LOCATION FORDUM WI+MNEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, nonacid, frigid Mollic Fluvaquents
TYPICAL PEDON: Fordum silt loam on a plane level slope on a flood plain at an elevation of about 1,160 feet. (Colors are for moist soil unless otherwise stated.)
A--0 to 6 inches; very dark brown (10YR 2/2) silt loam, grayish brown (10YR 5/2) dry; moderate fine subangular blocky structure; friable; many fine and medium roots; neutral; abrupt wavy boundary. (6 to 9 inches thick)
Cg1--6 to 18 inches; dark gray (5Y 4/1) silt loam; weak coarse subangular blocky structure; friable; few fine roots; common medium prominent yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; many thin strata of fine sandy loam; moderately acid; clear wavy boundary.
Cg2--18 to 30 inches; dark gray (10YR 4/1) fine sandy loam; massive; friable; common fine prominent strong brown (7.5YR 5/6) masses of iron accumulation in the matrix; many thin strata of silt loam and fine sand; moderately acid; clear wavy boundary. (Combined thickness of the Cg1 and Cg2 horizons is 18 to 34 inches.)
2Cg3--30 to 60 inches; gray (10YR 5/1) sand; single grain; loose; few thin strata of silt loam; slightly acid.
TYPE LOCATION: Marathon County, Wisconsin; about 2 miles west of Wausau; 2140 feet north and 2515 feet eastof the SW corner of sec. 33, T. 29 N., R. 7 E. USGS Wausau West, Wis. Quad. Latitude 44 degrees 57 minutes 1 second N. Longitude 89 degrees 40 minutes 53 seconds N. NAD 27.
RANGE IN CHARACTERISTICS: Thickness of the loamy alluvium and depth to sandy alluvium ranges from 24 to 40 inches. The particle-size control section averages from 7 to 17 percent clay. The coarse-loamy mantle has 50 percent or more fine or coarser sand. Volume of gravel ranges from 0 to 35 percent in the loamy mantle, but is typically less than 15 percent. Volume of gravel ranges from 0 to 60 percent in the sandy lower part. Volume of cobbles ranges from 0 to 10 percent throughout. Total volume of rock fragments is less than 35 percent as a weighted average in the particle-size control section. Reaction ranges from very strongly acid to moderately alkaline in the loamy alluvium and from moderately acid to moderately alkaline in the sandy alluvium. Carbonates are absent to 60 inches or more. Redox accumulations are typically throughout the loamy mantle below the A horizon. Aquic conditions occur at same time in most years and redox depletions are 50 percent or more of the matrix at a depth of 16 to 20 inches.
The A horizon has hue of 7.5YR, 10YR, 2.5Y, or 5Y or the hue is neutral. It has value of 2 or 3 and chroma of 0 to 3. Color value is 5 or less dry. Texture of the A horizon is silt loam, very fine sandy loam, loam, fine sandy loam, sandy loam, or the mucky analogs.
The upper loamy part of the Cg horizon has hue of 7.5YR, 10YR, 2.5Y, or 5Y, or the hue is neutral. It has value of 2 to 6 and chroma of 0 to 2. Some pedons have thin strata with higher value or chroma. Texture is commonly stratified layers of silt loam, loam, sandy loam, or fine sandy loam, or the gravelly, very gravelly, or mucky analogs but includes thin strata of very fine sandy loam, loamy very fine sand, loamy fine sand, loamy sand, very fine sand, fine sand, sand or the gravelly, very gravelly or mucky analogs. Strata of organic materials less than 8 inches thick are also included.
The sandy lower part of the Cg or C horizon has hue of 5YR, 7.5YR, 10YR, 2.5Y, or 5Y or the hue is neutral. It has value of 4 to 6 and chroma of 0 to 4 and has redox concentrations in some pedons. Texture is sand, coarse sand, fine sand, loamy sand, loamy coarse sand, loamy fine sand, or the gravelly or very gravelly analogs of these textures, or stratified sand and gravel. Thin strata of materials containing more clay and silt are also included.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Fordum soils are on the lowest part of the flood plain adjacent to stream or river channels. Numerous abandoned meander, small overflow channels, and scours produce an irregular microrelief. Slopes range from 0 to 2 percent. These soils formed in recent alluvium. Mean annual precipitation ranges from 22 to 33 inches. Mean annual temperature ranges from about 36 to 45 degrees F. The frost free period ranges from about 70 to 135 days. Elevation ranges from 680 to 1700 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These are Bowstring, Cathro, Markey, Minocqua, Moquah, and Roscommon soils. The very poorly drained Bowstring soils are in abandoned meander channels where there is more than 51 inches of organic material which contains thin strata of mineral material. The very poorly drained Cathro and Markey soils are in abandoned meander channels where there is 16 to 51 inches of organic material. Minocqua and Roscommon soils are nearby on terraces off the floodplain. The moderately well drained Moquah soils are in higher positions on the flood plain.
DRAINAGE AND PERMEABILITY: Poorly drained. The potential for surface runoff ranges from negligible to low. Permeability is moderate or moderately rapid in the upper loamy alluvium and rapid or very rapid in the lower sandy alluvium. Flooding is rare to frequent and of brief to long duration, but in some areas of lower rainfall in Western Minnesota, it is very brief duration. The main period of flooding is March to June, but flooding can occur following any period of high runoff. Fordum soils have an apparent seasonal high water table from 1 foot above to 1 foot below the surface at some time during the period January to December in most years.
USE AND VEGETATION: Most areas are used for in woodland. Common trees are silver maple, red maple, quaking aspen, big tooth aspen, paper birch, American elm, white spruce, and yellow birch. Tag alder is common in many places. Some areas are in marsh vegetation of grasses, seeds, sedges and shrubs. Some areas are used for pastureland and some small areas are used for harvesting marsh hay.
DISTRIBUTION AND EXTENT: Northern Wisconsin and northern Minnesota. The soil is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Shawano County, Wisconsin, 1981.
REMARKS: Diagnostic horizons recognized in this pedon are:
ochric epipedon (darker than typic) - 0 to 6 inches (A);
mixing to depth of 7 inches meets requirement for mollic subgroup;
Aquepts - chroma of 1 or less and value of 4 or more dominant in the matrix at a depth of 16 to 20 inches and saturation there.