LOCATION ATIRAS TXEstablished Series
TAXONOMIC CLASS: Mixed, hyperthermic Typic Ustipsamments
TYPICAL PEDON: Atiras fine sand--on a northeast facing, slightly convex, 1 percent slope, in complex with the Falfurrias and Medanito soils in rangeland at an elevation of 7.6 m (25 ft). (Colors are for dry soil unless otherwise stated)
A1--0 to 20 cm (0 to 8 in); brown (10YR 5/3) fine sand, brown (10YR 4/3) moist; single grain; loose; 6 percent fine and very fine and 1 percent coarse roots; moderately acid; gradual smooth boundary.
A2--20 to 43 cm (8 to 17 in); pale brown (10YR 6/3) fine sand, brown (10YR 5/3) moist; single grain; loose; 5 percent fine and medium and 1 percent coarse roots; moderately acid; clear smooth boundary. (combined thickness of the A horizons is 10 to 51 cm [4 to 20 in])
C1--43 to 71 cm (17 to 28 in); pale brown (10YR 6/3) fine sand, brown (10YR 5/3) moist; single grain; loose; 3 percent fine and medium distinct yellowish brown (10YR 5/6) masses of iron accumulation; 5 percent fine and very fine and 1 percent coarse roots; moderately acid; gradual smooth boundary.
C2--71 to 114 cm (28 to 45 in); light gray (10YR 7/2) fine sand, light brownish gray (10YR 6/2) moist; single grain; loose; 4 percent fine and very fine and 1 percent coarse roots; 5 percent fine and medium distinct yellowish brown (10YR 5/8) masses of iron accumulation; slightly acid; gradual smooth boundary.
C3--114 to 147 cm (45 to 58 in); light gray (10YR 7/2) fine sand, light brownish gray (10YR 6/2) moist; single grain; loose; 2 percent fine distinct yellowish brown (10YR 5/4) and 1 percent fine distinct dark yellowish brown (10YR 4/6) masses of iron accumulation; 4 percent fine and very fine and 1 percent medium roots; slightly acid; very abrupt smooth boundary. (combined thickness of the C horizon is 64 to 135 cm [25 to 53 in])
2Ab--147 to 155 cm (58 to 61 in); dark grayish brown (10YR 4/2) fine sand, very dark grayish brown (10YR 3/2) moist; upper inch of horizon is a very dark gray (10YR 3/1) band; weak fine and medium subangular blocky structure; slightly hard, very friable; 4 percent fine and very fine roots; 2 percent fine pores; 2 percent fine distinct yellowish brown (10YR 5/4) masses of iron accumulation; slightly acid; clear smooth boundary. (thickness of the 2Ab horizon is 5 to 28 cm [2 to 11 in])
2Bwb1--155 to 170 cm (61 to 67 in); light brownish gray (10YR 6/2) loamy fine sand, dark grayish brown (10YR 4/2) moist; weak coarse prismatic structure parting to weak medium and coarse subangular blocky structure; hard; very friable; 2 percent fine and very fine roots; 2 percent fine pores; 5 percent fine distinct yellowish brown (10YR 5/4) masses of iron accumulation; 10 percent fine black (10YR 2/1) iron-manganese masses; 1 percent fine pale brown (10YR 6/3) clean sand grains; 75 percent of prism faces covered with very dark gray (10YR 3/1) organic stains; slightly acid; clear smooth boundary.
2Bwb2--170 to 185 cm(67 to 73 in); light brownish gray (10YR 6/2) fine sandy loam, grayish brown (10YR 5/2) moist; weak coarse prismatic structure parting to weak medium and coarse subangular blocky ; hard, friable; 1 percent fine and very fine roots; 2 percent fine pores; 15 percent fine and medium distinct yellowish brown (10YR 5/6) masses of iron accumulation; 1 percent fine light gray (10YR 7/2) clean sand grains; 75 percent of prism faces covered with very dark gray (10YR 3/1) organic stains; slightly sodic; neutral; gradual smooth boundary. (combined thickness of the 2Bwb horizons is 23 to 104 cm [9 to 41 in])
2Bwb3--185 to 203 cm (73 to 80 in); light gray (2.5Y 7/2) loamy fine sand, light brownish gray (2.5Y 6/2) moist; weak medium and coarse subangular blocky structure; hard, friable; 1 percent fine and very fine roots; 2 percent fine pores; 10 percent fine and medium distinct yellowish brown (10YR 5/6) masses of iron accumulation; 1 percent fine black (10YR 2/1) iron-manganese masses; slightly sodic; neutral.
