LOCATION RUSHMORE MN+IAEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Typic Endoaquolls
TYPICAL PEDON: Rushmore silty clay loam, on a plane slope of less than 1 percent, on a ground moraine, in a cultivated field. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 8 inches; black (N 2/0) silty clay loam, very dark gray (10YR 3/1) dry; weak fine subangular blocky structure; friable; neutral; abrupt smooth boundary. (7 to 10 inches thick)
A1--8 to 14 inches; black (5Y 2/1) silty clay loam, very dark gray (5Y 3/1) dry; weak fine subangular blocky structure; friable; neutral; gradual wavy boundary. (4 to 8 inches thick)
AB--14 to 18 inches; very dark gray (5Y 3/1) silty clay loam, dark gray (5Y 4/1) dry; moderate fine subangular blocky structure; friable; neutral; clear wavy boundary. (3 to 6 inches thick)
Bg1--18 to 21 inches; olive gray (5Y 4/2) silty clay loam; weak fine subangular blocky structure; friable; many fine distinct olive (5Y 5/3) Fe concentrations; neutral; clear wavy boundary. (3 to 6 inches thick)
Bg2--21 to 24 inches; olive (5Y 5/3) silty clay loam; weak fine subangular blocky structure; friable; common fine distinct olive (5Y 5/6) Fe concentrations; neutral; abrupt wavy boundary. (2 to 8 inches thick)
Bg3--24 to 32 inches; olive (5Y 5/3) silty clay loam; weak fine subangular blocky structure; friable; common medium distinct grayish brown (2.5Y 5/2) Fe depletions; slightly effervescent; slightly alkaline; clear wavy boundary. (3 to 8 inches thick)
2Bk--32 to 44 inches; light olive brown (2.5Y 5/4) clay loam; weak coarse and extremely coarse prismatic structure parting to weak coarse angular blocky; firm; common fine soft lime accumulations; about 5 percent gravel; many fine and medium distinct grayish brown (2.5Y 5/2) Fe depletions; strongly effervescent; moderately alkaline.
2BC--44 to 80 inches; light olive brown (2.5Y 5/4) clay loam; weak coarse and extremely coarse prismatic structure parting to weak coarse angular blocky; firm; about 5 percent gravel; many fine and medium distinct grayish brown (2.5Y 5/2) Fe depletions; strongly effervescent; moderately alkaline.
TYPE LOCATION: Nobles County, Minnesota; about 1.5 miles southeast of Adrian; located about 535 feet south and 150 feet west of the northeast corner of section 29, T. 102 N., R. 42 W.; USGS Adrian SW topographic quadrangle; lat. 43 degrees 36 minutes 54 seconds N. and long. 95 degrees 53 minutes 41 seconds W., NAD 83.
RANGE IN CHARACTERISTICS: The depth to carbonates range from 15 to 36 inches. The thickness of the loess or silty glacial lacustrine sediments over the glacial till is 24 to 40 inches. The mollic epipedon ranges from 14 to 24 inches in thickness. Coarse fragments are essentially absent in the loess and comprise 2 to 8 percent by volume of the glacial till. A stone line ranging to as much as 4 inches in thickness and containing up to 20 percent by volume of coarse fragments commonly is at the contact of the glacial till. The coarse fragments are mixed in lithology. The particle-size control section averages between 24 and 36 percent clay and 5 to 15 percent sand coarser than very fine sand. The upper mantle averages between 27 and 38 percent clay with the higher contents in the upper part, and averages between 4 and 12 percent sand. The glacial till averages between 24 and 32 percent clay and 15 to 35 percent sand.
The A horizon has hue of 10YR, 2.5Y, or 5Y or is neutral, value of 2 or 3, and chroma of 0 or 1. It is silt loam or silty clay loam. Reaction is slightly acid or neutral.
The AB horizon has hue of 10YR, 2.5Y, or 5Y, value of 2 or 3, and chroma of 1 or 2. It is silt loam or silty clay loam. It ranges from slightly acid to neutral.
The Bg horizon has hue of 2.5Y or 5Y, value of 4 or 5, and chroma of 1 to 3 with chroma of 3 or 4 is in the lower part in some pedons. It is silt loam or silty clay loam. Reaction is neutral or slightly alkaline.
Some pedons have a Bk horizon.
The 2Bk horizon is similar to the 2BC horizon but has evidence of secondary carbonates and a calcium carbonate equivalent of 15 to 25 percent.
The 2BC horizon has hue of 2.5Y or 5Y, value of 4 to 6, and chroma of 1 to 4. It is loam or clay loam. It is firm. Reaction is slightly alkaline or moderately alkaline. Calcium carbonate equivalent is 10 to 20 percent. The moist bulk density is 1.6 to 1.8 g/cc.
COMPETING SERIES: These are the Drummer, Elvira, Garwin, Hartsburg, Leshara, Madelia, Marcus, Maxcreek, Maxfield, Ossian, Patton, Pella, Sable, and Wacousta soils in the same family and the Letri and Ransom series. Drummer soils have thicker sola. Elvira soils have concentration of iron and manganese oxides in the A and B horizons. Garwin, Hartsburg, Leshara, Madelia, Marcus, Ossian, Patton, Sable, and Wacousta soils have silt loam or silty clay loam B and C horizons extending to depths below 40 inches. In addition, all of these soils except Leshara, Madelia, and Marcus are in areas receiving more precipitation. Maxcreek soils have more sand in the lower part of the B horizon and in the 2C horizon. Maxfield soils have thicker sola and are in areas receiving more precipitation. Pella soils are in areas receiving more precipitation and in addition, have loamy 2C horizons formed in outwash or till. Letri soils contain more sand in the solum. Ransom soils are better drained and have browner B horizons.
GEOGRAPHIC SETTING: These soils have plane or slightly concave slopes with gradient of 0 to 2 percent on ground moraines. They formed in 24 to 40 inches of loess or silty glacial lacustrine sediments and calcareous, firm glacial till. Mean annual air temperature is about 45 to 52 degrees F. Mean annual precipitation is about 25 to 30 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: The Everly, Ransom, Sac, and Wilmonton soils are the main ones. The moderately well drained Everly and Sac soils are on higher lying more sloping terrain. The somewhat poorly drained Ransom and Wilmonton soils are on nearby gently sloping areas. The Sac and Ransom soils formed in materials similar to those of Rushmore. The Everly and Wilmonton soils typically have clay loam sola.
DRAINAGE AND PERMEABILITY: Poorly drained. Surface runoff is low. Permeability is moderately slow. The depth to seasonal high saturation in undrained areas is at or near the surface in spring in normal years.
USE AND VEGETATION: Mostly cropped to corn and soybeans. Native vegetation is a wet site association of the tall grass prairie.
DISTRIBUTION AND EXTENT: MLRA 107. Southwestern Minnesota and northwestern Iowa. Moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Nobles County, Minnesota, September, 1970.
REMARKS: Diagnostic horizons and features recognized in the pedon are: mollic epipedon - the zone from the surface to a depth of 18 inches (Ap, A1 and AB horizons); cambic horizon - the zone from 18 to 80 inches (Bg1, Bg1, Bg3, 2Bk and 2BC horizons); Aquic moisture regime.
Competing series were not updated as of this revision.
ADDITIONAL DATA: Refer to Minnesota Agricultural Experiment Station Central File Code No. 790 for results of some laboratory analysis of a representative pedon of this series.