LOCATION PRATLEY TX
Established Series
Rev. JWS-ALN-CLG-WJG
10/2016
PRATLEY SERIES
The Pratley series consists of soils that are moderately deep over a petrocalcic horizon. They are well drained, moderately slowly permeable soils formed in pedisediment over residuum from limestone bedrock. These soils occur on nearly level to gently sloping footslopes of ridges on dissected plateaus. Slope ranges from 0 to 5 percent. Mean annual precipitation is about 762 mm (30 in), and mean annual air temperature is about 19.4 degrees C (67 degrees F).
TAXONOMIC CLASS: Fine, smectitic, thermic Petrocalcic Calciustolls
TYPICAL PEDON: Pratley clay loam - rangeland.
(Colors are for dry soil unless otherwise stated.)
A--0 to 20 cm (0 to 8 in), very dark grayish brown (10YR 3/2) clay loam, very dark brown (10YR 2/2) moist; moderate fine subangular blocky and granular structure; very hard, firm; many fine roots; few fine and medium pores; few fine fragments of limestone; very slightly effervescent; moderately alkaline; clear smooth boundary. Thickness is 18 to 38 cm (7 to 15 in).
Bw1--20 to 61 cm (8 to 24 in), reddish brown (5YR 4/3) clay, dark reddish brown (5YR 3/3) moist; moderate medium subangular blocky structure parting to moderate very fine angular blocky; very hard, very firm; many fine roots; few fine and medium pores; few distinct discontinuous stress surfaces on vertical and horizontal faces of peds; few fine fragments of limestone and caliche; slightly effervescent; moderately alkaline; gradual smooth boundary. Thickness is 18 to 41 cm (7 to 16 in)
Bw2--61 to 89 cm (24 to 35 in), reddish brown (5YR 5/4) clay, reddish brown (5YR 4/4) moist; moderate medium subangular blocky structure parting to moderate very fine angular blocky; very hard, very firm; few fine roots; few distinct discontinuous stress surfaces on vertical and horizontal faces of peds; few fine fragments of limestone and caliche; violently effervescent; moderately alkaline; abrupt wavy boundary. Combined thickness of the Bw horizons is 18 to 76 cm (7 to 30 in).
Bk--89 to 99 cm (35 to 39 in), reddish brown (5YR 5/4) extremely flaggy clay, reddish brown (5YR 4/4) moist; moderate medium subangular blocky structure parting to moderate very fine angular blocky; about 85 percent by volume caliche rock fragments that lay in a horizontal position and are mainly 80 to 250 mm (3 to 10 in) across and 6 to 25 mm (1/4 to 1 in) thick; violently effervescent; moderately alkaline; abrupt wavy boundary. Thickness is 0 to 28 cm (0 to 11 in).
Bkm--99 to 102 cm (39 to 40 in), indurated caliche that is pitted on the surface and laminar in the upper part; abrupt wavy boundary. Thickness is 1 to 15 cm (1 to 6 in).
Cr--102 to 137 cm (40 to 54 in), very pale brown (10YR 8/2) and very pale brown (10YR 7/3) interbedded weakly cemented limestone, chalk, and marl.
TYPE LOCATION: Uvalde County, Texas; From the intersection of Farm Roads 187 and 1050 in Utopia; 2.45 miles west on Farm Road 1050; then 120 feet north of right of way in rangeland.
USGS topographic quadrangle: Utopia, Texas;
Latitude: 29 degrees, 35 minutes, 58.44 seconds N;
Longitude: 99 degrees, 33 minutes, 47.32 seconds W;
Datum: WGS84.
UTM Easting 445468.84 m, UTM Northing 3274547.88 m, UTM Zone 14
RANGE IN CHARACTERISTICS:
Soil Moisture: Typic Ustic soil moisture regime.
Depth to petrocalcic horizon: 56 to 102 cm (22 to 40 in)
Depth to paralithic contact: 57 to 117 cm (23 to 46 in)
Thickness of the mollic epipedon: 36 to 79 cm (14 to 31 in)
The soil cracks when dry, but the coefficient of linear extensibility is less than .07 in the Bw horizon.
