LOCATION COMITAS TXEstablished Series
TAXONOMIC CLASS: Loamy, mixed, active, hyperthermic Arenic Aridic Paleustalfs
TYPICAL PEDON: Comitas loamy fine sand, on a southeast facing, 2 percent slope in pasture; elevation is 152 m (500 ft). (Colors are for dry soil unless otherwise stated.)
Ap--0 to 13 cm (0 to 5 in); brown (10YR 5/3) loamy fine sand, dark brown (10YR 3/3) moist; single grained; loose, slightly hard, very friable, nonsticky and nonplastic; common fine roots; neutral; abrupt smooth boundary. (0 to 25 cm [0 to 10 in] thick)
A--13 to 79 cm (5 to 31 in); brown (10YR 4/3) loamy fine sand, dark brown (10YR 3/3) moist; weak fine subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; common fine roots and pores; neutral; clear smooth boundary. (51 to 102 cm [20 to 40 in] thick)
Bt--79 to 150 cm (31 to 59 in); brown (7.5YR 5/4) fine sandy loam, brown (7.5YR 4/4) moist; weak coarse prismatic structure parting to and weak subangular blocky; hard, friable; few roots; few faint clay films on surfaces of prism and lining pores; common fine roots and pores; neutral; gradual smooth boundary. (23 to 76 cm [9 to 30 in] thick)
Btk--150 to 221 cm (59 to 87 in); reddish yellow (7.5YR 6/6) fine sandy loam, strong brown (7.5YR 5/6) moist; weak fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few distinct clay films on surfaces of peds; 2 percent fine films and threads of calcium carbonate; common fine pores; violently effervescent; moderately alkaline; clear smooth boundary. (18 to 66 cm [7 to 26 in] thick)
Bk--221 to 279 cm (87 to 110 in); reddish yellow (7.5YR 6/6) sandy clay loam, strong brown (7.5YR 5/6) moist; massive; hard; friable, slightly sticky and slightly plastic; 5 percent masses and weakly cemented concretions of calcium carbonate; violently effervescent; moderately alkaline; clear smooth boundary. (38 to 61 cm [15 to 24 in] thick)
C--279 to 284 cm (110 to 112 in); reddish yellow (7.5YR 8/6) sandy clay loam, reddish yellow (7.5YR 7/6) moist; massive; hard; friable, slightly sticky and slightly plastic; violently effervescent; moderately alkaline.
TYPE LOCATION: Jim Hogg County, Texas; form of the intersection of Texas Highways 285 and 359 in Hebbronville; 3.15 miles east on Texas Highway 285 to ranch road; 0.65 mile south on ranch road; 75 feet east of a ranch road in pasture. Hebbronville, Texas USGS topographic quadrangle. Latitude: 27 degrees, 17 minutes, 15 seconds N; Longitude: 98 degrees, 38 minutes, 06 seconds W.; NAD 83.
RANGE IN CHARACTERISTICS:
Soil Moisture: An ustic soil moisture regime bordering on aridic. The soil moisture control section remains moist in some or all parts for less than 90 consecutive days in normal years. 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.
Mean annual soil temperature: 22 to 24 degrees C (72 to 76 degrees F)
Depth to argillic horizon: 51 to 102 cm (20 to 40 in)
Depth to secondary calcium carbonate: 91 to 203 cm (36 to 80 in)
Particle-size control section (weighted average)
Clay content: 5 to 18 percent
Coarse Fragments: 0 to 5 percent
CEC/clay ratio: 0.40 to 0.60
A Horizon
Hue: 7.5YR or 10YR
Value: 4 to 6
Chroma: 2 to 4
Texture: fine sand or loamy fine sand
Clay content: 2 to 12 percent
Base saturation: 80 to 100 percent
Calcium carbonate equivalent: 0 to 1 percent
EC (dS/m): 0 to 2
Effervescence: noneffervescent
Reaction: slightly acid or neutral
Bt Horizons
Hue: 5YR, 7.5YR, or 10YR
Value: 4 to 7
Chroma: 2 to 8
Texture: fine sandy loam or sandy clay loam
Clay content: 6 to 24 percent
Clay films: few or common, faint or distinct, on surfaces of peds and lining pores
Base saturation: 75 to 100 percent
Calcium carbonate equivalent: 0 to 5 percent
Identifiable secondary carbonate: 0 to 2 percent, fine or medium, in the form of films and threads.
