LOCATION DACOSTA            TX

DACOSTA SERIES

TAXONOMIC CLASS: Fine, smectitic, hyperthermic Vertic Argiudolls

TYPICAL PEDON: Dacosta sandy clay loam, on a southeast facing, convex, 0.3 percent slope in rangeland at an elevation of 13.7 m (45 ft). (Colors are for moist soil unless otherwise stated.)

A--0 to 15 cm (0 to 6 in); very dark gray (10YR 3/1) sandy clay loam, dark gray (10YR 4/1) dry; weak medium and coarse subangular blocky structure; very hard, firm; many fine and very fine roots; few fine pores; EC is 0.41; SAR is 2; slightly acid; clear smooth boundary. (10 to 41 cm [4 to 16 in] thick)

Bt1--15 to 30 cm (6 to 12 in); very dark gray (10YR 3/1) sandy clay loam, dark gray (10YR 4/1) dry; weak fine and medium subangular blocky structure; very hard, very firm; common fine and very fine roots; few fine pores; few thin gray (10YR 5/1) clay films on faces of peds; few black (10YR 2/1) iron-manganese concretions 2 to 5 mm in diameter; EC is 0.29; SAR is 4; slightly acid; clear smooth boundary.

Bt2--30 to 53 cm (12 to 21 in); dark gray (10YR 4/1) sandy clay, gray (10YR 5/1) dry; weak medium blocky structure; very hard, very firm; common fine and few medium roots; few pressure faces; few thin gray (10YR 5/1) clay films on faces of peds; few black (10YR 2/1) iron-manganese concretions 2 to 5 mm in diameter; EC is 0.47; SAR is 6; slightly acid; clear wavy boundary.

Bt3--53 to 74 cm (21 to 29 in); dark gray (10YR 4/1) clay, gray (10YR 5/1) dry; weak medium blocky structure; very hard, very firm; few fine, very fine, and medium roots; few pressure faces; few thin gray (10YR 5/1) clay films on faces of peds; few black (10YR 2/1) iron-manganese concretions 2 to 5 mm in diameter; EC is 1.14; SAR is 9; neutral; clear wavy boundary.

Bt4--74 to 102 cm (29 to 40 in); dark gray (10YR 4/1) clay, gray (10YR 5/1) dry; weak fine and medium subangular blocky structure; very hard, very firm; few fine and very fine roots; few pressure faces; few thin gray (10YR 5/1) clay films on faces of peds; few black (10YR 2/1) iron-manganese concretions 2 to 5 mm in diameter; few pitted concretions of calcium carbonate 4 to 10 mm in diameter; EC is 3.19; SAR is 10; slightly alkaline; gradual wavy boundary. (Combined thickness of the Bt is 76 to 152 cm [30 to 60 in].)

Btk1--102 to 132 cm (40 to 52 in); light brownish gray (2.5Y 6/2) sandy clay, light gray (2.5Y 7/2) dry; weak fine and medium subangular blocky structure; very hard, very firm; few fine and very fine roots; few thin gray (10YR 6/1) clay films on faces of peds; few black (10YR 2/1) iron-manganese concretions 2 to 5 mm in diameter; few pitted concretions of calcium carbonate 4 to 10 mm in diameter; EC is 4.15; SAR is 10; slightly effervescent; moderately alkaline; gradual wavy boundary.

Btk2--132 to 198 cm (52 to 78 in); light brownish gray (10YR 6/2) sandy clay loam, light gray (10YR 7/2) dry; common medium and coarse prominent yellowish red (5YR 4/6) vertically orientated mottles; weak fine and medium prismatic structure parting to weak fine and medium blocky; very hard, very firm; few fine and very fine roots; few thin light brownish gray (10YR 6/2) clay films on faces of peds; few black (10YR 2/1) concretions 2 to 10 mm in diameter; few coarse masses, parting to hard pitted concretions of calcium carbonate, and few concretions of calcium carbonate 2 to 10 cm across and 0.5 to 1 cm thick; EC is 3.35; SAR is 9; slightly effervescent; moderately alkaline; gradual wavy boundary. (0 to 76 cm [0 to 30 in] thick)

