LOCATION AUSTIN                  TX

Established Series
Rev. CLN-RM-JAW
08/2017

AUSTIN SERIES

The Austin series consists of moderately deep, well drained, moderately slowly permeable soils that formed in residuum weathered from chalk. These soils are on nearly level to sloping erosional uplands. Slopes range from 0 to 8 percent. Mean annual precipitation is about 915 mm (36 in) and the mean air temperature is about 19 degrees C (66 degrees F).

TAXONOMIC CLASS: Fine-silty, carbonatic, thermic Udorthentic Haplustolls

TYPICAL PEDON: Austin silty clay-cropland at an elevation of 174 m (571 ft). (Colors are for dry soil unless otherwise stated.)

Ap--0 to 15 cm (0 to 6 in); dark grayish brown (10YR 4/2) silty clay, very dark grayish brown (10YR 3/2) moist; weak fine granular and subangular blocky structure; hard, firm but crumbly, sticky, plastic; many fine roots; many fine and very fine pores; many wormcasts; few fine calcium carbonate concretions; calcareous, moderately alkaline; clear smooth boundary. (10 to 20 cm [4 to 8 in] thick)

A--15 to 41 cm (6 to 16 in); brown (10YR 4/3) silty clay, dark brown (10YR 3/3) moist; moderate very fine subangular blocky and granular structure; hard, firm but crumbly, sticky, plastic; many fine roots; many fine and very fine pores; many wormcasts; common fine calcium carbonate concretions; calcareous, moderately alkaline; gradual smooth boundary. (10 to 30 cm [4 to 12 in] thick)

Bw--41 to 56 cm (16 to 22 in); brown (10YR 5/3) silty clay, brown (10YR 4/3) moist; moderate fine subangular blocky structure; hard, firm, crumbly, sticky, plastic; few fine roots; many fine pores; many light yellowish brown (2.5Y 6/4) wormcasts; common fine calcium carbonate concretions; few fine fragments of chalk; calcareous, moderately alkaline; clear smooth boundary. (25 to 51 cm [10 to 20 in] thick)

Bk--56 to 74 cm (22 to 29 in); brown (10YR 5/3) silty clay, brown (10YR 4/3) moist; moderate fine subangular blocky structure; hard, firm, sticky, plastic; few fine roots; common wormcasts; about 30 percent platy fragments of chalk less than 8 cm (3 in) in the axis; calcareous, moderately alkaline; clear irregular boundary. (0 to 25 cm [0 to 10 in] thick)

Cr--74 to 144 cm (29 to 57 in); very pale brown (10YR 8/2) and very pale brown (10YR 8/4) platy chalk that is less hard than 3, Mohs scale; few thin tongues of brown silty clay in crevices between chalk plates, moderately alkaline.

TYPE LOCATION: McLennan County, Texas; 0.4 mile northeast of the intersection of Robinson Road and Interstate 35, which is 2 miles northeast of Lorena, 150 ft southeast of Robinson Road and 200 ft south of a metal barn;
USGS topographic quadrangle: Lorena, TX;
Latitude: 31 degress, 25 minutes, 2.09 seconds North;
Longitude: 97 degrees, 11 minutes, 32.71 seconds West
Datum: WGS84.

RANGE IN CHARACTERISTICS:
Solum depth: ranges from 51 to 102 cm (20 to 40 in) thick.
Soil Moisture: An ustic soil moisture regime. The soil moisture control section is dry in some or all parts for 90 or more cumulative days per year in normal years.
Mean annual soil temperature: 17 to 21 degrees C (63 to 70 degrees F)
Depth to paralithic contact: 74 to 76 cm (29 to 30 in)
Depth to cambic horizon (where present): 14 to 56 cm (6 to 22 in)
Thickness of mollic epipedon: 9 to 49 cm (4 to 19 in)

Particle-size control section (weighted average)
Clay content: 35 to 55 percent
Silicate clay content: 20 to 35 percent
Calcium carbonate equivalent: 40 to 70 percent
Rock fragments: amont-0 to 5 percent; kind-chalk; size-fine or medium

A or Ap horizon:
Hue: 7.5YR, 10YR, 2.5Y or 5Y, moist
Value: 3.5 or less moist
Chroma: 3 or less.
Texture: silty clay, silty clay loam
It is 20 to 51 cm (8 to 20 in) thick.

