LOCATION BENITO TXEstablished Series
TAXONOMIC CLASS: Very-fine, smectitic, hyperthermic Sodic Haplusterts
TYPICAL PEDON: Benito clay--pasture. (Colors are for dry soil unless otherwise stated.)
Az--0 to 8 inches; gray (N 5/0) clay, dark gray (N 4/0) moist; weak fine granular and subangular blocky structure; very hard, very firm, very sticky and very plastic; saline; strongly effervescent, moderately alkaline; gradual smooth boundary. (5 to 12 inches thick)
Anz--8 to 54 inches; gray (N 5/0) clay, dark gray (N 4/0)
moist; many prominent slickensides and many distinct
wedge-shaped aggregates parting to moderate fine angular blocky
structure; very hard; very firm; very sticky and very plastic;
common salt threads; saline; strongly effervescent; moderately alkaline; diffuse smooth boundary. (40 to 60 inches thick)
ACnz--54 to 63 inches; light brownish gray (10YR 6/2) silty
clay loam, grayish brown (10YR 5/2) moist;; streaks or
burrow fillings; many distinct intersecting slickensides and many
parallelepipeds; very hard, very firm; very sticky and very
plastic; common fine distinct pale brown (10YR 6/3) masses of iron accumulation and dark gray (10YR 4/1) iron depletions moist; few salt threads; saline; strongly effervescent; moderately alkaline; abrupt smooth boundary. (5 to 15 inches thick)
2CKnz--63 to 84 inches; pale brown (10YR 6/3) silt loam,
brown (10YR 5/3) moist;; land crab burrows; massive; slightly hard, very friable; common fine distinct brownish yellow (10YR 6/6) masses of iron accumulation; and many gray (10YR 5/1) iron depletions moist many concretions and soft of calcium carbonate; saline; violently effervescent, moderately alkaline.
TYPE LOCATION: Cameron County, Texas; 4 miles east, 10 degrees
north of San Benito; in a pasture 500 feet east of a field road, which point is 0.4 miles south of Farm Road 510 (this intersection is 4.3 miles north and east of the intersection of Farm Road 510 and U.S. Highway 77 east of San Benito).
RANGE IN CHARACTERISTICS: Solum thickness ranges from 50 to 72 inches. These soils, when dry, have cracks 0.4 inch to 3.0
inches in width to depths of 20 inches. Slickensides begin at 10 to 20 inches below the surface; parallelepipedsare titled 30 to 60 degrees from the horizontaland part to moderate very fine and medium angular blockystructure. Soil salinity increases with depth and ranges from 4to 20 dS/m in the 10- to 40-inch control section.
Exchangeable sodium increases with depth and exceeds 15 percent
in some part of the upper 30 inches of soil.
The A and AC horizons are gray (N 5/0; 10YR 5/1) or light gray (N 6/0; 10YR6/1). Moist values are more than 3.5. Chroma of less
than 1.5 extends to depths of 40 inches or more. Below 40 inches chromasare 2 in some pedons. The 10- to 40-inch control section ranges from 60 to78 percent clay. Sand content is less than 4 percent, and the norm is about2 percent.
The 2C horizon is pale brown (10YR 6/3), grayish brown (10YR
5/2), light gray (10YR 6/1), or light brownish gray (10YR 6/2).
It is silt loam, very fine sandy loam, silty clay, or silty clay loam. In some pedons a 3C horizon that is loamy fine sand or
fine sand occurs below 60 inches.
COMPETING SERIES: These include the Harlingen series. Similar soils are the Lomalta, Mercedes, Montell, Monteola, Tiocano, and Victoria series. Harlengen soils have chroma of 2 or 3 in the upper 40 inches. Lomalta soils have prismatic structure in the upper part of the control section. In addition, they have more than 15 percent exchangeable sodium throughout. Mercedes and Montell soils have less than 60 percent clay and the control section. Monteola, Tiocano, and Victoria soils have A horizons with color values less than 3.5 when moist and 5.5 when dry.
GEOGRAPHIC SETTING: Benito soils are on terraces above normal overflow.Surfaces are plane to weakly concave with slope
gradients less than 1/2 percent. The soil formed in thick
calcareous clayey and silty sediments. The climate is dry
subhumid, to semiarid. The mean annual precipitation ranges from
22 to 31 inches, the mean annual air temperature ranges from 74
to 76 degrees F. Thornthwaite P-E indices range from 29 to about
34.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the
Cameron,
Chargo,
Harlingen,
Laredo, and
Olmito series. Cameron, Chargo, Laredo, and Olmito soils lack intersecting slickensides. In addition, Cameron soils have clayey over loamy 10- to 40-inch
control sections, and Laredo soils have less than 35 percent clay
in the control section. Harlingen soils have chroma of more than
1.5 in the upper 12 inches of the A horizon.
DRAINAGE AND PERMEABILITY: Poorly drained. Runoff is very slow
to ponded. Permeability is very slow. These soils become
saturated and pond water for short periods following heavy rains during the fall and winter months. The loamy 2C material has a seasonal high water table at 4 to 6 feet from September to May.
USE AND VEGETATION: Mostly improved pasture. Improved grasses
are mainly coastal bermudagrass, African star and Angleton grass.
DISTRIBUTION AND EXTENT: Occurs principally along the lower
reaches of the Rio Grande River and its major tributaries in
southern Texas and probably in Mexico. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Cameron County, Texas; 1970.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: 0 to 8 inches. (Az horizon)
Cambic horizon: 8 to 63 inches. (Anz and ACnz horizons)
Vertic feature: Slickensides from 8 to 63 inches.
ADDITIONAL DATA: None