LOCATION ST. PAUL OK+KS+TXEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, thermic Pachic Argiustolls
TYPICAL PEDON: St. Paul silt loam--cultivated. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 7 inches; brown (7.5YR 5/2) silt loam, dark brown (7.5YR 3/2) moist; weak fine granular structure; hard, friable; many fine roots; neutral; abrupt smooth boundary. (0 to 10 inches thick)
A--7 to 12 inches; dark brown (7.5YR 3/2) silt loam, very dark brown (7.5YR 2.5/2) moist; moderate fine granular structure; hard, friable; many fine roots; neutral; gradual smooth boundary. (2 to 12 inches thick)
BA--12 to 18 inches; brown (7.5YR 4/2) silty clay loam, dark brown (7.5YR 3/2) moist; moderate fine subangular blocky structure; hard, friable; common fine roots; neutral; gradual smooth boundary. (4 to 12 inches thick)
Bt1--18 to 34 inches; reddish brown (5YR 4/3) silty clay loam, dark reddish brown (5YR 3/3) moist; moderate fine and medium subangular blocky structure; very hard, firm; distinct continuous clay films; few fine roots; slightly effervescent; slightly alkaline; gradual smooth boundary. (8 to 20 inches thick)
Bt2--34 to 45 inches; reddish brown (5YR 4/3) silty clay loam, dark reddish brown (5YR 3/3) moist; moderate medium subangular blocky structure; very hard, firm; distinct continuous clay films; few fine roots; few films of soft powdery calcium carbonate in lower part; strongly effervescent; moderately alkaline; gradual smooth boundary. (6 to 20 inches thick)
BCk--45 to 56 inches; reddish brown (5YR 5/4) silty clay loam, reddish brown (5YR 4/4) moist; weak medium subangular blocky structure; very hard, firm; faint discontinous clay films; few fine roots; many films of soft powdery calcium carbonate and a few small calcium carbonate concretions; strongly effervescent; moderately alkaline; gradual smooth boundary. (6 to 15 inches thick)
C--56 to 70 inches; yellowish red (5YR 5/6) silt loam, yellowish red (5YR 4/6) moist; massive; hard, friable; few small calcium carbonate concretions; slightly effervescent; moderately alkaline.
TYPE LOCATION: Roger Mills County, Oklahoma; about 2 miles south and 4 miles west of Leedey; 600 feet east and 200 feet north of SW corner of sec. 22, T. 16 N., R. 21 W.
RANGE IN CHARACTERISTICS: Solum thickness is 40 to more than 60 inches. Depth to soft powdery secondary calcium carbonate is 20 to 45 inches.
The A horizon has a hue of 5YR to 10YR, value of 3 to 5, and chroma of 2 or 3. Texture is silt loam or loam. It is slightly acid to slightly alkaline.
The BA horizon has a hue of 5YR to 10YR, value of 3 to 5, and chroma of 2 or 3. Texture is loam, silt loam, clay loam, or silty clay loam. The BA horizon has moderate or strong grade and granular or subangular blocky type structure. Reaction is neutral to moderately alkaline.
The Bt horizon has a hue of 2.5YR to 10YR, value of 4 to 6, and chroma of 2 to 6. It is clay loam or silty clay loam. Clay content is 27 to 35 percent in the upper part, ranging to 40 percent in the lower part. Reaction is slightly or moderately alkaline and effervescence ranges from noneffervescent to strongly effervescent.
The BC horizon has a hue of 2.5YR to 10YR, value of 4 to 6, and chroma of 2 to 6. It is loam, silt loam, clay loam, or silty clay loam and the clay content is 20 to 40 percent. The horizon is slightly or moderately alkaline and effervescence ranges from slightly effervescent to strongly effervescent.
The C horizon has a hue of 2.5YR to 7.5YR, value of 4 to 6, and chroma of 4 to 8. It is loam, very fine sandy loam, silt loam, clay loam, or silty clay loam. It is moderately alkaline and is slightly or strongly effervescent.
COMPETING SERIES: These are the Braman, Corbin, Irene, Lawrie, Pond Creek, and Westview series in the same family. And the Abilene, Altus, Carey, Dodson, Selman, and Tipton series in similar families. Abilene and Dodson soils have more than 35 percent clay in the control section. Altus, and Tipton soils have a fine-loamy control section. Braman, Corbin, Lawrie and Pond Creek soils are moist for longer periods of time. Carey and Selman soils have a mollic epipedon less than 20 inches thick. Irene soils are dry for longer periods of time. Westview soil are less developed and are located on low terraces above flood plains.
GEOGRAPHIC SETTING: St. Paul soils are on broad nearly level to moderately sloping summits of uplands of Central Rolling Red Plains (MLRA 78B, 78C). Slopes are 0 to 8 percent. The soil formed in a thin layer of silty sediments of Pleistocene age, or from residuum of weathered sandstone of Permian age or from a combination of these. Mean annual precipitation is 21 to 28 inches. Mean annual temperature ranges from 57 degrees to 64 degrees F. Thornthwaite annual P-E indices range from 32 to 44. Frost free days range from 190 to 221. Elevation ranges from 1500 to 2300 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Abilene, Carey, Madge, Obaro, Paducah, Selman and Woodward series. Abilene soils have fine particle-size control sections and are on similar areas. Carey, Madge, and Selman soils are on adjacent convex areas and have mollic surfaces less than 20 inches thick. Paducah soils have a ochric epipedon and are on slightly lower landscapes. Obaro and Woodward soils are on slightly lower sideslopes and lack an argillic horizon and a mollic epipedon. In addition, Woodward soils have a coarse-silty particle-size control section.
DRAINAGE AND PERMEABILITY: St. Paul soils are well drained; permeability is moderately slow. Runoff is low on 0 to 1 percent slopes, medium on 1 to 5 percent slopes and high on 5 to 8 percent slopes.
USE AND VEGETATION: Most areas are cultivated to wheat and other small grains; a few areas are in cotton, sorghums, and alfalfa. Native vegetation consists of tall and midgrasses.
DISTRIBUTION AND EXTENT: Central Rolling Red Plains (MLRA 78B, 78C) of Oklahoma, Texas, and Kansas. The series is extensive.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Kiowa County, Oklahoma; 1931.
REMARKS: Soil Interpretation Record: Series OK0070.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon- The zone from the surface of the soil to a depth of 45 inches (The A, BA, and upper Bt horizons).
Argillic horizon- The zone from 12 inches to a depth of 45 inches (The Bt horizons).
Moisture regime: Typic-Ustic.
ADDITIONAL DATA: Sample Numbers: S59-OK-77-3 and S59-OK-22-1 by the National Soil Survey Laboratory, Lincoln, Nebraska.