LOCATION ONECO ILEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, active, mesic Mollic Hapludalfs
TYPICAL PEDON: Oneco silt loam on a southeast-facing, convex, 3.5 percent slope in a pastured field at an elevation of about 265 meters (870 feet) above sea level. (Colors are for moist soil unless otherwise stated.)
A--0 to 23 cm (0 to 9 inches); very dark brown (10YR 2/2) silt loam; moderate medium and fine granular structure; friable; neutral, pH 7.0; clear smooth boundary. [15 to 23 cm (6 to 9 inches) thick]
E--23 to 33 cm (9 to 13 inches); 50 percent dark grayish brown (10YR 4/2) and 50 percent very dark grayish brown (10YR 3/2) silt loam; moderate medium and fine granular structure; friable; few distinct light gray (10YR 7/1) dry, silt coatings on faces of peds; neutral, pH 7.0; clear smooth boundary. [5 to 20 cm (2 to 8 inches) thick]
BE--33 to 43 cm (13 to 17 inches); 60 percent brown (10YR 4/3) and 40 percent dark brown (10YR 3/3) silty clay loam; moderate fine and very fine subangular blocky structure; firm; few distinct light gray (10YR 7/1) dry, silt coatings on faces of peds; few very dark grayish brown (10YR 3/2) worm casts; neutral, pH 7.0; clear smooth boundary. [5 to 20 cm (2 to 8 inches) thick where present]
Bt1--43 to 58 cm (17 to 23 inches); brown (10YR 4/3) crushed, silty clay loam; moderate fine and very fine subangular blocky structure; firm; very few distinct light gray (10YR 7/1) dry, silt coatings on faces of peds and common distinct very dark grayish brown (10YR 3/2) clay films on faces of peds; few very dark grayish brown (10YR 3/2) worm casts; strongly acid, pH 5.5; clear smooth boundary. [5 to 20 cm (2 to 8 inches) thick where present]
2Bt2--58 to 89 cm (23 to 35 inches); brown (7.5YR 4/4) clay loam; moderate medium and fine subangular blocky structure; firm; common distinct dark brown (7.5YR 3/2) clay films on faces of peds; many fine distinct black (7.5YR 2.5/1) accumulations of iron and manganese oxides in the matrix; 5 percent rounded 2 to 75 millimeter igneous rock fragments; very strongly acid, pH 5.0; gradual smooth boundary.
2Bt3--89 to 114 cm (35 to 45 inches); reddish brown (5YR 4/4) silty clay loam; moderate medium angular blocky and subangular blocky structure; very firm; common distinct dark brown (7.5YR 3/2) clay films on faces of peds; many fine distinct black (7.5YR 2.5/1) accumulations of iron and manganese oxides in the matrix; 8 percent rounded 2 to 75 millimeter igneous rock fragments; strongly acid, pH 5.5; clear smooth boundary. [Combined thickness of the 2Bt horizon is 51 to 102 cm (20 to 40 inches)]
3Bt4--114 to 132 cm (45 to 52 inches); reddish brown (5YR 4/4) silty clay; moderate medium angular blocky structure; very firm; many distinct dark brown (7.5YR 3/2) clay films on faces of peds; moderately acid, pH 6.0; abrupt smooth boundary. [5 to 25 cm (2 to 10 inches) thick]
3R--132 cm (52 inches); very pale brown (10YR 7/3) and brownish yellow (10YR 6/8) limestone bedrock; slightly effervescent; partially disintegrated rock in the upper 5 or 8 cm (2 or 3 inches) and slight tonguing of residuum into this horizon.
TYPE LOCATION: Stephenson County, Illinois; about 4 miles northwest of Orangeville; 1,100 feet west and 600 feet south of the northeast corner of sec. 29, T. 29 N., R. 7 E.; USGS Orangeville topographic quadrangle; lat. 42 degrees 29 minutes 11 seconds N., and long. 89 degrees 43 minutes 00 seconds W., NAD 83.
