LOCATION PRADE                   TX

Established Series
WJG-MLG-RM
01/2018

PRADE SERIES

The Prade series consists of very shallow and shallow, well drained, moderately slowly permeable soils that formed in clayey residuum over marl and soft limestone bedrock. These soils are on gently sloping undulating plains on dissected plateaus. Slopes range from 1 to 8 percent. Mean annual precipitation is about 787 mm (31 in), and mean annual air temperature is about 17.8 degrees C (64 degrees F).

TAXONOMIC CLASS: Clayey-skeletal, smectitic, thermic, shallow Petrocalcic Calciustolls

TYPICAL PEDON: Prade very cobbly clay--rangeland. (Colors are for dry soil unless otherwise stated.)

A-- 0 to 30 cm (0 to 12 in); very dark gray (10YR 3/1) very cobbly clay, black (10YR 2/1) moist; moderate medium subangular blocky and weak very fine and fine granular structure; many very fine and fine roots and common medium roots throughout; many fine interstitial and tubular pores; roots are matted on the upper surface of the Bkm horizon; 15 percent subrounded limestone gravel, 30 percent subrounded limestone cobbles, and 10 percent subrounded conglomerate-calcareous gravel; limestone rock fragments are cleanly etched; conglomerate-calcareous fragments are from degrading Bkm horizon; very slightly effervescent throughout; neutral; abrupt smooth boundary. (Thickness is 10 to 50 cm [4 to 20 in]).

Bkkm--30 to 38 cm (12 to 15 in); very pale brown (10YR 8/3) indurated caliche, very pale brown (10YR 7/3) moist; massive; indurated laminar cap is 15 to 25 mm thick; violently effervescent throughout; moderately alkaline; abrupt smooth boundary. (Thickness is 8 to 18 cm [3 to 7 in]).

Cr--38 to 157 cm (15 to 62 in); very pale brown (10YR 8/2) moderately cemented marl bedrock, very pale brown (10YR 8/2) moist; massive; no fractures or roots in marl bedrock; moderately alkaline; violently effervescent throughout.

TYPE LOCATION: Real County, Texas; from the intersection of of Farm Road 336 and Farm Road 3525, about 2.9 miles south southwest on Farm Road 3525, and about 185 ft east in rangeland.

USGS topographic quadrangle: Bee Cave Hollow quadrangle;
Latitude- 29 degrees, 56 minutes, 3.0 seconds N,
Longitude- 99 degrees, 50 minutes, 43.1 seconds W;
Datum: WGS84.

RANGE OF CHARACTERISTICS:
Depth to the petrocalcic horizon: 10 to 50 cm (4 to 20 in)
Depth to paralithic contact: 18 to 53 cm (7 to 21 in)
Thickness of the mollic epipedon: 10 to 50 cm (4 to 20 in)

Particle-size control section (weighted average)
Clay content: 35 to 60 percent
Rock fragments: 35 to 75 percent

A horizon:
Hue: 7.5YR or 10YR
Value: 2 to 4
Chroma: 1 to 3
Texture: clay loam or clay or gravelly or cobbly to extremely gravelly or extremely cobbly phases
Clay content: 35 to 60 percent
Rock fragments: 4 to 75 percent by volume; 4 to 40 percent gravels, 0 to 31 percent cobbles, and 0 to 6 percent stones and boulders; petrocalcic and limestone fragments
Calcium carbonate equivalent: 0 to 30 percent
Electrical conductivity (decisiemens per meter): 0 to 2
Effervescence: very slight to strong
Reaction (pH): neutral or slightly alkaline (6.6 to 7.8)

Bw horizon (where present):
Hue: 7.5YR or 10YR
Value: 3 to 4, 2 to 3 moist
Chroma: 1 to 3
Texture: clay and very gravelly, very cobbly, extremely gravelly, or extemely cobbly phases
Clay content: 40 to 60 percent
Rock fragments: 35 to 75 percent by volume; 35 to 70 percent gravels, 0 to 45 percent cobbles, and 0 to 6 percent stones and boulders; petrocalcic and limestone fragments.
Calcium carbonate equivalent: 0 to 40 percent
Electrical conductivity (decisiemens per meter): 0 to 2
Effervescence: very slight to strong
Reaction (pH): neutral or slightly alkaline (7.0 to 7.8)

