LOCATION FORKHORN WIEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, active, mesic Mollic Hapludalfs
TYPICAL PEDON: Forkhorn sandy loam - on a 1 percent slope in a cultivated field at an elevation of 815 feet. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 9 inches; very dark brown (10YR 2/2) sandy loam, dark grayish brown (10YR 4/2) dry; weak medium and coarse subangular blocky structure; friable; many very fine to medium roots; about 3 percent gravel; slightly acid; abrupt smooth boundary. (6 to 9 inches thick)
Bt1--9 to 17 inches; brown (7.5YR 4/4) sandy loam; moderate medium subangular blocky structure; friable; many very fine and fine roots; few faint brown (7.5YR 4/3) clay films on faces of peds and in pores; few prominent very dark brown (10YR 2/2) worm casts; about 10 percent gravel; slightly acid; clear smooth boundary.
Bt2--17 to 25 inches; brown (7.5YR 4/4) sandy loam; moderate fine and medium subangular blocky structure; friable; common very fine and fine roots; common faint brown (7.5YR 4/3) clay films on faces of peds and in pores; about 5 percent gravel; moderately acid; gradual smooth boundary. (Combined thickness of the Bt horizons ranges from 11 to 32 inches.)
2Bt3--25 to 32 inches; strong brown (7.5YR 4/6) gravelly loamy sand; weak coarse subangular blocky structure; very friable; few very fine and fine roots; common faint brown (7.5YR 4/3) clay bridges between sand grains; about 30 percent gravel; slightly acid; clear smooth boundary. (0 to 10 inches thick)
2BC--32 to 46 inches; strong brown (7.5YR 5/6) stratified gravelly coarse sand and very gravelly coarse sand; single grain; loose; about 25 percent gravel as an average; slightly acid; gradual smooth boundary. (0 to 25 inches thick)
2C--46 to 72 inches; stratified brown (7.5YR 5/4) sand and multi-colored coarse sand; single grain; loose; about 10 percent gravel; slightly acid.
TYPE LOCATION: Pepin County, Wisconsin; about 3 miles north of Durand; 1850 feet north and 1780 feet west of the southeast corner of sec. 4, T. 25 N., R. 13 W.: USGS Durand North, WI quad.; Lat. 44 degrees, 40', 28" N; Long. 91 degrees, 57', 38" W.
RANGE IN CHARACTERISTICS: Thickness of the loamy alluvium and depth to sandy outwash range from 20 to 40 inches. The substratum averages 90 percent or more total sand and 10 percent or more coarse and very coarse sand. Volume of gravel ranges from 0 to 15 percent but averages less than 12 percent in the loamy alluvium. Volume of gravel averages from 1 to 35 percent in the sandy outwash but ranges from 0 to 50 percent in individual strata. Volume of cobbles ranges from 0 to 5 percent throughout the pedon.
The Ap horizon has hue of 7.5YR or 10YR, value of 2 or 3, and chroma of 1 to 3. Uncultivated pedons have an A horizon with color and texture like the Ap horizon. Reaction naturally ranges from strongly acid to slightly acid but ranges to neutral, where the soil is limed.
Some pedons have an E horizon with hue of 7.5YR or 10YR, value of 4 or 5, and chroma of 2 or 3. It is sandy loam, fine sandy loam, or loam. Reaction naturally ranges from strongly acid to slightly acid, but ranges to neutral, where the soil is limed.
The Bt horizon has hue of 7.5YR or 10YR, value of 4 or 5, and chroma of 3 to 6. Typically, it is sandy loam but in some pedons it has subhorizons of fine sandy loam or loam. Reaction naturally ranges from strongly acid to slightly acid, but ranges to neutral in the upper part, where the soil is limed.
The 2Bt horizon has hue of 7.5YR or 10YR, value of 4 or 5, and chroma of 4 to 6. It is loamy sand, loamy coarse sand, sand, coarse sand, or the gravelly or very gravelly analogs. Reaction ranges from strongly acid to slightly acid.
The 2BC horizon has hue of 7.5YR or 10YR, value of 4 to 7, and chroma of 3 to 6, or it is multicolored. It typically is stratified layers of sand, coarse sand, or the gravelly or very gravelly analogs. Reaction ranges from strongly acid to slightly acid.
The 2C horizon has color, texture, and reaction like the 2BC horizon described above.
COMPETING SERIES: These are the Backbone, Bainter, Billett, Desker, Kevilar(T), Kingsley, Oronoco, Pardeeville, Renwick, Rusktown(T), and Ulster series. Backbone soils have carbonates at depths of less than 40 inches. Billett and Ulster soils have less than 10 percent coarse and very coarse sand in the sandy outwash in the lower part of the series control section. In addition, Ulster soils do not have rock fragments in the sandy outwash in the lower part of the series control section. Desker soils average 12 to 25 percent rock fragments in the loamy upper part of the series control section. Kevilar, Kingsley, Oronoco, and Pardeeville soils have less than 90 percent sand in the lower part of the series control section. In addition, Oronoco soils have redox features in the series control section. Renwick soils have lamellae (E&Bt horizon) in the lower part of the argillic horizon. Rusktown soils have redox features and a water table in the lower part of the series control section.
GEOGRAPHIC SETTING: Forkhorn soils are on outwash terraces of valley trains. Slope gradients range from 0 to 20 percent. These soils formed in loamy alluvium and in the underlying sandy outwash. Mean annual precipitation ranges from 28 to 33 inches. Mean annual air temperature ranges from 46 to 51 degrees F. The frost free period ranges from about 135 to 160 days. Elevation ranges from 600 to 1100 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Meridian, Plainfield, and Rusktown(T) series. The well drained Meridian soils are in landscape positions similar to those of the Forkhorn soils where there is more clay and less sand in the upper part of the particle size control section. The excessively drained Plainfield soils are in similar landscape positions where the soil is sandy throughout. The moderately well drained Rusktown soils are in slightly lower landscape positions and form a drainage sequence with Forkhorn soils.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is slow or medium. Permeability is moderate or moderately rapid in the loamy alluvium and rapid or very rapid in the sandy outwash.
USE AND VEGETATION: Most areas of Forkhorn soils are used for cropland. Corn, soybeans, small grain, and hay are the principal crops. A few small areas remain in native vegetation or are used for pastureland. Native vegetation is a mixture of deciduous forest and prairie grasses.
DISTRIBUTION AND EXTENT: West-central Wisconsin. These soils are of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Pepin County, Wisconsin, 1998. The name is coined.
REMARKS: Prior to 1995, this soil was mapped as the Billett series. Diagnostic horizons and other features recognized in this pedon are: ochric epipedon (darker than Typic) - 0 to 8 inches (Ap); argillic horizon - 8 to 28 inches (Bt1, Bt2, Bt3).
Lab data from similar soils indicates that Forkhorn soils have base saturation of 50 percent or more (by NH4OAc) in all horizons between the upper boundary of the argillic and a depth of 125 cm. However, it is suspected that the very low CEC in the sandy outwash results in drastic changes in B.S. with the addition of few bases from fertilization in cropland areas. These soils may be Ultic in their natural state.
ADDITIONAL DATA: Soil Interpretation Record - WI0590.