LOCATION ANGELO TX

Established Series
Rev. CCW-WJG-ACT
11/2013

ANGELO SERIES

The Angelo series consists of deep or very deep, well drained, moderately slowly permeable soils formed in calcareous loamy and clayey alluvium derived from limestone. These nearly level to very gently sloping soils occur on treads of terraces on dissected plateau. Slope ranges from 0 to 3 percent. Mean annual precipitation is about 610 mm (24 in), and the mean annual air temperature is about 18 degrees C (65 degrees F)..

TAXONOMIC CLASS: Fine-silty, mixed, superactive, thermic Aridic Calciustolls

TYPICAL PEDON: Angelo clay loam--cultivated.
(Colors are for dry soil unless otherwise stated.)

Ap--0 to 15 cm (0 to 6 in); dark grayish brown (10YR 4/2) clay loam, very dark grayish brown (10YR 3/2) moist; weak very fine granular and subangular blocky structure; hard, firm, sticky and plastic; common fine roots; violently effervescent; moderately alkaline; clear smooth boundary.

A--15 to 30 cm (6 to 12 in); dark grayish brown (10YR 4/2) clay loam, very dark grayish brown (10YR 3/2) moist; moderate very fine granular and moderate very fine and fine subangular blocky structure; hard, firm, sticky and plastic; few fine roots; violently effervescent; moderately alkaline; gradual wavy boundary. Combined thickness of the A horizon is 18 to 66 cm (7 to 26 in)

Bw--30 to 72 cm (12 to 28 in); reddish brown (5YR 5/3) clay, reddish brown (5YR 4/3) moist; moderate very fine and fine subangular blocky and weak fine angular blocky structure; very hard, firm, very sticky and plastic; few roots and pores; shiny peds when moist; few wormcasts, violently effervescent; moderately alkaline; gradual smooth boundary. Thickness is 20 to 76 cm (8 to 30 in)

Bk1--72 to 148 cm (28 to 58 in); pink (7.5YR 7/4) silty clay loam, reddish yellow (5YR 6/6) moist; moderate very fine and fine subangular blocky structure; hard, firm; few fine roots; contains 25 percent visible calcium carbonate mostly in soft masses; shiny peds when moist; violently effervescent; moderately alkaline; diffuse smooth boundary. Combined thickness of the Bk horizon is 102 to 142 cm (40 to 56 in)

Bk2--148 to 234 cm (58 to 92 in); reddish yellow (5YR 6/6) silty clay loam, yellowish red (5YR 5/6) moist; weak very fine to fine subangular blocky structure; hard, firm; less than 5 percent visible calcium carbonate; shiny peds when moist; violently effervescent; moderately alkaline.

TYPE LOCATION: Tom Green County, Texas; 14.9 miles northeast of the Tom Green County Courthouse in San Angelo along U.S. Highway 67 to its intersection with a county road; 0.25 mile north along the county road from the intersection and 150 feet west of the county road.
USGS topographic quadrangle: Miles, TX; Latitude: 31 degrees, 34 minutes, 40.5 seconds N; Longitude: 100 degrees, 14 minutes, 30.7 seconds W; Datum: WGS84.

RANGE IN CHARACTERISTICS:
Soil moisture: Aridic-ustic soil moisture regime
Depth to Bedrock: dominantly greater than 203 cm (80 in), but some pedons are underlain by indurated limestone below 102 cm (40 in).
Depth to Calcic horizon: 61 to 102 cm (24 to 40 in)
Thickness of Calcic horizon: dominantly 15 to 102 cm (6 to 40 in), but ranges to 152 cm (60 in)
Coefficient of linear extensibility: 0.07 to 0.10 above the calcic horizon and 0.02 to 0.07 in the calcic horizon and to a depth of 125 cm (50 in)
Reaction: moderately alkaline throughout

Particle-size control section (weighted average):
Total clay content: 35 to 50 percent
Silicate clay content: 28 to 35 percent
Carbonate clay content: 7 to 15 percent
Silicate clay mineralogy: dominately smectitic

A horizon
Hue: 7.5YR, 10YR
Value: 3 to 5, 2 to 4 moist
Chroma: 2 or 3, dry or moist
Texture: clay loam, silty clay loam, clay, silty clay
Total clay: 30 to 45 percent
Carbonate clay: 0.5 to 10 percent
Calcium carbonate equivalent: 5 to 15 percent
Electrical conductivity (mmhos/cm): 0 to 2
Effervescence: strong to violent

