LOCATION COPITA TX
Established Series
Rev. RSS-CKH-GWH
11/2013
COPITA SERIES
The Copita series consists of well drained, moderately deep soils over sandstone. These nearly level to gently sloping soils formed in calcareous loamy residuum derived from sandstone predominantly of the Claiborne and Jackson Groups. These soils occur on side slopes of low hills. Slope ranges from 0 to 5 percent. Mean annual air temperature is about 22.8 degrees C. (73 degrees F.) and mean annual precipitation is about 559 mm (22 in).
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, hyperthermic Aridic Calciustepts
TYPICAL PEDON: Copita fine sandy loam, on a west facing, 3 percent slope in rangeland; elevation is 119 meters (390 feet). (Colors are for dry soil unless otherwise stated.)
A1--0 to 5 cm (0 to 2 in); light brownish gray (10YR 6/2) fine sandy loam, dark grayish brown (10YR 4/2) moist; weak fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few snail shell fragments; strongly effervescent; moderately alkaline; abrupt smooth boundary.
A2--5 to 28 cm (2 to 11 in); grayish brown (10YR 5/2) fine sandy loam, dark grayish brown (10YR 4/2) moist; moderate medium and coarse prismatic structure parting to weak fine and medium subangular blocky when dry, massive when moist; hard, friable, slightly sticky and slightly plastic; common roots; common fine pores; few snail shell fragments; 1 percent films and threads of calcium carbonate; strongly effervescent; moderately alkaline; clear wavy boundary. (combined thickness of the A horizon is 8 to 41 cm [3 to 16 in])
Bk1--28 to 66 cm (11 to 26 in); pale brown (10YR 6/3) sandy clay loam, brown (10YR 5/3) moist; moderate medium and coarse prismatic structure parting to weak fine and medium subangular blocky when moist; hard, friable, slightly sticky and slightly plastic; common roots; common fine pores; few snail shell fragments; 2 percent films and threads of calcium carbonate; violently effervescent; moderately alkaline; clear wavy boundary.
Bk2--66 to 94 cm (26 to 37 in); light yellowish brown (10YR 6/4) sandy clay loam; yellowish brown (10YR 5/4) moist; weak medium subangular blocky structure; slightly hard, friable; few roots; common fine pores; few snail shell fragments; 22 percent films and threads of calcium carbonate; violently effervescent; moderately alkaline; clear wavy boundary. (combined thickness of the Bk horizon is 30 to 81 cm [12 to 32 in])
Crk--94 to 125 cm (37 to 49 in); very pale brown (10YR 7/3) weakly cemented calcareous sandstone bedrock with thin strata and pockets of sandy loam; fractured; brittle; contains a few roots in the sandy loam in crevices; 5 percent calcium carbonate as coatings on upper boundary, and in fractures or partings; violently effervescent; moderately alkaline; gradual wavy boundary. (18 to 51 cm [7 to 20 in] thick)
R--125 to 152 cm (49 to 60 in); very pale brown (10YR 7/3) strongly cemented calcareous sandstone bedrock; contains a few fractures with calcium carbonate coatings; moderately alkaline.
TYPE LOCATION: Starr County, Texas; from the intersection of Loma Blanca Road and U.S. Highway 83 (which is 4.0 miles north-northwest of Roma); 1.2 miles north on Loma Blanca Road; 240 feet west in a rangeland. Roma-Los Saenz West, Texas USGS topographic quadrangle. Latitude: 26 degrees, 28 minutes, 42 seconds N.; Longitude: 99 degrees, 1 minute, 40 seconds W.; NAD 83.
RANGE IN CHARACTERISTICS:
Soil Moisture: An aridic-ustic soil moisture regime. The soil moisture control section remains moist in some or all parts for less than 90 consecutive days in normal years.
Mean annual soil temperature: 22 to 24 degrees C. (72 to 76 degrees F.)
Depth to bedrock: 50 to 100 cm (20 to 40 in)
Depth to calcic horizon: 15 to 46 cm (6 to 18 in)
Particle-size control section (weighted average)
Clay content: 18 to 30 percent
Coarse Fragments: 0 to 10 percent
CEC/clay ratio: 0.40 to 0.60
A horizon:
Hue: 7.5YR, 10YR, or 2.5Y
Value: 4 to 7
Chroma: 2 to 4
Texture: fine sandy loam or sandy clay loam
Clay content: 14 to 25 percent
Calcium carbonate equivalent: 1 to 10 percent
Electrical conductivity (dS/m): 0 to 4
Gypsum: 0 to 1 percent
Sodium adsorption ratio: 0 to 1
Effervescence: slight to strong
Reaction: moderately alkaline
Bk horizon:
Hue: 7.5YR, 10YR, or 2.5Y
Value: 4 to 7
Chroma: 2 to 4
Texture: fine sandy loam, loam, or sandy clay loam
Clay content: 18 to 35 percent
Coarse fragments: 0 to 10 percent; strongly cemented sandstone gravel
Identifiable secondary carbonate: 1 to 25 percent; fine to medium; films, threads, and masses on surfaces of peds and as coatings on coarse fragments.