Particle-size control section (weighted average)
Clay content: 40 to 60 percent
Rock fragments: 0 to 35 percent
A Horizon
Hue: 7.5YR or 10YR
Value: 3 or 4
Chroma: 2 or 3
Texture: clay loam, clay, or silty clay
Clay content: 35 to 45 percent
Rock fragments: 0 to 5 percent; gravels; limestone
Calcium carbonate equivalent: 0 to 15 percent
Electrical conductivity (mmhos/cm): 0 to 2
Effervescence: very slight to slight
Reaction (pH): slightly alkaline to moderately alkaline (7.4 to 8.4)
Bw Horizon
Hue: 5YR or 7.5YR
Value: 4 or 5
Chroma: 3 or 4
Texture: clay
Clay content: 45 to 60 percent
Rock fragments: 0 to 15 percent; gravels; limestone
Calcium carbonate equivalent: 3 to 25 percent
Electrical conductivity (mmhos/cm): 0 to 2
Effervescence: slight to violent
Reaction (pH): slightly alkaline to moderately alkaline (7.4 to 8.4)
Bk Horizon (where present)
Hue: 5YR or 7.5YR
Value: 4 or 5
Chroma: 3 or 4
Texture: clay or silty clay and extremely channery or flaggy counterparts
Clay content: 40 to 60 percent
Rock fragments: 60 to 90 percent; channers or flagstones; limestone
Calcium carbonate equivalent: 3 to 25 percent
Electrical conductivity (mmhos/cm): 0 to 2
Effervescence: strong to violent
Reaction (pH): slightly alkaline to moderately alkaline (7.4 to 8.4)
Bkm Horizon
indurated petrocalcic horizon, usually occurs as a thin laminar cap
Cr Horizon
ranges from weakly consolidated limestone, to interbedded chalk, marl, and indurated limestone
COMPETING SERIES: This is the
Valera series in the same family. Similar soils include the
Cho,
Kavett,
Mailtrail,
Mereta,
Prade series.
Valera soils: have a lithic contact below the petrocalcic horizon
Cho soils: have a loamy particle-size control section and are shallow to a petrocalcic horizon
Kavett soils: are shallow to a lithic contact
Mailtrail soils: have a loamy-skeletal particle-size control section and are shallow to a petrocalcic horizon
Mereta soils: are shallow to petrocalcic horizon
Prade soils: have a clayey-skeletal particle-size control section
GEOGRAPHIC SETTING:
Parent material: clayey pedisediment/slope alluvium over residuum derived from interbedded marl, chalk, and limestone bedrock of the Glen Rose Formation
Landscape: dissected plateaus
Landform: ridges
Slope: 0 to 5 percent, but are dominantly less than 3 percent
Mean annual precipitation: 635 to 889 mm (25 to 35 in)
Thornthwaite P-E Index: 32 to 44
Mean annual air temperature: 18.3 to 21.1 degrees C (65 to 70 degrees F)
Frost-free period: 220 to 260 days
Elevation: 243.8 to 624.8 m (800 to 2050 ft)
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing
Kavett series, and the
Dev,
Oakalla,
Orif,
Kerrville,
Real, and
Topia series.
Dev and
Orif soils: have a skeletal particle-size control section and occur on floodplains
Oakalla soils: have a fine-loamy particle-size control with a mollic epipedon at least 50 cm thick and occur on floodplains
Kerrville and
Real soils: have a loamy-skeletal particle-size control section and occur higher in the landscape with no petrocalcic horizon
Topia soils: has an argillic horizon and occurs on similar footslope positions
DRAINAGE AND PERMEABILITY: Well drained; low to medium runoff; moderately slow permeability.
USE AND VEGETATION: Mostly in native rangeland. Some small areas are cultivated to small grain and grain sorghums. Native vegetation is mainly red grama, threeawn, Halls panicum, fall witchgrass, Texas wintergrass, and sideoats grama. Woody plants include live oak, mesquite, Texas persimmon, agarita, and pricklypear cactus.
DISTRIBUTION AND EXTENT: Eastern Edwards Plateau of Texas. The series is of large extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Uvalde County, Texas; 1970. The name is coined word from the name of the small community of Tarpley in Bandera County, Texas.
REMARKS: These soils have previously been included in the Valera series.
Edited 10/2016 (RFG-THW): 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 99 in. (Bw and Bk horizons)
Mollic epipedon - 0 to 61 cm (0 to 24 in) (A and Bw1 horizon)
Cambic horizon - 61 to 89 cm (24 to 35 in) (Bw2 horizon)
Petrocalcic horizon - 99 to 102 cm (39 to 40 in) (Bkm horizon)
Paralithic contact - The contact with weakly cemented limestone at 102 cm (40 in) (Cr horizon)
Taxonomic Version: Keys to Soil Taxonomy, Twelfth Edition, 2014
National Cooperative Soil Survey
U.S.A.