LOCATION STOOKEY ILEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Typic Hapludalfs
TYPICAL PEDON: Stookey silt loam - in a wooded area on a west-facing slope with a gradient of 40 percent at an elevation of about 530 feet above mean sea level. (Colors are for moist soil unless otherwise stated).
A--0 to 3 inches; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; moderate medium granular structure; friable; many very fine and fine roots; about 16 percent clay; moderately acid; abrupt smooth boundary. (2 to 6 inches thick)
E--3 to 6 inches; dark yellowish brown (10YR 4/4) silt loam, light yellowish brown (10YR 6/4) dry; weak medium platy structure parting to weak medium granular; friable; common very fine and fine roots; about 18 percent clay; strongly acid; clear smooth boundary. (2 to 8 inches thick)
Bt1--6 to 13 inches; brown (7.5YR 4/4) silt loam; moderate fine subangular blocky structure; friable; common very fine and fine roots; few distinct light gray (10YR 7/2), dry, clay depletions on faces of peds; common faint continuous brown (7.5YR 4/4) clay films on faces of peds; about 25 percent clay; strongly acid; clear smooth boundary.
Bt2--13 to 24 inches; brown (7.5YR 4/4) silt loam; weak fine prismatic structure parting to moderate fine subangular blocky; friable; common very fine and fine roots; common faint continuous brown (7.5YR 4/4) clay films on faces of peds; about 24 percent clay; strongly acid; gradual smooth boundary.
Bt3--24 to 35 inches; brown (7.5YR 5/4) silt loam; weak fine prismatic structure parting to weak fine subangular blocky; friable; few very fine roots; common faint continuous brown (7.5YR 4/4) clay films on faces of peds; about 23 percent clay; moderately acid; gradual smooth boundary.
Bt4--35 to 53 inches; brown (7.5YR 5/4) silt loam; weak fine prismatic structure parting to weak medium subangular blocky; friable; few very fine roots; few faint patchy brown (7.5YR 4/4) clay films on faces of peds; about 22 percent clay; moderately acid; gradual smooth boundary. (Combined thickness of the Bt horizon is 36 to 56 inches.)
BC--53 to 62 inches; brown (7.5YR 4/4) silt loam; weak medium subangular blocky structure; friable; few very fine roots; about 20 percent clay; slightly acid; gradual smooth boundary. (0 to 18 inches thick)
C--62 to 80 inches; dark yellowish brown (10YR 4/4) silt loam; massive; very friable; few very fine roots; about 17 percent clay; neutral.
TYPE LOCATION: Monroe County, Illinois; about one mile northeast of Fults; approximately 2,300 feet north of the intersection of Sutterville Road and Fults Road and 125 feet west of Sutterville Road, T. 4 S., R. 10 W. in Renault Grant; USGS Renault, IL. topographic quadrangle; lat. 38 degrees 10 minutes, 27 seconds N. and long. 90 degrees 12 minutes 5 seconds W. NAD 27.
RANGE IN CHARACTERISTICS: Depth to the base of soil development is 40 to more than 80 inches. Loess thickness is greater than 80 inches. The particle-size control section averages 18 to 27 percent clay. The ratio of coarse silt to fine silt is 1.5 or greater. The series control section averages less than 7 percent sand coarser than very fine. Carbonates are below a depth of 60 inches in some pedons.
The Ap or A horizon has value of 3 to 5 (5 or 7 dry) and chroma of 1 to 3. Texture is silt loam or silt. Clay content is 8 to 22 percent. Reaction is very strongly acid to neutral.
The E horizon has value of 4 to 6 (6 to 8 dry) and chroma of 2 to 4. Texture is silt loam or silt. Clay content is 8 to 22 percent. Reaction is very strongly acid to slightly acid. The E horizon is incorporated into the Ap horizon in some pedons.
Some pedons have an EB or a BE horizon.
The Bt and BC horizons have hue of 5YR, 7.5YR, and 10YR; value of 4 to 6; and chroma of 3 to 6. Texture typically is silt loam but is silty clay loam in some thin subhorizons. Clay content averages 18 to 27 percent but ranges to 30 percent in thin subhorizons in some pedons. Reaction is very strongly acid to slightly acid.
The lower part of the control section (C) has hue of 7.5YR or 10YR, value of 4 to 6, and chroma of 2 to 6. Texture is silt loam or silt. Clay content is 10 to 24 percent. Reaction is moderately acid to moderately alkaline.
COMPETING SERIES: These are the Baraboo, Bertrand, Blackhammer, Camden, Dodge, Dubuque, Fayette, Flagg, Greenridge, Hackers, Jackson, Jemerson, La Farge, Lambeau, Martinsburg, Menfro, Middletown, Navlys, Palermo, Palsgrove, Pepin, Piscasaw, Ridgway, Rozetta, Ruma, Rush, Russell, Seaton, St. Charles, Sylvan, Thebes, and Yellowriver series. Baraboo, Dubuque, La Farge and Palsgrove soils are moderately deep or deep to a lithic or paralithic contact. Bertrand, Fayette, Martinsburg, Pepin, Seaton, and Yellowriver soils are in areas that have a mean annual soil temperature less than 56 degrees F. Blackhammer, Camden, Flagg, Greenridge, Jackson, Lambeau, Middletown, Piscasaw, Ridgway, Rush, Russell, St. Charles and Thebes soils have 2B horizons with more than 7 percent fine sand or coarser. Dodge, Navlys and Sylvan soils contain carbonates above a depth of 60 inches. Hackers soils have hues of 2.5YR or 5YR dominant in the solum and throughout the substratum. Jemerson soils contain more sand in all parts of the series control section. Menfro, Palermo, Rozetta and Ruma soils average more than 27 percent clay in all parts of the particle-size control section.
GEOGRAPHIC SETTING: Stookey soils are on gently sloping to very steep convex slopes on the bluffs along the Mississippi River Valley. Slope ranges from 2 to 70 percent. These soils formed in thick coarse loess. Mean annual temperature is 54 to 57 degrees F., mean annual precipitation is 36 to 44 inches, frost-free period is 180 to 210 days, and elevation is 350 to 800 feet above mean sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Drury, Hamburg, and Menfro soils. The well drained Drury soils are on footslopes below the Stookey soils. The somewhat excessively drained Hamburg soils formed in calcareous loess and are typically nearer to the bluff escarpment. The well drained Menfro soils are in a fine-silty family and are on summits and shoulders above the Stookey soils.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderate. Saturated hydraulic conductivity is moderately high or high (4.23 to 14.11 micrometers/sec). Potential for surface runoff is low to very high. Depth to an intermittent apparent high water table is greater than 6 feet in most years.
USE AND VEGETATION: Most areas are wooded. A few areas are pastured. Native vegetation is deciduous trees.
DISTRIBUTION AND EXTENT: Southern and southwestern Illinois. Extent is moderate, and mainly in MLRA 115.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Alexander County, Illinois, 1931.
REMARKS: The 3/98 revision reactivated the Stookey series. The Stookey series was inactivated in 1975. At that time the Stookey soils were included with the Seaton series.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from the surface to a depth of 6 inches (A and E horizons).
Argillic horizon - the zone from approximately 6 to 53 inches (Bt1, Bt2, Bt3, and Bt4 horizons).
Udic moisture regime.
ADDITIONAL DATA: Data for several pedons in Illinois are on file at the NRCS/USDA state office in Champaign, Illinois.