Bw horizon
Hue: 5YR, 7.5YR, 10YR
Value: 4 to 6, 3 to 5 moist
Chroma: 2 to 4, dry or moist
Texture: clay loam, silty clay loam, clay, silty clay
Total clay: 35 to 50 percent
Carbonate clay: 5 to 12 percent
Calcium carbonate equivalent: 15 to 25 percent
Visible calcium carbonate: some pedons may contain a small amount
Electrical conductivity (mmhos/cm): 0 to 2
Effervescence: violent

Bk horizon
Hue: 5YR, 7.5YR, 10YR
Value: 5 to 8, 4 to 7 moist
Chroma: 2 to 6, 2 to 5 moist
Texture: clay loam, silty clay loam, clay, silty clay
Total clay: 30 to 45 percent
Carbonate clay: 7 to 15 percent
Calcium carbonate equivalent: 15 to 60 percent
Visible calcium carbonate: 5 to 20 percent and some pedons have two distinct horizons of carbonate accumulation
Electrical conductivity (mmhos/cm): 0 to 2
Effervescence: violent

COMPETING SERIES: There are no series in the same family. Similar soils are the Knippa, Nuvalde, Texon, and Valera series.
Knippa and Texon soils: have a fine particle-size control section and COLE value of more than 0.09 leading to vertic features
Nuvalde soils: are moist in the moisture control section for longer periods of time
Valera soils: have a fine particle-size control section and are moderately deep to a petrocalcic horizon

GEOGRAPHIC SETTING:
Parent material: calcareous loamy and clayey alluvium derived from limestone
Landscape: dissected plateau
Landform: treads of terraces
Slopes: 0 to 3 percent, but dominantly less than 1 percent
Precipitation Pattern: The majority of the yearly rainfall occurs during the fall and spring months. The winter and summer months are normally drier.
Mean annual precipitation: 432 to 686 mm (17 to 27 in)
Thornthwaite PE indices: 23 to 36
Mean annual air temperature: 16.7 to 18.9 degrees C (62 to 66 degrees F)
Frost-free period: 210 to 240 days
Elevation: 472.4 to 853.4 m (1550 to 2800 ft)

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cho, Ector, Lipan, Mereta, Rioconcho and Tobosa series.
Cho and Mereta soils: are shallow to a petrocalcic horizon and typically occur on slightly higher positions
Ector soils: occur on higher limestone hills adjacent to the Angelo and are shallow to a lithic contact
Lipan and Tobosa soils: have a fine particle-size control section with slickensides and occur slightly lower in elevation in depressions
Rioconcho soils: have a fine particle-size control section with vertic features and occur on lower adjacent flood plains

DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderately slow. Runoff is low on 0 to 1 percent slopes and medium on 1 to 3 percent slopes.

USE AND VEGETATION: These soils are mainly planted to grain sorghum, cotton, wheat, and forage crops. Many areas are in rangeland. Present native grasses are sideoats grama, cane bluestem, buffalograss, curlymesquite, Texas wintergrass, and threeawns. Mesquite trees are abundant.

DISTRIBUTION AND EXTENT: Southwest Plateaus and Plains Range and Cotton Region, LLR-I: MLRA 81A-Edwards Plateau, Western Part and MLRA 81B-Edwards Plateau, Central Part. The series is extensive.

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

SERIES ESTABLISHED: Tom Green County, Texas; 1971.

REMARKS:
Edited 11/2013 (RFG-THW): Converted to tabular format and added metric measurements. Updated competing series, geographic setting, and associated soils sections.

Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 30 cm (0 to 12 in) (Ap and A horizons)
Cambic horizon - 30 to 72 cm (12 to 28 in) (Bw horizon)
Calcic horizon - 72 to 148 cm (28 to 58 in) (Bk1 horizon)
Shrink-swell features - high shrink-swell behavior above the calcic horizon.

ADDITIONAL DATA: Lab data available from NSSL is one pedon 3/82 from the type location in Tom Green County, Texas, Nos. 814669-814673, and one pedon 3/82 Irion County, Texas Nos. 814663-814668. Also, one pedon 9/65 from Tom Green County, Texas, by Texas Tech No. S65TX-226-1, which is now considered to be outside the range of characteristic for the Angelo series as reclassified 10/82. As a result of the 1982 NSSL data, the classification of the Angelo series is changed from fine, mixed, thermic Torrertic Calciustolls, to fine-silty, mixed, thermic Aridic Calciustolls for the correlation of the Irion County, Texas, soil survey. The NSSL data shows the silicate clay fraction to be dominated by smectite, causing the A and B horizons above the calcic horizon to have high shrink swell properties with COLE of more than 0.07.

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

National Cooperative Soil Survey
U.S.A.