LOCATION STOY IL+INEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Fragiaquic Hapludalfs
TYPICAL PEDON: Stoy silt loam on a slope of 3 percent in a cultivated field at an elevation of about 389 feet. (Colors are for moist soil unless otherwise stated.)
Ap--O to 6 inches; brown (10YR 4/3) silt loam; weak fine granular structure; friable; many roots; few fine concretions of iron and manganese oxides throughout; very strongly acid; abrupt smooth boundary. (6 to 10 inches thick)
El--6 to 9 inches; mixed light yellowish brown (10YR 6/4) and yellowish brown (IOYR 5/4) silt loam; weak thin platy structure parting to weak fine granular; friable; common roots; common-very dark grayish brown (10YR 3/2) specks; few medium distinct light brownish gray (10YR 6/2) iron depletions in the matrix; many fine concretions of iron and manganese oxides throughout; very strongly acid; clear smooth boundary.
E2--9 to 13 inches; yellowish brown (IOYR 5/4) silt loam; weak fine and medium granular structure; friable; common roots; common medium distinct light brownish gray (10YR 6/2) iron depletions and yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; many fine concretions of iron and manganese oxides throughout; very strongly acid; clear smooth boundary. (Combined thickness of the E horizon is 0 to 10 inches)
BE--13 to 16 inches; yellowish brown (10YR 5/6) silty clay loam; weak fine and medium subangular blocky structure; friable; common roots; few medium distinct light brownish gray (10YR 6/2) iron depletions in the matrix; many fine concretions of iron and manganese oxides throughout; very strongly acid; clear smooth boundary. (O to 6 inches thick)
Btl--16 to -24 inches; yellowish brown (10YR 5/8) silty clay loam; moderate fine subangular blocky structure; firm;
common roots; common prominent light brownish gray (10YR 6/2) clay depletions on faces of peds, light gray (IOYR 7/1) dry; few fine prominent light brownish gray (10YR 6/2) and brown (10YR 5/3) iron depletions in the matrix; many fine concretions of iron and manganese oxides throughout; very strongly acid; clear smooth boundary.
Bt2--24 to 27 inches; yellowish brown (IOYR 5/8 and 5/4) silty clay loam; moderate coarse subangular blocky structure parting to moderate fine and very fine angular blocky; firm; common roots; prominent continuous light brownish gray (10YR 6/2) clay depletions on faces of larger peds and continuous brown (10YR 4/3) clay films on faces of smaller angular peds; few fine prominent light gray (10YR 7/1) iron depletions in the matrix; many medium concretions of iron and manganese oxides throughout; many black (IOYR 2/1) specks and streaks; very strongly acid; clear smooth boundary.
Bt3--27 to 32 inches; yellowish brown (10YR 5/8 and 5/4) silty clay loam; moderate medium subangular blocky structure; very firm; common roots; continuous brown (10YR 4/3) clay films on faces of peds; few fine prominent light gray (10YR 7/1) and light brownish gray (10YR 6/2) iron depletions in the matrix; many fine concretions of iron and manganese oxides throughout; some splotches of black (10YR 2/1) stains or streaks; very strongly acid; gradual smooth boundary. (Combined thickness of the Bt horizon is 10 to 30 inches)
Btxl--32 to 36 inches; mottled grayish brown (10YR 5/2), brown (10YR 5/3), and yellowish brown (10YR 5/8) silty clay loam; weak coarse subangular blocky structure; firm; common roots; discontinuous brown (IOYR 4/3) clay films; few fine distinct light gray (10YR 7/1) iron depletions in the matrix; many fine concretions of iron and manganese oxides throughout; very strongly acid; gradual smooth boundary.
