LOCATION STAMFORD TX+OK
Established Series
Rev. ERB:CLG:JCW:WJG
11/2015
STAMFORD SERIES
The Stamford series consists of moderately deep, well drained, very slowly permeable soils that formed in calcareous clayey alluvium over residuum derived from shale and siltstone. These nearly level to gently sloping soils occur on hillslopes and pediments on dissected plains. Slopes range from 0 to 5 percent. Mean annual precipitation is about 533.4 mm (21 in) and the mean annual air temperature is about 17.2 degrees C (63 degrees F).
TAXONOMIC CLASS: Fine, smectitic, thermic Chromic Haplusterts
TYPICAL PEDON: Stamford clay--on a 1 percent slope in rangeland at an elevation of 521.2 m (1710 ft).
(Colors are for dry soil unless otherwise stated.)
A--0 to 23 cm (0 to 9 in); reddish brown (2.5YR 4/4) clay, dark reddish brown (2.5YR 3/4) moist; moderate fine and very fine blocky structure; very hard, very firm, very sticky, plastic; surface mulch of very hard, fine peds; few fine roots; few fine pores; few wormcasts; calcareous; moderately alkaline; gradual wavy boundary. Thickness is 15 to 76 cm (6 to 30 in)
Bkss--23 to 89 cm (9 to 35 in); red (2.5YR 4/6) clay, dark red (2.5YR 3/6) moist; moderate medium angular blocky structure; extremely hard, very firm, sticky, plastic; few fine roots and very fine pores; below 50 cm many parallelepipeds have the long axes tilted about 30 degrees from the horizontal; few prominent intersecting slickensides; few concretions of calcium carbonate about 2 to 5 mm in diameter; calcareous; moderately alkaline; gradual smooth boundary. Thickness is 46 to 91 cm (18 to 36 in)
Cd--89 to 152 cm (35 to 60 in); clay, dark red (10R 3/6) moist; massive; extremely hard, very firm, sticky, plastic; some thin strata of light gray clay; calcareous; moderately alkaline.
TYPE LOCATION: Runnels County, Texas; from the courthouse in Ballinger, 12.5 miles southwest on U.S. Highway 67, then 4.2 miles north on County Road 347 and 0.5 mile west on County Road 394, then 100 feet north in rangeland. USGS topographic quad: Rowena, Texas;
Latitude, 31 degrees, 41 minutes, 6.06 seconds N;
Longitude, 100 degrees, 7 minutes, 4.58 seconds W.
Datum: WGS84.
RANGE IN CHARACTERISTICS:
Soil Moisture: A typic-ustic soil moisture regime. The soil moisture control section is dry in some or all parts for more than 90 but less than 150 cumulative days in normal years.
Depth to densic bedrock: 71 to 137 cm (28 to 54 in)
Depth to cambic horizon: 15 to 76 cm (6 to 30 in)
Depth to identifiable secondary carbonates: 15 to 76 cm (6 to 30 in)
Depth to slickensides: 15 to 76 cm (6 to 30 in)
Vertic properties: The soil surface, where undisturbed, has gilgai microrelief. The soil has cracks more than 1 cm wide at a depth of 50 cm (20 in). Cracks remain open for more than 150 but less than 210 cumulative days during most years.
Particle-size control section (weighted average):
Clay content: 40 to 60 percent
A horizon
Hue: 2.5YR or 5YR
Value: 4 or 5
Chroma: 2 to 4
Texture: silty clay, clay
Color features: Where the A horizon is less than 30 cm (12 in) thick, dry value is less than 6 and moist value is less than 4 in more than half of the pedon.
Bkss horizon
Hue: 10R to 5YR
Value: 4 or 5
Chroma: 3 to 6
Texture: silty clay, clay
Identifiable secondary carbonates: amount-1 to 10, kind-films and threads, masses, and concretions
Cd horizon
Hue: 10R to 5YR
Value: 4 or 5
Chroma: 3 to 6
Texture: silty clay, clay
Some pedons have a Cr layer that ranges from massive unaltered clayey shale to partially weathered clayey or silty redbeds. Thin strata of sandstone, shale, or dolomitic limestone occur below 40 inches in some pedons.
