LOCATION RIDOTT ILInactive Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Mollic Epiaqualfs
TYPICAL PEDON: Ridott silt loam - near the crest of a low ridge in a cultivated field. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 8 inches; very dark grayish brown (10YR 3/2) silt loam, dark grayish brown (10YR 4/2) dry; few fine prominent reddish brown (5YR 4/4) and yellowish red (5YR 4/6) mottles; moderate fine granular structure; friable; slightly acid; clear smooth boundary. (7 to 10 inches thick)
Eg--8 to 11 inches; dark grayish brown (2.5Y 4/2) and grayish brown (2.5Y 5/2) silt loam; few fine prominent yellowish brown (10YR 5/4) mottles; moderate thin platy structure parting to moderate fine granular; friable; very dark gray (10YR 3/l) organic fillings in root channels; moderately acid; clear smooth boundary. (3 to 8 inches thick)
Btg1--11 to 15 inches; grayish brown (2.5Y 5/2) silty clay loam; few fine prominent yellowish brown (10YR 5/6) mottles; moderate fine subangular blocky structure; friable; many distinct dark gray (10YR 4/1) clay films on faces of peds; moderately acid; clear smooth boundary.
Btg2--15 to 24 inches; gray (5Y 5/1) silty clay loam; common fine prominent yellowish brown (10YR 5/6) mottles; strong fine subangular blocky structure; firm; many distinct dark gray (10YR 4/1) clay films on faces of peds; moderately acid; clear smooth boundary.
Btg3--24 to 33 inches; gray (5Y 5/1) silty clay loam; many medium prominent yellowish brown (10YR 5/6) mottles; strong fine and medium subangular blocky structure; firm; many distinct dark gray (10YR 4/1) clay films on faces of peds; common black (N 2.5/0) concretions (iron and manganese oxides); moderately acid; clear smooth boundary.
Btg4--33 to 38 inches; dark gray (5Y 4/1) silty clay loam; many medium prominent yellowish brown (10YR 5/6) mottles; moderate medium subangular blocky structure; firm; common distinct dark gray (10YR 4/1) and gray (10YR 5/1) clay films on faces of peds; common black (N 2/0) concretions (iron and manganese oxides); moderately alkaline; clear smooth boundary. (Combined thickness of the Btg horizons is 20 to 36 inches.)
2Btg5--38 to 44 inches; grayish brown (2.5Y 5/2) silty clay; common medium prominent yellowish brown (10YR 5/6) mottles; weak medium subangular and angular blocky structure; firm; few faint dark gray (N 4/0) and gray (N 5/0) clay films on faces of peds; many black (N 2/0) concretions (iron and manganese oxides); slick or soapy feel as in shale material; moderately alkaline; clear smooth boundary. (5 to 10 inches thick)
2Cr--44 to 60 inches; mixed light olive brown (2.5Y 5/4) and greenish gray (5G 6/1) shale; extremely firm; streaks and spots of white (10YR 8/1) concretions (calcium carbonate); strong effervescence; moderately alkaline.
TYPE LOCATION: Stephenson County, Illinois; about 4 miles northeast of Pearl City; 330 feet south of the center of sec. 22; T. 27 N., R. 6 E.
RANGE IN CHARACTERISTICS: The solum is 40 to 55 inches in thickness. The paralithic contact is at a depth between 40 and 60 inches. The loess mantle is 30 to 50 inches in thickness. The dominant clay mineral in the loess is montmorillonite and in the
shale is illite.
The Ap or A horizon has hue of 10YR, value of 2 or 3, and chroma of 1 or 2. It is silt loam, except eroded pedons include silty clay loam. It is slightly acid or neutral.
The E horizon has hue of 10YR or 2.5Y, value of 4 or 5, and chroma of 2. It is medium acid to neutral. In some pedons it has been incorporated into the Ap horizon.
The Btg horizon has hue of 10YR, 2.5Y, or 5Y; value of 4 through 6; and chroma of 1 or 2. It typically is mottled with higher chroma. It is medium acid in some part, typically in
the upper part, and grades to neutral to moderately alkaline with increasing depth.
The 2Btg horizon has hue of 10YR, 2.5Y, or 5Y; value of 5 or 6; and chroma of 1 or 2. Mottles have chroma of 1 through 8. Clay films have hue of 10YR, 2.5Y, 5Y, or are neutral; value of 4 or 5; and chroma of 0 through 2. The 2Btg horizon is silt loam, silty clay loam, silty clay or clay. Some pedons exhibit rock structure or contain fragments of weathered shale. It is neutral to moderately alkaline. Some pedons contain free carbonates.
The 2Cr horizon has hue of 10YR, 2.5Y, 5Y, 5GY, 5G, or is neutral; value of 5 or 6; and chroma of 0 through 8. It is calcareous, noncalcareous, or nonacid shale. It is silty to
clayey and contains variable amounts of hard rock fragments of shale, sandstone, or limestone.
COMPETING SERIES: These are the
Ansgar,
Coppock,
Cory,
Newberry, and
Walford series in the same family, and the
Loran and
Massbach serie. Ansgar soils formed in loess and the underlying till or till-derived sediments and contain more sand in the 2Btg
horizon. Coppock soils have a thicker E horizon and do not have a 2Bt horizon. Cory and Walford soils formed entirely in loess and do not have a 2Bt horizon. Newberry soils formed in loess and the underlying silty or loamy deposits that overlie a strongly developed paleosol in Illinoian till. They are more acid in the upper part of the Btg horizon. Loran soils have a mollic epipedon. Massbach soils have browner colors in the
control section.
GEOGRAPHIC SETTING: Ridott soils are on gently rolling ridges and side slopes of loess covered, bedrock controlled uplands. Slope gradients are 1 to 7 percent. Ridott soils formed in 30 to 50 inches of loess and in the underlying residuum weathered from shale. Mean annual temperature varies from 45 to 52 degrees F, and mean annual precipitation varies from 32 to 36 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing
Loran and
Massbach soils and the
Calamine,
Keltner, and
Eleroy soils. The somewhat poorly drained Loran soils are on similar parts of the landscape nearby, with slope gradients ranging from 0 to 12 percent. The well drained and moderately well drained Massbach,
Eleroy and Keltner soils are on similar and generally more sloping parts of the landscape nearby. Massbach soils form a drainage sequence with Ridott soils. Eleroy soils are Typic
Hapludalfs. Keltner soils are Typic Argiudolls. Calamine soils have thinner loess and have a mollic epipedon. They are in slightly depressed areas and on foot slopes where seepage occurs.
DRAINAGE AND PERMEABILITY: Poorly drained. Permeability is moderate in the loess and slow or very slow in the residuum weathered from shale. Runoff is medium.
USE AND VEGETATION: Most areas are cultivated. Corn, soybeans, small grain and meadow are the principal crops. Native vegetation is prairie grass and scattered trees.
DISTRIBUTION AND EXTENT: Northwestern and west-central Illinois. Extent is small.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Stephenson County, Illinois, 1969.
REMARKS: Classification was adjusted to agree with ST Issue #17 on 23 Aug 94 by CLG.
Diagnostic horizons and features recognized in this pedon are: ochric epipedon - the zone from the surface to a depth of 8 inches (Ap horizon); albic horizon - the zone from 8 to 11 inches (Eg horizon); argillic horizon - the zone from 11 to 44 inches (Btg1, Btg2, Btg3, Btg4, and 2Btg5 horizons); a lithologic discontinuity from loess to residuum weathered from shale at a depth of 38 inches; a paralithic contact at a depth of 44 inches.