Established Series


The Dodgeville series consists of well drained soils formed in loess and in the underlying clay residuum (paleosol weathered from dolomite or limestone. These upland soils are underlain by dolomite or limestone bedrock at depths of 20 to 40 inches. They have moderately slow permeability. Slopes range from 0 to 30 percent. Mean annual precipitation is about 31 inches. Mean annual air temperature is about 49 degrees F.

TAXONOMIC CLASS: Fine-silty over clayey, mixed, superactive, mesic Typic Argiudolls

TYPICAL PEDON: Dodgeville silt loam, on a northeast-facing, convex slope of 8 percent, in a cultivated field, at an elevation of about 1,165 feet above sea level. (Colors are for moist soil unless otherwise stated.)

Ap--0 to 7 inches; very dark brown (10YR 2/2) silt loam, dark grayish brown (10YR 4/2) dry; moderate very fine and fine subangular blocky structure; friable; many fine fibrous roots; many earthworm casts; slightly acid; abrupt smooth boundary. (6 to 10 inches thick)

A--7 to 13 inches; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; weak coarse platy structure parting to moderate fine subangular blocky; friable; common fine fibrous roots; strongly acid; clear wavy boundary. (3 to 6 inches thick)

BA--13 to 16 inches; brown (10YR 4/3) and dark yellowish brown (10YR 4/4) silt loam; moderate medium subangular blocky structure; friable; common fine fibrous roots; moderately acid; gradual wavy boundary.

Bt1--16 to 23 inches; dark yellowish brown (10YR 4/4) silty clay loam; moderate medium angular blocky structure; firm; common roots; few fine angular chert fragments; thin clay films on faces of peds; moderately acid; gradual smooth boundary. (Combined thickness of the Bt horizon is 5 to 19 inches.)

2Bt2--23 to 35 inches; yellowish red (5YR 4/6) and reddish brown (5YR 4/4) clay; strong medium angular blocky structure; very firm; thin continuous clay films on faces of peds; many very fine and fine angular chert fragments that increase in number with depth; moderately acid; gradual irregular boundary. (10 to 20 inches thick)

2R--35 to 60 inches; partially weathered dolomite bedrock that is shattered in the upper part and has clay residuum in thin, widely spaced rock fissures.

TYPE LOCATION: Iowa County, Wisconsin; about 2 miles south of Ridgeway; about 1,320 feet west and 820 feet north of the southeast corner of section 22, T. 6 N., R. 4 E.; USGS Jonesdale quadrangle; lat. 42 degrees 58 minutes 32 seconds N. and long. 90 degrees 00 minutes 03 seconds W., NAD83.

RANGE IN CHARACTERISTICS: Solum thickness ranges from 24 to 40 inches, which corresponds to the depth to the bedrock. The solum, other than the Ap, which is neutral or slightly acid, is slightly acid or medium acid, but horizons that are strongly acid are within the range. In some places the bedrock is solid, but in other places, it has fissures filled with clay that extend downward for several feet. Slopes over 20 percent generally are underlain by fragmental material rather than solid bedrock.

The Ap and A horizon has 10YR hue, value of 2 or 3, and chroma of 1 through 3.

The BA horizon has 10YR hue, value of 3 through 5, and chroma of 3 or 4. It is silt loam or silty clay loam.

The Bt horizon has 10YR hue, value of 3 through 5, and chroma of 3 or 4. It is silt loam or silty clay loam. Clay content averages between 25 and 35 percent.

The 2Bt horizon has 7.5YR, 5YR, and 2.5YR hue; value and chroma is 3 through 5. It is silty clay or clay. Clay content averages between 55 and 75 percent. Coarse fragments, mainly chert, range from 2 to 10 percent and up to 5 percent of the fragments are greater than 3 inches in size.

COMPETING SERIES: This is the only series in this family. Other series in closely related families are Ashdale, Dubuque, Edmund, Hitt, Mendota, NewGlarus, Ogle, Plano, Saybrook, and Tama. Ashdale, Dubuque, Hitt, Mendota, Ogle, Plano, Saybrook and Tama soils do not have a strongly contrasting particle-size class within a depth of 40 inches. In addition, Dubuque soils do not have a mollic epipedon and Hitt soils are fine-loamy. Edmund soils are clayey and lithic. New Glarus soils are fine-silty over clayey but do not have a mollic epipedon.

GEOGRAPHIC SETTING: Dodgeville soils are on ridgetops and on side slopes in undulating to rolling landscapes underlain by dolomite or limestone. Slope gradients range from 0 to 30 percent. The soils formed in 15 to 30 inches of loess and in the underlying clay residuum (paleosol) weathered from dolomite or limestone. The residuum ranges from 10 to 20 inches in thickness. Mean annual precipitation ranges from 28 to 35 inches. Mean annual air temperature ranges from 45 to 53 degrees F.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the well drained Ashdale, Dubuque, Edmund, Hitt, NewGlarus, Rockton, Sogn, and Whalan soils. Ashdale soils are on ridgetops where the bedrock is deeper. Dubuque soils are in areas where the clay residuum is less than 6 inches thick. Edmund and Sogn soil are nearby in areas where the limestone is at a depth of less than 20 inches. In addition, Sogn soils are in dry sites and do not have argillic horizons. Hitt and Rockton soils are both fine-loamy and similar. In addition, Hitt soils have from 10 to 25 inches of loess overlying the drift and residuum. NewGlarus and Dodgeville soils form a biosequence. NewGlarus soils formed under forest vegetation. Whalan soils are in nearby glaciated area that is dominated by forest vegetation.

DRAINAGE AND PERMEABILITY: Well drained. Runoff is medium to rapid. Permeability is moderately slow.

USE AND VEGETATION: The less sloping areas are in corn, small grain, and hay. Steeper sloping areas are in pasture. Native vegetation was prairie grasses and forbs with a scattering of oak trees.

DISTRIBUTION AND EXTENT: Southwestern Wisconsin, northwestern Illinois, southeastern Minnesota, and northeastern Iowa. This soil is moderately extensive.


SERIES ESTABLISHED: Iowa County, Wisconsin, 1912.

REMARKS: Diagnostic horizons and features recognized in this pedon: mollic epipedon - the zone from the surface of the soil to a depth of 13 inches (Ap and A horizons); argillic horizon - zone from 16 to 35 inches (Bt1 and 2Bt2 horizons).

As the Dodgeville series is defined in this description, thickness of loess is permitted to range from 15 to 30 inches and the residuum from 10 to 20 inches in any combination. Thus in some pedons, the B horizon is formed mostly in loess, in others, mostly in residuum. This permits a wide range in properties in the control section. Fine-silty over clayey and clayey particle-size classes can be recognized in the setting of these soils but fine-silty over clayey will be the concept. Additional study is needed to determine if more narrowly defining the thickness of loess and residuum would be appropriate and thus separate two series.

National Cooperative Soil Survey