LOCATION CREAL IL+IAEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Aeric Endoaqualfs
TYPICAL PEDON: Creal silt loam - on an east-facing slope of 1 percent in a cultivated field. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 9 inches; dark grayish brown (10YR 4/2) silt loam, pale brown (10YR 6/3) dry; moderate medium granular structure; friable; slightly acid; abrupt smooth boundary. (6 to 10 inches thick)
E--9 to 18 inches; brown (10YR 5/3) silt loam; weak thick platy structure; friable; few thin dark grayish brown (10YR 4/2) organic coatings on faces of peds; few medium distinct yellowish brown (10YR 5/6) and common medium faint dark yellowish brown (10YR 4/4) masses of iron and manganese accumulations; few fine nodules (iron and manganese oxides); moderately acid; clear smooth boundary.
Eg--18 to 27 inches; light brownish gray (10YR 6/2) silt loam; weak thick platy structure; friable; common medium vesicular pores; common medium distinct yellowish brown (10YR 5/6) masses of iron and manganese accumulations; common coarse nodules (iron and manganese oxides); very strongly acid; clear smooth boundary. (The combined thickness of the E and Eg horizon is 14 to 26 inches.)
Btg1--27 to 32 inches; light brownish gray (10YR 6/2) silty clay loam; moderate medium angular and subangular blocky structure; firm; many distinct grayish brown (10YR 5/2) clay films on faces of peds; common medium prominent strong brown (7.5YR 5/6) masses of iron and manganese accumulations; very strongly acid; clear smooth boundary.
Btg2--32 to 41 inches; light brownish gray (10YR 6/2) silty clay loam; moderate medium prismatic structure parting to moderate medium subangular blocky; firm; many distinct grayish brown (10YR 5/2) clay films on faces of peds; many medium distinct yellowish brown (10YR 5/6) masses of iron and manganese accumulations; many medium nodules (iron and manganese oxides); very strongly acid; clear smooth boundary.
Btg3--41 to 55 inches; light brownish gray (10YR 6/2) silty clay loam; weak coarse prismatic structure; firm; few faint grayish brown (10YR 5/2) clay films on faces of peds; many medium distinct yellowish brown (10YR 5/6) masses of iron and manganese accumulations; common medium nodules (iron and manganese oxides); strongly acid; clear smooth boundary. (The combined thickness of the Bt horizon is 10 to 36 inches.)
BCg--55 to 60 inches; light brownish gray (10YR 6/2) silt loam; weak coarse prismatic structure; friable; many medium distinct yellowish brown (10YR 5/6) masses of iron and manganese accumulations; slightly acid.
TYPE LOCATION: Hamilton County, Illinois; about 2 miles west of Belle Prairie City; 2,448 feet east and 513 feet south of the center of sec. 36, T. 3 S., R. 5 E.
RANGE IN CHARACTERISTICS: The depth to the top of the argillic horizon ranges from 24 to 36 inches. The particle size control section averages between 25 and 35 percent clay and less than 15 percent sand. Coarse fragment content ranges from 0 to 2 percent in the upper two-thirds of the series control section and from 0 to 5 percent in the lower one-third of the control section. One or more subhorizons between the base of the Ap and a depth of 30 inches has colors with chroma of 3 or more in 40 percent or more of the matrix. The argillic has a cation exchange complex that averages less than 5 percent saturation with exchangeable sodium.
The Ap or A horizon has hue of 10YR, value of 4 or 5, and chroma of 2 or 3. The clay content averages between 20 and 27 percent and content of fine sand or coarser averages less than 15 percent. Reaction ranges from strongly acid to neutral. Some pedons in uncultivated areas have an A horizon less than 5 inches in thickness that has value of 3 or 4 (5 or 6 dry) and chroma of 2 or 3.
The E or Eg horizon has hue of 10YR, value of 4 to 6, and chroma of 2 to 4. The clay content averages between 18 and 25 percent and content of fine sand or coarser averages less than 15 percent. Reaction typically is extremely acid to strongly acid, but ranges to neutral in the upper part of some pedons that have been limed.
The Btg or Bt horizon has hue of 10YR or 2.5Y, value of 4 to 6, and chroma of 2 to 4. Redox features have hue of 10YR or 7.5YR, value of 4 to 7, and chroma of 1 to 8. Clay films have value of 4 or 5 and chroma dominantly of 2, but ranging from 1 to 3 in some sub-horizons. The clay content averages between 25 and 35 percent and content of fine sand or coarser averages less than 10 percent. Reaction is very strongly acid or strongly acid in the most acid part and ranges from very strongly acid to slightly acid.
The BCg, 2Btg, 2BCg, or Cg horizon has hue of 10YR or 2.5Y, value of 4 to 6, and chroma of 2 to 4. Redox features have hue of 10YR or 7.5YR, value of 4 to 7, and chroma of 1 to 8. The average clay content ranges from 20 and 30 percent and content of fine sand or coarser ranges from 3 to 20 percent. Reaction ranges from very strongly acid to neutral.
COMPETING SERIES: These are the Caseyville, Fitchville, Iva, Kendall, Starks, Stronghurst, Waynetown and Yeddo soils in the same family and the Aptakisic and Hatmaker soils in a closely related family (cation exchange activity class not assigned). All of these soils are less than 24 inches to the top of the argillic horizon.
GEOGRAPHIC SETTING: Creal soils are on foot slopes and at the heads of drainageways in uplands and on terrace treads. They formed in a mixture of loess and silty local alluvium. Slopes typically are concave, but range to plane or convex; commonly are short; and have gradients from 0 to 7 percent. Mean annual air temperature ranges from 52 to 57 degrees F, mean annual precipitation ranges from 38 to 45 inches, frost free days ranges from 180 to 210 days, and elevation ranges from 350 to 600 feet above sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ava, Banlic, Belknap, Bluford, Parke, and Racoon soils. The moderately well drained Ava soils have a fragipan horizon and are on adjacent or nearby similar or steeper slopes in the uplands. Banlic soils average less than 18 percent clay in the particle size control section and are on adjacent or nearby low terraces or elevated positions on flood plains typically at lower elevations than Creal soils. Belknap soils are on flood plains below Creal soils. Bluford soils contain more clay in the control section and are on broad upland ridges and knolls typically above Creal soils. Parke soils contain more sand in the lower part of the solum and typically are above Creal soils on loess-mantled ridges nearby. The poorly drained Racoon soils are on low terraces or elevated positions on the flood plains below Creal soils.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained. The potential for surface runoff is low or medium. Permeability is moderately slow. At some time during normal years the apparent water table is at a depth of 1 to 1.5 feet. The top of the water table is commonly at a depth of 1 to 3 feet below the surface during February to May.
USE AND VEGETATION: Most areas are used grow corn and soybeans. Other areas are used to grow small grain or meadow. Native vegetation is hardwood forest.
DISTRIBUTION AND EXTENT: Southern Illinois and Southeast Iowa. Creal soils are moderately extensive (more than 16,000 acres correlated).
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Williamson County, Illinois, 1952.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
ochric epipedon - the zone from the surface to a depth of 27 inches (Ap, E, and Eg horizons);
albic horizon - the zone from a depth of 9 inches to 27 inches (E and Eg horizons);
argillic horizon - the zone from 27 to 55 inches (the Btg horizons).