LOCATION ALLAMAKEE IAEstablished Series
TAXONOMIC CLASS: Fine-silty over clayey, mixed, superactive, mesic Mollic Hapludalfs
TYPICAL PEDON: Allamakee silt loam on a 12 percent convex north-facing slope in a pasture. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 8 inches; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; few (<5%) brown (10YR 4/3) streaks and pockets; weak fine and very fine subangular blocky structure; friable; common very fine roots; slightly acid; abrupt smooth boundary. (6 to 9 inches thick)
BE--8 to 10 inches; brown (10YR 4/3) silt loam; weak fine and coarse platy structure parting to weak fine and very fine subangular blocky; friable; few very fine roots; slightly acid; clear smooth boundary. (0 to 5 inches thick)
Bt1--10 to 16 inches; dark yellowish brown (10YR 4/4) silt loam; weak medium and fine subangular blocky structure; friable; thin continuous brown (10YR 4/3) clay films on faces of peds; few very fine roots; slightly acid; gradual smooth boundary.
Bt2--16 to 23 inches; dark yellowish brown (10YR 4/4) silty clay loam; moderate fine subangular blocky structure; friable; thin continuous brown (10YR 4/4) clay films on faces of peds; few very fine roots; moderately acid; clear smooth boundary. (Combined thickness of the Bt horizon is 12 to 30 inches)
2Bt3--23 to 27 inches; dark yellowish brown (10YR 4/4) and dark brown (7.5YR 4/4) clay loam; moderate fine and medium subangular blocky structure; friable; thin continuous brown (10YR 4/4) clay films on faces of peds; few very fine roots; common black (10YR 2/1) organic stains on faces of peds; about 5 percent coarse fragments 1/2 to 1 inch in diameter; strongly acid; abrupt wavy boundary (0 to 5 inches thick)
2Bt4--27 to 32 inches; yellowish red (5YR 4/6) clay; moderate medium and fine subangular blocky structure; firm; thin continuous reddish brown (5YR 4/4) clay films on faces of peds; few very fine roots; common black (10YR 2/1) organic stains on faces of peds; about 10 percent coarse fragments 1/2 to 1 inch in diameter; very strongly acid; gradual wavy boundary.
2Bt5--32 to 48 inches; yellowish red (5YR 4/6) cobbly clay; moderate medium and fine subangular blocky and angular blocky structure; firm; thin continuous reddish brown (5YR 4/4) clay films on faces of peds; common black (10YR 2/1) organic stains on faces of peds; 30 percent coarse chert and sandstone fragments 1 to 8 inches in diameter; very strongly acid; clear wavy boundary. (Combined thickness of the 3Bt horizon is 15 to 40 inches)
3BC--48 to 60 inches; yellowish red (5YR 4/6) and dark yellowish brown (10YR 4/4 and 10YR 4/6) stratified sandy loam, loam, sandy clay loam, sandy clay and clay; weak medium and fine subangular blocky structure; friable; few black (10YR 2/1) organic stains on faces of peds; 10 to 20 percent coarse sandstone fragments 1 to 6 inches in diameter; strongly acid.
TYPE LOCATION: Allamakee County, Iowa; about 5 miles west and 1 mile north of Lansing; 1400 feet west and 750 feet north of the southeast corner of section 21, T. 99 N., R. 4 W. U.S.G.S. Church, Iowa Topographic Quadrangle; latitude 43 degrees, 22 minutes, 21 seconds N., and longitude 91 degrees, 18 minutes, 33 seconds W.
RANGE IN CHARACTERISTICS: The thickness of the solum is typically more than 60 inches but ranges from 48 to more than 60 inches. Thickness of the loess is 20 to 40 inches. Depth to dolomite bedrock is typically 60 to 90 inches but may range to 120 inches. Sand content of the loess is less than 10 percent and typically less than 5 percent. Sand content of the clayey pedisediment or residuum ranges from 15 to 35 percent.
The Ap horizon has hue of 10YR, value of 2 or 3 moist and 4 or 5 dry, and chroma of 1 to 3.
The A horizon when present has hue of 10YR, value of 2 or 3, and chroma of 1 or 2, and is 5 to 8 inches thick.
An E horizon is present in some pedons. It has hue of 10YR, value of 3 or 4 and chroma of 2 or 3. It is silt loam, and is 3 to 7 inches thick.
The Bt horizons have hue of 10YR or 7.5YR, value of 4 or 5 and chroma of 3 to 6. It is silt loam or silty clay loam with a clay content of 20 to 30 percent. Reaction ranges from slightly acid to very strongly acid.
The 2Bt horizons have hue of 2.5YR, 5YR, 7.5YR, or 10YR value of 3 to 7 and chroma of 3 to 8. It is clay loam, silty clay, clay, cobbly silty clay or cobbly clay. Coarse fragments range from less than 5 percent in the upper part to 35 percent in the lower part. Clay content ranges from 35 to 70 percent and reaction ranges from moderately acid to extremely acid.
The 3BC horizon has hue of 5YR, 7.5YR or 10YR, value of 4 or 5 and chroma of 4 to 6. It has stratified textures of sandy loam, loam, sandy clay loam, sandy clay, clay loam, or clay.
The 3C horizon when present has hue of 10YR, 7.5YR or 5YR, value of 4 to 6 and chroma of 4 to 6. It is stratified sandy loam, loam, sandy clay loam, sandy clay or clay loam.
COMPETING SERIES: No other series in this family. Similar series are Frankville, Massbach, Nassett, Valton and the Village(T) series. Frankville and Nassett soils have limestone bedrock within 60 inches. Massbach soils have shale bedrock within 50 inches. Valton soils do not have a 20 percent clay decrease from the clay maximum within 150 cm. The Village(T) soils do not have mollic colors in the surface layer.
GEOGRAPHIC SETTING: The Allamakee soils are on convex upland ridgetops and side slopes. Slope gradient ranges from 5 to 18 percent. Allamakee soils formed in 20 to 40 inches of loess over clayey pedisediment or residuum. Mean annual temperature is about 45 to 50 degrees F. and mean annual precipitation ranges from 29 to 38 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Downs, Lacrescent, Paintcreek(T), Tama and Village(T) soils. The Downs and Tama soils formed entirely in loess and are on the less sloping, broader ridgetops above the Allamakee soils. Lacrescent soils formed in loamy colluvial material and are on the steeper side slopes below the Allamakee soils. The Paintcreek(T) soils have a thinner loess mantle and are typically down slope from the Allamakee soils. The Village(T) soils formed in similar materials and are on similar landscape positions.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderate in the loess material and slow in the clayey pedisediment or residuum. Surface runoff is medium to rapid.
USE AND VEGETATION: The less sloping areas are commonly used to grow corn, small grains and legume hay. The steeper slopes are used for pasture. Native vegetation was prairie grasses and deciduous trees.
DISTRIBUTION AND EXTENT: Northeast Iowa, and possibly southeast Minnesota and southwest Wisconsin. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES PROPOSED: Allamakee County, Iowa, 1991. The name is from a creek in the county.
REMARKS: Diagnostic horizons and features recognized in this pedon are: Ochric epipedon - the zone from the surface of the soil to a depth of approximately 8 inches (Ap horizon); Argillic horizon - the zone from approximately 10 to 48 inches (Bt1, Bt2, 2Bt3, 2Bt4, 2Bt5 horizons). Udic moisture regime.
ADDITIONAL DATA; Mechanical analysis data available for this soil at Iowa State University Laboratory, sample numbers 48358 through 48366.