Established Series


The Depalt series consists of very deep, well drained, very slowly permeable soils that formed in calcareous clayey terrestrial sediments of Lower Cretaceous age. These soils occupy nearly level to gently sloping uplands. Slopes are dominantly 0 to 2 percent but range to 3 percent.

TAXONOMIC CLASS: Fine, smectitic, thermic Chromic Udic Haplusterts

TYPICAL PEDON: Depalt silty clay loam on a south facing slope of 1 percent, in rangeland in post oak and blackjack oak savannah, at about 1640 feet elevation. (The colors are for dry soil unless otherwise stated.) When described, the soil was moist below 6 inches.

A--0 to 6 inches; very dark gray (10YR 3/1) silty clay loam, black (10YR 2/1) moist; strong medium angular blocky structure; extremely hard, extremely firm, very plastic; common fine roots; common fine pores; few pebbles of angular chert; neutral; gradual wavy boundary. (4 to 11 inches thick)

Bss1--6 to 26 inches; reddish brown (5YR 4/3) clay, dark reddish brown (5YR 3/3) moist; coarse strong blocky structure; extremely hard, extremely firm, very plastic; common fine roots; common fine pores; distinct slickensides; shiny ped surfaces; discontinuous vertical streaks of darker colored soil in closed cracks; few chert pebbles; neutral; gradual wavy boundary. (12 to 25 inches thick)

Bss2--26 to 30 inches; reddish brown (5YR 4/4) clay, dark reddish brown (5YR 3/4) moist; moderate medium angular blocky structure; extremely hard, extremely firm, very plastic; few fine roots; common fine pores; common distinct slickensides; shiny ped surfaces; ;few fine limestone pebbles; slightly alkaline; gradual wavy boundary. (0 to 10 inches thick)

Bk1--30 to 35 inches; reddish brown (5YR 5/4) clay, reddish brown (5YR 4/4) moist; moderate medium subangular blocky structure; hard, firm; few fine roots and pores; about 15 percent by volume calcium carbonate concretions; strong effervescence; moderately alkaline; gradual wavy boundary. (4 to 10 inches thick)

Bk2--35 to 63 inches; yellowish red (5YR 5/6) gravelly clay, yellowish red (5YR 4/6) moist; weak medium subangular blocky structure; hard, firm; estimated 35 percent by volume limestone pebbles; strong effervescence; moderately alkaline. (20 to 50 inches thick)

TYPE LOCATION: Kerr County, Texas; from the intersection of Texas Highways 16 and 173 in Kerrville; southeast 5.7 miles on Texas 173 to entrance to "The Woods" subdivision, then southwest 1.4 miles on improved road, then 50 feet south from center of road between a large blackjack and a large post oak tree in rangeland.

RANGE IN CHARACTERISTICS: Solum thickness ranges from 60 to 80 inches. The weighted average clay content of the particle-size control section ranges from 40 to 60 percent. When dry, cracks 1/2 to more than 1 inch wide extend from the surface to a depth of more than 12 inches. Cracks remain open from 90 to 150 cumulative days in most years. Slickensides and wedge-shaped peds begin at a depth of 6 to 24 inches. Gilgai microrelief is indistinct but slickensides are common below 6 inches. Coarse fragments chert and limestone pebbles range from few to 15 percent by volume in the upper Bss and 10 to 40 percent in the lower part of the Bk horizon.

The Bss and Bk horizon have colors mainly in shades of gray, brown, or red with hue of 2.5YR or 5YR, value of 4 to 6 , and chroma of 2 to 6. Clay content in the 10 to 40 inch control section is 40 to 60 percent. Texture of the B horizons is dominantly clay or silty clay. In some pedons below 24 inches, it is silty clay loam or clay loam or their gravelly counterparts. Some pedons contain horizons that are very gravelly and 2 to 6 inches thick. Fragments are mostly chert but include some limestone. Reaction is neutral through moderately alkaline.

Weakly consolidated to cemented and weathered or indurated limestone occurs in some pedons at depths below 60 inches.

COMPETING SERIES: These include the Deport, Frelsburg, Ferris, Latium, Medlin. Deport soils have developed over clayey sediments and are over 80 inches thick. Frelsburg, Ferris, Latium and Medlin soils have hue of 10YR or grayer throughout and are calcareous in the surface layers. Crawford series has sola less than 40 inches thick over limestone. Heiden, Luling, Ovan, and Sanger soils have dominant hue of 10YR or grayer throughout. Tamford soils occur over clayey Permian sediments and occur in areas where the mean temperature is less than 65 degrees F.

GEOGRAPHIC SETTING: Depalt soils are on smooth to gently undulating high stream terraces, probably of Pleistocene age.. Slope gradients range from 0 to 3 percent. The soil formed in clayey calcareous sediments. The climate is dry subhumid. Average annual precipitation ranges from 25 to 32 inches. Average annual temperature ranges from 63 to 70 degrees F. Frost free days range from 215 to 240, and elevation ranges from 1200 to 2200 feet. The Thornthwaite annual P-E index ranges from 42 to 48.

GEOGRAPHICALLY ASSOCIATED SOILS: Anhalt soils are moderately deep to limestone and contain over 60 percent clay. Barbarosa and Denton soils have color values less than 3.5. Denton soils also have carbonatic mineralogy. Tarpley and Roughcreek soils have sola less than 20 inches thick. Tarpley and Roughcreek soils occur at slightly higher elevations. Anhalt soils occur in similar positions.

DRAINAGE AND PERMEABILITY: Well drained; slow runoff; very slow permeability.

USE AND VEGETATION: Used for rangeland and cropland. Native vegetation consists of Texas wintergrass, sideoats grama, vine-mesquite, and little bluestem. Woody vegetation is post oak, blackjack oak, and greenbrier. Grain sorghum, wheat, oats, forage sorghum, and improved bermudagrass are the principal crops grown.

DISTRIBUTION AND EXTENT: South Central Texas in the southeastern part of the Edwards Plateau. The series is of moderate extent.


SERIES ESTABLISHED: Kerr County, Texas; 1983.

REMARKS: Depalt series was formerly included in the Topia series.

Diagnostic horizons and features recognized:

Ochric epipedons - 0 to 6 inches

Vertic features - Slickensides at a depth of 6 to 30 inches, High shrink-swell potential and cracks that are 0.5 to 2 inches wide when dry.

SIR Number. TX0910

National Cooperative Soil Survey