LOCATION CHO TXEstablished Series
TAXONOMIC CLASS: Loamy, carbonatic, thermic, shallow Petrocalcic Calciustolls
TYPICAL PEDON: Cho loam--rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 10 inches; brown (10YR 4/3) loam, dark brown (10YR 3/3) moist; weak fine granular and weak medium subangular blocky structure; slightly hard, friable; many fine roots; common fine pores; about 5 percent surface cover of indurated caliche fragments; about 10 percent fragments of indurated caliche in soil; violently effervescent; moderately alkaline; abrupt wavy boundary. (7 to 20 inches thick)
Bkm--10 to 14 inches; pinkish white (7.5YR 8/2) indurated caliche, broken into plates 6 to 18 inches across by 1 inch to 2 inches thick; laminar in upper part; about 5 percent brown loam between plates and in solution channels; violently effervescent; clear wavy boundary. (2 to 12 inches thick)
Bk--14 to 60 inches; pink (7.5YR 8/4) loam; massive; hard, friable; estimated more than 50 percent by volume of calcium carbonate; 20 to 30 percent weakly to strongly cemented concretions and fragments of caliche; violently effervescent; moderately alkaline.
TYPE LOCATION: McCulloch County, Texas; From the courthouse in Brady, 17.3 miles northwest on U. S. Highway 87, 15.9 miles north on Farm Road 503 (or 3.7 miles north of Doole), 0.4 mile northeast on ranch trail, 200 feet northwest in rangeland.
RANGE IN CHARACTERISTICS: Depth to the strongly cemented or indurated petrocalcic horizon ranges from 7 to 20 inches.
The A horizon has hue of 7.5YR or 10YR, value of 3 to 5, and chroma of 2 or 3. The fine earth fraction is loam or clay loam with a range in clay content from 15 to 35 percent. Calcium carbonate equivalent in the soil fraction less than 20mm is 40 to about 65 percent. Pebbles of caliche comprise 5 to 35 percent by volume. Cobbles comprise 0 to about 5 percent by volume.
The Bkm horizon is platy or massive, usually having a laminar cap from 1 to about 5 cm thick.
The Bk horizon has hue of 5YR, 7.5YR or 10 YR, value of 7 or 8, and chroma of 2 to 4. Texture of the fine earth fraction is loam or clay loam. Calcium carbonate equivalent is 40 to 85 percent. Siliceous and limestone pebbles comprise 2 to about 50 percent by volume.
COMPETING SERIES: There are no other series in this family. Closely similar series are Boracho, Conger, Eola, Kavett, Kimbrough, Mereta, Noelke, Pitzer, and Valco. Boracho soils contain more than 35 percent coarse fragments in the surface layer and are dry for longer periods of time in the control section. Conger soils have a cambic horizon and are dry in the control section for longer periods of time. Eola and Noelke soils have more than 35 percent coarse fragments in the control section. Noelke soils also have mixed mineralogy. Kavett and Mereta soils are more clayey, and the mineralogy of Kavett is montmorillonitic and Mereta is mixed Kimbrough and Pitzer soils have less than 40 percent calcium carbonate equivalent in the control section. Valco soils have average annual soil temperatures of more than 72 degrees F.
GEOGRAPHIC SETTING: Cho soils are on alluvial fans plains and ancient stream terraces. Slope gradient range from 0 to 8 percent. The soil formed in loamy calcareous gravelly alluvium several feet thick. The climate is dry subhumid. The mean annual precipitation ranges from 20 to about 30 inches and the the mean annual temperature ranges from 64 to 68 degrees F. Frost free days range form 210 to 240 days and elevation ranges form 1,200 to 1,750 feet. The Thornthwaite P-E index ranges from 25 to 50.
GEOGRAPHIC ASSOCIATED SOILS: These are the competing Kavett and Mereta series and Nuvalde and Rowena series. Nuvalde and Rowena soils lack petrocalcic horizons and have sola more than 20 inches thick. In addition, Rowena soils have clayey control sections.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is negligible on 0 to 1 percent slopes, very low on 1 to 3 percent slopes, low on 3 to 5 percent slopes and medium on 5 to 8 percent slopes. Permeability is moderate.
USE AND VEGETATION: Mainly used as rangeland. Present native vegetation is mainly threeawn, red grama, hairy triden, Texas wintergrass, sideoats grama, buffalograss, curlymesquite, mesquite bushes, catclaw, and cacti. Some areas are used for growing small grains.
DISTRIBUTION AND EXTENT: In west central Texas, mainly in the North Central Prairies, Rolling Limestone Prairies, Central Rolling Plains, Central Basin, and Central Edwards Plateau. The series is extensive with over 500,000 acres.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: McCulloch County, Texas; 1970.
REMARKS: These soils were formerly included in the Kimbrough and Mereta series.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 10 inches. (A horizon)
Petrocalcic horizon - 10 to 14 inches (Bkm horizon)