LOCATION CRAWFORD TX

Established Series
Rev. DLW
08/2012

CRAWFORD SERIES

The Crawford series consists of moderately deep, well drained, very slowly permeable soils that formed in clayey sediments that are underlain by indurated limestone bedrock. These soils are on broad nearly level or gently sloping uplands and slopes range from 0 to 5 percent. Mean annual air temperature is about degrees 18.9 degrees C (66 degrees F), and mean annual precipitation is about 864 mm (34 in).

TAXONOMIC CLASS: Fine, smectitic, thermic Leptic Udic Haplusterts

TYPICAL PEDON: Crawford silty clay--cropland. (Colors are for dry soil unless otherwise stated.)

Ap--0 to 13 centimeters (0 to 5 inches); brown (7.5YR 4/2) silty clay, dark brown (7.5YR 3/2) moist; weak very fine angular blocky structure; very hard, firm, few fine pebbles of quartz and few fragments of limestone; neutral; abrupt smooth boundary. [10 to 20 cm (4 to 8 in) thick]

A--13 to 30 centimeters (5 to 12 inches); brown (7.5YR 4/2) silty clay, dark brown (7.5YR 3/2) moist; moderate medium angular blocky structure parting to very fine blocky structure; extremely hard, very firm, very sticky, plastic; common pressure faces; few fine pebbles of quartz and fragments of limestone; neutral; gradual irregular boundary. [13 to 30 cm (5 to 12 in) thick]

Bss1--30 to 53 centimeters (12 to 21 inches); brown (7.5YR 4/2) silty clay, dark brown (7.5YR 3/2) moist; moderate medium angular blocky and weak very fine blocky structure; extremely hard, very firm, very sticky, plastic; few slickensides tilted 20 degrees to 40 degrees from horizontal; many pressure faces; few fine pebbles of quartz and fragments of limestone; neutral; gradual wavy boundary. [15 to 30 cm (6 to 12 in) thick]

Bss2--53 to 71 centimeters (21 to 28 inches); dark reddish brown (5YR 3/2) silty clay, dark reddish brown (5YR 3/2) moist; crushed peds are dark reddish brown (5YR 3/3) moist; strong medium blocky structure; extremely hard, very firm, very sticky, plastic; common slickensides about 4 cm (1-1/2 in) across the long axis; many pressure faces; few pebbles of quartz and limestone; neutral; abrupt irregular boundary. [13 to 38 cm (5 to 15 in) thick]

R--71 to 97 centimeters (28 to 38 inches); indurated fractured limestone; fractures are about 25 to 51 cm (10 to 20 in) apart; dark reddish brown clay in the fine crevices.

TYPE LOCATION: Coryell County, Texas; from the intersection of Texas Highway 36 and Farm Road 107 in Fort Gates, 17.1 miles east on Farm Road 107, 2.2 miles north on county road, and 200 feet east in cropland, on Bluebonnet Experiment Station.

RANGE IN CHARACTERISTICS:
Soil Moisture: An ustic moisture regime bordering on udic(udic-ustic).

Depth to lithic contact: 51 to 102 cm (20 to 40 in)
Depth to slickensides: 20 to 46 cm (8 to 18 in)
Cracks: When dry, 0.5 to more than 5 cm (1/2 to 2 inches) wide that extend from the surface to a depth of more than 12 inches and remain open from 90 to 150 cumulative days in most years.
Effervescence: mainly noneffervescent, but microknolls are effervescent throughout in some pedons

Particle-size control section (weighted average)
Clay content: 40 to 60 percent
Rock fragments: 0 to 10 percent, some pedons have a thin layer in the lower part containing 18 to 35 percent limestone fragments.
CEC/clay ratio: greater than 0.6

A and Ap Horizons
Hue: mainly 5YR to 7.5YR, but some pedons have 10YR in the upper part
Value: 2 to 4
Chroma: mainly 2 to 3, but some microdepressions are less than 2 near the center
Texture: clay, silty clay
Clay content: 40 to 60 percent
Rock fragments: 0 to 10 percent, by volume, strongly cemented to indurated limestone or siliceous gravel and/or cobbles
Effervescence: mainly noneffervescent, but some microknolls are slightly effervescent
Reaction: slightly acid to slightly alkaline (pH 6.1-7.8)