COMPETING SERIES: These are the
Lipan and
Reap series in the same family. Similar soils are the
Leeray,
Mangum,
Tilvern,
Tobosa, and
Vernon series.
Leeray soils: have dry value greater than 5.5, moist value greater than 3.5, or chroma less than 2.5 in more than half of the pedon in one or more horizons within 30 cm of the soil surface
Lipan and
Reap soils: do not have contact with densic bedrock and have chroma less than 3 throughout the profile
Mangum soils: do not have intersecting slickensides and parallelepipeds which are tilted 10 degrees to 60 degrees from the horizontal
Tilvern soils: have mixed mineralogy and do not have gilgai microrelief in undisturbed areas
Tobosa soils: do not have contact with densic bedrock and have cracks that remain open for more than 210 cumulative days during most years
Vernon soils: have a mixed mineralogy and do not have intersecting slickensides
GEOGRAPHIC SETTING:
Parent material: calcareous clayey slope alluvium over residuum derived from claystone and siltstone of Permian age
Landscape: dissected plains
Landform: hillslopes and pediments
Slope: 0 to 5 percent
Mean annual precipitation: 508 to 711 mm (20 to 28 in)
Thornthwaite annual P-E indices: 24 to 44
Mean annual air temperature: 15.6 to 18.3 degrees C (60 to 65 degrees F)
Frost-free days: 200 to 230 days
Elevation: 304.8 to 762.0 m (1000 to 2500 ft)
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Mangum,
Rowena,
Sagerton, and
Vernon soils.
Mangum soils: do not have intersecting slickensides and parallelepipeds which are tilted 10 degrees to 60 degrees from the horizontal. These soils are lower on the landform and are subject to flooding hazards.
Rowena soils: do not have intersecting slickensides and are higher on the landform.
Sagerton soils: do not have intersecting slickensides and have an argillic horizon. These soils are on higher convex positions.
Vernon soils: do not have intersecting slickensides. These soils are on higher positions.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is very slow. Runoff is high on slopes less than 1 percent and very high on 1 to 5 percent slopes. Water enters the soil rapidly through cracks when the soil is dry, but very slowly when the soil is wet.
USE AND VEGETATION: Mostly in native range, but some is cropped to small grains and sorghums. Short grasses, mainly tobosa and buffalograss, are dominant and some curly mesquite and various woody plants such as mesquite and lotebush, and some tasajillo and pricklypear.
DISTRIBUTION AND EXTENT: Mainly in the western parts of the Rolling Red Plains of Texas and western Oklahoma. Land Resource Region - H; MLRAs - 78B and 78C (Central Rolling Red Plains). The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Harmon County, Oklahoma; 1941.
REMARKS: Stamford series was formerly classified in the Grumusol great soil group. The Stamford soils correlated in the Aridic Ustic moisture regime area over the Triassic Redbeds is moderately deep and has more sodium.
Edited 11/2015 (RFG-CJV): Changed to tabular format. Added metric measurements. Updated competing series, geographic setting, and associated soils sections.
Diagnostic horizons and features recognized in this pedon are:
Particle-size control section: 25 to 89 cm (10 to 35 in). (AC horizon)
Ochric Epipedon: 0 to 23 cm (0 to 9 in). (A horizon)
Cambic horizon: 23 to 89 cm (9 to 35 in). (Bkss horizon)
Slickensides: 23 to 89 cm (9 to 35 in). (Bkss horizon)
Secondary carbonates: 23 to 89 cm (9 to 35 in). (Bkss horizon)
Densic contact: 89 to 152 cm (35 to 60 in). (Cd horizon)
Densic materials: 89 to 152 cm (35 to 60 in). (Cd horizon)
ADDITIONAL DATA: KSSL data from type location 81TX169002 and S05TX-415-001
Taxonomic Version: Keys to Soil Taxonomy, Twelfth Edition, 2014
National Cooperative Soil Survey
U.S.A.