LOCATION MT. CARROLL IL+IA MN WIEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Mollic Hapludalfs
TYPICAL PEDON: Mt. Carroll silt loam on a south-facing, 2 percent slope in a cultivated field at an elevation of 728 feet (222 meters) above mean sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 18 cm (0 to 7 inches); very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; moderate fine and medium granular structure; friable; common very fine and fine roots; slightly acid (pH 6.2); clear smooth boundary. [18 to 25 cm (7 to 10 inches) thick]
E--18 to 25 cm (7 to 10 inches); dark grayish brown (10YR 4/2) silt loam; moderate medium platy structure; friable; few fine roots; many faint very dark grayish brown (10YR 3/2) organic coats on faces of peds; few distinct light gray (10YR 7/2) dry, silt coatings on faces of peds; slightly acid (pH 6.2); clear smooth boundary. [8 to 20 cm (3 to 8 inches) thick]
BE--25 to 43 cm (10 to 17 inches); brown (10YR 4/3) silt loam; moderate fine subangular blocky structure; friable; few fine roots; many faint dark brown (10YR 3/3) organic coats on faces of peds; few faint very dark grayish brown (10YR 3/2) organic coats in root channels; moderately acid (pH 6.0); clear smooth boundary. [0 to 20 cm (0 to 8 inches)]
Bt1--43 to 64 cm (17 to 25 inches); dark yellowish brown (10YR 4/4) silt loam; moderate fine and medium subangular blocky structure; friable; few fine roots; many faint brown (10YR 4/3) clay films on faces of peds; few distinct very dark grayish brown (10YR 3/2) organic coats in root channels; moderately acid (pH 6.0); clear smooth boundary.
Bt2--64 to 99 cm (25 to 39 inches); yellowish brown (10YR 5/4) silt loam; moderate fine and medium subangular blocky structure; friable; few fine roots; common faint brown (10YR 4/3) clay films on faces of peds; common prominent very dark grayish brown (10YR 3/2) organic coats in root channels; few distinct light gray (10YR 7/2) dry, silt coatings on faces of peds; moderately acid (pH 5.8); gradual smooth boundary.
Bt3--99 to 140 cm (39 to 55 inches); yellowish brown (10YR 5/4) silt loam; weak medium and coarse subangular blocky structure; friable; common faint brown (10YR 4/3) clay films on faces of peds; few distinct light gray (10YR 7/2) dry, silt coatings on faces of peds; moderately acid (pH 5.6); gradual smooth boundary. [Combined thickness of the Bt horizon is 51 to 102 cm (20 to 40 inches)]
BC--140 to 157 cm (55 to 62 inches); yellowish brown (10YR 5/4) silt loam; weak medium prismatic structure; friable; few distinct light gray (10YR 7/2) dry, silt coatings on faces of peds; few fine dark reddish brown (5YR 2.5/2) soft masses of iron-manganese oxides within the matrix; moderately acid; gradual smooth boundary.
C--157 to 200 cm (62 to 80 inches); mixed yellowish brown (10YR 5/4) and pale brown (10YR 6/3) silt loam; massive; friable; few fine distinct light brownish gray (10YR 6/2) iron depletions and few fine faint yellowish brown (10YR 5/6 and 10YR 5/8) iron masses in the matrix; common fine and medium black (5YR 2.5/1) soft masses of iron-manganese oxides within the matrix; slightly acid.
TYPE LOCATION: Whiteside County, IL; 2,250 feet south and 720 feet east of the northwest corner of sec. 32, T. 22 N., R. 5 E.; USGS Morrison topographic quadrangle; lat. 41 degrees 51 minutes 09 seconds N. and long. 89 degrees 57 minutes 22 seconds W., NAD 27.
RANGE IN CHARACTERISTICS: The solum typically is 102 to 127 centimeters (40 to 50 inches) in thickness, but ranges from 76 to 203 centimeters (30 to 80 inches). Thickness of loess is greater than 203 centimeters (80 inches). It typically is moderately acid to neutral, but ranges to strongly acid in the Bt horizon in some pedons. Depths to carbonates are typically greater than 152 centimeters (60 inches), but are as shallow as 114 centimeters (45 inches) in some pedon. The control section averages 18 to 27 percent clay. The content of rock fragment is less than 1 percent throughout. Sand content ranges from 0 to 15 percent.
