LOCATION ELPAM SDEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, calcareous, mesic Mollic Endoaquepts
TYPICAL PEDON: Elpam silt loam - on a flat in native grassland. (Colors are for moist soil unless otherwise stated.)
A--0 to 4 inches; black (10YR 2/1) silt loam, gray (10YR 5/1) dry; weak medium granular structure; soft, very friable; strong effervescence; moderately alkaline; clear wavy boundary. (3 to 6 inches thick)
Bk--4 to 15 inches; dark gray (2.5Y 4/1) and very dark gray (5Y 3/1) silty clay loam, gray (N 6/) and 2.5Y 5/1) dry; weak medium prismatic structure parting to weak fine granular; soft, friable; slightly sticky; violent effervescence; moderately alkaline; clear wavy boundary. (3 to 12 inches thick)
Bkg1--15 to 36 inches; gray (5Y 5/1) silty clay loam, light gray (N 7/1) dry; very weak coarse blocky structure; slightly hard, friable; slightly sticky; violent effervescence; moderately alkaline; gradual wavy boundary. (10 to 25 inches thick)
Bkg2--36 to 52 inches; gray (5Y 6/1) silty clay loam, white (5Y 8/1) dry; massive; hard, firm, slightly sticky; violent effervescence; moderately alkaline; clear smooth boundary.
2C--52 to 60 inches; olive brown (2.5Y 4/4) and gray (5Y 5/1) clay loam, light olive brown (2.5Y 5/4) and light gray (5Y 7/1) dry; massive; hard, firm, slightly sticky; violent effervescence; moderately alkaline.
TYPE LOCATION: Sully County, South Dakota; about 1 1/2 miles east of Stone Lake; 1430 feet west and 2870 feet north of the southeast corner of sec. 2, T. 14 N., R. 10 E.
RANGE IN CHARACTERISTICS: The soil is slightly alkaline or moderately alkaline throughout.
The A horizon has hue of 10YR, 2.5Y, or neutral; value of 2 to 4 and 4 or 5 dry; and chroma of 1 or less. A horizons dark enough to be mollic typically are 4 inches thick and do not exceed 6 inches in thickness. It is silt loam or silty clay loam.
The Bk horizon has mixed colors of the A and C horizons. It is silt loam or silty clay loam. Some pedons have AC horizons.
The Bkg horizon has hue of 5Y, 2.5Y, or neutral; value of 5 or 6 and 6 to 8 dry; and chroma of 1 or less. Calcium carbonate equivalent ranges from 15 to 40 percent. Carbonates are disseminated or as accumulations. Clay loam glacial till typically is between depths of 40 and 60 inches but is below 60 inches in some pedons. Few to many accumulations of gypsum are in some pedons.
COMPETING SERIES: This is the Rafael series. The Rafael soils have more than 15 percent exchangeable sodium in the upper 20 inches.
GEOGRAPHIC SETTING: The Elpam soils are in shallow depressions and along glacial meltwater channels within the glacial till plain. Slopes are smooth to slightly concave with gradients less than 1 percent. These soils formed in silty glacio-fluvial sediments. The mean annual precipitation ranges from 15 to 20 inches, and mean annual temperature ranges from 45 to 48 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Egas and Durrstein soils. The Egas soils are in the lower positions and contain more visible salts. The Durrstein soils have natric horizons and are fine textured.
DRAINAGE AND PERMEABILITY: Poorly drained. Water table fluctuates between the surface and depths of one foot. Runoff is low. Permeability is moderate in the upper part of the profile and moderately slow in the lower part.
USE AND VEGETATION: Rangeland. Native vegetation is big bluestem, Indiangrass, switchgrass, western wheatgrass, sedges, and forbs.
DISTRIBUTION AND EXTENT: Central and south-central South Dakota. The series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Sully County, South Dakota, 1976.
REMARKS: Diagnostic horizons and features recognized in this pedon are: ochric epipedon - the zone from the surface of the soil to a depth of about 4 inches (A horizon).