Btx2--36 to 45 inches; mottled grayish brown (10YR 5/2) brown (10YR 5/3) and yellowish brown (10YR 5/8) silty clay loam; weak coarse prismatic structure; extremely firm; few roots; patchy brown (10YR 4/3) clay films; common fine and medium distinct light gray (IOYR 7/1) iron depletions in the matrix; many fine concretions of iron and manganese oxides throughout; very strongly acid; gradual smooth boundary. (Combined thickness of the Btx horizon is 8 to 30 inches)
Cx--45 to 65 inches; mottled grayish brown (10YR 5/2), pale brown (10YR 6/3), yellowish brown (10YR 5/8), and light gray (10YR 7/1) silt loam; weak medium prismatic structure; extremely firm; few very dark grayish brown (IOYR 3/2) specks and splotches; many fine concretions of iron and manganese oxides; very strongly acid.
TYPE LOCATION: Gallatin County, Illinois, about 2 miles southwest of Omaha; 1,320 feet east of southwest corner of sec. 28, T. 7 S., R. 8 E.; USGS Norris City topographic quadrangle; lat. 37 degrees 52 minutes 43 seconds N., and long. 88 degrees 19 minutes 58 seconds W.
RANGE IN CHARACTERISTICS: Depth to the base of the argillic horizon ranges from 35 to 65 inches. Depth to the horizon with fragipan chracteristics ranges from 25 to about 45 inches. The particle-size control section averages between 27 and 35 percent clay. The series control section has less than 10 percent fine sand or coarser throughout
The upper part of the series control section (Ap,, A, or E horizons) has properties as follows. The Ap or A horizons have hue of IOYR, value of 4 or 5, and chroma of 2 or 3. It is commonly silt loam but may be silty clay loam where severely eroded. Where the soil is undisturbed it has A horizons less than 4 inches thick that have value of 2 or 3 and chroma of 1 or 2. Reaction ranges from very strongly acid to neutral.
The E horizon, where present, has hue of IOYR, value of 5 or 6, and chroma of 3 or 4. Reaction ranges from very strongly acid to slightly acid. Some pedons have a BE or B/E horizon less than 4 inches thick.
The next part of the series control section (Bt horizon) has hue of IOYR or 2.5Y, value of 4 to 6, and chroma of 2 to
8. Reaction is very strongly acid or strongly acid.
The next part of the series control section (Btx or Bx horizon) has hue of 10YR, value of 5 or 6, and chroma of 2 to 8. It is commonly silty clay loam but may be silt loam in the lower part in some pedons. Clay content ranges from 24 to 35 percent. Reaction ranges from very strongly acid to moderately acid.
The lower part of the series control section (C or Cx horizon) has hue of 10YR, value of 5 to 7, and chroma of 1 to 8. It is silt loam with clay content of 20 to 27 percent. Reaction ranges from very strongly acid to neutral.
COMPETING SERIES: No other series is in this family.
GEOGRAPHIC SETTING: The Stoy soils are on nearly level to gently sloping ridgetops on loess covered Illinoian till plains and bedrock plateaus. Slopes range from 0 to 10 percent. The soils are formed in loess. Mean annual air temperature ranges from 54 to 57 degrees F, mean annual precipitation ranges from 35 to 45 inches, frost free period ranges from 180 to 200 days, and elevation ranges from 340 to 1,020 feet above sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hosmer and Weir soils. Hosmer soils are moderately well drained and have fragipan horizons and are on nearby landscapes generally with steeper slope gradients. Weir soils are poorly drained and are dominated by chroma of 1 and 2 in the solum.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained. An intermittent perched seasonal high water table is at a depth of 1 to 2 feet below the surface at some time between January and May in most years. Surface runoff is slow or medium. Permeability is slow.
USE AND VEGETATION: Used mostly for cropland but some still remains in forest. Native vegetation is hardwood forest.
DISTRIBUTION AND EXTENT: Southern Illinois and possibly southern Indiana. Extent is moderate in MLRAs 113, 114, 115, and 122.
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Lawrence County, Illinois, 1952.
REMARKS: Diagnostic horizons and features recognized in this pedon are: ochric epipedon - the zone from the surface to a depth of 16 inches (Ap, E1, E2, BE horizons); argillic horizon - the zone from 16 to 45 inches (Bt1, Bt2, Bt3, Btx1, Btx2 horizons); udic moisture regime.