LOCATION COMITAS            TX

COMITAS SERIES

TAXONOMIC CLASS: Loamy, mixed, active, hyperthermic Arenic Aridic Paleustalfs

TYPICAL PEDON: Comitas loamy fine sand--cultivated. (Colors are for dry soil unless otherwise stated.)

Ap--0 to 5 inches; 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 10 inches thick)

A--5 to 31 inches; 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. (20 to 40 inches thick)

Bt--31 to 59 inches; brown (7.5YR 5/4) fine sandy loam, dark 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. (9 to 30 inches thick)

Btk--59 to 87 inches; 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; few fine films and threads of calcium carbonate; common fine pores; violently effervescent; moderately alkaline; clear smooth boundary. (7 to 26 inches thick)

Bk--87 to 110 inches; 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. (15 to 24 inches thick)

C--110 to 112 inches; 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, in a cultivated field 75 feet east of a private road, which point is 0.65 mile south of its intersection with Texas Highway 285 intersection is 3.15 miles east of the intersection of Texas Highways 285 and 359 in Hebbronville.

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 June through August and December through February. These soils are intermittently moist in September through November and March through May.

Solumn thickness: 60 to more than 80 inches
Mean annual soil temperature: 72 to 76 degrees F.
Depth to argillic horizon: 20 to 40 inches
Depth to secondary calcium carbonate: 36 to 80 inches
Depth to calcic horizon: below 80 inches

Particle-size control section (weighted average)
Clay content: 31 to 87 percent
Coarse Fragments: 0 to 5 percent
CEC/clay ratio: 0.40 to 0.60

A Horizon
Hue: 7.5YR, 10YR
Value: 4 to 6
Chroma: 2 to 4
Texture: fine sand, 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 Horizon
Hue: 5YR, 7.5YR, 10YR
Value: 4 to 7
Chroma: 2 to 8
Texture: fine sandy loam, 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
EC (dS/m): 0 to 2
Effervescence: noneffervescent to slightly effervescent in the upper part and strongly effervescent to 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, 10YR
Value: 6 to 8
Chroma: 3 to 8
Texture: fine sandy loam, loam, sandy clay loam
Clay content: 6 to 24 percent
Base saturation: 100
Calcium carbonate equivalent: 5 to 15 percent
Identifiable secondary carbonate: 2 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: violently effervescent
Reaction: moderately alkaline

COMPETING SERIES: There are no series in the same family. Similar soils
include the Brennan, Duval, Hebbronville, Nobscot, and Nueces series.

Brennan, Duval, and Hebbronville soils: do not have sandy A horizons more than 20
inches thick.
Nobscot soils: are in the thermic temperature regime.
Nueces soils: have redoximorphic features due to wetness in the upper B horizon.

GEOGRAPHIC SETTING:
Parent material: sandy and loamy sediments derived from eolian materials overlying ancient alluvium.
Landform: uplands and terraces of Pleistocene age.
Slope: 0 to 8 percent
Mean annual air temperature: 70 to 74 degrees F.
Mean annual precipitation: 18 to 25 inches
Precipitation pattern: moist spring and fall months and dry winter and summer months.
Frost-free period: 280 to 360 days
Elevation: 50 to 750 feet
Thornthwaite annual P-E indices: 24 to 34

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Brennan, Duval,
Falfurrias, Hebbronville, and Nueces and Sarita series.

Brennan, Duval, and Hebbronville soils: are on lower landscape positions.
Falfurrias soils: do not have an argillic horizon, and occur on similar surfaces.
Nueces soils: occur on similar surfaces.
Sarita soils: have sandy surface horizons more than 40 inches thick, and occur on similar surfaces.

DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderately rapid. Runoff is negligible on slopes less than 3 percent, very low on 3 to 5 percent slopes, and low on 5 to 8 percent.

USE AND VEGETATION: Rangeland 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.

DISTRIBUTION AND EXTENT: Northern and south-central Rio Grande Plain, Texas; LRR I; MLRA 83C; the series is of moderate extent.

MLRA OFFICE RESPONSIBLE: Temple, Texas

SERIES ESTABLISHED: Jim Hogg County, Texas, 1970.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Particle size control section: 31 to 51 inches. (upper 20 inches of Bt horizon)

Ochric (Arenic) epipedon: 0 to 31 inches. (A horizons)

Argillic horizon: 31 to 87 inches. (Bt and Btk horizons)

Calcic horizon: 87 to 110 inches. (Bk horizons)

Pale feature: clay content does not significantly decrease from the maximum above 60 inches and contains hue of 7.5YR with chroma of more than 4 in the lower argillic.

The assignment of the cation-exchange activity class is inferred from lab data from surrounding counties in the region.

Taxonomic version: Soil Taxonomy, Second Edition, 1999