Bw or Bk horizon:
Hue: 7.5YR, 10YR or 2.5Y
Value: 3 to 7
Chroma: 2 to 6
Texture: silty clay, silty clay loam, clay

The substrata are platy chalk, interbedded chalk and marl, or soft limestone bedrock.

COMPETING SERIES: These are the Lott series in the same family and the Altoga, Bolar, Brackett, Denton, Krum, Lewisville, Nuvalde, Patrick, Somervell, Stephen, and Valera series.
Lott soils: have sola more than 102 cm (40 in) deep and are underlain by marl.
Altoga and Brackett soils lack mollic epipedons, and Brackett soils have sola less than 51 cm (20 in) thick.
Bolar soils: have more than 15 percent coarser than very fine sand in the control section.
Denton and Krum soils: have cracks 0.4-in wide at depths of 51 cm (20 in) when dry.
Lewisville soils: have less than 40 percent calcium carbonate within depths of 102 cm (40 in) and are not underlain by chalk. Nuvalde soils: have more than 35 percent noncarbonate clay in the control section.
Patrick soils: are sandy in the lower part of the control section.
Somervell soils: contain more than 35 percent coarse fragments.
Stephen soils: lack B horizons and are less than 51 cm (20 in) thick.
Valera soils: have petrocalcic horizons.

GEOGRAPHIC SETTING:
Parent material: residuum weathered from chalk and is mostly of the Austin Formation
Landscape: dissected plains
Landform: ridge
Slope: 0 to 8 percent but mainly less than 5 percent
Mean annual precipitation: 584 to 1143 (23 to 45 in)
Mean annual air temperature: 17 to 21 degrees C (63 to 70 degrees F)
Frost-free period: 220-293 days
Elevation: 127 to 319 m (417 to 1047 ft)
Thornthwaite P-E Index: 44 to 66

GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Stephen series and the Eddy, Dalco, Fairlie, Houston Black, Howe, and Whitewright series.
Eddy and Whitewright soils: have sola less than 51 cm (20 in) deep and in addition, they have ochric epipedons; in addition, Whitewright soils occupy adjacent sideslopes.
Dalco, Fairlie and Houston Black soils: have intersecting slickensides and occupy lower positions in the landscape.
Howe soils: have ochric epipedons and occupy adjacent sideslopes
Eddy and Stephen soils: occupy similar positions. .

DRAINAGE AND PERMEABILITY:
Drainage class: Well;
Permeability class: Moderately slow
Runoff: low on slopes less than 1 percent; medium on slopes of 1 to less than 5 percent, and high on slopes of 5 to 8 percent.

USE AND VEGETATION: Mainly cultivated. Principal crops are small grains, cotton, and grain sorghums. Some areas are used for native range. Original vegetation was mid and tall grasses such as little bluestem, indiangrass, and sideoats grama. Grasses now are mainly gramas and buffalograss.

DISTRIBUTION AND EXTENT: The Blackland Prairies of Texas MLRA 86A. The series is extensive.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Temple, Texas

SERIES ESTABLISHED: Travis County, Texas; 1904.

REMARKS: Classification was changed 11/89 from fine-silty, carbonatic, thermic Entic Haplustolls to fine-silty, carbonatic, thermic Udorthentic Haplustolls.

Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: 0 to 41 cm (0 to 16 in), (Ap and A horizons).
Cambic horizon: 41 to 74 cm (16 to 29 in), (Bw1 and Bw2 horizons).
Paralithic contact of platy chalk at a depth of 74 cm (29 in).

ADDITIONAL DATA: KSSL data from Bell County, Texas (S78TX027006)

Taxonomic Version: Keys to Soil Taxonomy, Twelfth Edition, 2014.

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National Cooperative Soil Survey
U.S.A.