BtC2--198 to 203 cm (78 to 80 in); very pale brown (10YR 7/4) sandy clay loam, very pale brown (10YR 8/4) dry; few fine light gray and yellow mottles; weak fine subangular blocky structure; very hard, very firm; few fine roots; few thin patchy clay films; few dark concretions 2 to 10 mm in diameter; few fine distinct yellow (10YR 7/8) masses of oxidized iron with sharp boundaries in matrix; few fine distinct light gray (10YR 7/1) iron depletions with sharp boundaries in matrix; EC is 2.94; SAR is 9; neutral.

TYPE LOCATION: Victoria County, Texas, from the intersection of Farm Road 616 and U.S. Highway 87 in Placedo, 1.85 miles southeast on U.S. Highway 87, 1.1 miles northeast on gravel road to a drainage ditch, 0.15 mile southeast along drainage ditch, 686 feet south in a pasture. Placedo USGS Quad; Latitude is 28 degrees 40 minutes 48 seconds N; Longitude is 96 degrees 47 minutes 16 seconds W. NAD 83

RANGE IN CHARACTERISTICS: Solum thickness ranges from 60 to more than 80 in. The COLE value in the upper part of the Bt horizon ranges from 0.09 to 0.12. When dry, there are cracks 0.4 to about 2 in wide that extend from the surface to a depth of more than 20 in. The A horizon ranges from nonsaline to very slightly saline, below the soil ranges from nonsaline to slightly saline.

Soil Moisture: An udic soil moisture regime. The soil moisture control section is moist in some or all parts for more than 275 days in normal years.

Mean annual soil temperature: 22 to 23.5 cm (72 to 74 degrees F).
Depth to argillic horizon: 10 to 41 cm (4 to 16 in)
Depth to secondary calcium carbonate: 102 to 152 cm 40 to 60 in)

Particle-size control section (weighted average)
Clay content: 40 to 50 percent
Depth to secondary carbonates: 102 cm

A Horizon
Hue: 10YR
Value: 2 or 3
Chroma: 1 or 2
Texture: loam, sandy clay loam, clay loam
Clay content: 20 to 35 percent
Redox concentrations: amount-0 to 2 percent, shades-brown
Iron manganese concretions: amount- 0 to 2 percent; size-4 to 10 mm; shades-black
EC: 0 to 1
SAR: 0 to 4
Reaction: slightly acid or neutral

Bt Horizon
(upper Bt Horizons)
Hue: 10YR
Value: 2 or 3
Chroma: 1
Texture: sandy clay loam, clay loam, clay (When the clay content of the A horizon is more than 30 percent, the Bt horizon is usually a clay.)
Clay content: 30 to 45 percent
Redox concentrations: amount-0 to 2 percent, shades-brown
Iron manganese concretions: amount- 0 to 2 percent; size-4 to 10 mm; shades-black
EC: 0.2 to 1
SAR: 2 to 6
Reaction: slightly acid to slightly alkaline

Bt Horizon
(lower part)
Hue: 10YR or 2.5Y
Value: 2 to 5
Chroma: 1 or 2
Texture: sandy clay, clay loam, clay
Clay content: 35 to 55 percent
Redox concentrations: amount-0 to 2 percent, shades-brown
Iron manganese concretions: amount- 0 to 2 percent; size-4 to 10 mm; shades-black
Identifiable secondary carbonate: amount-0 to 5 percent, kind-concretions, threads, or masses
EC: 2 to 6
SAR: 6 to 12
Reaction: slightly acid to slightly alkaline

