LOCATION MOKENA ILEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, active, mesic Aquic Argiudolls
TYPICAL PEDON: Mokena silt loam - on a north-facing slope of 1 percent in a cultivated field at an elevation of 194 meters (636 feet) above mean sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 13 cm (0 to 5 inches); black (10YR 2/1) silt loam, dark gray (10YR 4/1) dry; weak fine and medium granular structure; friable; common very fine and fine roots; neutral; clear smooth boundary.
A--13 to 30 cm (5 to 12 inches); black (10YR 2/1) loam, dark gray (10YR 4/1) dry; weak fine subangular blocky structure parting to weak fine and medium granular; friable; common very fine and fine roots; neutral; gradual wavy boundary. [Combined thickness of the A horizon is 25 to 46 cm (10 to 18 inches).]
AB--30 to 38 cm (12 to 15 inches); 70 percent black (10YR 2/1) and 30 percent very dark grayish brown (10YR 3/2) loam, dark gray (10YR 4/1) dry; weak fine and medium subangular blocky structure parting to weak fine and medium granular; friable; few very fine and fine roots; neutral; gradual wavy boundary. [0 to 15 cm (0 to 6 inches) thick]
Bt1--38 to 51 cm (15 to 20 inches); olive brown (2.5Y 4/3) loam; moderate medium subangular blocky structure; firm; few very fine and fine roots; many distinct dark grayish brown (2.5Y 4/2) clay films on faces of peds; common prominent black (10YR 2/1) organic coatings on surfaces along root channels; common fine faint grayish brown (10YR 5/2) iron depletions in the matrix; neutral; gradual wavy boundary.
Bt2--51 to 64 cm (20 to 25 inches); light olive brown (2.5Y 5/3) loam; moderate medium subangular blocky structure; firm; few very fine roots; common distinct dark grayish brown (2.5Y 4/2) clay films on faces of peds; common prominent black (10YR 2/1) organic coatings on surfaces along root channels; common medium black (N 2.5/) iron-manganese nodules throughout; common fine faint grayish brown (2.5Y 5/2) iron depletions in the matrix; neutral; gradual wavy boundary.
Bt3--64 to 81 cm (25 to 32 inches); dark yellowish brown (10YR 4/4) clay loam; moderate medium prismatic structure; firm; few very fine roots; common distinct very dark grayish brown (10YR 3/2) organo-clay films on faces of peds; common medium black (N 2.5/) iron-manganese nodules throughout; many medium distinct yellowish brown (10YR 5/6) masses of oxidized iron in the matrix; common medium distinct light brownish gray (2.5Y 6/2) iron depletions in the matrix; slightly alkaline; gradual smooth boundary.
Bt4--81 to 97 cm (32 to 38 inches); 50 percent yellowish brown (10YR 5/4) and 50 percent dark grayish brown (2.5Y 4/2) clay loam; weak medium and coarse angular blocky structure; firm; few very fine roots; few distinct very dark grayish brown (10YR 3/2) organo-clay films on faces of peds; common medium black (N 2.5/) iron-manganese nodules throughout; many medium distinct yellowish brown (10YR 5/6) masses of oxidized iron in the matrix; 1 percent gravel; slightly alkaline; clear smooth boundary. [Combined thickness of the Bt horizon is 30 to 91 cm (12 to 36 inches).]
2Bt5--97 to 107 cm (38 to 42 inches); gray (5Y 5/1) silty clay; weak fine and medium subangular blocky structure; very firm; few very fine and fine roots; few prominent dark grayish brown (2.5Y 4/2) clay films on faces of peds; common medium black (N 2.5/) iron-manganese nodules throughout; many medium prominent yellowish brown (10YR 5/4) masses of oxidized iron in the matrix; 1 percent gravel; slightly effervescent; slightly alkaline; gradual wavy boundary. [8 to 38 cm (3 to 15 inches) thick]
2Cd--107 to 152 cm (42 to 60 inches); 80 percent gray (5Y 5/1) and 20 percent yellowish brown (10YR 5/4) silty clay; massive; very firm; few fine black (N 2.5/) iron-manganese nodules throughout; common medium light gray (2.5Y 7/1) calcium carbonate concretions throughout; 2 percent gravel; strongly effervescent; moderately alkaline.
