LOCATION TIGUA TXEstablished Series
TAXONOMIC CLASS: Very-fine, smectitic, calcareous, thermic Vertic Torrifluvents
TYPICAL PEDON: Tigua silty clay--irrigated cropland. Colors are dry conditions unless otherwise stated.)
Ap--0 to 10 inches; pinkish gray (7.5YR 6/2) silty clay, brown (7.5YR 5/2) moist; massive; very hard, very firm; effervescent; moderately alkaline; clear smooth boundary. (6 to 12 inches thick)
C1--10 to 50 inches; pinkish gray (5YR 6/2) clay, reddish gray (5YR 5/2) moist; few parallel piped structural aggregates; extremely hard, extremely firm; contains a few cracks 1-1/2 cm wide extending from upper boundary to 30 inches; bedding planes that become more pronounced with depth; few salt deposits; effervescent; moderately alkaline; abrupt wavy boundary. (35 to 60 inches thick)
2C2--50 to 60+ inches; light gray (10YR 7/2) stratified silt loam, very fine sandy loam, and silt, grayish brown (10YR 5/2) moist; structureless; soft; friable; effervescent; moderately alkaline.
TYPE LOCATION: El Paso County; Texas; in cultivated field 65 feet southeast of Denton Road; from a point 0.6 mile southwest of intersection of Denton Road and U. S. Highway 80, which intersection is 1.1 miles southeast of Farm Road 1110 in Clint, Texas; via U. S. Highway 80.
RANGE IN CHARACTERISTICS:
Soil moisture - Intermittently moist in the soil moisture control section during July-August. Typic aridic soil moisture regime.
Depth to sandy or loamy substratum: 40 to 70 inches
This soil has cracks, when not irrigated, 1/2 to 4 inches wide and 12 inches or more long that extend to a depth of 20 inches or more from the surface or the base of the Ap
Texture of the 10- to 40- inch control section: clay
Clay content: 60 to about 70 percent
Weak bedding planes begin at depths ranging from 15 to 25 inches below the surface. They become more pronounced with depth
Soil salinity: none to moderate
A and C horizons
Texture: silty clay to clay
Hue: 5YR to 10YR
Value: 5 or 6
Chroma: 2 or 3
2C horizon
Texture: silt, silt loam, loam, and very fine sandy loam stratified with sandy to clayey layers
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Tigua soils are on nearly level to slightly depressed flood plains of major streams. The soil formed in clayey over loamy alluvial sediments many feet thick. The climate is arid with an average annual precipitation of 4 to 12 inches and a Thornthwaite P-E index of 10 to 15. The mean annual temperature ranges from 60 degrees to 65 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These Saneli, Gila, Glendale, Harkey, and Vinton series. Gila, Glendale, Harkey, and Vinton soils contain less than 35 percent clay in the 10- to 40- inch control section. Saneli soils are clayey over sandy in the control section.
DRAINAGE AND PERMEABILITY: Moderately well drained. Surface runoff is very slow to ponded. Permeability is very slow.
USE AND VEGETATION: Almost all of this series is used for irrigated cropland. Crops grown are cotton, alfalfa, grain sorghum, small grains, and vegetables. Principal vegetation is cottonwood trees, salt cedar, tornillo bush, fourwing saltbush, and alkali sacaton.
DISTRIBUTION AND EXTENT: Occurs in the southern part of the Trans-Pecos area in West Texas, along the Rio Grande and major tributaries and in southeast New Mexico. This soil occurs in LRR-D, MLRA 42.The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: El Paso County, Texas; 1975.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 0 to 10 inches (Ap horizon)
Entisol feature - The absence of diagnostic subsurface horizons
Fluvial feature - Irregular decrease in organic carbon in the zone from 10 to 60 inches (C1, 2C2 horizons)
Vertic feature - soil cracks
These soils were formerly classified in the Alluvial great soil group.
Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy Tenth Edition, 2006.
When the competing series section was updated in September 2001, questions were raised about the pedon description of this series. A field study of the type location is recommended to update the description.