LOCATION HILLCO TXEstablished Series
TAXONOMIC CLASS: Fine-loamy, carbonatic, thermic Entic
Haplustolls
TYPICAL PEDON: Hillco clay loam--cropland.
(Colors are for dry soil unless otherwise stated.)
Ap--O to 4 inches; dark brown (7.5YR 4/2) clay loam, dark
brown (7.5YR 3/2) moist; moderate medium subangular blocky and
fine granular structure; very hard, firm, slightly plastic; many
fine roots; few fine calcium carbonate concretions; few siliceous pebbles; calcareous; moderately alkaline; clear smooth boundary.
(3 to 6 inches thick)
A1--4 to 11 inches; dark brown (7.5YR 4/2) clay loam, dark
brown (7.5YR 3/2) moist; moderate medium blocky structure; very
hard, firm, slightly plastic; few fine roots; few fine calcium carbonate concretions; few siliceous pebbles; calcareous,
moderately alkaline; gradual smooth boundary. (5 to 8 inches
thick)
B21ca--11 to 16 inches; reddish brown (5YR 4/4) clay loam,
dark reddish brown (5YR 3/4) moist; moderate medium subangular
blocky structure; very hard, firm, plastic; few fine roots; few
fine calcium carbonate concretions; few siliceous pebbles; calcareous, moderately alkaline; gradual smooth boundary. (4 to 9 inches thick)
B22ca--16 to 25 inches; reddish yellow (5YR 6/6) clay loam, yellowish red (5YR 5/6) moist; strong fine granular structure;
hard, friable, slightly plastic; few fine roots; few fine calcium carbonate and black concretions; few siliceous pebbles;
calcareous, moderately alkaline, gradual smooth boundary. (7 to
11 inches thick)
B23ca--25 to 34 inches; reddish yellow (5YR 6/8) gravelly
clay loam, yellowish red (5YR 5/8) moist with many medium distinct mottles of pinkish white (5YR 8/2), pinkish gray (5YR 7/2) moist; moderate fine granular structure; hard, friable, very sticky; few limestone pebbles and about 30 percent cemented calcium carbonate concretions ranging up to about 2 cm; few pebbles; calcareous, moderately alkaline; gradual smooth boundary. (8 to 12 inches
thick)
B3ca&R--34 to 38 inches; light brown (7.5YR 6/4) gravelly
clay loam, brown (7.5YR 5/4) moist; many medium distinct yellow
(10YR 7/8) mottles; strong fine granular structure; hard, friable, sticky; hard white fragments of limestone 2 to 4 inches thick; few medium soft bodies of calcium carbonate; many medium calcium carbonate concretions; calcareous, moderately alkaline; clear wavy boundary. (3 to 10 inches thick)
R--38 to 50 inches; white limestone that becomes massive and nearly continuous with increase in depth; hardness of about 3 on
Mohs scale.
TYPE LOCATION: Hill County, Texas; about 16 miles northwest of Hillsboro. North from Whitney on Farm Road 933 for 13.5 miles,
west on field road for 0.5 mile, site is on south side of road
about 50 feet out in field.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 20 to 40 inches. The soil is moderately alkaline and, except for the A horizon in some pedons, is calcareous. The calcium carbonate equivalent ranges from 35 to about 50 percent in the control
section.
The A horizon is dark reddish gray (5YR 4/2), reddish brown (5YR 4/3), dark brown (7.5YR 4/2), dark grayish brown (10YR 4/2), very dark grayish brown (10YR 3/2), or dark brown (10/YR 4/3, 3/3). It ranges from clay loam to silty clay loam and contains common fragments and pebbles of limestone.
The B21ca and B22ca horizons are reddish brown (5YR 5/3, 5/4,
4/4), reddish gray (5YR 5/2), reddish yellow (5YR 6/6), yellowish
red (5YR 5/6, 5/8), brown (7.5YR 5/2, 5/4), dark brown (7.5YR
4/4), reddish yellow (7.5YR 6/6), or dark yellowish brown (10YR
4/4). They are clay loam or silty clay loam and contain common fragments and pebbles of limestone. The silicate clay content
ranges from 24 to 35 percent.
The B23ca and B3ca horizons are pinkish white (5YR 8/2), reddish yellow (5YR 7/8, 6/8), brown (7.5YR 5/4), reddish yellow (7.5YR
6/6, 6/8), very pale brown (10YR 8/3, 7/4), pale brown (10YR 6/3,
or light yellowish brown (10YR 6/4). They are gravelly loam, gravelly clay loam, or gravelly silty clay loam. Bodies of soft
lime are common in the B3ca. The B3ca contains 15 to 35 percent fragments of limestone 2 mm to 2 inches in diameter.
A Cca horizon is present in some pedons above the lithic contact. Where present, it also contains about 15 to 35 percent fragments
of limestone 2 mm to 2 inches in diameter.
The R layer is platy to massive limestone that is fractured in the upper part and massive below. The upper 2 to 3 feet is rippable.
COMPETING SERIES: These are the
Aledo,
Altoga,
Asher,
Austin,
Bolar,
Chatt,
Denton,
Ector,
Engle,
Lewisville,
Lott,
Lueders,
Quanah, and
Venus series. Aledo, Ector, and Lueders soils have
sola less than 20 inches thick and contain more than 35 percent coarse fragments in the control section. Altoga soils have ochric epipedons. Asher, Engle, Lewisville, Quanah, and Venus soils have mixed mineralogy and lack lithic materials within 40 inches.
Austin soils have a paralithic contact to soft chalk. Bolar soils have a calcic horizon, a paralithic contact, and generally have
hues yellower than 7.5YR. Chatt soils lack a lithic contact and
have sola 40 to 60 inches thick. Denton soils have vertic
properties and have a fine textured control section. Lott soils
lack a lithic or paralithic contact.
GEOGRAPHIC SETTING: Hillco soils are on gently sloping uplands. Slope gradients range from 1 to about 3 percent. The soil formed
in calcareous loamy and clayey material over hard limestone along
the eastern edge of the Grand Prairie land resource area. Climate
is moist subhumid. Mean annual rainfall ranges from 28 to 35
inches. Mean annual temperature ranges from 64 degrees to 69
degrees F. Thornthwaite P-E indices range from 48 to 62.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Aledo and Bolar
soils of the competing series and the
Hensley and
Lindy series. Hensley and Lindy soils have argillic horizons and Hensley soils
have sola less than 20 inches thick. Lindy soils have fine
textured control sections
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderate permeability.
USE AND VEGETATION: Mostly cropped to small grain, grain sorghum, hay sorghums, and cotton. Native vegetation is mainly big
bluestem, little bluestem, indiangrass, and sideoats grama.
DISTRIBUTION AND EXTENT: Central Texas, along the eastern edge of the Grand Prairie land resource area. These soils are of minor extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Hill County, Texas; 1975.
REMARKS: These soils were formerly classified in the Rendzina
great soil group and included in the Denton series.
ADDITIONAL DATA: Texas Highway Department (Soils and Base
Material Test Report) Laboratory No. 73-48-R.