LOCATION DODSON TX+OKEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Pachic Argiustolls
TYPICAL PEDON: Dodson silt loam - cultivated. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 8 inches, brown (7.5YR 4/3) silt loam, dark brown (7.5YR 3/3) moist; weak fine granular structure; hard, friable; common wormcasts; noneffervescent, neutral; clear smooth boundary. (4 to 20 inches thick)
Bt1--8 to 15 inches, brown (7.5YR 4/2) silty clay loam, dark brown (7.5YR 3/2) moist; moderate fine and medium subangular blocky structure; hard, friable; common wormcasts; few distinct clay films on faces of peds; noneffervescent, slightly alkaline; clear smooth boundary. (7 to 14 inches thick)
Bt2--15 to 24 inches, reddish brown (5YR 4/3) silty clay loam, dark reddish brown (5YR 3/3) moist; strong medium subangular blocky structure; hard, friable; few distinct clay films on faces of peds; noneffervescent, slightly alkaline; gradual smooth boundary. (6 to 14 inches thick)
Bt3--24 to 30 inches, reddish brown (5YR 4/4) silty clay loam, dark reddish brown (5YR 3/4) moist; moderate medium subangular blocky structure; hard, friable; few distinct clay films on faces of peds; noneffervescent, moderately alkaline; gradual wavy boundary. (12 to 30 inches thick)
Btk--30 to 50 inches, reddish brown (5YR 4/4) silty clay loam, dark reddish brown (5YR 3/4) moist; moderate medium subangular blocky structure; hard, friable; few faint clay films on faces of peds; few fine masses of calcium carbonate; slightly effervescent, moderately alkaline; gradual wavy boundary. (12 to 30 inches thick)
BCk--50 to 80 inches, brown (7.5YR 5/4) silty clay loam, brown (7.5YR 4/4) moist; weak fine and medium subangular blocky structure; hard, friable; common films, threads, and fine masses of calcium carbonate; strongly effervescent, moderately alkaline.
TYPE LOCATION: Wheeler County, Texas; 2 miles east of water tower in downtown Shamrock on Farm Road 2033, then 0.7 mile south on county road, then 500 feet east in cultivated field. This location is also 0.3 mile north and 0.1 mile east of SW corner of sec. 39, Block 17 H&GN RR Survey ; Latitude: 35 degrees, 12 minutes, 06 seconds N; Longitude: 100 degrees, 12 minutes, 58 seconds W. Shamrock east, TX topographic quadrangle; NAD 1927.
RANGE IN CHARACTERISTICS:
Particle-size control section (weighted average)
Clay content: 35 to 45 percent
CEC/clay ratio: more than 0.6
Thickness of the mollic epipedon, 20 to 40 inches
Thickness of the solum, 60 to more than 80 inches
Depth to secondary calcium carbonate: 25 to 60 inches
Depth to calcic horizon (where present): more than 70 inches
A Horizon
Hue: 7.5YR or 10YR
Value: 3 to 5 (2 or 3 moist)
Chroma: 2 or 3
Texture: loam or silt loam
Clay content: 15 to 27 percent
Effervescence: noneffervescent
Reaction: slightly acid to slightly alkaline (pH 6.1 7.8)
Upper Bt Horizon
Hue: 5YR to 10YR
Value: 3 or 4 (2 or 3 moist)
Chroma: 2 or 3
Texture: clay loam, silty clay loam, silty clay, or clay
Clay content: 30 to 45 percent
Effervescence: noneffervescent to slightly effervescent
Reaction: neutral or slightly alkaline (pH 6.6 7.8)
Lower Bt Horizon
Hue: 2.5YR to 7.5YR
Value: 4 to 6 (3 to 5 moist)
Chroma: 3 to 6
Texture: clay loam, silty clay loam, sandy clay loam, loam, or silt loam
Clay content: 20 to 40 percent
Calcium carbonate equivalent: 0 to 15 percent
EC (dS/m): less than 2
Effervescence: noneffervescent to strongly effervescent
Reaction: neutral to moderately alkaline (pH 6.6 8.4)
Bk or BCk Horizon
Hue: 2.5YR to 7.5YR
Value: 5 or 6 (4 or 5 moist)
Chroma: 3 to 6
Texture: silty clay loam, clay loam, sandy clay loam, sandy loam, loam, or silt loam
Clay content: 10 to 35 percent
Calcium carbonate equivalent: 2 to 20 percent
EC (dS/m): less than 2
Effervescence: slightly effervescent to violently effervescent
Reaction: moderately alkaline (pH 7.9 8.4)
2BC or 2C Horizon (where present)
Hue: 2.5YR or 5YR
Value: 5 or 6 (4 or 5 moist)
Chroma: 4 to 8
Texture: ranges from very fine sandy loam to clay and is weathered from Permian age sandstone or shale
Clay content: 10 to 50 percent
Calcium carbonate equivalent: 2 to 20 percent
EC (dS/m): less than 2
Effervescence: slightly effervescent to violently effervescent
Reaction: slightly alkaline or moderately alkaline (pH 7.4 8.4)
COMPETING SERIES: These are the
Abilene,
Blanket,
Marfa,
McLain,
Roark,
Tenaga, and
Wolco series.
