LOCATION KOKERNOT TXEstablished Series
TAXONOMIC CLASS: Loamy, mixed, superactive, thermic Lithic Haplustalfs
TYPICAL PEDON: Kokernot gravelly sandy loam - rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 3 inches; brown (7.5YR 5/4) gravelly sandy loam, dark brown (7.5YR 3/4) moist; moderate fine subangular blocky and granular structure; hard, friable; many fine roots, about 20 percent by volume pebbles mostly less than 1/2 inch in diameter; neutral; clear smooth boundary. (2 to 6 inches thick)
BA--3 to 8 inches; reddish brown (5YR 5/4) gravelly loam, dark reddish brown (5YR 3/4) moist; moderate fine subangular blocky structure; hard, friable; many fine roots; common fine pores; about 20 percent by volume coarse fragments mostly less than 1/2 inch in diameter; neutral; smooth clear boundary. (0 to 7 inches thick)
Bt1--8 to 14 inches; reddish brown (5YR 5/4) gravelly clay loam, dark reddish brown (5YR 3/4) moist; moderate fine subangular blocky structure; hard, firm; many fine roots; few fine pores; thin patchy clay films; about 30 percent by volume coarse fragments mostly less than 1 inch in diameter; neutral, clear irregular boundary. (5 to 9 inches thick)
Bt2--14 to 18 inches; reddish brown (5YR 5/4) gravelly clay loam, dark reddish brown (5YR 3/4) moist; moderate fine subangular blocky structure; hard, firm; few fine roots and pores; about 30 percent by volume coarse fragments mostly less than 3 inches in diameter; patchy clay films; neutral; irregular abrupt boundary. (2 to 8 inches thick)
R--18 to 26 inches; trachyte bedrock; contains a few clay seams up to 1 inch in diameter in fractures of bedrock; bedrock is partially weathered in upper 2 or 3 inches.
TYPE LOCATION: Jeff Davis County, Texas; 5 miles south and 11 miles east of Fort Davis (on Grierson Mesa); Section 21, Block WJG 10, 1/2 mile west of southeast section corner and 1/4 mile north of south section line.
RANGE IN CHARACTERISTICS:
Soil moisture Aridic ustic soil moisture regime.
Depth to hard rock ranges from - 12 to 20 inches.
Reaction of the solum is typically neutral, but ranges from slightly acid to slightly alkaline.
A and B horizons
Hue: 5YR or 7.5YR
Value: 4 or 5 dry, 3 or 4 moist
Chroma 2 to 4.
A horizon
Texture : sandy loam or gravelly sandy loam.
Bt horizon
Texture: loam or clay loam,
Clay content: 18 to 35 percent clay with more than 15 percent coarser than very fine sand.
Rock fragments: 15 to 35 percent by volume
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Kokernot soils are on mesa tops. The soils formed in material accumulated over fine grained igneous rocks such as trachyte, rhyolite, or similar rocks. The surface gradient ranges from less than 1 percent to about 8 percent. The climate is semiarid to arid with average annual precipitation of 14 to 20 inches which occurs in the late spring and summer months. Elevation is 4,000 to 5,000 feet. The Thornthwaite P-E indices range from about 14 to 30. The mean annual air temperature ranges from 57 to 70 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Mainstay, Boracho, Brewster, Espy, Liv, Medley, Sanmoss, and Sproul series. Boracho and Espy soils have petrocalcic horizons. Brewster soils lack Bt horizons. Liv soils are clayey-skeletal. Medley and Sanmoss soils have a mollic epipedon. Sproul soils have more than 60 percent clay and smectitic mineralogy.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff, and moderate permeability.
USE AND VEGETATION: Used for rangeland. Grasses include black grama, blue grama, sprucetop grama, cane bluestem, lovegrass, sideoats grama, and a few widely scattered junipers.
DISTRIBUTION AND EXTENT: Southwestern Texas. MLRA 42. Moderately extensive (about 10,000 acres).
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Jeff Davis County, Texas; 1971.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 8 inches.
Argillic horizon - 8 to 14 inches.
Lithic contact - at 18 inches.