LOCATION SOUTHAM ND+SD
Established Series
Rev. RJB-KJL
07/2015
SOUTHAM SERIES
The Southam series consists of very deep, very poorly drained, slowly permeable soils that formed in local alluvium from glacial drift. These soils are in basins and depressions on till plains, moraines and lake plains. Slope is 0 to 1 percent. Mean annual air temperature is 41 degrees F, and mean annual precipitation is 17 inches.
TAXONOMIC CLASS: Fine, smectitic, calcareous, frigid Cumulic Vertic Endoaquolls
TYPICAL PEDON: Southam silty clay loam - on a level slope in a deep depression in aquatic vegetation. When described the depth of surface water was 50 inches. (Colors are for moist soil unless otherwise stated)
Ag1--0 to 16 inches; black (5Y 2/1) silty clay loam, dark gray (5Y 4/1) dry; massive; firm, sticky and plastic; common fine snail shell fragments; strong effervescence; slightly alkaline; gradual wavy boundary.
Ag2--16 to 26 inches; black (5Y 2/1) silty clay, dark gray (5Y 4/1) dry; few fine prominent olive brown (2.5Y 4/4) redox concentrations; massive; firm, sticky and plastic; common fine snail shell fragments; strong effervescence; slightly alkaline; gradual wavy boundary.
Ag3--26 to 32 inches; black (5Y 2/1) silty clay, dark gray (5Y 4/1) dry; massive; very firm, very sticky and very plastic; few fine prominent olive brown (2.5Y 4/4) redox concentrations; common fine snail shell fragments; common fine concentrations of gypsum in nests and along planes; strong effervescence; moderately alkaline; gradual wavy boundary.
Ag4--32 to 40 inches; black (5Y 2/1 and 5Y 2/2) silty clay, dark gray (5Y 4/1) and olive gray (5Y 4/2) dry; massive; very firm, very sticky and very plastic; few fine prominent olive brown (2.5Y 4/4) redox concentrations; common fine snail shell fragments; common fine concentrations of gypsum in nests and along planes; slight effervescence; moderately alkaline; gradual wavy boundary. (Combined thickness of the A horizon 24 to 60 inches)
Cg1--40 to 48 inches; very dark grayish brown (2.5Y 3/2) and dark grayish brown (2.5Y 4/2) silty clay, grayish brown (2.5Y 5/2) and light brownish gray (2.5Y 6/2) dry; massive; very firm, very sticky and very plastic; few fine prominent yellowish red (5YR 4/6) and few fine distinct olive brown (2.5Y 4/4) redox concentrations; few fine rounded manganese concretions; common fine snail shell fragments; common fine concentrations of gypsum in nests and along planes; strong effervescence; moderately alkaline; gradual wavy boundary.
Cg2--48 to 54 inches; grayish brown (2.5Y 5/2) silty clay, light brownish gray (2.5Y 6/2) dry; massive; very firm, very sticky and very plastic; many fine and medium distinct olive brown (2.5Y 4/4) and few medium prominent yellowish red (5YR 4/6) redox concentrations; few medium prominent threadlike light gray (N 7/0) redox depletions; common fine snail shell fragments; common fine rounded manganese concretions; common fine concentrations of gypsum in nests and along planes; strong effervescence; moderately alkaline; gradual wavy boundary.
Cg3--54 to 60 inches; dark grayish brown (2.5Y 4/2) and light gray (N 7/0) silty clay, light gray (2.5Y 7/2) and white (2.5Y 8/2) dry; common medium prominent strong brown (7.5YR 5/6) and yellowish brown (10YR 5/6) redox concentrations; few fine rounded manganese concretions; massive; very firm, very sticky and very plastic; common fine snail shell fragments; common fine concentrations of gypsum in nests and along planes; strong effervescence; moderately alkaline.
TYPE LOCATION: Ramsey County, North Dakota; about 2 miles north of Doyon; 2,450 feet north and 1,050 feet west of the southeast corner, sec. 6, T. 153 N., R. 61 W.
RANGE IN CHARACTERISTICS: The mollic epipedon is 24 to more than 60 inches thick. Some pedons have an 0 horizon as much as 6 inches thick. The 10- to 40-inch particle size control section averages between 35 to 50 percent clay. Depth to carbonates ranges from 0 to 10 inches. The electrical conductivity ranges from less than 2 to 8 mmhos/cc. It typically does not have coarse fragments but some pedons contain as much as 10 percent in some horizons.
The A horizon has hue of 10YR, 2.5Y, 5Y or is neutral, value of 2 or 3 and 3 to 5 dry, and chroma of 2 or less. It typically is silty clay loam or silty clay, but the range includes clay loam and clay. In some pedons the surface layer is silt loam. It is neutral to moderately alkaline. Some pedons have a 2A or AC horizon or both.
The C horizon has hue of 2.5Y, 5Y, 5GY or is neutral, value of 3 to 7 and 4 to 8 dry, and chroma of 2 or less. Some pedons do not have prominent mottles. It typically is silty clay, but the range includes silty clay loam, clay loam and clay. It is slightly alkaline or moderately alkaline. Some pedons have a 2C horizon.
COMPETING SERIES: This is the
Oldham series. Oldham soils are not saturated in the upper 15 cm (6 inches) for at least one month during the months of July to September.
GEOGRAPHIC SETTING: Southam soils are in closed basins and deep depressions on till plains, moraines and lake plains. Slope gradient is 0 to 1 percent. The soils formed in local clayey alluvium from glacial drift. Mean annual air temperature ranges from 34 to 45 degrees F, and mean annual precipitation from 12 to 23 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Aastad,
Barnes,
Forman,
Hamerly,
Hamlet,
Parnell,
Svea and
Vallers soils. These soils are all above Southam soils on the landscape. All these soils, except Parnell, formed in loam or clay loam glacial till. Barnes and Forman soils are well drained; Aastad, Hamlet and Svea soils are moderately well drained; Hamerly soils are moderately well and somewhat poorly drained; and Vallers soils are poorly drained. Parnell soils have an argillic horizon.
DRAINAGE AND PERMEABILITY: Very poorly drained. Runoff is ponded. Permeability is slow. A seasonal high water table is at a depth of 5.0 feet above the surface to 1.0 foot below the surface throughout the year. The soils are usually ponded continuously throughout the growing season. Only in some dry years is the soil surface exposed.
USE AND VEGETATION: Most areas are in native vegetation. Native vegetation is mostly bulrushes, cattails, reeds and aquatic submergents.
DISTRIBUTION AND EXTENT: Northern, eastern and central North Dakota, and possibly western Minnesota, and northeastern South Dakota. The Southam soils are extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Ramsey County, North Dakota, 1984.
REMARKS: Revised 5/94.
Diagnostic horizons and features recognized in this pedon are: mollic epipedon - zone from the surface of the soil to a depth of 40 inches (Ag horizons); vertic subgroup criteria - LE of more than 6 cm in the upper 1 meter.
This soil competes with the Oldham series based only on duration of ponding and depth to saturation. Additional studies are needed in the future to see if both series are needed, or if ponded and drained phases of one of these series would be appropriate.
The soil is from the deep marsh vegetative zone of a Class IV wetland as defined by Stewart and Kantrud, 1971 in Resource Publication 92.
ADDITIONAL DATA: Bigler, R. J. Correlation of Wetland Soils and Plants, M.S. Thesis - N.D.S.U.
National Cooperative Soil Survey
U.S.A.