Abilene soils: These soils have a calcic horizon within 60 inches.
Blanket soils: These soils occur in a warmer and moister climate and have BC horizons at depths of less than 60 inches with more than 20 percent calcium carbonate.
Marfa and Tenaga soils: These soils occur in drier climates.
McLain soils: These soils occur on flood plains in areas with more than 35 inches of mean annual precipitation.
Roark soils: These soils occur on lower terraces and have redoximorphic features in the lower part.
GEOGRAPHIC SETTING:
Parent material: loamy or clayey alluvium or lacustrine deposits over Permian age redbed sediments
Landform: Toe slopes to slightly concave areas of treads of high stream terraces or shoulders and summits of dissected stream terraces on alluvial plains.
Slope: 0 to 3 percent
Mean annual air temperature range: 58 to 64 degrees F.
Mean annual precipitation range: 20 to 28 inches
Frost-free period: 190 to 230 days
Elevation: 1500 to 2400 feet
Thornthwaite annual P-E indices: 32 to 44
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Carey,
Clairemont,
Lutie,
Obaro,
Paducah,
Quinlan, and
Woodward series.
Carey: These soils occur on slightly higher convex slopes, have a mollic epipedon less than 20 inches thick and have less than 35 percent clay in the particle-size control section.
Clairemont: These soils occur on lower flood plains, have an ochric epipedon and less than 35 percent clay in the particle-size control section.
Lutie: These soils occur on surrounding convex areas, have a mollic epipedon less than 20 inches thick and less than 35 percent clay in the particle-size control section.
Obaro, Quinlan, and Woodward series: These soils occur on lower side slopes, have an ochric epipedon, and are less than 40 inches deep to sandstone.
Paducah: These soils occur on slightly higher convex slopes, have an ochric epipedon and less than 35 percent clay in the particle-size control section.
DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability; runoff is low on less than 1 percent slopes and medium on 1 to 3 percent slopes.
USE AND VEGETATION: Most areas are used for growing cotton, wheat, and grain sorghums. Native vegetation is a mixed grass prairie. Dominant species are little bluestem, sideoats grama, blue grama, western wheatgrass, and buffalograss.
DISTRIBUTION AND EXTENT: Northwestern part of Central Rolling Red Plains of Texas and in adjoining western Oklahoma; LRR H; MLRA 78C; The series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Wheeler County, Texas; 1969.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Particle size control section: 8 to 28 inches. (Bt1, Bt2, and Bt3 horizons)
Mollic epipedon: 0 to 24 inches. (Ap, Bt1, and Bt2 horizons)
Argillic horizon: 8 to 50 inches. (Bt1, Bt2, Bt3, and Btk horizons)
Additional Comments:
This series formerly was formerly classified in the Reddish Chestnut great soil group.
These soils were formerly included in the Abilene series in the earlier soil surveys of Greer Co., Oklahoma issued 1967, and Harmon Co., Oklahoma issued 1984.
The assignment of the cation-exchange activity class is supported by NSSL laboratory data number S2003-OK-057-001 from Harmon County, Oklahoma and S2001-OK-055-003 from Greer county, Oklahoma.
Range Site: OK Hardland (south), 078XY042OK; TX Clay Loam PE 25-36 ,078BY072TX
Soil Interpretation Record Number: TX0481
Taxonomic version: Soil Taxonomy, Second Edition, 1999
ADDITIONAL DATA: NSSL data number S2003-OK-057-001 from Harmon County, Oklahoma, S2001-OK-055-001 and S2001-OK-055-003 from Greer County, Oklahoma