EC (dS/m): 0 to 2
Effervescence: noneffervescent or slightly effervescent in the upper part and strongly or violently effervescent in the lower part.
Reaction: slightly acid to slightly alkaline in the upper part and neutral to moderately alkaline in the lower part.
Bk and C Horizons
Hue: 5YR, 7.5YR, or 10YR
Value: 6 to 8
Chroma: 3 to 8
Texture: fine sandy loam, loam, or sandy clay loam
Clay content: 6 to 24 percent
Base saturation: 100
Calcium carbonate equivalent: 0 to 15 percent
Identifiable secondary carbonate: 0 to 8 percent, fine or medium, in the form of weakly cemented concretions and masses
EC (dS/m): 0 to 2
Gypsum: 0 to 2 percent
SAR: 0 to 1
Effervescence: slightly to violently effervescent
Reaction: slightly or moderately alkaline
COMPETING SERIES: There are no series in the same family. Similar soils
include the
Brennan(TX),
Brownfield (TX),
Duval (TX),
Hebbronville (TX),
Nobscot (OK), and
Nueces (TX) series.
Brennan, Duval, and Hebbronville soils: do not have sandy A horizons more than 51 cm (20 in) thick.
Brownfield and Nobscot soils: are in the thermic temperature regime.
Nueces soils: have redoximorphic features due to wetness in the upper B horizon and have more than 20 percent clay in the control section.
GEOGRAPHIC SETTING:
Parent material: eolian sands over eolian deposits and alluvium of the Sand Sheet Prairie.
Landform: vegetated sand sheet.
Slope: 0 to 8 percent
Mean annual air temperature: 21 to 23 degrees C (70 to 74 degrees F)
Mean annual precipitation: 457 to 635mm 20 to 28 in)
Precipitation pattern: moist spring and fall months and dry winter and summer months.
Frost-free period: 280 to 360 days
Elevation: 31 to 229 m (100 to 750 ft)
Thornthwaite annual P-E indices: 20 to 32
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Brennan, Duval, Falfurrias, Hebbronville, Nueces and Sarita series.
Brennan and
Duval soils: have argillic horizons; in addition Duval soils are deep to sandstone. These soils are on lower positions.
Hebbronville soils: are on lower positions.
Falfurrias soils: do not have an argillic horizon and occur on slightly higher positions.
Nueces soils: occur on similar positions.
Sarita soils: have sandy surface horizons more than 102 cm (40 in) thick and occur on slightly higher positions.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderately rapid. Runoff is negligible on slopes less than 1 percent, very low on 1 to 5 percent slopes, and low on 5 to 8 percent slopes.
USE AND VEGETATION: Rangeland, wildlife habitat, pasture, and cultivated land. Crops grown include peanuts, watermelons and grain sorghums. Native vegetation consists of tanglehead, trichloris, hooded windmillgrass, sand lovegrass, tasajillo, mesquite, prickly pear, and live oak. The ecological site is Loamy Sand 25-35 PZ(R083EY705TX)
DISTRIBUTION AND EXTENT: Sandsheet Prairie, Texas; LRR I; MLRA 83E; the series is of large extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Jim Hogg County, Texas, 1970.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Particle size control section: 79 to 130 cm (31 to 51 in).
Ochric (Arenic) epipedon: 0 to 79 cm (0 to 31 in). (A horizons)
Argillic horizon: 79 to 221 cm (31 to 87 in). (Bt and Btk horizons)
Calcic horizon: 221 to 279 cm (87 to 110 in). (Bk horizons)
Pale feature: clay content does not significantly decrease from the maximum above 152 cm (60 in) and contains hue of 7.5YR with chroma of more than 4 in the lower argillic.
Additional data: NSSL data number S01TX-505-004 from Zapata Co. The assignment of the cation-exchange activity class is assigned from lab data.
Taxonomic version: Keys to Soil Taxonomy, Tenth Edition, 2006.