TYPE LOCATION: Kenedy County, Texas; from the intersection of La Parra Avenue and U.S. Highway 77 in Sarita; 4.8 miles south on U.S. Highway 77 to ranch gate; 2.13 miles east on ranch road; 1.7 miles north and northeast on ranch road; 0.43 mile east on pipeline right-of-way; 500 feet southeast along fenceline; 150 feet west in rangeland. La Parra Ranch, Texas USGS topographic quadrangle; Latitude: 27 degrees, 10 minutes, 30.11 seconds N. and Longitude: 97 degrees, 44 minutes, 45.34 seconds W., NAD 83.
RANGE IN CHARACTERISTICS:
Soil Moisture: An Ustic moisture regime. The soil moisture control section is dry in some or all parts for more than 90, but less than 150, cumulative days in normal years. The SMCS is also either moist in some or all parts for 180 cumulative days or more, or moist for 90 or more consecutive days in normal years. November through April are the driest months, with a second low in July, while September is the wettest.
Depth to buried soil: 102 to 203 cm (40 to 80 in)
Depth to redox concentrations: 41 to 76 cm (16 to 30 in)
Particle-size control section (weighted average):
Clay content: 9 to 18 percent
Sand content: 80 to 86 percent
A horizon
Hue: 10YR
Value: 5 or 6
Chroma: 2 or 3
Texture: fine sand
Clay content: 2 to 8 percent
Base saturation: 40 to 65 percent
EC (dS/m): 0 to 2
SAR: 0 to 4
Reaction: moderately acid to neutral
The A2 horizon, where present, has value or chroma of one unit higher.
C horizon
Hue: 10YR
Value: 6 to 8
Chroma: 2 to 4
Texture: fine sand
Clay content: 1 to 7 percent
Redox concentrations: none to common, fine or medium, faint to distinct, with clear or distinct boundaries in shades of brown or yellow
Base saturation: 40 to 65 percent
EC (dS/m): 0 to 2
SAR: 0 to 8
Reaction: moderately acid to neutral
2Ab horizon
Hue: 10YR
Value: 3 to 5
Chroma: 2 or 3
Texture: fine sand, loamy fine sand, or fine sandy loam
Clay content: 6 to 14 percent
Redox concentrations: none to common, fine or medium, faint to distinct, with clear or distinct boundaries, in shades of brown
Base saturation: 55 to 80 percent
EC (dS/m): 0 to 2
SAR: 0 to 8
Reaction: moderately acid to neutral
2Bwb1 horizon
Hue: 10YR
Value: 5 to 7
Chroma: 2 or 3
Texture: loamy fine sand or fine sandy loam
Clay content: 9 to 18 percent
Redox concentrations: none to common, fine or medium, faint to distinct, with clear or distinct boundaries, in shades of brown or yellow
Redox depletions: none to few, fine or medium, faint to distinct, with clear or distinct boundaries in shades of gray
Base saturation: 60 to 85 percent
EC (dS/m): 0 to 2
SAR: 3 to 8
Reaction: moderately acid to slightly alkaline
2Bwb2 horizon
Hue: 10YR
Value: 5 to 7
Chroma: 2 to 4
Texture: fine sandy loam
Clay content: 13 to 22 percent
Redox concentrations: none to common, fine or medium, faint to distinct, with clear or distinct boundaries in shades of brown or yellow
Base saturation: 80 to 95 percent
EC (dS/m): 0 to 2
SAR: 4 to 12
Reaction: moderately acid to slightly alkaline
2Bwb3 horizon
Hue: 10YR or 2.5Y
Value: 5 to 7
Chroma: 2 to 4
Texture: loamy fine sandy or fine sandy loam
Clay content: 10 to 18 percent
Redox concentrations: none to common, fine or medium, faint to distinct, with clear or distinct boundaries in shades of brown.
