LOCATION BLUM TXEstablished Series
TAXONOMIC CLASS: Fine, mixed, active, thermic Aquic Argiustolls
TYPICAL PEDON: Blum loam--cropland.
(Colors are for dry soil unless otherwise stated.)
Ap--0 to 5 inches; dark brown (10YR 4/3) loam, dark brown
(10YR 3/3) moist; moderate fine granular structure; hard, friable; common fine roots; common fine pores; few fine pebbles of quartz; medium acid; abrupt smooth boundary. (4 to 8 inches thick)
A11--5 to 14 inches; dark brown (10YR 4/3) loam, dark brown (10YR 3/3) moist; few fine faint mottles and streaks of yellowish brown; moderate medium subangular blocky structure; hard, firm;
few fine roots; few medium pores; few pebbles of quartz; neutral; gradual smooth boundary. (4 to 11 inches thick)
A12--14 to 19 inches; very dark grayish brown (10YR 3/2) loam, very dark brown (10YR 2/2) moist; few fine faint streaks and mottles of dark brown; moderate medium blocky structure; hard, firm; few fine roots; few pebbles of quartz; slightly acid; gradual wavy boundary. (4 to 10 inches thick)
B21t--19 to 36 inches; grayish brown (2.5Y 5/2) clay loam, dark grayish brown (2.5Y 4/2) moist; common medium faint mottles of olive brown and common medium distinct mottles of yellow (10YR 7/8) and brownish yellow (10YR 6/8); moderate coarse blocky structure; very hard, very firm; few fine roots; few discontinuous clay films; few shiny faces on peds; few black concretions; few pebbles of quartz; slightly acid; gradual smooth boundary. (10 to 24 inches thick)
B22t--36 to 52 inches; light brownish gray (10YR 6/2) clay, grayish brown (10YR 5/2) moist; common medium prominent reddish yellow (7.5YR 7/8), yellowish red (5YR 5/8), yellow (2.5Y 7/8), and olive yellow (2.5Y 6/8) mottles; moderate coarse blocky structure; extremely hard, extremely firm; few fine black concretions; few fine pebbles of quartz; slightly acid; gradual smooth boundary. (10 to 20 inches thick)
B23t--52 to 74 inches; inches, mottled, grayish brown (2.5Y 5/2), dark grayish brown (2.5Y 4/2) moist, and light yellowish brown (2.5Y 6/4), light olive brown (2.5Y 5/4) moist, clay; weak medium blocky structure; extremely hard, very firm; common fine pitted calcium carbonate concretions; few fine black concretions; calcareous, moderately alkaline; gradual smooth boundary. (6 to 24 inches thick)
Cca--74 to 90 inches; mottled, grayish brown (2.5Y 5/2), dark grayish brown (2.5Y 4/2) moist, and yellow (10YR 7/8) and brownish yellow (10YR 6/8) moist, clay; massive; very hard, very firm; common fine and medium masses of soft lime and many fine calcium carbonate concretions that are pitted; common fine black concretions; moderately alkaline; calcareous.
TYPE LOCATION: Hill County, Texas; about 4 miles north of Aquilla on FR 933, 3/4 mile east, 3/4 mile north, and 1/2 mile west on county road; 400 feet south into field.
RANGE IN CHARACTERISTICS: Solum thickness is 60 to more than 80 inches. The mollic epipedon is 12 to 20 inches thick. Depth to free carbonates is more than 30 inches.
The Ap horizon is dark grayish brown (10YR 4/2), grayish brown (10YR 5/2), dark brown (10YR 4/3; 7.5YR 4/2), or brown (10YR 5/3; 7.5YR 5/2). The A horizon is loam or fine sandy loam and ranges from slightly acid through mildly alkaline. The A11 and A12 horizons are very dark grayish brown (10YR 3/2), dark grayish brown (10YR 4/2), grayish brown (10YR 5/2), dark brown (10YR 4/3), or brown (10YR 5/3) and most pedons contain a few fine mottles of
yellowish brown, yellowish red, reddish yellow, olive yellow, or grayish brown.
The clay content of the upper 20 inches of the Bt horizon ranges
from 35 to 50 percent. The B21t horizon is grayish brown (2.5Y
5/2; 10YR 5/2), or olive gray (5Y 5/2) with common to many fine
and medium mottles of dark grayish brown (10YR 4/2), brownish
yellow (10YR 6/8), yellow (10YR 7/8), yellowish red (5YR 5/8), reddish brown (5YR 5/4), pink (5YR 7/4), olive brown (2.5Y 4/4), olive yellow (2.5Y 6/6), yellow (2.5Y 7/6). It is clay or clay
loam, and ranges from slightly acid through neutral. The B22t and B23t horizons are light brownish gray (10YR 6/2), gray (10YR 5/1, 6/1), or grayish brown (2.5Y 5/2) with common to many fine and
medium mottles of olive yellow (2.5Y 6/6, 6/8), yellow (2.5Y 7/8), light olive brown (2.5Y 5/4), yellowish red (5YR 5/8), reddish
yellow (7.5YR 7/8, 6/8), dark reddish gray (5YR 4/2), yellow (10YR 7/8), and brownish yellow (10YR 6/8). The B22t and B23t horizons
are clay or clay loam and range from neutral through moderately alkaline.
The Cca horizon is grayish brown, with mottles as described above. It is clay or clay loam. Few to common soft pockets of calcium carbonate are in most pedons. The Cca horizon ranges from mildly through moderately alkaline and is calcareous.
COMPETING SERIES: These are the
Abilene,
Blanket,
Bonham,
Brewer,
Carwile, Cutter,
Dodson,
Luckenbach,
Mayes,
McLain, and
Muldrow series. Abilene, Blanket, Brewer, Cutter, Dodson, and McLain
soils have mollic epipedons thicker than 20 inches and lack gray mottles in the upper Bt horizon. Bonham soils are dry for less
than 90 cumulative days each year. Carwile soils have a solum thickness of less than 60 inches and have an aquic moisture
regime. Luckenbach soils lack mottling in the Bt horizon and have hues mainly redder than 10YR in the Bt horizons. Mayes soils have
a high shrink-swell potential. Muldrow soils have mollic epipedons thicker than 20 inches and have an aquic moisture regime.
GEOGRAPHIC SETTING: Blum soils are on nearly level to gently sloping old terraces or colluvial foot slopes and valley fills. Slope gradients range from 0 to 3 percent. The soil formed in loamy and clayey sediments that are high in calcium carbonate. Climate is moist subhumid. Average annual precipitation ranges from 28 to 35 inches. Mean annual temperature ranges from 64 degrees to 69 degrees F. Thornthwaite P-E indices are 48 to 62.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Blanket series, and the Crockett, Mabank, Venus, and Wilson series. Crockett, Mabank, and Wilson soils have high shrink-swell potential and montmorillonitic mineralogy. Venus soils have calcic horizons and fine-loamy control sections.
DRAINAGE AND PERMEABILITY: Moderately well drained; slow runoff; slow permeability.
USE AND VEGETATION: Mostly cropped to cotton, corn, grain
sorghum, and oats. Native vegetation is mainly big bluestem,
little bluestem, switchgrass, and indiangrass. Some areas are
used for pasture.
DISTRIBUTION AND EXTENT: Central Texas, mainly on old stream terraces within the Blackland Prairie land resource area. The
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 Reddish
Prairie great soil group and were included in the Bonham series.
ADDITIONAL DATA: Field COLE data of the B21t horizon is 0.06.