LOCATION ROTAN TXEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, thermic Pachic Paleustolls
TYPICAL PEDON: Rotan clay loam--cultivated.
(Colors are for dry soil unless otherwise stated.)
Ap--0 to 6 inches; dark brown (10YR 4/3) clay loam, dark brown (10YR 3/3) moist; weak fine granular structure; hard, friable; mildly alkaline; abrupt smooth boundary. (4 to 12 inches thick)
BA--6 to 14 inches; dark grayish brown (10YR 4/2) clay loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; hard, friable, sticky; common fine and very fine pores; patchy clay films on peds; mildly alkaline; clear wavy boundary. (4 to 14 inches thick)
Bt1--14 to 25 inches; dark grayish brown (10YR 4/2) clay, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; very hard, firm, very sticky; common fine and very fine pores; nearly continuous clay films on peds; few films of calcium carbonate on peds; calcareous; moderately alkaline; clear wavy boundary. (6 to 15 inches thick)
Bt2--25 to 48 inches; dark brown (7.5YR 4/4) clay, dark brown (7.5YR 3/4) moist; moderate medium blocky structure; very hard, firm, very sticky; few very fine pores; nearly continuous clay films on peds; common films and threads of calcium carbonate; calcareous; moderately alkaline; gradual wavy boundary. (9 to 30 inches thick)
Btk1--48 to 68 inches; reddish yellow (7.5YR 8/6) clay loam, reddish yellow (7.5YR 6/6) moist; weak medium blocky structure; very hard, friable; sticky; contains about 25 percent visible soft masses and concretions of calcium carbonate; calcareous; moderately alkaline; gradual smooth boundary. (8 to 30 inches thick)
Btk2--68 to 80 inches; reddish yellow (5YR 7/6) clay loam, yellowish red (5YR 5/6) moist; weak medium blocky structure; hard, firm; sticky; about 5 percent visible soft masses and concretions of calcium carbonate; few siliceous pebbles; patchy clay films on peds; calcareous; moderately alkaline.
TYPE LOCATION: Taylor County, Texas; from intersection of Farm Road 707 and Interstate 20 in the northern edge of Tye, one mile east along northern access road to Interstate 20, then 1 mile north on unnumberd paved county road to intersection with an unpaved county road, then 0.2 mile east on county road and 100 feet north into cultivated field.
RANGE IN CHARACTERISTICS: Solum thickness exceeds 60 inches. Carbonates are within 10 to 28 inches of the surface. Depth to a calcic horizon ranges from 30 to 60 inches. Thickness of the mollic epipedon ranges from 20 to about 40 inches.
The A horizon is grayish brown (10YR 5/2), dark grayish brown (10YR 4/2), brown (10YR 5/3; 7.5YR 5/2), or dark brown (10YR 4/3; 7.5YR 4/2). It is loam, clay loam, or silty clay loam. It is mildly alkaline or moderately alkaline.
The Bt horizons are silty clay loam, clay loam, or clay with a clay content of 35 to 45 percent. Their structure ranges from subangular blocky to blocky. The B horizons above the Btca horizon are reddish brown (5YR 5/3, 4/3, 5/4, 4/4), brown (7.5YR 5/2, 5/4; 10YR 5/3), dark brown (7.5YR 4/2, 4/4, 10YR 4/3), grayish brown (10YR 5/2), or dark grayish brown (10YR 4/2). The Btca horizon is pink (5YR 8/4, 7/4, 6/4; 7.5YR 8/4, 7/4), reddish yellow (5YR 8/6, 7/6, 6/6; 7.5YR 8/6, 7/6, 6/6), brown (10YR 5/3), or white (5YR 8/1; 10YR 8/1, 8/2). It contains 15 to 50 percent calcium carbonate by volume, mainly in the form of soil masses and concretions.
The Bt horizon below the calcic horizon is light red (2.5YR 6/6), red (2.5YR 5/6), reddish yellow (5YR 6/6, 7/6; 7.5YR 6/6, 7/6), yellowish red (5YR 5/6), or strong brown (7.5YR 5/6).
COMPETING SERIES: These include the Abilene, Bethany, Blanket, Brewer, Dodson, Frankirk, Hollister, McLain, Pullman, Renfrow, Rowena, and Sagerton series. Abilene and Dodson soils have sola less than 60 inches thick, or have chromas of 4 or less throughout the Bt horizon. Bethany, Blanket, Brewer, Hollister, and McLain soils lack calcic horizons. In addition, Blanket, Brewer, and McLain soils lack carbonates within a depth of 28 inches. Frankirk and Sagerton soils have mollic epipedons less than 20 inches thick and Frankirk soils lack carbonates within a depth of 28 inches. Pullman soils have a COLE greater than 0.07 and have more than 45 percent clay in the upper part of the Bt horizon. Rowena soils lack Bt horizons.
GEOGRAPHIC SETTING: Rotan soils occur on nearly level to gently sloping upland plains. Slopes are mainly less than 1 percent, but range to 3 percent. The soil formed in calcareous alluvium presumably deposited during the Quaternary age. The climate is subhumid. The average annual precipitation ranges from 20 to 28 inches. The mean annual air temperature is 62 degrees to 68 degrees F.; the annual Thornthwaite P-E indices range from 28 to 44.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Abilene, Hollister, Rowena, and Sagerton series and the Miles and Roscoe series. Miles soils have less than 35 percent clay in the control section and lack mollic epipedons. Roscoe soils lack Bt horizons.
DRAINAGE AND PERMEABILITY: Well drained; very slow to slow runoff; slow internal drainage; moderately slow permeability.
USE AND VEGETATION: Mainly in cotton, grain sorghum, and wheat. Native vegetation is blue grama, sideoats grama, Arizona cottontop, buffalograss, and vine mesquite and mesquite trees.
DISTRIBUTION AND EXTENT: Rolling Plains of northwest Texas and probably southwestern Oklahoma. The series is moderately extensive.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Stonewall County, Texas; 1970.
REMARKS: This series was formerly included with Abilene and Rowena soils.
Diagnostic horizons and features recoginzed in this pedon are:
Mollic epipedon - 0 to 25 inches.
Argillic horizon - 14 to 80 inches.
Pachic feature - the mollic epipedon ranges from 20 to 40 inches.