LOCATION DENROCK IL+IA WIEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, mesic Aquic Argiudolls
TYPICAL PEDON: Denrock silt loam - in a nearly level cultivated field. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 8 inches; very dark brown (10YR 2/2) silt loam, grayish brown (10YR 5/2) dry; weak very fine granular structure; friable; mildly alkaline; abrupt smooth boundary.
A--8 to 13 inches; very dark brown (10YR 2/2) silt loam, grayish brown (10YR 5/2) dry; strong very fine granular structure; friable; medium acid; clear smooth boundary. (Combined thickness of the A horizon is 10 to 18 inches.)
2Bt1--13 to 19 inches; dark reddish brown (5YR 3/3) silty clay loam; strong fine subangular blocky structure; firm; many thin dark reddish brown (5YR 2/2) clay films on faces of peds; medium acid; clear smooth boundary.
2Bt2--19 to 25 inches; mottled red (2.5YR 4/6) and dark reddish brown (5YR 3/3) silty clay; strong medium angular blocky structure; very firm; many thin dark reddish brown (5YR 2/2) clay films on faces of peds; strongly acid; gradual smooth boundary. (Combined thickness of the 2Bt horizon is 10 to 25 inches.)
3Bt3--25 to 35 inches; dark grayish brown (10YR 4/2) clay loam; common fine distinct yellowish brown (10YR 5/6), common fine prominent light olive brown (2.5Y 5/6), and few medium prominent dark red (2.5YR 3/6) mottles; strong medium angular blocky structure; very firm; common thin dark reddish brown (5YR 2/2) clay films on faces of peds; strongly acid; clear smooth boundary.
3Bt4--35 to 50 inches; dark brown (7.5YR 4/4) clay loam; common fine distinct strong brown (7.5YR 5/3) and few fine prominent dark reddish brown (2.5YR 3/4) mottles; moderate medium and coarse angular blocky structure; friable; common thin dark reddish brown (5YR 3/2) clay films on faces of peds; slightly acid; gradual smooth boundary. (Combined thickness of the 3Bt horizon is 10 to 30 inches.)
3C--50 to 60 inches; reddish brown (5YR 4/4) sand; single grain; loose; slightly acid.
TYPE LOCATION: Henderson County, Illinois; 168 feet north and 20 feet west of the center of sec. 9, T. 10 N., R. 5 W.
RANGE IN CHARACTERISTICS: The solum ranges from 36 to 60 inches in thickness. The mollic epipedon ranges from 10 to 20 inches in thickness. It does not include the upper part of the 2Bt horizon in some pedons.
The A horizon, including the Ap horizon, has hue of 10YR, value of 2 or 3 (4 or 5 dry), and chroma of 1 through 3. It is silt loam or silty clay loam. It is medium acid to mildly alkaline.
The 2Bt horizon has hue of 5YR or 2.5YR, value of 3 through 5, and chroma of 3 through 6. It is silty clay loam, silty clay or clay and averages between 38 and 60 percent clay. It is strongly acid or medium acid.
The 3Bt horizon has hue of 2.5YR, 5YR, 7.5YR, 10YR, or 2.5Y; value of 4 or 5; chroma of 2 through 4, and is mottled. Mottles have hue of 2.5YR, 5YR, 7.5YR, 10YR, 2.5Y; value of 3 through 6; and chroma of 2 through 8. The 3Bt horizon is dominantly clay loam, sandy clay loam, or loam, and contains strata of sandy loam, silty clay loam, or silt loam in some pedons. Sandy loam, loam, or silt loam strata are less than 6 inches in thickness above a depth of 40 inches. The 3Bt horizon is strongly acid to slightly acid.
The 3C horizon has hue of 5YR, 7.5YR, or 10YR; value of 4 or 5; and chroma of 3 or 4. It typically is loamy sand or sand at depths below 40 inches and is stratified in many pedons. Strata include clay loam, loam, silty clay loam, silt loam, or sandy loam. The 3C horizon is slightly acid or neutral.
COMPETING SERIES: These are the Shullsburg and Swygert series in the same family, and the Elliott, Flanagan, Herrick, Ipava, Keller, Martin, Martinton, and Rutland series. All these soils lack hue redder than 7.5YR. In addition, Shullsburg soils have shale bedrock at depths between 20 and 40 inches; Swygert, Elliott, Martin, and Rutland soils contain more clay and less sand in the lower part of the solum, and Martin soils have a mollic epipedon greater than 24 inches in thickness; Flanagan, Herrick, Ipava, and Keller soils are dominated by montmorillonitic clay, and typically contain less clay, in the control section; and Martinton soils are dominated by illitic clay, and typically contain less clay, in the control section.
GEOGRAPHIC SETTING: Denrock soils are on nearly level, slightly convex terraces. Slope gradients are 0 to 2 percent. The soils formed in loess or other silty material, clayey lacustrine sediments, and stratified alluvium. The mean annual temperature varies from 48 degrees to 53 degrees F., and mean annual precipitation varies from 32 to 34 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Coyne, Joslin, Niota, and Zwingle soils. The well drained Coyne and Joslin soils contain less clay in the control section and are on slightly higher elevations or more crested convex ridges nearby. The poorly drained Niota and Zwingle soils lack mollic epipedons, have albic horizons, and are on slightly lower elevations nearby.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained. Runoff is slow. Permeability is very slow in the 2Bt horizon, moderately slow in the 3Bt horizon, and rapid in the underlying material.
USE AND VEGETATION: Most areas are cultivated. Corn, soybeans, small grain, and meadow are the principal crops. Native vegetation was prairie grasses.
DISTRIBUTION AND EXTENT: Northwestern Illinois. These soils are of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Henderson County, Illinois, 1947.
REMARKS: The morphology is similar to that of Typic Argiudolls, but these soils behave more like Aquic Argiudolls and are so classified. Denrock soils perch water at depths of 1 to 2 feet during the spring and are considered to have horizons at depths less than 24 inches that are saturated with water for brief periods during the growing season.
OSED scanned by SSQA. Last revised by state on 2/82.