LOCATION KERNAN ILEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Aeric Chromic Vertic Epiaqualfs
TYPICAL PEDON: Kernan silt loam, 2 to 4 percent slopes, at an elevation of 192 meters (632 feet) above mean sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 13 cm (0 to 5 inches); dark gray (10YR 4/1) silt loam, gray (10YR 6/1) dry; weak medium granular structure; friable; common very fine and fine roots; neutral; abrupt smooth boundary. [5 to 20 cm (2 to 8 inches) thick]
E--13 to 30 cm (5 to 12 inches); light brownish gray (10YR 6/2) silt loam, very pale brown (10YR 8/2) dry; moderate medium platy structure; friable; common very fine and fine roots; neutral; abrupt wavy boundary. [13 to 25 cm (5 to 10 inches) thick]
Btg--30 to 51 cm (12 to 20 inches); grayish brown (10YR 5/2) silty clay loam; moderate fine and medium angular blocky structure; friable; common fine roots; few faint very dark grayish brown (10YR 3/2) organo-clay films on faces of peds; very few faint light brownish gray (10YR 6/2) dry, silt coatings on faces of peds; few fine black (10YR 2/1) very weakly cemented iron-manganese oxide concretions throughout; common fine and medium prominent yellowish brown (10YR 5/6) masses of iron accumulation in the matrix strongly acid; gradual wavy boundary.
Bt1--51 to 74 cm (20 to 29 inches); brown (10YR 5/3) silty clay loam; moderate fine and medium prismatic structure; friable; common very fine and fine roots; very few faint very dark grayish brown (10YR 3/2) organic coatings along root channels and pores; common faint dark grayish brown (10YR 4/2) clay films on faces of peds and in pores; common medium brown (7.5YR 4/4) and few fine black (10YR 2/1) very weakly cemented iron- manganese oxide concretions throughout; common medium and coarse distinct yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; common medium faint grayish brown (10YR 5/2) iron depletions in the matrix; strongly acid; gradual wavy boundary.
Bt2--74 to 91 cm (29 to 36 inches); brown (10YR 5/3) silty clay loam; moderate medium prismatic structure parting to moderate fine and medium subangular blocky; friable; common very fine and fine roots; very few distinct very dark gray (10YR 3/1) organic coatings along root channels and pores; common faint dark grayish brown (10YR 4/2) clay films on faces of peds and in pores; common medium brown (7.5YR 4/4) and black (10YR 2/1) very weakly cemented iron-manganese oxide concretions throughout; many medium distinct brownish yellow (10YR 6/6) masses of iron accumulation in the matrix; common medium faint grayish brown (2.5Y 5/2) iron depletions in the matrix; moderately acid; clear wavy boundary. [Combined thickness of the Btg and Bt horizons is 38 to 76 cm (15 to 30 inches).]
2Btg--91 to 102 cm (36 to 40 inches); grayish brown (2.5Y 5/2) silty clay loam; moderate medium subangular blocky structure; firm; few very fine and fine roots; few distinct very dark gray (10YR 3/1) organic coatings along root channels and pores; common faint dark gray (10YR 4/1) clay films on faces of peds; common medium brown (7.5YR 4/4) and black (10YR 2/1) very weakly cemented iron-manganese oxide concretions throughout; many medium prominent yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; 4 percent gravel; neutral; gradual wavy boundary. [15 to 33 cm (6 to 13 inches) thick]
2BC--102 to 109 cm (40 to 43 inches); 60 percent light olive brown (2.5Y 5/3) and 40 percent olive gray (5Y 5/2) silty clay loam; weak medium and coarse subangular blocky structure; firm; few medium strong brown (7.5YR 5/6) and few fine black (10YR 2/1) very weakly cemented iron-manganese oxide concretions throughout; common medium prominent brownish yellow (10YR 6/6) masses of iron accumulation in the matrix; 2 percent gravel; slightly alkaline; clear wavy boundary. [0 to 15 cm (0 to 6 inches) thick]
2Cd--109 to 152 cm (43 to 60 inches); 90 percent brown (10YR 5/3) and 10 percent olive gray (5Y 5/2) silty clay; massive; very firm; few fine black (10YR 2/1) very weakly cemented iron-manganese oxide concretions throughout; common medium very pale brown (10YR 8/2) carbonate masses throughout; common medium distinct yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; 1 percent gravel; violently effervescent; moderately alkaline.
