LOCATION SCHULENBURG TXEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, thermic Udic Argiustolls
TYPICAL PEDON: Schulenburg sandy clay loam on a 6 percent slope. (Colors are for dry soil unless otherwise stated.)
A1--0 to 5 inches; dark gray (10YR 4/1) sandy clay loam, very dark gray (10YR 3/1) moist; moderate medium subangular blocky structure; slightly hard, friable; many fine roots: few fine pores; slightly acid; clear smooth boundary. (4 to 13 inches thick)
A2--5 to 13 inches; dark grayish brown (10YR 4/2) sandy clay loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; slightly hard, friable; many fine roots; common fine and medium pores; slightly acid; clear smooth boundary. (5 to 7 inches thick)
Bt1--13 to 19 inches; brown (7.5YR 5/4) sandy clay loam, dark brown (7.5YR 4/4) moist, moderate medium subangular blocky structure; hard, firm; common fine roots; few fine pores; common thin faint clay films on surfaces of peds; neutral; gradual smooth boundary.
Bt2--19 to 29 inches; brown (7.5YR 5/4) sandy clay loam, dark brown (7.5YR 4/4) moist; moderate medium subangular blocky structure parting to moderate fine subangular blocky; hard, firm; common fine roots; few fine pores; common thin faint clay films on surfaces of peds; neutral; gradual wavy boundary. (Combined thickness of Bt horizons is 10 to 24 inches)
Btk1--29 to 36 inches; dark brown (7.5YR 3/4) sandy clay loam, dark brown (7.5YR 3/4) moist; strong medium angular blocky structure; hard, firm; common fine roots; common fine pores; common thin faint clay films on surfaces of peds; 2 percent calcium carbonate as fine threads, 5 percent threads and concretions of calcium carbonate; strongly effervescent; moderately alkaline; gradual wavy boundary.
Btk2--36 to 42 inches; dark brown (7.5YR 3/4) sandy clay loam, dark brown (7.5YR 3/4) moist; strong coarse subangular blocky structure parting to moderate medium subangular blocky; very hard, firm; few fine roots; few thin faint clay films on surfaces of peds; 20 percent fine and medium concretions of calcium carbonate; strongly effervescent; moderately alkaline; gradual wavy boundary.
Btk3--42 to 49 inches; brown (7.5YR 4/4) sandy clay loam, brown (7.5YR 4/4) moist; strong medium subangular blocky structure; very hard, firm; few fine roots; common fine pores; few fine wormcasts; few thin faint clay films on surfaces of peds; 15 percent masses and concretions of calcium carbonate; violently effervescent; moderately alkaline; clear wavy boundary.
Btk4--49 to 57 inches; yellowish brown (10YR 5/6) sandy clay loam, yellowish brown (10YR 5/8) moist; weak coarse subangular blocky structure; hard, friable; few fine roots; common fine and medium pores; few fine wormcasts; few thin faint clay films on surfaces of peds; 7 percent fine threads, masses and concretions of calcium carbonate; common fine fragments of brown (7.5YR 4/4) material; violently effervescent; moderately alkaline; gradual wavy boundary. (Combined thickness of Btk horizons is 18 to 36 inches)
BCk--57 to 80 inches; brownish yellow (10YR 6/6) very fine sandy loam, yellowish brown (10YR 5/6) moist; weak coarse prismatic structure; hard, friable; few fine pores; 7 fine threads and concretions of calcium carbonate; strongly effervescent; moderately alkaline.
TYPE LOCATION: Fayette County, Texas; In La Grange, from the intersection of U.S. Highway 77 and Texas Highway 71, 13.2 miles south on U.S. Highway 77, 0.4 mile east on ranch road, 0.3 mile north along fence line, and 50 feet east in pasture. (Latitude: 96 degrees, 53 minutes, 45 seconds North; Longitude: 29 degrees, 44 minutes, 06 seconds West).
RANGE IN CHARACTERISTICS: Thickness of the solum ranges from 60 to more than 80 inches. Depth to masses and threads of calcium carbonate ranges from 22 to 36 inches. The clay content of the control section ranges from 20 to 35 percent. Coarse fragments range from 0 to 15 percent. The mollic epipedon ranges from 10 to 20 inches thick.
