LOCATION QUIHI TXEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, mixed, active, hyperthermic Petrocalcic Paleustolls
TYPICAL PEDON: Quihi gravelly clay loam - rangeland.
(Colors are for dry soil unless otherwise stated.)
A1--0 to 3 inches; dark brown (7.5YR 3/2) gravelly clay loam, very dark brown (7.5YR 2/2) moist; moderate fine and very fine subangular blocky and granular structure; hard, friable; many fine roots; contains about 15 percent rounded chert pebbles mainly 1/2 to 2 inches in diameter; neutral; clear wavy boundary. (0 to 4 inches thick)
A2--3 to 9 inches; very dark brown (7.5YR 2/2) gravelly clay loam, very dark brown (7.5YR 2/2) moist; moderate fine subangular blocky structure; hard, friable; many fine roots and pores; contains about 25 percent rounded chert pebbles mainly 1/2 to 3 inches in diameter; few chert cobbles and stones; neutral; clear wavy boundary. (3 to 10 inches thick)
Bt1--9 to 18 inches; dark reddish brown (5YR 3/3) very gravelly clay, dark reddish brown (5YR 2/2) moist; moderate fine blocky structure; very hard, firm; common fine roots; few fine pores; contains about 75 percent of rounded chert pebbles mainly 1/2 to 2 inches in diameter; few cobbles; thin clay films on surface of peds and coarse fragments; neutral; gradual wavy boundary. (6 to 15 inches thick)
Bt2--18 to 26 inches; dark reddish brown (2.5YR 3/4) very gravelly clay, dark reddish brown (2.5YR 2/4) moist; moderate fine blocky structure; very hard, firm; few fine roots; few pores; contains about 65 percent of rounded chert pebbles to 2 inches in diameter; thin clay films on surfaces of peds and coarse fragments; mildly alkaline; clear wavy boundary. (6 to 20 inches thick)
Bt3--26 to 30 inches; red (2.5YR 5/6) gravelly clay, red (2.5YR 4/6) moist, with a few fine faint mottles of light yellowish brown (2.5YR 6/4); moderate medium blocky structure; very hard, firm; few roots; about 15 percent rounded chert pebbles; patchy clay films on surfaces of peds and coarse fragments; moderately alkaline; abrupt wavy boundary. (0 to 12 inches thick)
Bkm--30 to 31 inches; very pale brown (10YR 7/3) strongly cemented caliche layer; contains about 10 percent chert pebbles; calcareous; abrupt wavy boundary. (1/4 to 4 inches thick)
Ck--31 to 46 inches; white (10YR 8/2) weakly cemented caliche containing a few chert gravel; massive; calcareous; moderately alkaline.
TYPE LOCATION: Medina County, Texas; 13.1 miles east of Hondo, Texas, on U.S. Highway 90 from its intersection with Texas Highway 173; 1 mile northwest on Quihi-Castroville Road; site is in rangeland 50 feet north of fenceline.
RANGE IN CHARACTERISTICS: Solum thickness to the petrocalcic horizon is 20 to 40 inches.
The A horizon is dark grayish brown (10YR 4/2), dark brown (10YR 3/3, 4/3; 7.5YR 3/2, 4/2), very dark brown (7.5YR 2/2; 10YR 2/2), reddish brown (5YR 4/3), or dark reddish brown (5YR 3/2, 3/3). It is gravelly sandy clay loam, gravelly clay loam, gravelly loam, sandy clay loam, or clay loam with coarse fragments comprising 5 to 50 percent by volume. It is slightly acid through mildly alkaline.
Bt1 and Bt2 horizons are dark brown (7.5YR 3/2, 4/2), dark reddish gray (5YR 4/2), reddish brown (5YR 4/3), dark reddish brown (5YR 3/2, 3/3; 2.5YR 3/4), red (2.5YR 4/6), or dusky red (2.5YR 3/2). Texture of the soil fraction less than 2 mm is clay with clay content ranging from 40 to 70 percent. Rounded chert pebbles comprise 35 to 85 percent by volume. The Bt horizon is slightly acid through moderately alkaline. The Bt3 horizon is reddish brown (5YR 4/4, 5/4; 2.5YR 4/4), yellowish red (5YR 4/6, 5/6), or red (2.5YR 4/6, 5/6). Few to common faint or distinct yellowish and brownish mottles in hues of 7.5YR or 10YR occur on most pedons. It is clay, sandy clay, or sandy clay loam with less than 20 percent coarse fragments. Visible calcium carbonate content is the Bt3 horizon may be as high as 5 percent in some pedons. The Bt3 horizon is lacking in some pedons.
The upper part of the Bkm horizon is laminar in most pedons. The Ck horizon ranges from strongly cemented caliche to weakly consolidated pinkish limy earth of about clay loam texture.
COMPETING SOILS: There are no other soils in the same family. Similar soils include the Dina, Hanis, Hesselberg, Hindes, Pratley, Rumple, and Yologo series. Dina, Hanis, Hindes, and Rumple soils lack petrocalcic horizons. In addition, Dina, Hindes, and Rumple soils as well as Pratley soils have mean annual soil temperatures less than 72 degrees F. Hesselberg soils have mean annual soil temperatures that vary less than 9 degrees F. between the summer and winter seasons and, in addition, they are shallow and contain less than 35 percent coarse fragments in the control section. Pratley soils have calcareous sola that contain less than 15 percent by volume of coarse fragments. Yologo soils have loamy-skeletal control sections.
GEOGRAPHIC SETTING: Quihi soils occur on undulating to gently rolling uplands. Slope gradients range from 1 to 8 percent but mainly are less than 4 percent. The soil formed in very gravelly clay and clay loams presumed to be ancient alluvial sediments. The climate is dry subhumid. Annual rainfall ranges from 26 to 32 inches, mean annual temperature ranges from 70 to 73 degrees F., and Thornthwaite P-E indices range from 31 to 44 .
GEOGRAPHICALLY ASSOCIATED SOILS: These include the similar Hanis soils and the Knippa, Olmos, and Valco soils which have calcareous sola. Knippa soils have less than 35 percent coarse fragments and Olmos and Valco soils have sola less than 20 inches thick.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderately slow permeability.
USE AND VEGETATION: Used for rangeland. Present native grasses include purpletop tridens, red grama, threeawn, Texas grama, Texas wintergrass, curlymesquite, and silver bluestem. Woody vegetation includes live oak, mesquite, bluewood condalia, Texas colubrina, Texas persimmon, whitebrush, little-leaf sumac, agrito, yucca, and cacti.
DISTRIBUTION AND EXTENT: Mainly in the northeast Rio Grande Plain. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Medina County, Texas; 1972.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 18 inches.
Argillic horizon - 9 to 30 inches.
Petrocalcic horizon - 30 to 31 inches.