Bss1 Horizon
Hue: 5YR to 7.5YR
Value: 2 to 5
Chroma: mainly 2 to 4, but some microdepressions are less than 2 near the center
Texture: clay, silty clay
Clay content: 40 to 60 percent
Rock fragments: 0 to 10 percent, by volume, strongly cemented to indurated limestone or siliceous gravel and/or cobbles
Effervescence: mainly noneffervescent, but some microknolls are slightly effervescent
Reaction: slightly acid to moderately alkaline (pH 6.1-8.4)

Bss2 Horizon
Hue: 5YR to 7.5YR
Value: 2 to 5
Chroma: mainly 2 to 4, but some microdepressions are less than 2 near the center
Texture: clay, silty clay
Clay content: 40 to 60 percent
Rock fragments: 0 to 35 percent, by volume, strongly cemented to indurated limestone or siliceous gravel and/or cobbles
Effervescence: mainly noneffervescent but ranges to strongly effervescent
Reaction: neutral to moderately alkaline (pH 6.6-8.4)

R Horizon
Indurated limestone bedrock that is coarsely fractured. It is continuous or is interbedded with marl or shaly clay at vertical intervals of 15 to 46 cm (6 to 18 in). In most pedons the bedrock cannot be excavated with conventional digging equipment such as a backhoe machine.

COMPETING SERIES: These include the Dalco, Greenvine and San Saba series in the same family and the similar Anhalt and Vertel series.
Dalco and Greenvine soils: These soils have a paralithic contact at a depth of 51 to 102 cm (20-40 in).
San Saba soils: These soils have hue of 10YR to 5Y.
Anhalt and Vertel soils: These soils are in a very-fine particle size class.

GEOGRAPHIC SETTING:
Parent material: clayey residuum and/or slope alluvium underlain by limestone at depths of 51 to 102 cm (20-40 in). It occurs mainly on the Main Street Limestone and Georgetown Formation of the Lower Cretaceous system.
Landscape: Hills
Landform: Summits and shoulders of ridges
Slope: 0 to 5 percent, but mainly less than 2 percent
Mean annual air temperature: 17.8 to 19.4 degrees C (64 to 67 degrees F)
Mean annual precipitation: 762 to 889 mm (30 to 35 in)
Precipitation Pattern: The soil is intermittently moist in some part from September to June; driest in July and August.
Frost-free period: 220 to 250 days
Elevation: 122.0 to 365.8 m (400 to 1200 feet)
Thornthwaite annual P-E indices range from 44 to 56

GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing San Saba series, and the Denton, Purves, and Slidell series.
Denton soils: These soils occur on slightly lower positions and do not have intersecting slickensides.
Purves soils: These soils occur on slightly higher positions and have lithic bedrock within 51 cm (20 in).
San Saba soils: These soils occur on slightly higher positions and have hue of 10YR to 5Y.
Slidell soils: These soils occur in lower drainageways and are more than 203 cm (80 in) to bedrock.

DRAINAGE AND PERMEABILITY: This soil is well drained. Permeability is very slow. Runoff is high on slopes less than 1 percent and very high on 1 to 5 percent slopes.

USE AND VEGETATION: Used for cropland, pasture, and range. Crops grown are small grains, grain sorghums, and cotton. Native vegetation is little bluestem, sideoats grama, blue grama, and buffalograss. Trees are live oak, Spanish oak, post oak, juniper, and elm.

DISTRIBUTION AND EXTENT: The Grand Prairie of central Texas; LRR J; MLRA 85. The series is moderately extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas

SERIES ESTABLISHED: McLennan County (Waco area), Texas; 1905.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Mollic epipedon - 0 to 71 cm (0 to 28 inches).

Deep, wide cracks that remain open 90 to 150 cumulative days in most years.

Vertic features: Slickensides at depth of 30 to 71 cm (12 to 28 inches)

Lithic contact - occurs at 71 centimeters (28 inches).

Taxonomic version: Keys to Soil Taxonomy, Eleventh Edition, 2010

ADDITIONAL DATA: TAES data - SSIR 30 - Texas page 293.

National Cooperative Soil Survey
U.S.A.