LOCATION TAPPAN MIEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, active, calcareous, mesic Typic Endoaquolls
TYPICAL PEDON: Tappan loam - on a nearly level area of 1 percent on till plain cropped to navy beans. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 11 inches; very dark grayish brown (10YR 3/2) loam, grayish brown (10YR 5/2) dry; weak coarse granular structure; friable; few fine roots; about 1 percent gravel; slight effervescence; moderately alkaline; abrupt smooth boundary. (8 to 12 inches thick)
A--11 to 13 inches; very dark grayish brown (10YR 3/2) loam, grayish brown (10YR 5/2) dry; weak medium subangular blocky structure; friable; few fine roots; about 2 percent gravel; slight effervescence; moderately alkaline; abrupt wavy boundary. (0 to 4 inches thick)
Bg1--13 to 15 inches; light brownish gray (10YR 6/2) (50 percent) and gray (10YR 5/1) (50 percent) loam; few fine prominent yellowish brown (10YR 5/6) mottles; weak medium subangular blocky structure; friable; few fine roots; about 5 percent gravel and cobbles; slight effervescence; moderately alkaline; clear wavy boundary.
Bg2--15 to 21 inches; grayish brown (10YR 5/2) (60 percent) and dark yellowish brown (10YR 4/4) (40 percent) silt loam; few fine distinct yellowish brown (10YR 5/6) mottles; moderate fine angular blocky structure; friable; about 6 percent gravel and cobbles; strong effervescence; moderately alkaline; clear wavy boundary.
Bg3--21 to 31 inches; gray (10YR 5/1) loam; common medium prominent yellowish brown (10YR 5/6) and few fine prominent strong brown (7.5YR 5/6) mottles; moderate thick platy structure parting to moderate angular blocky; firm; about 4 percent gravel and cobbles; strong effervescence; moderately alkaline; gradual wavy boundary. (Combined thickness of the Bg horizon is 3 to 25 inches.)
C1--31 to 48 inches; yellowish brown (10YR 5/4) loam; common medium distinct gray (10YR 5/1) and common fine distinct yellowish brown (10YR 5/6) mottles; weak coarse angular blocky fragments; firm; about 4 percent gravel and cobbles; strong effervescence; moderately alkaline; gradual smooth boundary.
C2--48 to 60 inches; yellowish brown (10YR 5/4) loam; few fine distinct yellowish brown (10YR 5/6) and few medium distinct light gray (10YR 6/1) mottles; weak thick platy fragments; firm; about 4 percent gravel and cobbles; strong effervescence; moderately alkaline.
TYPE LOCATION: Huron County, Michigan; about 4 miles west and 1 mile south of Owendale; 152 feet south and 2,340 feet west of the northeast corner, sec. 19, T. 15 N., R. 10 E.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 11 to 36 inches. The mollic epipedon ranges from 8 to 14 inches in thickness. The surface 10 inches is mildly alkaline without effervescence in some pedons. Gravel and cobble content throughout the profile ranges from 1 to 10 percent.
The A horizons have hue of 10YR, value of 2 or 3, and chroma of 1 or 2. They are loam, sandy loam, mucky loam, or mucky silt loam. Some pedons have a thin loamy sand surface layers.
The Bg horizons have hue of 5Y to 10YR, value of 4 to 6, and chroma of 1 or 2. The texture is dominantly loam or clay loam, but textures of silt loam or sandy loam are found in the upper part of the Bg horizon in some pedons.
The C horizons have hue of 7.5YR to 5Y, value of 4 to 6, and chroma of 1 to 4. It is loam, silt loam, silty clay loam, or clay loam. Consistence is firm or very firm.
COMPETING SERIES: There are no competing series. Closely related are the Canisteo, Hetz, Hooppole, Jeffers, Kish and Tilfer series. These soils are superactive. Also, Canisteo and Kish soils have thicker mollic epipedons. Hetz soils are in areas receiving less precipitation. Hooppole soils have sand within 40 to 60 inches. Jeffers soils contain gypsum in their solum and are found in areas receiving less precipitation. Tilfer soils have limestone bedrock within 40 inches.
GEOGRAPHIC SETTING: Tappan soils are on nearly level and depressional areas of till plains and moraines. Slopes range from 0 to 2 percent. They formed in calcareous loam till of Wisconsinan Age. Mean annual temperature ranges from 44 to 48 degrees F. Mean annual precipitation ranges from 28 to 36 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: Tappan soils are associated with the poorly drained Parkhill soil and the somewhat poorly drained Londo and Corunna soils. Parkhill, Londo, and Corunna soils are more deeply leached.
DRAINAGE AND PERMEABILITY: Poorly drained. Potential for surface runoff is medium or high. Surface runoff is slow to ponded. Permeability is moderate or moderately slow in solum and slow in C horizon.
USE AND VEGETATION: Soils are mostly cultivated. Corn, sugar beets, beans, and small grain are the principal crops.
DISTRIBUTION AND EXTENT: Thumb area and east-central part of Lower Michigan. The series is of large extent.
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Sanilac County, Michigan, 1955. The source of the name is a local road.
REMARKS: Classification changed to agree with ST Issue #17 on 2 Sept 94 by CLG. Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface to 13 inches (Ap and A horizons); cambic horizon - the zone from 13 to 31 inches (Bg1, Bg2, Bg3 horizons); aquic soil moisture regime; calcareous feature - effervescence throughout control section.