LOCATION VELASCO TX
Established Series
GWC-JKW-RM
09/2015
VELASCO SERIES
The Velasco series consists of very deep, very poorly drained very slowly permeable soils that formed in calcareous saline clayey alluvium of Holocene age. These nearly level soils occur on flood plains on delta plains. Mean annual precipitation is about 1295 mm (51 in) and mean annual air temperature is about 21.1 degrees C (70 degrees F)
TAXONOMIC CLASS: Very-fine, mixed, superactive, calcareous, hyperthermic Cumulic Endoaquolls
TYPICAL PEDON: Velasco clay on 0.1 percent slope--in rangeland at elevation less than 1.5 m (5 ft).(Colors are for moist soils unless otherwise stated.)
Ag1--0 to 20 cm (0 to 8 in); dark reddish brown (5YR 3/3) clay, reddish brown (5YR 4/3) dry; moderate coarse angular blocky structure; very hard, very firm; few fine roots; few fine tubular pores; common fine and medium distinct gray (7.5YR 6/1); few fine distinct very dark gray (10YR 3/1) iron depletions; few fine calcium carbonate concretions; slightly effervescent; moderately saline; moderately alkaline; clear smooth boundary. (13 to 38 cm [5 to 15 in] thick)
Ag2--20 to 76 cm (8 to 30 in); 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; many medium and coarse distinct dark gray (N 4/0) and gray (N 5/0) iron depletions; strongly effervescent; strongly saline; moderately alkaline; clear smooth boundary. (51 to 127 cm [20 to 50 in] thick)
Bg--76 to 203 cm (30 to 80 in); variegated matrix of reddish brown (2.5YR 4/4), yellowish red (5YR 4/6), and dark gray (10YR 4/1) clay; moderate coarse angular blocky structure; very firm, very sticky and plastic; few fine roots; few calcium carbonate concretions; strongly effervescent; strongly saline; strongly alkaline.
TYPE LOCATION: Brazoria County, Texas; from the intersection of the Brazos River and the Intracoastal Waterway about 3 miles south of Freeport, 1.2 miles west along Intracoastal Waterway, 200 ft north from bank in rangeland. Jones Creek USGS Quad; Latitude: 28 degrees, 53 minutes, 49.5 seconds N; Longitude: 95 degrees, 24 minutes, 15.45 seconds W. WGS84.
RANGE IN CHARACTERISTICS:
Solum thickness is 152 to more than 203 cm (60 to more than 80 in).
Soil Moisture: These soils are in an aquic moisture regime.
Mean annual soil temperature: 22.2 to 23.4 degrees C (72 to 74 degrees F)
The soil is calcareous throughout.
The 25 to 102 cm (10- to 40-in) control section averages between 60 and 70 percent clay.
The soil is saturated to the surface for periods of 4 to 8 months and seldom dries to below field capacity. Soil salinity ranges from moderate through strong.
Some pedons have an organic surface horizon less than 10 cm (4 in) thick.
Some pedons have buried horizons below 102 cm (40 in).
A horizons:
Hue: 5YR to 10YR
Value: of 2 or 3
Chroma: 1 to 3. Most pedons have few to many distinct or prominent iron depletions.
Texture: but a thin layer of silty clay is on the surface of some pedons.
Reaction: neutral to strongly alkaline.
Salinity: moderate or strong.
B horizon:
Hue: 2.5YR to 7.5YR
Value: 3 to 5
Chroma: 2 to 8
Reaction: slightly alkaline or moderately alkaline
Some pedons have thin buried horizons. The buried horizons have lower chroma and hue.
In some pedons, a 2C horizon, that is stratified loamy or sandy materials, is encountered at 152 cm (60 in) or more below the surface.
COMPETING SERIES: There are no competing series in the same family. Similar soils include the
Beaumont,
Brazoria,
Harris,
Iberia,
Lomalta,
Surfside, and
Tracosa series.
Beaumont,
Brazoria,
Iberia,
Lomalta, and
Surfside soils: have vertic properties. In addition, Beaumont, Brazoria, and Iberia soils are non-saline.
Harris soils: have gray colors throughout, are noncalcareous.
Tracosa soils: have a peraquic moisture regime and are flooded daily by tidal action.
GEOGRAPHIC SETTING:
Parent material: calcareous saline clayey alluvium of Holocene age
Landscape: Delta plains
Landform: flood plains
Slope: less than 1 percent
Mean annual precipitation: 1,041 to 1,295 mm (41 to 51 in)
Mean annual air temperature: 20.6 to 21.7 degrees C (69 to 71 degrees F)
Frost-free period: 300 to 365 days
Elevation: 0 to 1.5 m (5 ft) above sea level
Thornthwaite P-E Index: exceed 48
GEOGRAPHICALLY ASSOCIATED SOILS: These are the similar
Beaumont,
Harris, and
Tracosa series and the
Francitas,
Galveston,
Ijam,
Mustang,
Narta, and
Veston series.
Beaumont,
Francitas,
Ijam, and
Narta soils: are on slightly higher areas. In addition, Francitas and Narta soils are on slightly higher areas. They are gray and noncalcareous.
Harris soils: are in similar positions.
Tracosa soils: are on slightly lower elevations.
Veston soils: are loamy
Galveston and
Mustang: soils are sandy.
DRAINAGE AND PERMEABILITY: Velasco soils are very poorly drained. Runoff is high, and permeability is very slow. A water table fluctuates from the soil surface to a depth of about 76 cm (30 in). These soils are occasionally flooded by both fresh and salt water during Gulf storms. In a few places very high tides cover the soil.
USE AND VEGETATION: Used for rangeland and wildlife habitat. Native vegetation is water loving and salt tolerant grasses and sedges such as marshhay cordgrass, common reed, and seashore saltgrass.
DISTRIBUTION AND EXTENT: Gulf Coast Saline Prairie (MLRA 150B) areas of Texas. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
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 is waived on the assumption that the saturated zone is devoid of oxygen and the red colors remain after citrate dithionate extraction.
Classification changed from Cumulic Haplaquolls to Cumulic Endoaquolls 11/2000 based on typifying pedon description. Further study and characterization data of the series is needed to verify hydrology and classification.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon:0 to 76 cm (0 to 30 in) (A1g and A2g horizons).
Aquic features: low chroma redox features and reduction.
Cambic horizon: 76 to 203 cm (30 to 80 in) (Bg horizon0
ADDITIONAL DATA: THD data from a pedon in Brazoria County, Texas (S76TX-039-011).
Taxonomic Version: Keys to Soil Taxonomy, Twelfth Edition, 2014.
National Cooperative Soil Survey
U.S.A.