BtC, BCk, Bk, or Btk horizon (where present)
(lower Bt horizons)
Hue: 10YR or 2.5Y
Value: 5 to 7
Chroma: 1 to 4
Texture: sandy clay loam, clay loam, or sandy clay
Clay content: 22 to 45 percent
Redox concentrations: amount-0 to 5 percent, shades-yellow, brown, or red
Iron depletions: amount-0 to 2 percent, shades-gray
Iron manganese concretions: amount- 0 to 2 percent; size-4 to 10 mm; shades-black
Identifiable secondary carbonate: amount-0 to 8 percent, kind-concretions, threads, or masses
EC: 2 to 6
SAR: 6 to 12
Effervescence: none to slight
Reaction: neutral to moderately alkaline

2C
(where present, typically below 152 cm [60 in])
Hue: 2.5YR to 10YR
Value: 5 to 7
Chroma: 4 to 6
Texture: loam, sandy clay loam,, clay loam, clay
Effervescence: none to slight
Reaction: neutral to moderately alkaline
These layers contain few fine flakes of mica in some pedons.

COMPETING SERIES: There are no other series in this family. Similar soils are the Coy (TX), Elmendorf (TX), Kenoma (KS), Oska (KS), Parisian (TX), Peever (SD), and Wagstaff (KS) series.

Coy and Elmendorf soils: in an ustic soil moisture regime
Kenoma, Parisian, and Wagstaff soils: in a thermic soil temperature regime; have sola less than 152 cm (60 in)
Oska soils: in a mesic soil temperature regime; have sola less than 152 cm (60 in)
Peever soils: in a frigid soil temperature regime; have sola less than 152 cm (60 in)

GEOGRAPHIC SETTING:
Parent material: clayey fluviomarine deposits derived from the Beaumont Formation of Pleistocene age
Landscape: flat coastal plain
Landform: flats
Slope: mainly less than 1 percent, but range up to 3
Mean annual air temperature range: 22 to 24 cm (72 to 75 degrees F)
Mean annual precipitation range: 762 to 1067 mm (30 to 42 in)
Precipitation Pattern: Precipitation is uniform throughout the year with slight peaks from May to June and from September to October.
Frost-free period: 275 to 300 days
Elevation: 7.6 to 68 m (25 to 225 ft)
Thornthwaite annual P-E indices: 40 to 56

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Contee (TX), Edna (TX), Francitas (TX), Telferner (TX), and Laewest (TX) series.

Contee soils: do not have an argillic horizon; are on microhighs adjacent to Dacosta soils in complex soil areas.
Telferner and Edna soils: an abrupt texture change between the A and Bt horizons; lighter surface layer; on meander ridges
Laewest soils: are clayey throughout on a similar landform

DRAINAGE AND PERMEABILITY: Moderately well drained; low runoff on 0 to 1 percent slopes, medium runoff on 1 to 3 percent slopes; very slow permeability. Water enters the soil rapidly when it is dry and cracked and moves through the cracks freely. Water moves very slowly through the soil when it is wet. Water perches on top of the argillic horizon for periods of 1 to 2 weeks following extended heavy rains. During wet years planting may be delayed for short periods.

USE AND VEGETATION: Mainly used for growing grain sorghums, cotton, and rice. Common use is made of bermudagrass in improved pasture. Native grasses are mainly species of andropogons and paspalums. Elm, mesquite, and huisache trees are common in some areas. (Ecological site name: Blackland 24-44" Pz; Ecological site number: R150AY526TX)

DISTRIBUTION AND EXTENT: Middle and lower Gulf Coastal Prairies of Texas. MLRA 150A; LRR T. The series is moderately extensive.

MLRA OFFICE RESPONSIBLE: Temple, Texas

SERIES ESTABLISHED: Calhoun County, Texas; 1972.

REMARKS: Dacosta soils were formerly included in the Bernard series.

The classification is changed from Vertic Albaqualfs to Vertic Argiudolls based on the soil moisture study "ISCOM VIII, Classification and Management of Wet Soils, 1990." This soil does not have an aquic moisture regime.

Diagnostic horizons and features recognized in this pedon are:

Mollic epipedon 0 to 30 cm (0 to 12 in).

Argillic horizon 15 to 203 cm (6 to 80 in).

ADDITIONAL DATA: NSSL data from the type location in Victoria County, TX (S78TX-469-001).