is dark reddish gray (5YR 4/2), dark reddish brown
(5YR 3/4), reddish brown (5YR 4/4), or dark brown (7.5YR 4/4). It
is clay or silty clay and is moderately alkaline and usually calcareous with calcium carbonate concretions.
COMPETING SERIES: These are the Baldwin, Dowellton, Gore,
Jackport, Mayhew, McKamie, Midland, Panola, Sessum, Tensas, White Store, and Wilson series. Baldwin, Dowellton, Jackport, Mayhew, Midland, Panola, Sessum, Tensas, and Wilson soils have montmorillonitic mineralogy. In addition, Dowellton and Jackport soils have more than 60 percent clay in the control section. Boswell, Gore, McKamie, and White Store soils are more red in at least the upper part of the B2t horizon. In addition McKamie
soils decrease in clay content at depths of 24 to 60 inches and
White Store soils have sandstone bedrock at depths of 24 to 40 inches.
GEOGRAPHIC SETTING: Pocola soils are on nearly level to very
gently sloping flood plains of the Ouachita Mountains and Arkansas valley and ridges. Slope gradients range from 0 to 3 percent.
They have formed in calcareous clayey alluvium. They are rare or occasionally flooded. The climate is humid. Mean annual precipitation ranges from 40 to 55 inches. Mean annual
temperature ranges from 60 degrees to 64 degrees F. Thornthwaite annual P-E indices range from 64 to 80.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Latanier,
Moreland, Muldrow, and Neff series. Latanier and Moreland soils
lack B2t horizons. In addition, Latanier soils are loamy at
depths of 20 to 40 inches. Muldrow soils have mollic epipedons. Neff soils have less than 35 percent clay in the control section.
DRAINAGE AND PERMEABILITY: Pocola soils are somewhat poorly
drained. Runoff is slow, and permeability is very slow. A
perched water table is at a depth of 0.5 to 2.0 feet in winter and spring for short periods of time.
USE AND VEGETATION: Most areas have been cleared and used mainly
for tame pasture for beef cattle. Native vegetation is an open
stand of elm and post oak with understory of mid and tall grasses.
DISTRIBUTION AND EXTENT: Ouachita Mountains and Arkansas valley
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
and ridges of southeast Oklahoma and Arkansas. The series is of minor extent.
SERIES ESTABLISHED: LeFlore County, Oklahoma; 1981.
REMARKS: Pocola soils were unnamed and formerly classified in the Planosols great soil group.