LOCATION WENONA ILEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Oxyaquic Argiudolls
TYPICAL PEDON: Wenona silt loam on a west facing 2 percent slope in a cultivated field at an elevation of 218.5 meters (718 feet) above mean sea level. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 23 cm (0 to 9 inches); very dark brown (10YR 2/2) silt loam; very dark grayish brown (10YR 3/2) dry; moderate fine granular structure; friable; many fine roots; slightly acid; abrupt smooth boundary.
A--23 to 36 cm (9 to 14 inches); very dark brown (10YR 2/2) silt loam; very dark grayish brown (10YR 3/2) dry; moderate fine and medium granular structure; friable; many fine and very fine roots; moderately acid; clear smooth boundary. [Combined thickness of the A horizons is 25 to 51 cm (10 to 20 inches).]
Bt1--36 to 51 cm (14 to 20 inches); brown (10YR 4/3) silty clay loam; moderate fine subangular blocky structure; firm; common fine roots; many distinct dark brown (10YR 3/3) organo-clay films on faces of peds; moderately acid; clear smooth boundary.
Bt2--51 to 66 cm (20 to 26 inches); dark yellowish brown (10YR 4/4) silty clay loam; moderate medium subangular blocky structure; firm; common fine roots; many distinct brown (10YR 4/3) clay films on faces of peds; moderately acid; clear smooth boundary.
Bt3--66 to 79 cm (26 to 31 inches); dark yellowish brown (10YR 4/4) silty clay loam; weak medium prismatic structure parting to moderate medium subangular blocky; firm; few fine roots; common distinct brown (10YR 4/3) clay films on faces of peds; few fine black (10YR 2/1) iron-manganese oxide nodules throughout; few fine prominent yellowish brown (10YR 5/8) masses of iron accumulation in the matrix; slightly acid, clear smooth boundary.
Bt4--79 to 94 cm (31 to 37 inches); dark yellowish brown (10YR 4/4) silty clay loam; weak medium prismatic structure parting to weak medium subangular blocky; firm; common distinct brown (10YR 4/3) clay films on faces of peds; few very fine roots; few fine black (10YR 2/1) iron-manganese oxide nodules throughout; common fine and medium faint brown (10YR 5/3) masses of iron accumulation in the matrix; common fine and medium distinct grayish brown (10YR 5/2) iron depletion in the matrix, neutral; clear smooth boundary. [Combined thickness of the Bt horizons ranges from 46 to 76 cm (18 to 30 inches).]
2BCt--94 to 127 cm (37 to 50 inches); olive (5Y 5/3) silty clay; weak medium prismatic structure parting to weak coarse subangular blocky; very firm; few fine roots, few faint olive gray (5Y 5/2) clay films on vertical faces of peds; common fine distinct yellowish brown (10YR 5/4) and common fine prominent yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; about 5 percent gravel; slightly effervescent; slightly alkaline; clear smooth boundary. [18 to 36 cm (7 to 14 inches)thick]
2Cd--127 to 152 cm (50 to 60 inches); olive gray (5Y 5/2) silty clay; massive; very firm; common fine and medium distinct light olive brown (2.5Y 5/4) and few fine prominent yellowish brown (10YR 5/6 and 5/8) masses of iron accumulation in the matrix; about 5 percent gravel; strongly effervescent; slightly alkaline.
TYPE LOCATION: LaSalle County, Illinois; about 1.6 kilometers (1 mile) east of Rutland; 99 meters (324 feet) east and 66 meters (216 feet) north of southwest corner of sec. 8, T. 29 N., R. 2 E.; USGS Minonk topographic quadrangle; lat. 40 degrees 59 minutes 07 second N. and long. 89 degrees 01 minutes and 35 seconds W., NAD 27; UTM zone 16 0329543 easting and 4539089 northing, NAD 83.
RANGE IN CHARACTERISTICS: The depth to the base of soil development typically is 114 to 140 cm (45 to 55 inches)and ranges to shallow as 102 cm (40 inches) in some pedons. The loess or silty material typically is 89 to 114 cm (35 to 45 inches) thick and ranges to 140 cm (55 inches) in thickness and is underlain by till or lacustrine sediments. The dominant clay mineral in the loess or silty material is smectite and in the till or lacustrine sediments is illite. The mollic epipedon is 25 to 51 cm (10 to 20 inches) thick. The particle-size control section averages from 35 to 42 percent clay and less than 5 percent fine sand or coarser. Reaction commonly ranges from moderately acid to strongly acid in the upper part of the series control section and from slightly acid to slightly alkaline in the lower part.
The Ap or A horizon has hue of 10YR, value of 2 or 3, and chroma of 1 or 2. It is silt loam or silty clay loam.
The Bt horizon has hue of 10YR, value of 4 to 6, and chroma of 3 to 6. It is silty clay loam or silty clay.
The 2Bt, 2BCt, 2BC, or 2Bk horizon commonly has hue of 2.5Y or 5Y, value of 4 to 6, and chroma of 2 to 6. Chroma of 2 is present either as redoximorphic features or matrix color. The texture is silty clay or silty clay loam.
The 2Cd horizon commonly has a hue of 2.5Y or 5Y, value of 4 to 6 , and chroma of 2 to 4. It is silty clay or clay. Carbonates are present, and reaction is slightly alkaline or moderately alkaline.
COMPETING SERIES: This is the Otley series. Otley soils average less than 30 percent clay in the lower third of the series control section.
GEOGRAPHIC SETTING: Wenona soils typically are on convex slopes in the relatively undissected till and lakebed plains of Wisconsinan Age. Slope gradients commonly are 4 to 7 percent but range from 2 to 15 percent. The soils formed in loess or other silty material and in silty clay or clay till or lacustrine sediments. Summers are hot and winters are cold. Mean annual air temperature ranges from about 7 to 12 degrees C (45 to 53 degrees F),mean annual precipitation ranges between 762 to 1016 mm (30 and 40 inches),frost free days range from 140 to 180 days, and elevation ranges from 183 to 311 meters (600 to 1020 feet) above sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: The somewhat poorly drained Rutland soils and poorly drained Streator soils form a drainage sequence with Wenona soils. Swygert and Clarence soils are associated in areas with thinner loess coverings while Osco soils are associated in areas with thicker loess coverings.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Moderately well drained. The potential for surface runoff is low or medium. Saturated hydraulic conductivity is moderately high (1.41 to 4.23 micrometers per second) in the upper part of the series control section and moderately low to moderately high (0.14 to 1.41 micrometers per second) in the lower part. Permeability is moderately slow in the upper part of the series control section and very slow or slow in the lower part.
USE AND VEGETATION: Mostly cultivated; corn, soybeans, small grains and hay are the major crops. Native vegetation was prairie grasses.
DISTRIBUTION AND EXTENT: Mainly in central and north-central Illinois. These soils are of small extent in MLRAs 108A, 110, and 115C.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: LaSalle County, Illinois, 1969.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth 36 cm (14 inches) (Ap and A horizons); argillic horizon - the zone from approximately 36 to 94 cm (14 to 37 inches) (Bt1, Bt2, Bt3, and Bt4 horizons); udic moisture regime.