LOCATION TAOPI MNEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Mollic Hapludalfs
TYPICAL PEDON: Taopi loam in a cultivated field with a 2 percent convex south-facing slope. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 7 inches; very dark grayish brown (10YR 3/2) loam; grayish brown (10YR 5/2) dry; weak very fine granular structure; friable; about 2 percent coarse fragments; medium acid; abrupt smooth boundary. (3 to 8 inches thick)
BE--7 to 11 inches; dark brown (10YR 4/3) loam; moderate very fine subangular blocky structure; friable; about 2 percent coarse fragments; common thin grayish brown (10YR 5/2) silt coating on faces of peds; common very dark grayish brown (10YR 3/2) tubular mixings; slightly acid; clear wavy boundary. (0 to 6 inches thick)
Bt1--11 to 18 inches; yellowish brown (10YR 5/4) loam; moderate fine subangular blocky structure; friable; common faint dark brown (10YR 4/3) clay films on the faces of peds; about 4 percent coarse fragments; neutral; abrupt wavy boundary.
Bt2--18 to 24 inches; yellowish brown (10YR 5/4) clay loam; moderately fine angular blocky structure; friable; common distinct dark brown (10YR 4/3 and 7YR 3/2) clay films on faces of peds and in root channels; about 6 percent coarse fragments concentrated in lower part; neutral; abrupt wavy boundary. (Combined thickness of Bt horizons is 12 to 30 inches.)
2Bt3--24 to 30 inches; very dark grayish brown (10YR 3/2) clay; strong fine subangular blocky structure; very firm; about 4 percent coarse fragments; neutral; clear wavy boundary. (2 to 6 inches thick)
3C--30 to 60 inches; light gray (10YR 7/2) cobbly silt loam; massive; very friable; strong effervescence; mildly alkaline.
TYPE LOCATION: Mower County, Minnesota; 2 miles south of Racine, 1300 feet north and 2050 feet east of the southwest corner of sec. 2, T. 103 N., R. 14 W.
RANGE IN CHARACTERISTICS: Thickness of solum and depth to carbonates range from 20 to 40 inches. The A horizon and the upper part of the B horizon range from medium acid to neutral and the 2B horizon is neutral or slightly acid. Coarse fragments make up about 2 to 10 percent of the solum. The 3C horizon which is a soft limestone or siltstone, contains 10 to 40 percent dominantly limestone coarse fragments ranging from pebbles to cobbles or channers that are in a fine earth consisting of silt loam, loam or fine sandy loam. Hard limestone is at depths of 50 inches or more.
The A horizon is typically very dark grayish brown (10YR 3/2) but includes values of 2 and chroma of 1 through 3. The texture of the A horizon is loam, silt loam or fine sandy loam.
Some pedons have a 3 to 8 inches thick sandy loam, loam or silt loam E horizon that is dark grayish brown (10YR 4/2) or brown (10YR 5/3).
The Bt horizons have hue of 10YR, value of 4 or 5, and chroma of 3 or 4. The texture is loam or clay loam.
The 2Bt horizon has a 10YR or 7.5YR hue, value of 3 to 5, and chroma of 2 to 4. It is sandy clay loam, clay loam or clay. In many pedons, a stone line is common in the 2Bt horizon.
The 3C horizon has a hue of 10YR, values of 6 or 7, and chromas of 1 through 6.
COMPETING SERIES: There are the Argyle, Baltimore, Bassett, Blooming, Cadmus, Caleb, Crocker, Dowagiac, Dunbridge, Gara, Koronis, Lester, Longlois, Lydick, Mohawk, Neda, Octagon, Oneco, Orwood, Racine, Razort, Renox, Waucoma, and Winneshiek soils in the same family. All of the above soils lack the material weathered from soft limestone or siltstone which is characteristic of Taopi soils.
GEOGRAPHIC SETTING: Taopi soils are on nearly level to sloping uplands with plane to convex slopes. Slopes range from 1 to 12 percent. They formed in 20 to 40 inches of a loamy mantle and clayey residuum over channery or cobbly soft limestone or siltstone. Mean annual temperature is about 45 to 52 degrees F, and mean annual precipitation is about 28 to 33 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: The Mottland and Rossfield soils are associated in similar upland positions but have mollic epipedons.
DRAINAGE AND PERMEABILITY: These soils are well drained. They have moderate permeability in the solum and moderately rapid permeability in the underlying material. Surface runoff is medium.
USE AND VEGETATION: Commonly used for cultivated crops. Some areas are in woods and some are used for pasture. Native vegetation was principally oak.
DISTRIBUTION AND EXTENT: The soils are inextensive in southeastern Minnesota and possibly in northern Iowa.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Mower County, Minnesota, 1986.
REMARKS: This soil had been called Winneshiek Variant but during checking of atlas sheets it was estimated to be approximately 3000 acres in extent.
Diagnostic horizons and features recognized in this pedon are: ochric epipedon - the zone from the surface to a depth of 11 inches (Ap and BE horizons); mollic subgroup based upon dark color of Ap horizon; argillic horizon - the zone from 11 to 31 inches (Bt and 2Bt horizons); base saturation is greater than 60 percent.