The Ap or A horizon has hue of 10YR, value of 2 or 3 (4 or 5 dry), and chroma of 1 to 3.
The E horizon has hue of 10YR, value of 4 to 6, and chroma of 2 to 4.
Some pedons do not have E horizon because of erosion and cultivation.
The Bt horizon has hue of 10YR or 7.5YR, value of 4 or 5, and chroma of 3 to 6. Some pedons have redoximorphic features in the lower part of the Bt horizon. The Bt horizon has weak or moderate subangular or angular blocky structure. The structure typically becomes coarser with increasing depth.
The BC horizon (where present) is silt loam or silt.
The C horizon has hue of 2.5Y, 10YR, or 7.5YR; value of 5 or 6; and chroma of 1 to 8. It is silt loam or silt. It is moderately acid to moderately alkaline.
COMPETING SERIES: These are the Batavia, Bowes, Churchtown, Deroin, Downs, Ella, Festina, Frankville, Gladek, Greenbush, Harvard, Hersey, Knox, Luana, Mannon, Massbach, Mellott, Myrtle, Nasset, Newhouse, Shelbyville, Watkins, Waubeek, and Yutan series. Batavia, Deroin, Downs, Harvard, Knox, Luana, Watkins, Waubeek and Yutan soils average 27 to 35 percent clay in the particle size control section. Bowes soils have more than 15 percent rock fragments in the lower part of the series control section. Churchtown, Myrtle, and Newhouse soils have more than 15 percent sand in the upper part of the series control section. Ella and Festina soils are stratified in the lower part of the series control section and average more than 15 percent sand. Frankville, Massbach, and Nasset soils have a lithic or paralithic contact at depths less than 152 cm (60 inches). Gladek soils formed in lacustrine sediments. Greenbush and Mannon soils have zones within 60 inches that are frequently saturated for periods longer than one month. Hersey soils have rock fragments in the lower part of the series control section and average more than 15 percent fine or coarser sand. Mellott soils have less than 50 percent silt in a horizon in the lower part of the series control section. Shelbyville soils have more than 35 percent clay in the lower part of the series control section.
GEOGRAPHIC SETTING: Mt. Carroll soils are on ridgetops and side slopes on loess hills and stream benches. They formed in thick loess deposits. Slope gradients typically are 2 to 15 percent, but range from 0 to 45 percent. Mean annual temperature varies from 7 to 12 degrees C (45 to 54 degrees F), and mean annual precipitation varies from 760 to 910 mm (30 to 36 inches).
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Downs, Fayette, Port Byron, Seaton soils, and Tama soils. Downs soils are on similar landforms nearby. Port Byron and Tama soils are on similar slopes, but are on broad interstream divides further from the drainageways. Tama soils have a mollic epipedon and contain more clay in the finest part of the Bt horizon. Seaton and Fayette soils are on similar or more sloping areas closer to the drainageways. Fayette soils are Typic Hapludalfs and contain more clay in the finest part of the Bt horizon.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained. Saturated hydraulic conductivity is 4.23 to 14.11 micrometers per second (moderate permeability).
USE AND VEGETATION: Most areas of Mt. Carroll soils with slopes less than 20 percent are cropped. Corn, soybeans, small grain and meadow are the principal crops. Most steeper areas are in meadow for hay or pasture. Native vegetation is prairie grasses and scattered hardwood
trees.
DISTRIBUTION AND EXTENT: LRR?s L and M, MLRA?s 95B, 104, 105, and 108. Western Illinois, eastern Iowa, southeastern Minnesota, and southwestern and west-central Wisconsin. Extent is small to moderate.
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Henderson County, Illinois, 1947.
REMARKS: Diagnostic horizons and features recognized in this pedon include:
Ochric epipedon ? the zone from the surface to a depth of 43 cm (0 to 17 inches);
Argillic horizon ? the zone from about 43 to 103 cm (17 to 55 inches) (Bt1 and Bt2 horizons).
The 4 to 6 foot water table phase of Mt. Carroll has been correlated to the recently established Mannon series.