LOCATION CLARENCE ILEstablished Series
TAXONOMIC CLASS: Fine, illitic, mesic Aquic Argiudolls
TYPICAL PEDON: Clarence silty clay loam - on a west-facing slope of 1 percent in a pasture at an elevation of 235 meters (770 feet) above mean sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 18 centimeters (0 to 7 inches); very dark gray (10YR 3/1) silty clay loam, dark grayish brown (10YR 4/2) dry; moderate fine and medium granular structure; friable; many fine roots; slightly acid; abrupt smooth boundary.
A--18 to 28 centimeters (7 to 11 inches); very dark grayish brown (10YR 3/2) silty clay loam, dark grayish brown (10YR 4/2) dry; moderate fine and medium granular structure; friable; many fine roots; very dark gray (10YR 3/1) organic coatings on faces of peds; slightly acid; clear smooth boundary. (Combined thickness of the A horizon is 25 to 51 centimeters or 10 to 20 inches.)
Btg1--28 to 41 centimeters (11 to 16 inches); dark grayish brown (2.5Y 4/2) silty clay; weak fine subangular blocky structure; firm; common fine roots; common distinct dark grayish brown (10YR 4/2) clay films and very dark gray (10YR 3/1) organo-clay films on faces of peds; few fine prominent yellowish brown (10YR 5/6) masses of oxidized iron in the matrix; neutral; clear smooth boundary.
Btg2--41 to 61 centimeters (16 to 24 inches); dark grayish brown (2.5Y 4/2) clay; moderate medium angular blocky structure; firm; few fine roots; many distinct dark grayish brown (10YR 4/2) clay films and few distinct very dark gray (10YR 3/1) organo-clay films on faces of peds; many fine distinct light olive brown (2.5Y 5/4) and common fine prominent yellowish brown (10YR 5/6) masses of oxidized iron in the matrix; neutral; clear smooth boundary.
Btg3--61 to 74 centimeters (24 to 29 inches); grayish brown (2.5Y 5/2) silty clay; weak medium prismatic structure parting to moderate medium angular blocky; firm; few fine roots; many distinct dark gray (10YR 4/1) clay films on faces of peds; few distinct very dark gray (5Y 3/1) organic coatings along root channels; few fine black (10YR 2/1) very weakly cemented iron-manganese concretions throughout; very dark gray (10YR 3/1) krotovina; common fine prominent yellowish brown (10YR 5/6) and distinct light olive brown (2.5Y 5/4) masses of oxidized iron in the matrix; common fine faint gray (10YR 5/1) iron depletions in the matrix; 3 percent gravel; slightly alkaline; clear smooth boundary. (Combined thickness of the Bt horizon is 30 to 64 centimeters or 12 to 25 inches.)
BCtg--74 to 99 centimeters (29 to 39 inches); dark grayish brown (2.5Y 4/2) silty clay; moderate medium prismatic structure; very firm; few fine roots; few faint dark gray (10YR 4/1) clay films on faces of peds; few faint very dark gray (10YR 3/1) organic coatings along root channels; common medium white (10YR 8/1) soft masses of calcium carbonate throughout; common fine prominent yellowish brown (10YR 5/6) masses of oxidized iron in the matrix; few fine distinct gray (10YR 6/1) iron depletions in the matrix; 1 percent gravel; slightly effervescent; moderately alkaline; gradual wavy boundary. (0 to 25 centimeters or 0 to 10 inches thick)
Cdg--99 to 152 centimeters (39 to 60 inches); variegated dark grayish brown (2.5Y 4/2) light olive brown (2.5Y 5/4), and gray (5Y 5/1) silty clay; massive; very firm; common medium white (10YR 8/1) soft masses of calcium carbonate throughout; few calcium carbonate coatings on cleavage planes; 2 percent gravel; strongly effervescent (18 percent calcium carbonate equivalent); moderately alkaline.
TYPE LOCATION: Iroquois County, Illinois; about 0.8 kilometers (1/2 mile) north of Loda; 146 meters (480 feet) south and 485 meters (1,590 feet) east of the northwest corner of sec. 21, T. 24 N., R. 10 E.; USGS Buckley, Illinois, topographic quadrangle; lat. 40 degrees 31 minutes 48 seconds N. and long. 88 degrees 04 minutes 26 seconds W., NAD 27; UTM Zone 16, 0409054 Easting and 4487191 Northing, NAD 83.
RANGE IN CHARACTERISTICS: The depth to the base of soil development ranges from 64 to about 102 centimeters (25 to about 40 inches). Depth to carbonates ranges from 51 to 97 centimeters (20 to 38 in). Depth to high bulk density till, which is a restricting layer to penetration of roots and water, is about 64 to 102 centimeters (25 to 40 inches). The mollic epipedon is 25 to 51 centimeters (10 to 20 inches) thick. The average clay content of the particle-size control section is 50 to 60 percent, but some subhorizons may contain as little as 45 percent. The content of coarse fragments is low, commonly less than 5 percent in the series control section.