TYPE LOCATION: Kankakee County, Illinois; about 3.2 kilometers (2 miles) west of St. Anne; 604 meters (1,980 feet) south and 59 meters (194 feet) east of the northwest corner of sec. 7, T. 29 N., R. 12 W.; USGS Kankakee topographic quadrangle; lat. 41 degrees 00 minutes 53 seconds N. and long. 87 degrees 46 minutes 15 seconds W., NAD 27; UTM Zone 16, 0435183 easting and 4540680 northing, NAD 83.
RANGE IN CHARACTERISTICS: The depth to the base of soil development and densic contact ranges from 76 to 152 cm (30 to 60 inches). The depth to carbonates and the clayey lacustrine deposits or till ranges from 76 to 127 cm (30 to 50 inches). The mollic epipedon is 25 to 51 cm (10 to 20 inches) thick and includes the upper part of the B horizon in some pedons. The particle-size control section averages 27 to 35 percent clay, and 15 to 40 percent fine and coarser sand. The volume of rock fragments is less than 10 percent in the series control section.
The Ap, A, or AB horizon has hue of 10YR, value of 2 or 3 (4 or 5 dry), and chroma of 1 or 2. It is silt loam, loam, or silty clay loam. Reaction is moderately acid to neutral.
The Bt or 2Bt horizon has hue of 10YR or 2.5Y, value of 3 to 6, and chroma of 2 to 4. It typically is clay loam, loam, silty clay loam with a high content of sand, sandy clay loam or less commonly sandy loam or fine sandy loam. If a mantle of loess is present, it is silty clay loam or silt loam. Reaction ranges from slightly acid to slightly alkaline.
The 2Bt or 3Bt horizon, which formed in lacustrine sediments or till, has hue of 10YR, 2.5Y, or 5Y; value of 4 to 6; and chroma of 1 to 4. It is silty clay or clay. Clay content ranges from 40 to 60 percent. Reaction ranges from slightly acid to moderately alkaline.
The 2Cd or 3Cd horizon has hue of 10YR, 2.5Y, or 5Y; value of 4 to 6, and chroma of 1 to 4. It is silty clay or clay and is stratified in some pedons. Clay content ranges from 40 to 60 percent. Reaction is slightly alkaline or moderately alkaline, and carbonates are present.
COMPETING SERIES: These are the Aurand, Crane, Nachusa, Nenno, and Tiderishi series. The Aurand, Crane, Nachusa, Nenno and Tiderishi soils average less than 40 percent clay in the lower part of the series control section.
GEOGRAPHIC SETTING: Mokena soils are nearly level to slightly undulating on till plains or lake plains. They formed in loamy outwash and silty clay or clay lacustrine sediments or till. They have as much as 61 cm (24 inches) of loess or silty material at the surface of many pedons. Slope ranges from 0 to 5 percent. Mean annual air temperature ranges from 8 to 11 degrees C (48 to 52 degrees F), mean annual precipitation ranges from 787 to 1020 mm (31 to 40 inches), frost-free period ranges from 140 to 180 days, and elevation ranges from 158 to 285 meters (512 to 935 feet) above mean sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Brenton, Clarence, Mona, Reddick, and Swygert soils. The somewhat poorly drained Brenton, Clarence, and Swygert soils are on nearby landscapes. Brenton soils have less sand in the particle-size control section and less clay in the lower solum. Clarence and Swygert soils contain more clay in the particle-size control section. The moderately well drained Mona soils are on slightly higher positions on the landscape. The poorly drained Reddick soils are on lower positions of the landscape.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat poorly drained. These soils have a perched seasonal high water table at a depth of 30 to 61 cm (1 to 2 feet) at some time between January and May in most years. The potential for surface runoff is low or medium. Saturated hydraulic conductivity is moderately high or high (1.41 to 14.11 micrometers/s) in the loess and outwash and moderately low or moderately high (0.14 to 1.41 micrometers/s) in the lacustrine sediments or till. Permeability is moderately slow or moderate in the loess and outwash and very slow or slow in the lacustrine sediments or till.
USE AND VEGETATION: Most areas of the soil are cropped. Corn and soybeans, are the principal crops. A few areas are used for pasture. Native vegetation is tall prairie grasses.
DISTRIBUTION AND EXTENT: Northeastern Illinois. Extent is moderate in MLRA 110 and 108A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana.
SERIES ESTABLISHED: Will County, Illinois, 1951.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - 0 to 38 cm (0 to 15 inches) (Ap, A, and AB horizons); argillic horizon - 38 to 107 cm (15 to 42 inches) (Bt1, Bt2, Bt3, Bt4, and 2Bt5 horizons); densic contact - at 107 cm (42 inches); udic moisture regime.