Bkkm horizon
Hue: 10YR or 2.5Y
Value: 7 or 8
Chroma: 2 to 4. The upper 3mm to 25 mm of the Bkkm is laminar and cementation ranges from strongly cemented to indurated.
Reaction (pH): slightly alkaline or moderately alkaline

Cr layer:
Weakly to moderately cemented weathered marl bedrock, chalk bedrock, or soft limestone bedrock that can be scraped or dug with a spade or backhoe. Some pedons are moderately cemented in the upper part and weakly cemented and massive below. Layers of limestone are mostly less than 20 cm (8 in) thick. Hard limestone layers are present below 102 cm (40 in) in some pedons.
Reaction (pH): slightly alkaline or moderately alkaline

COMPETING SERIES: There are no competing series in the same family. Series in similar families include the Eola, Kavett, Mailtrail, Mereta, Real, and Tarrant series.
Eola, Mailtrail, and Real soils: have loamy-skeletal particle size classes
Kavett and Mereta soils: have less than 35 percent coarse fragments in particle size control section
Tarrant soils: have lithic contact and no petrocalcic horizon

GEOGRAPHIC SETTING:
Parent material: clayey residuum over marl and soft limestone
Landscape: dissected plateaus
Landform: undulating plains
Slope: 1 to 8 percent
Mean annual precipitation: 559 to 864 mm (22 to 34 in)
Thornthwaite P-E Index: 31 to 44
Mean annual air temperature: 16.7 to 20.5 degrees C (62 to 69 degrees F)
Frost-free period: 220 to 250 days
Elevation: 563.9 to 731.5 m (1900 to 2,400 ft)

GEOGRAPHICALLY ASSOCIATED SOILS: These include the Dina, Eckrant, Tarrant, and Harper series.
Dina soils: have an argillic horizon directly over a lithic contact
Eckrant soils: have a lithic contact within 51 cm (20 in)
Harper soils: have less than 35 percent coarse fragments and have a lithic contact within 51 cm (20 in)
All of these soils are on similar positions in the landscape to Prade soils.

DRAINAGE AND PERMEABILITY:
Drainage class: Well.
Permeability class: moderately slow.
Runoff: medium on 1 to 5 percent slopes and high on 5 to 8 percent slopes.

USE AND VEGETATION: Used mainly as rangeland. Native plants now growing on these soils are evax, Texas wintergrass, hairy tridens, sideoats grama, red grama, cedar sedge, fall witchgrass, threeawn, Hall's panicum, little bluestem, twinleaf senna, dogweed, greenbriar, Linheimer's muhly, sacahuista, twistleaf yucca, smooth yucca, Scribner's panicum, Texas grama, common curlymesquite, croton, seep muhly, Canada wildrye, dutchman's britches, hairy grama, knotleaf stemflower, plains lovegrass, prairie coneflower, snoutbean, bundleflower, silver bluestem, and tasajillo. Native woody plants are agarito, blueberry cedar, pricklypear, vasey oak, Texas persimmon, Spanish oak, evergreen sumac, green condalia, hackberry, and scattered liveoak and mesquite mainly growing on bands of limestone outcrops.

DISTRIBUTION AND EXTENT: In Southwest Texas, mainly in the Edwards Plateau. The series is of moderate extent.

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

SERIES PROPOSED: Real County, Texas; 1995.

REMARKS: These soils were formerly included in the Tarrant and Eola series.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: 0 to 30 cm (0 to 12 in) (A horizon)
Petrocalcic horizon: 30 to 38 cm (12 to 15 in) (Bkkm horizon)
Paralithic contact: 38 cm (15 in)

Soil Interpretation Record: TX1311

ADDITIONAL DATA: None

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

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National Cooperative Soil Survey
U.S.A.