Calcium carbonate equivalent: 10 to 35 percent
Electrical conductivity (dS/m): 2 to 8
Gypsum: 0 to 2 percent
Sodium adsorption ratio: 0 to 12
Effervescence: strong or violent
Reaction: moderately alkaline
Cr horizon:
Texture: mainly weakly to moderately cemented sandstone bedrock, but may be noncemented sandy densic material that slakes in water in some pedons
Excavation difficulty: high or very high when moist, can be dug with a spade with difficulty in some pedons
Effervescence: calcareous
R horizon:
strongly cemented sandstone bedrock.
COMPETING SERIES: There are no competing series in the same family. Similar soils are the
Aguilares (TX),
Hebbronville (TX), McAllen (TX),
Moglia (TX),
Palafox (TX), and
Tonio (TX) series.
Aguilares soils: have very deep solum.
Hebbroville soils: have an argillic horizon and are coarse-loamy in the particle-size control section.
McAllen soils: have very deep solum and superactive cation exchange activity class
Moglia soils: have SAR greater than 15 within 25 inches of the soil surface.
Palafox soils: are fine-silty in the particle-size control section.
Tonio soils: have an argillic horizon and do not have a calcic horizon.
GEOGRAPHIC SETTING:
Parent material: calcareous loamy residuum derived from sandstone predominantly of the Claiborne and Jackson Groups
Landform: side slopes of low hills
Slope: 0 to 5 percent
Mean annual precipitation: 533 to 660 mm (21 to 26 in)
Precipitation pattern: spring and fall moisture with dry summers and winters; The soil is driest during the months of June through August and December through February. These soils are intermittently moist in September through November and March through May.
Thornthwaite annual P-E indices: 20 to 31
Mean annual air temperature: 21.1 to 23.9 degrees C. (70 to 75 degrees F.)
Frost-free period: 263 to 339 days
Elevation: 106.7 to 304.8 m (350 to 1000 ft)
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Brennan,
Catarina,
Comitas,
Hebbronville,
Maverick, and
Verick series.
Brennan soils: have very deep solum, an argillic horizon, and occur on similar positions.
Catarina soils: have a fine particle-size control section and occur on broad valleys on lower positions.
Comitas soils: have sandy surfaces and occur on lower positions.
Hebbronville soils: have very deep solum, a coarse-loamy particle-size control section , and occur on lower positions.
Maverick soils: have a fine particle-size control section and occur on higher positions.
Verick soils: are shallow to sandstone, and occur on ridges and shoulder slopes on slightly higher positions.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderate. Runoff is negligible on slopes less than 1 percent and low on 1 to 5 percent slopes.
USE AND VEGETATION: Primarily used for rangeland and wildlife habitat. Small areas are cultivated to such crops as cotton and grain sorghum in the extreme eastern area of the series province. Vegetation consists of mid grasses, such as trichloris, Arizona cottontop, plains bristlegrass, lovegrass tridens, hooded windmillgrass, and pink pappusgrass. Woody vegetation consists of mesquite with a heavy understory of spiny hackberry, guayacan, condalia, blackbrush, cenizo, and guajillo. The ecological site is Gray Sandy Loam 18-25 PZ (R083BY421TX).
DISTRIBUTION AND EXTENT: Western Rio Grande Plain, Texas; LRR I; MLRA 83B; large extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Jim Hogg County, Texas, 1970.
REMARKS: Classification change from Ustollic Calciorthids to Aridic Calciustepts based on geographic distribution of the series, rainfall patterns, and vegetative production and composition.
Edited 11/2013 (RFG-GWH): edited Geographic setting section and increased Bk to 35% clay.
Diagnostic horizons and features recognized in this pedon are:
Particle size control section: 25 to 94 cm (10 to 37 in) (lower A horizon and Bk horizons)
Ochric epipedon: 0 to 28 cm (0 to 11 in) (A horizons)
Calcic horizon: 28 to 94 cm (11 to 37 in) (Bk horizons)
Paralithic contact: 94 cm (37 in) (top of Crk horizon)
Lithic contact: 125 cm (49 in) (top of R horizon)
ADDITIONAL DATA: NSSL data number S02TX-505-001A from Zapata Co. The assignment of the cation-exchange activity class is assigned from lab data.
Taxonomic version: Keys to Soil Taxonomy, Eleventh Edition, 2010.
National Cooperative Soil Survey
U.S.A.