LOCATION VELASCO                 TX

Established Series
GWC-JKW-RM
08/2025

VELASCO SERIES

Depth class: Very deep
Drainage class: Very poorly drained
Flooding frequency and duration: Occasional, brief
Saturated hydraulic conductivity: Low to moderately low
Shrink-swell potential: High
Parent material: Calcareous saline clayey estuarine deposits
Slope: 0 to 1 percent
Mean annual air temperature: 21 C (70 degrees F)
Mean annual precipitation: 1263 millimeters (50 inches)

TAXONOMIC CLASS: Very-fine, mixed, superactive, calcareous, hyperthermic Cumulic Endoaquolls

TYPICAL PEDON: Velasco clay on a nearly level slope of a mainland marsh at elevation of 1 meter. (Colors are for moist soils unless otherwise stated.)

A--0 to 20 centimeters; dark reddish brown (5YR 3/3) clay, reddish brown (5YR 4/3) dry; moderate coarse angular blocky structure; very hard, very firm; very sticky and plastic; few fine roots; few fine tubular pores; 6 percent fine and medium distinct gray (7.5YR 6/1) iron depletions and 1 percent fine distinct very dark gray (10YR 3/1) iron depletions; 1 percent fine calcium carbonate concretions; slightly effervescent (HCl); moderately saline; moderately alkaline (pH 8.0); clear smooth boundary.

Ag--20 to 76 centimeters; dark brown (7.5YR 3/2) clay, brown (7.5YR 4/2) dry; weak medium and coarse angular blocky structure; very firm, very sticky and plastic; common fine roots; 25 medium and coarse distinct gray (N 5/) iron depletions; strongly effervescent (HCl); strongly saline; moderately alkaline (pH 8.0); clear smooth boundary. (A horizons 13 to 127 centimeters thick)

Bg--76 to 200 centimeters; variegated matrix of 60 percent dark gray (10YR 4/1), 30 percent reddish brown (2.5YR 4/4) and 10 percent yellowish red (5YR 4/6); clay; moderate coarse angular blocky structure; very firm, very sticky and plastic; few fine roots; few calcium carbonate concretions; strongly effervescent (HCl); strongly saline; strongly alkaline (pH 9.0).

TYPE LOCATION: Brazoria County, Texas; approximately 3.4 kilometers (3 miles) southwest of the center of the Bryan Mound Strategic Petroleum Reserve and approximately 1.6 kilometers (1 mile) west of the western Lock at the intersections of the Brazos River and the Intracoastal Waterway; USGS quadrangle: Jones Creek, Texas

Latitude: 28.8970833
Longitude: -95.4042917
Datum: WGS84
Coordinate source: From hand-held GPS

RANGE IN CHARACTERISTICS:
Depth to bedrock: Greater than 200 centimeters
Moisture regime: Peraquic
Depth to redox features: 0 to 25 centimeters
Some pedons have an organic surface horizon less than 10 centimeters thick
Some pedons have buried horizons below 102 centimeters
Particle-size control section (weighted average):
Clay content-60 to 70 percent
Sand content-0 to 10 percent
The particle-size control section has less than 30 percent silt plus clay

A horizons:
Hue-5YR to 10YR
Value-2 or 3
Chroma-1 to 3
Redox concentrations-0 to 20 percent; iron depletions
Texture-clay
Reaction-neutral to moderately alkaline (pH 6.6 to 8.4)

Ag Horizons:
Hue-5YR to 10YR
Value-2 or 3
Chroma-1 to 2
Redox concentrations-0 to 15 percent; iron depletions
Texture-clay
Reaction-strongly alkaline (pH 8.5 to 9.0)

Bg horizon:
Hue-2.5YR to 7.5YR
Value-3 to 5
Chroma-1 or 2
Texture-silty clay loam, clay loam, silty clay, or clay
Reaction: slightly alkaline or moderately alkaline (pH 7.6 to 8.1)

COMPETING SERIES: There are no competing series in the same family. Similar soil series are Beaumont, Brazoria, Harris, Incell, Lomalta, Surfside, and Tracosa series.
Beaumont, Brazoria, Lomalta, and Surfside soils: have vertic properties.
Harris soils: have gray colors throughout and are noncalcareous.
Incell soils: are fine-loamy.
Tracosa soils: have a peraquic moisture regime and flooded daily by tide.

GEOGRAPHIC SETTING:
Parent material: Calcareous saline clayey estuarine deposits
Landscape: Barrier Islands and coastal plains
Landform: Tidal marshes
Slope:0 to 1 percent
Mean annual precipitation: 812 to 1499 millimeters (32 to 59 inches)
Mean annual air temperature: 20 to 23 degrees C (69 to 71 degrees F)
Frost-free period: 315 to 365 days
Elevation: 0 to 1.5 meters (5 feet)

GEOGRAPHICALLY ASSOCIATED SOILS: These are the similar Aransas, Beaumont, Francitas, Galveston, Harris, Ijam, Mustang, Narta, Tracosa and Veston series.
Aransas, Beaumont, and Francitas soils: are slightly higher on the landscape and have slickensides throughout much of their solums.
Galveston and Mustang soils: are on slightly higher landscapes on barrier island, sandy in the control section and have a sodium adsorption ratio greater than 13.
Harris soils: are on similar landscapes, are smectitic, have slickenslides throughout and lack a mollic epipedon.
Ijam soils: are on human-altered landforms and formed from human-transported material (dredgic).
Narta soils: found slightly higher on the landscape, have a natric horizon and, are on flats on the mainland side with ochric epipedons.
Tracosa soils: found on similar landscapes, have a ESP of greater than 20 and lack mollic epipedons.
Veston soils: found slightly higher on the landscape have fine-silty control sections, have irregular decrease in organic matter with depth, and have ochric epipedons.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: Very poorly drained
Saturated hydraulic conductivity: Low to moderately low
Flooding frequency and duration: Occasional, brief
Seasonal water table: Soil surface to 25 centimeters
Surface runoff: Very low

USE AND VEGETATION:
Major uses: Rangeland and wildlife habitat
Vegetation: salt tolerant such as marsh hay cordgrass, common reed, and seashore saltgrass
Ecological site: R150BY550TX-Northern Salt Marsh

DISTRIBUTION AND EXTENT:
General Area: Along the coast of Texas on mainland marsh areas
Land Resource Region: T-Atlantic and Gulf Coast Lowland Forest and Crop Region
MLRA(s): 150B-Gulf Coast Saline Prairies
Extent: Moderate

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Special Projects Office

SERIES ESTABLISHED: Brazoria County, Texas, 1978

REMARKS:
Velasco soils were previously considered as a saline phase of the Roebuck series. The high chromas in the lower horizons are related to the red parent materials. The requirements for low chroma are waived on the assumption that the saturated zone is devoid of oxygen and the red colors remain after citrate dithionate extraction.

Typical pedon taxonomic features:
Calcareous: 0 to 200 centimeters
Cambic horizon: 76 to 203 centimeters (Bg horizon)
Mollic epipedon:0 to 76 centimeters (A and Ag horizons).
Peraquic moisture: Low-chroma redox features and reduced horizons immediately below the surface (A, Ag, and Bg horizons)
Taxonomic Version: Keys to Soil Taxonomy, 13th edition (2022)

ADDITIONAL DATA:
THD data from a pedon in Brazoria County, Texas (S76TX-039-011)
OSD User Pedon ID: 2015TX039435
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National Cooperative Soil Survey
U.S.A.