The Ap or A horizon has hue of 10YR, value of 2 or 3 moist (4 or 5 dry), and chroma of 1 or 2. It commonly is silty clay loam, but in some pedons it is silt loam or silty clay. It is moderately acid to neutral.
The Bt or Btg horizon has hue of 10YR or 2.5Y, value of 4 or 5, and chroma of 1 to 4 in the upper part and 2 to 6 in the lower part. Chroma of 2 is either in the matrix or in redoximorphic features. The Bt horizon is silty clay loam or silty clay in the upper part and is silty clay or clay in the lower part. It is moderately acid to slightly alkaline in the upper part and is neutral to moderately alkaline in the lower part. Some pedons are slightly to strongly effervescent in the lower part. Consistence is firm or very firm.
The BC, BCg, BCt, or BCtg horizon has hue of 2.5Y or 5Y, value of 4 or 5, and chroma of 2 to 4. It has redoximorphic features which have value of 4 through 6 and chroma of 1 through 6. It is silty clay or clay. It is slightly alkaline or moderately alkaline and contains carbonates. Moist bulk density is 1.7 g/cc or greater and is restricting to penetration of roots and water.
The Cd or Cdghorizon commonly has hue of 2.5Y, 5Y, or 5GY; value of 4 to 6; and chroma of 1 to 6. It is silty clay or clay. It is slightly alkaline or moderately alkaline and contains carbonates. Consistence is very firm. Moist bulk density is 1.7 g/cc or greater and is restricting to penetration of roots and water.
COMPETING SERIES: These are the Chenoa, Elliott, Martinton, and Strole soils in the same family and the Rutland and Swygert soils. Chenoa, Elliott, Martinton, Rutland, and Swygert soils average less 50 percent clay in the particle-size control section and have moderate or high available water capacity. Strole soils do not have a root restrictive layer.
GEOGRAPHIC SETTING: Clarence soils typically have convex slopes and are on relatively undissected parts of Wisconsinan till plains. Slope gradients range from 0 to 7 percent. The soils formed in calcareous, silty clay or clay till. Some pedons have a surface mantle of loess or silty glacial sediments as much as 51 centimeters (20 inches) in thickness. Mean annual air temperature ranges from 9 to 11 degrees C. (48 to 52 degrees F), mean annual precipitation ranges from 889 to 1,016 millimeters (35 to 40 inches), frost free days range from 140 to 180 days, and elevation ranges from 165 to 290 meters (540 to 950 feet) above sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Rutland soils and the Chatsworth, Mokena, Mona, Nappanee, and Rowe soils. Rutland soils are on higher parts of the topography where the loess or silty material is thicker. The moderately well drained Chatsworth soils have an ochric epipedon and lack an argillic horizon. Mokena and Mona soils are on higher parts of the topography and have less than 35 percent clay in the particle-size control section and have part of their subsoil formed in loamy outwash. Nappanee soils lack a mollic epipedon and form a biosequence on nearby similar landforms. The poorly drained Rowe soils are on adjacent lower lying parts of the landscape and have water-sorted sediments in the upper 51 to 102 centimeters (20 to 40 inches) of the profile. Rowe soils commonly are in a drainage sequence with Clarence soils.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat poorly drained. An intermittent perched water table is at a depth 30 to 61 centimeters (1.0 to 2.0 feet) below the surface during January through May in normal years, but these soils still have a deficit of available water for crops during the summer. The potential for surface runoff is medium to very high. Saturated hydraulic conductivity is very low to moderately low (0.0 to 0.42 micrometers per second). The available water capacity is low. Permeability is very slow
USE AND VEGETATION: Most areas are cropped. Corn, soybeans, small grain, and meadow are the principal crops. Native vegetation is prairie grass.
DISTRIBUTION AND EXTENT: Northeastern Illinois. Extent is moderate in MLRA 110.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Ford County, Illinois, 1929.
REMARKS: As a result of a characterization study of some soils on fine textured tills in northeastern Illinois, Clarence soils are classified as fine, illitic, mesic Aquic Argiudolls. The data from the characterization study indicate that Clarence soils have clay content less than 60 percent and low available water capacity due to the high bulk density of the B and C horizons. These soils are not considered to have an aquic moisture regime at suborder level of soil taxonomy because conditions are not right for reduction to occur. The wetness during late winter and early spring is caused by very slow permeability. The soils are not saturated for significant periods at a time when the soil temperature is above biologic zero.
Diagnostic horizons and features recognized in this pedon are: mollic epipdon - the zone from the surface of the soil to a depth of 28 centimeters (11 inches) (Ap and A horizons); argillic horizon - the zone from 28 to 74 centimeters (11 to 29 inches) (Btg1, Btg2, and Btg3 horizons).
ADDITIONAL DATA: The typical pedon is S77IL-075-9 from the characterization study of soils formed in fine textured materials in northeastern Illinois. NSSL Nos. 77P2646 - 77P2651.