Identifiable secondary carbonates: none to few, fine to medium, in the form of masses or concretions
Base saturation: 70 to 100 percent
EC (dS/m): 0 to 2
SAR: 4 to 13
Reaction: neutral to slightly alkaline
COMPETING SERIES: These are the
Arenisco (TX),
Falfurrias (TX), and
Medanito (TX), series in the same family. Similar soils include the
Dougherty (OK),
Dutek (TX),
Lopeno (TX),
Nueces (TX),
Padrones (TX), and
Sarita (TX) series.
Arenisco and Falfurrias soils: do not have buried soils and Arenisco soils have a water table within 102 to 203 cm (40 to 80 in)
Medanito soils: have a buried soil from 51 to 102 cm (20 to 40 in)
Dougherty and Dutek soils: have thermic temperature regimes and Dutek soils have siliceous mineralogy
Lopeno soils: have redoximorphic features indicating wetness closer to the surface and have common or many coarse redoximorphic features with hue 7.5YR or redder in the lower part of the argillic horizon
Nueces and Padrones soils: have a sandy surface horizon 20 to 40 inches thick and Padrones soils have a natric horizon
Sarita soils: do not have buried A horizons and are less saline and sodic
GEOGRAPHIC SETTING:
Parent material: Eolian sands of Holocene age deposited over loamy alluvium of Quaternary age
Landform: ridges and sideslopes associated with vegetated longitudinal dunes on the Sandsheet
Slope: 1 to 5 percent
Mean annual air temperature: 22 to 23 degrees C (72 to 74 degrees F)
Mean annual precipitation: 635 to 711 mm (25 to 28 in)
Frost-free period: 310 to 341 days
Elevation: 3 to 15 m (10 to 50 ft)
Thornthwaite P-E Index: 31 to 36
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Cayo,
Falfurrias,
Medanito, and the
Padrones series.
Cayo soils: are calcareous to the surface and occur in lower concave positions
Falfurrias soils: do not have argillic horizons and occur on slightly higher ridgetop positions
Medanito soils: less than 102 cm (40 in) to a buried soil and occur on similar to slightly lower positions
Padrones soils: have a natric horizon and are on slightly lower positions
DRAINAGE AND PERMEABILITY: Somewhat excessively drained. Rapidly permeable. Runoff is negligible.
USE AND VEGETATION: Used for livestock grazing and wildlife habitat. Native vegetation consists of liveoak, seacoast bluestem, switchgrass, seashore paspalum, Scribner's panicum, partridge pea and turk's cap. The ecological site is Sand, PE 31-44 (R083EY706TX).
DISTRIBUTION AND EXTENT: Sandsheet Prairie (MLRA 83E in LRR I) of southern Texas. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Kenedy County, Texas, 2007. The name is coined.
REMARKS: The series was formerly included in the Sarita series. The series was separated based on the presence of the buried A horizons and difference in drainage class.
Diagnostic horizons and features recognized in this pedon are:
Particle size control section: 155 to 203 cm (61 to 80 in) (Btb1, Btb2 and Btb3 horizons)
Ochric epipedon: 0 to 43 cm (0 to 17 in) (A horizons)
Cambic horizon: 155 to 203 cm (61 to 80 in) (Bwb1, Bwb2 and Bwb3 horizons)
Redoximorphic concentrations: 41 to 203 cm (16 to 80 in)
Lithologic discontinuity: 147 to 203 cm (58 to 80 in)
The assignment of the cation-exchange activity class is supported by lab sample number S98TX-261-005 from Kenedy County, Texas.
ADDITIONAL DATA: TAMU data from Kenedy County, TX (S98TX-261-005)
TAXONOMIC VERSION: Keys to Soil Taxonomy, Tenth Edition, 2006