RANGE IN CHARACTERISTICS: The solum commonly is 102 to 127 cm (40 to 50 inches) thick but ranges to 152 cm (60 inches). The loess typically is 25 to 76 cm (10 to 30 inches) thick, the drift is 51 to 102 cm (20 to 40 inches) thick, and their combined thickness is about 91 to 127 cm (36 to 50 inches). The depth to limestone bedrock ranges from 102 to 152 cm (40 to 60 inches) and is considered to be a lithic contact. The
dominant clay mineral in the loess and upper part of the 2Bt horizon is smectite. Illite increases with depth and becomes the dominant clay mineral in the lower part of the 2Bt horizon.
The A or Ap horizon has hue of 10YR, value of 2 or 3, and chroma of 1 to 3. It is silt loam.
The E horizon (where present) is silt loam.
The BE and/or Bt horizon (where present) has a hue of 10YR or 7.5YR, value of 4 or 5, and chroma of 3 or 4. It is typically silty clay loam but ranges to silt loam.
The 2Bt horizon has hue of 2.5YR, 5YR, or 7.5YR, value of 3 to 5, and chroma of 3 to 5. Hue of 5YR or redder is present on ped surfaces or in the matrix in at least one subhorizon. It is typically clay loam but includes thin subhorizons of sandy clay loam, or silty clay loam with moderate content of sand in some pedons. Reaction ranges from slightly acid to very strongly acid.
The 3Bt horizon has hue of 5YR and value and chroma of 3 or 4. It is silty clay or clay with a variable content of chert. Content of clay commonly ranges from 45 to 70 percent. The finest textured horizon is below 91 cm (3 feet) and commonly is the deepest horizon in the solum.
COMPETING SERIES: These are the Dunbridge, Lauramie, Longlois, Lydick, Mohawk, and Razort series. All of the series except Dunbridge do not have a lithic contact within depths of 152 cm (60 inches). Dunbridge series have a lithic contact at depths less than 102 cm (40 inches).
GEOGRAPHIC SETTING: Oneco soils are on undulating to rolling till plains and moraines that are partially controlled by the underlying limestone bedrock. Slopes range from 1 to 12 percent. These soils formed 25 to 76 cm (10 to 30 inches) of loess, 51 to 102 cm (20 to 40 inches) of Late Sangamon age paleosols that formed in Illinoian drift, and 5 to 25 cm (2 to 10 inches) of residuum from weathered limestone bedrock. Summers are hot and winters are cold. Mean annual air temperature ranges from 7 to 10 degrees C (45 to 50 degrees F). Mean annual precipitation ranges from 810mm to 910mm (32 to 36 inches). Frost-free period ranges from 140 to 160 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Woodbine and Hitt soils. Oneco soils generally are between Woodbine and Hitt soils in the landscape. Oneco is the intermediate member of a biosequence with Hitt soils (Typic Argiudolls) and Woodbine soils (Typic Hapuldalfs).
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained. Saturated hydraulic conductivity is 4.23 to 14.11 micrometers per second in the loess and drift and 0.42 to 1.41 micrometers per second in the residuum. Permeability is moderate in the loess and slow in the residuum. Surface runoff potential is low to medium as related to slope.
USE AND VEGETATION: Largely under cultivation with corn, soybeans, small grain and grass and legume hay as major crops. Native vegetation probably is prairie grass and scattered trees.
DISTRIBUTION AND EXTENT: Northwestern Illinois. LRRs K and M, MLRAs 95B and 108B. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Stephenson County, Illinois, 1969.
REMARKS: Many of the properties of the 2Bt and 3Bt horizons are believed to have been inherited from a Paleosol of Late Sangamon Age.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon -- from a depth of 0 to 43 cm (0 to 17 inches) (A, E, and BE horizons)
Albic horizon -- from a depth of 23 to 33 cm (9 to 13 inches). (E horizon)
Argillic horizon -- from a depth of 43 to 132 cm (17 to 52 inches). (Bt1, 2Bt2, 2Bt3, and 3Bt4 horizons)
Lithic contact -- at a depth of 132 cm (52 inches)
Udic moisture regime; Mesic temperature regime.