TYPE LOCATION: LaSalle County, Illinois; 425 meters (1,400 feet) north and 36 meters (120 feet) west of the southeast corner of sec. 21, T. 33 N., R. 2 E.; USGS Starved Rock topographic quadrangle; lat. 41 degrees 18 minutes 45 seconds N. and long. 88 degrees 59 minutes 29 seconds W., NAD 27; UTM Zone 16, 333303 easting and 4575364 northing, NAD 83.
RANGE IN CHARACTERISTICS: The depth to the base of soil development is typically 102 to 127 cm (40 to 50 inches) but ranges to 152 cm (60 inches). The thickness of the loess or silty sediments ranges from 89 to 140 cm (35 to 55 inches). The particle-size control section averages between 35 and about 42 percent clay. Sand content in the loess or silty material is less than 15 percent.
The A or Ap horizon has hue of 10YR, value of 3 to 5, and chroma of 1 to 3. It is silt loam.
The E horizon has hue of 10YR, value of 4 to 6, and chroma of 2. It is silt loam.
The Bt and Btg horizons have hue of 10YR or 2.5Y, value of 4 or 5, and chroma of 2 to 4. At least one horizon between the Ap and 76 cm (30 inches) does not have chroma of 2 or less in 60 percent of the matrix. This horizon commonly occurs in the upper part of the B horizon. Texture is silty clay loam or silty clay. Reaction is strongly acid or moderately acid.
The 2Btg horizon has hue of 10YR, 2.5Y or 5Y, value of 4 or 5, and chroma of 2 to 4. It is silty clay loam or silty clay. It has redoximorphic features and has chroma of 2 or less either in the matrix or as redox depletions. Reaction ranges from slightly acid to slightly alkaline.
Some pedons have a 2BC or 2BCg horizon.
The 2Cd or 2Cdg horizon has hue of 10YR, 2.5Y, or 5Y, value of 4 or 5, and chroma of 2 to 4. It is silty clay or clay and is calcareous.
COMPETING SERIES: These are the Ashgrove, Atlas, and Hurst soils. Ashgrove and Atlas soils are less than 89 cm (35 inches) to horizons with more 15 percent sand. Hurst soils have a mean soil temperature of greater than 13 degrees C (56 degrees F) in the temperature control section.
GEOGRAPHIC SETTING: The Kernan soils are on nearly level to gently undulating slopes in till plains and lake plains of Wisconsinan Age. They formed in 89 to 140 cm (35 to 55 inches) of loess or silty sediments with low content of sand and in silty clay or clay till or lacustrine sediments. Slope gradients range from 0 to 5 percent. Mean annual air temperature ranges from 7 to 12 degrees C (46 to 54 degrees F), mean annual precipitation ranges from 810 to 1020 mm (32 to 40 inches), frost free period ranges from 140 to 180 days, and elevation ranges from 155 to 311 m (510 to 1,020 feet) above sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These include Wenona, Rutland, Swygert, Nappanee, and Streator soils. Wenona and Rutland soils formed in similar materials but have mollic epipedons and on similar positions nearby. Streator soils formed in low, wet areas and are poorly drained. Swygert and Nappanee soils both formed primarily in silty clay glacial till and are on nearby landscapes.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat poorly drained. An intermittent perched high water table is at a depth of 15 to 61 cm (0.5 foot to 2.0 feet) at some time between January and May in normal years. The potential for surface runoff is low on level areas and medium or high on sloping areas. Saturated hydraulic conductivity is moderately high (1.41 to 4.23 micrometers/s) in the upper part of the series control section and moderately low or moderately high (0.14 to 1.41 micrometers/s) 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: Used mostly for cultivated crops such as corn, soybeans, small grain, and meadow. Native vegetation is hardwood forest.
DISTRIBUTION AND EXTENT: Northern and eastern Illinois, primarily in MLRA 110. Extent is small.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana.
SERIES ESTABLISHED: La Salle County, Illinois, 1969.
REMARKS: More study is needed to ascertain that the Kernan soils typically meet the saturation requirements of Aqualfs.
Diagnostic horizons and features recognized in this pedon are: ochric epipedon - the zone from the surface to 30 cm (0 to 12 inches) (A and E horizons); albic horizon - the zone from 13 to 30 cm (5 to 12 inches) (E horizon); argillic horizon - the zone from 30 to 102 cm (12 to 40 inches) (Btg, Bt1, Bt2, and 2Btg horizons).