LOCATION BIGSTONE MNEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, calcareous, frigid Cumulic Endoaquolls
TYPICAL PEDON: Bigstone silt loam on a slope of less than 1 percent in a depression on a till plain. (Colors are for moist soil unless otherwise stated.)
A1--0 to 11 inches; black (N 2/) silt loam, very dark gray (N 3/) dry; weak medium subangular blocky fine granular structure parting to weak fine granular; friable; common fine roots; slightly effervescent; moderately alkaline; clear wavy boundary.
A2--11 to 21 inches; black (N 2/) silty clay loam, very dark gray (N 3/) dry; weak medium and fine subangular structure; friable; common fine roots; slightly effervescent; moderately alkaline; clear wavy boundary.
A3--21 to 30 inches; black (N 2/) silty clay loam, very dark gray (N 3/) dry; weak fine subangular blocky structure; friable; few fine roots; few light brownish gray (2.5Y 6/2) gypsum crystals; common prominent olive brown (2.5Y 4/4) Fe concentrations; slightly effervescent; moderately alkaline; clear wavy boundary. (Combined thickness of A horizons is 24 to 60 inches.)
2Cg--30 to 60 inches; olive gray (5Y 5/2) clay loam; massive; friable; few light gray (5Y 6/1) lime accumulations; few light gray (5Y 6/1) gypsum crystals; 1 percent gravel; common medium distinct gray (5Y 5/1) Fe depletions and common medium prominent yellowish brown (10YR 5/8) Fe concentrations; strongly effervescent; moderately alkaline.
TYPE LOCATION: Lac Qui Parle County, Minnesota, about 5 miles south and 1 mile west of Marietta; 1700 feet south and 150 feet east of the northwest corner of section 21, T. 117 N., R. 46 W.
RANGE IN CHARACTERISTICS: The thickness of the mollic epipedon is 24 to 60 inches. Depth to free carbonates is 0 to 10 inches. The soil is slightly alkaline or moderately alkaline throughout. The upper 10 inches of the series control section contains 0 to 20 percent calcium carbonate equivalent; the remainder of the profile has 5 to 30 percent. Some pedons contain fragments of snail shells. The series control section typically is silty clay loam, but is silt loam or clay loam with less than 15 percent fine sand or coarser is in some pedons. The A horizon typically is free of rock fragments, but the lower part in some pedons contains up to 3 percent by volume. The 2Cg horizon contains 1 to 8 percent rock fragments by volume. Depth to 2Cg horizon ranges from 36 to 80 inches. This soil is saturated in the moisture control section for more than 20 days following the summer solstice in most years.
The A horizon has hue of 10YR to 5Y or is neutral, value of 2 or 3 and 3 to 5 dry, and chroma of 0 or 1. It has mottles in some pedons. It is silty clay loam or silt loam, but in some pedons it is clay loam with less than 15 percent fine sand and coarser throughout.
Some pedons have a Cg horizon with hue of 2.5Y or 5Y, value of 4 or 5, and chroma of 1 or 2. Textures are silty clay loam or silt loam.
The 2Cg horizon has hue of 2.5Y or 5Y, value of 4 or 5, and chroma of 1 or 2. It commonly has distinct or prominent mottles. Textures are loam or clay loam.
COMPETING SERIES: These are in the Downata, Hallek, Inkom, Lamoure, Playmoor, and Rauville Series. Downata, Inkom, and Playmoor soils are not saturated in the moisture control section for more than 20 days following the summer solstice in most years. Hallek soils do not have coarse fragments throughout the profile. The Lamoure soils typically have buried A horizons within the series control section and are poorly drained. The Rauville soils have a moderately rapid permeability below 45 inches.
GEOGRAPHIC SETTING: The Bigstone soils have plane or concave slopes ranging from 0 to 1 percent in depressions on till plains. They have primarily formed in calcareous local alluvium and the underlying calcareous, glacial till. Mean annual air temperature ranges from 40 to 44 degrees F. Mean annual precipitation ranges from 24 to 27 inches. The frost-free days range from 120 to 172. The elevation above sea level ranges from 990 to 1950 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Esmond, Flom, Fram, Hamerly, Heimdal, Lakepark, Svea, and Vallers. The well drained Esmond and Heimdal soils are on adjacent uplands. The moderately well drained and somewhat poorly drained Fram, Hamerly, and Svea soils are on low convex rises, concave foot slopes, and side slopes. The poorly drained Lakepark and Vallers soils are in drainageways and on flats.
DRAINAGE AND PERMEABILITY: Very poorly drained. Runoff is very slow or ponded. Permeability is moderately slow or moderate. The apparent seasonal high water table is at depths of 1 foot above to 1 foot below the surface. A ponded phase is recognized with the water table at 0 to 3 feet above the surface in most years.
USE AND VEGETATION: These soils are cropped to corn, soybeans, and small grains where drained. Native vegetation is grasses, rushes, sedges, and reeds.
DISTRIBUTION AND EXTENT: West central Minnesota. The series is of limited extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Big Stone County, Minnesota, 1992.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface to a depth of 30 inches (A1, A2, and A3 horizons); cumulic subgroup - mollic epipedon is more than 24 inches thick; calcareous family - free carbonates throughout. (Field calcimeter kit data indicates a range of 5 to 30 percent below a depth of about 10 inches.)