The A horizon has hue of 7.5YR or 10YR, value of 3 to 5, and chroma of 1 or 2. Texture is loam or sandy clay loam. The clay content ranges from 15 to 25 percent. Reaction is slightly acid or neutral.
The Bt horizons have hue of 5YR to 10YR, value of 3 to 5, and chroma of 2 to 4. Texture is sandy clay loam or clay loam. Reaction is slightly acid or neutral.
The Btk horizons have hue of 5YR to 10YR, value of 3 to 6, and chroma of 2 to 6. Texture is sandy clay loam or clay loam. Calcium carbonate equivalent ranges from 5 to 25 percent.
The BCk horizon has hue of 5YR to 10YR, value of 4 to 6, and chroma of 2 to 6. Clay content ranges from 10 to 20 percent. Calcium carbonate equivalent ranges from 5 to 25 percent.
When present, the C horizon is variable and ranges from weakly consolidated calcareous sandstone to massive calcareous loamy or sandy materials.
COMPETING SERIES: These are the Carman (OK), Chickasha (OK), Lovedale (OK), Milan (KS), Navina (OK), Ravia (OK), Stoneburg (TX), Teller (OK), and Wynoka series. Similar soils are the Cuero and Weesatche series. Carman soils are calcareous to the surface and have redoximorphic features due to wetness. Chickasha soils have a paralithic contact between 40 and 60 inches. Lovedale soils have sola from 30 to 60 inches. Milan and Teller soils do not have secondary carbonates. Navina soils do not have carbonates within 36 inches. Ravia soils contain 10 to 30 percent coarse fragments in the argillic horizon. Stoneburg soils have a paralithic contact at a depth of 20 and 40 inches. Wynoka soils have a lithologic discontinuity between 30 to 60 inches of the surface. Cuero and Weesatche soils have mollic epipedons more than 20 inches thick. In addition, Weesatche soils have hyperthermic temperature regimes.
GEOGRAPHIC SETTING: Schulenburg soils are on gently to moderately sloping uplands. Slope gradient ranges from 3 to 8 percent. Surfaces are weakly convex to plane. The soil formed in calcareous loamy material that contains weakly consolidated calcareous sandstone, mainly of the Fleming and Oakville Formations. Mean annual temperature ranges from 67 to 70 degrees F., and mean annual precipitation ranges from 34 to 40 inches. Frost free days range from 260 to 280 and elevation ranges from 400 to 600 feet. Thornthwaite P-E indices range 42 to 62.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Carbengle, Dubina, Frelsburg, Hallettsville, Klump and Knolle series. Carbengle soils do not have an argillic horizon and are on similar positions. Dubina and Hallettsville soils have clayey argillic horizons and are on lower positions. Frelsburg soils are clayey and are on higher positions. Klump soils have siliceous mineralogy and are on similar positions. Knolle soils do not have a mollic epipedon and are on higher convex positions.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderate. Runoff is low on 3 to 5 percent slopes and medium on 5 to 8 percent slopes.
USE AND VEGETATION: Used mainly for improved pasture. A small acreage is in corn and other crops. Native vegetation is little bluestem and other prairie grasses. Trees include scattered post oak, live oak and hackberry.
DISTRIBUTION AND EXTENT: Southern claypan and southern blackland prairie of Texas. The series is of minor extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Fayette County, Texas 1992. The name is from a city in Fayette County.
REMARKS: The soils have formerly been included in the Cuero and Weesatche series.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 13 inches. (A1 and A2 horizons)
Argillic horizon - 13 to 57 inches. (Bt and Btk horizons)
Calcic horizon - 36 to 80 inches. (Btk and BCk horizons)
Udic feature- soil is in an ustic bordering udic moisture regime.
ADDITIONAL DATA: A complete characterization report was provided by the Texas Agricultural Experiment Station Soil Characterization Laboratory from a 1990 pit study in Fayette County. (S90TX149-1-1-9)