LOCATION VOCA TXEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, thermic Typic Paleustalfs
TYPICAL PEDON: Voca gravelly sandy loam--native rangeland. (Colors are for dry soil unless otherwise stated.)
A1--0 to 5 inches; brown (10YR 5/3) gravelly sandy loam, dark brown (10YR 4/3) moist; weak fine granular structure; hard, very friable; many fine roots; common very fine pores; 25 percent granite pebbles; neutral; clear smooth boundary. (3 to 8 inches thick)
A2--5 to 9 inches; light brown (7.5YR 6/4) gravelly sandy loam, brown (7.5YR 5/4) moist; weak fine granular structure; hard, very friable; many fine roots, many very fine pores; 25 percent granite pebbles neutral; abrupt smooth boundary. (3 to 12 inches thick)
Bt1--9 to 30 inches; dark red (2.5YR 3/6) gravelly clay, dark red (2.5YR 3/6) moist; moderate fine angular and subangular blocky structure; very hard, firm; few fine roots; few very fine pores; 30 percent granite pebbles continuous clay films on faces of peds; few feldspar crystals and flakes of mica; slightly acid; gradual wavy boundary. (10 to 25 inches thick)
Bt2--30 to 48 inches; reddish brown (5YR 5/4) very gravelly clay, reddish brown (5YR 4/4) moist; moderate fine subangular blocky structure; very hard, firm; few fine roots; 50 percent granite pebbles; clay films on faces of peds; many feldspar crystals and flakes of mica; slightly acid; gradual wavy boundary. (8 to 20 inches thick)
Cr--48 to 60 inches; 90 percent pinkish finely fragmented granite with thin films of soil material from above; many flakes of mica; slightly acid.
TYPE LOCATION: McCulloch County, Texas; about 15 miles south-southeast of Brady; 30 feet north of private road at a point 1440 feet west of intersection of private road and Ranch Road 1851, 4.3 miles south of Voca. Site is 0.6 mile north of the Mason County Line.
RANGE IN CHARACTERISTICS: Thickness of the solum and depth to weathered granite bedrock ranges from 40 to 60 inches. Coarse fragments consist of granite fragments (mainly quartz and feldspar).
The A horizon has hue of 10YR to 5YR, value of 4 to 6 and chroma of 3 to 6. It is sandy loam, fine sandy loam or loam averaging 10 to 19 percent clay. Coarse fragments content ranges from 5 to 30 percent. Reaction ranges from slightly acid to mildly alkaline.
The Bt horizon has hue 5YR or 2.5YR, chroma of 3 to 5 and value of 4 to 8. It is clay or sandy clay averaging 35 to 60 percent clay in the fine earth fraction. Coarse fragments in the upper 20 inches of the Bt horizon range from 25 to 35 percent and from 25 to 70 percent in the lower part. Reaction of the Bt horizon ranges from medium acid to neutral. The boundary between the Bt horizon and Cr horizon ranges from gradual to diffuse.
COMPETING SERIES: These are the Castell, Hamby, Pedernales, Weswind, Wichita and Winters soils in the same family. Similar soils include the Callisburg, Chigley, Cona, Edge, Margie, Minwells, Truce and Windthorst series. Castell soils are 20 to 40 inches thick over gneiss. Hamby, Pedernales, Weswind, Wichita and Winters soils have secondary carbonates in the lower Bt horizon. All of the similar soil receive more rainfall. Callisburg and Minwells soils are more than 20 to 40 inches thick over sandstone. Chigley soils are underlain with conglomerate at depths of 60 inches. Truce soils are underlain with shale at depths of 20 to 40 inches. Windthorst are underlain with sandstone at 40 to 60 inches.
GEOGRAPHIC SETTING: Voca soils occur on erosional uplands. Slopes are mainly less than 5 percent, but range from 0 to 12 percent. The soil developed in residuum and colluvium from granite. Outcrops of granite and quartz dikes are common in the landscape. The climate is dry subhumid with a Mean annual rainfall ranging from 24 to 28 inches and mean annual temperature ranging from 65 to 67 degrees F. Frost free days range from 210 to 240 days and elevation ranges from 700 to 1800 feet. The Thornthwaite P-E index ranges from 38 to 44.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Castell soils and the Click, Lou and Katemcy soils. The Castell and Katemcy soils occur on similar surfaces. Katemcy soils are formed in residuum from schist and have a gradual boundary between the A and Bt horizons. Click soils are loamy skeletal and contain more than 35 percent coarse fragments in the control section and are on slightly convex positions above. Lou soils are fine- loamy and contain less than 35 percent clay on the control section and are on slightly convex positions above.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is medium; Permeability is slow.
USE AND VEGETATION: Used mainly for rangeland. A limited acreage is used for growing small grains and sorghums for grazing. Native vegetation consists of mid grasses and short grasses, such as little bluestem, silver bluestem, purpletop, sideoats grama, threeawn, Arizona cottontop, windmill grass, and sand dropseed. Post oak, blackjack oak, and live oak trees occur in places.
DISTRIBUTION AND EXTENT: In the Central Basin of Texas, possibly in Oklahoma. The series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: McCulloch County, Texas; 1970.
REMARKS: Available data are Lincoln Lab. Samples 68L311-68L315. and 87P2410-2416. Properties and Reconstruction of Pedon 584TX-299-01, Larry T. West, 1984
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the surface to about 9 inches (A1 and A2 horizons)
Argillic horizon -The zone from about 9 to 48 inches (Bt1 and Bt2 horizons)
Paralithic contact - 48 inches to weathered granite bedrock.