LOCATION ECTOR TX+NMEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, carbonatic, thermic Lithic Calciustolls
TYPICAL PEDON: Ector very gravelly loam--rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 4 inches; dark grayish brown (10YR 4/2) very gravelly loam; very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; slightly hard, friable, nonsticky and nonplastic; common fine roots; 25 percent limestone gravel, 5 percent limestone cobbles; violently effervescent; moderately alkaline; clear wavy boundary. (2 to 15 inches thick)
Bk--4 to 8 inches; dark grayish brown (10YR 4/2) very gravelly loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium granular and subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; 40 percent limestone gravel 15 percent limestone cobbles; the fragments of limestone are coated with secondary carbonates on the lower side; violently effervescent; moderately alkaline; abrupt irregular boundary. (2 to 15 inches thick)
Rk/Bk--8 to 15 inches; fractured hard limestone with fractures less than 4 inches apart; coatings of calcium carbonate on surface of fragments; cracks and fractures are filled and partially sealed with calcium carbonate in the upper 4 inches; in some cracks a thin seam of dark earth 3 mm thick is present; moderately alkaline; gradual wavy boundary. (0 to 12 inches thick)
R--15 to 40 inches; fractured limestone bedrock; few seams of calcium carbonate in fractures in the upper part.
TYPE LOCATION: Terrell County, Texas; 14 miles north via Texas Highway 349
from its intersection with U.S. Highway 90 at Dryden, 100 feet west of Texas Highway 349.
RANGE IN CHARACTERISTICS: Thickness of the solum to limestone bedrock ranges from 6 to 20 inches. Content of coarse fragments of limestone or hard calcium carbonate fragments ranges from 35 to 80 percent. About 30 to 75 percent are gravel size; 5 to 35 percent cobble size, and 0 to 20 percent stone size. More than 40 percent of soil mass less than 20 mm is made up of limestone fragments and secondary carbonates. Thickness of the calcic horizon is 6 to 17 inches. Mean annual soil temperatures range from 64 to 72 degree F.
The A and Bk horizons have hue of 7.5YR or 10YR, value of 3 to 5, and chroma of 2 or 3. Moist value and chroma are 2 or 3. Texture exclusive of coarse fragments, is silty clay loam, loam, silt loam, or clay loam, with a clay content ranging from about 20 to 40 percent, but averaging 20 to 35
percent in the particle size control section. Calcium carbonate equivalent in the fine earth fraction ranges from 10 to 30 percent in the A horizon, and from 40 to 60 percent in the Bk horizon.
The Rk/Bk horizon has soil material between fractures and coarse fragments. The calcium carbonate equivalent is 40 to 60 percent in the fine earth fraction. Colors of the soil material are similar to the overlying horizon. Many fracture faces and surfaces of fragments are coated with cemented calcium carbonate.
COMPETING SERIES: These are the Aledo (TX), Altuda (TX), Lueders (TX), and Oplin (TX) series. Similar soils are the Eckrant, Kimbrough, Latom, Lozier, Talpa, and Tarrant series. Aledo, Lueders, and Oplin soils are moist in the moisture control section for longer periods of time. Altuda soils have mean annual soil temperatures from 59 to 64 degrees F. Eckrant and Tarrant soils contain more than 35 percent clay in the fine earth fraction. Kimbrough soils have a petrocalcic horizon. Latom and Lozier soils do not have mollic epipedons, and are dry in the moisture control section for longer periods. Talpa soils average less than 35 percent coarse fragments in the control section.
GEOGRAPHIC SETTING: Ector soils are on limestone plateaus, plains, and erosional landscapes. Slopes range from 1 to 60 percent. Rock outcrops are common where gradients are over 15 percent. Stones generally occupy 1 to 10 percent of the surface. The underlying rock is hard limestone mainly of Cretaceous age, but some are of Permian or Pennsylvanian age. Mean annual precipitation ranges from 12 to 24 inches, and mean annual air temperature ranges from 57 to 70 degrees F. Frost-free days range from 210 to 240 days and elevation ranges from 1,095 to 3,995 feet. Thornthwaite annual P-E indices range from 16 to 32.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the competing Eckrant, Kimbrough, and Lozier series, and Conger, Midessa, Nuvalde, Reagan, Sanderson, Tobosa, Upton, and Veal series. Conger and Upton soils have a petrocalcic horizon and do not have a mollic epipedon. Midessa, Reagan, Sanderson, and Veal soils do not have a mollic epipedon and have sola thicker than 20 inches. Nuvalde and Tobosa soils have less than 35 percent coarse fragments and have sola thicker than 20 inches.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderate above a very slowly permeable limestone bedrock. Runoff is medium on 1 to 3 percent slopes, high on 3 to 5 percent slopes, and very high on slopes greater than 5 percent.
USE AND VEGETATION: Used entirely for rangeland. Native vegetation is short and mid grasses with some low desert shrubs. Grasses are mainly grama, triden, or threeawn. Shrubs are juniper, lotebush, dalea, guajillo, and blackbrush.
DISTRIBUTION AND EXTENT: Texas in MLRA 81A, and New Mexico. Extensive, comprising several million acres.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Reeves County, Texas; 1922.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 8 inches. (A and Bk horizons)
Calcic horizon - 4 to 15 inches. (Bk and Bk portion of Rk/Bk layer)
Lithic contact - 15 inches. (top of the R layer)
ADDITIONAL DATA:
TAXONOMIC VERSION: Keys to Soil Taxonomy, Tenth Edition, 2006