LOCATION FORDTOWN SDEstablished Series
TAXONOMIC CLASS: Fine-loamy over sandy or sandy-skeletal, mixed, superactive, frigid Pachic Hapludolls
TYPICAL PEDON: Fordtown loam - on a plane slope of less than 1 percent, in a cultivated field. When described the soil was moist throughout. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 9 inches; very dark gray (10YR 3/1) loam, black (10YR 2/1) moist; moderate medium and coarse subangular blocky structure parting to moderate fine and medium granular; soft, very friable, slightly sticky and slightly plastic; common very fine and fine roots throughout; many very fine pores; noneffervescent; 1 percent subrounded gravel; moderately acid (pH 6.0); abrupt smooth boundary.
A--9 to 13 inches; very dark gray (10YR 3/1) loam, black (10YR 2/1) moist; weak coarse prismatic structure parting to moderate medium and coarse subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine roots throughout; common fine and very fine pores; noneffervescent; 1 percent subrounded gravel; slightly acid (pH 6.1); abrupt smooth boundary. (Combined thickness of the A horizon is 6 to 14 inches)
Bw1--13 to 21 inches; dark gray (10YR 4/1) loam, very dark gray (10YR 3/1) moist; moderate coarse prismatic structure parting to moderate medium and coarse subangular blocky; hard, friable, slightly sticky and slightly plastic; common very fine roots throughout; common fine pores; noneffervescent; 1 percent subrounded gravel; neutral (pH 6.6); clear wavy boundary.
Bw2--21 to 29 inches; light olive brown (2.5Y 5/3) loam, olive brown (2.5Y 4/3) moist; moderate coarse prismatic structure parting to moderate medium and coarse subangular blocky; slightly hard, friable; common very fine roots throughout; common fine pores; common prominent continuous very dark gray (10YR 3/1), moist, organic coats on vertical faces of peds; noneffervescent; 3 percent subrounded gravel; neutral (pH 6.8); abrupt smooth boundary. (Combined thickness of the Bw horizon is 9 to 30 inches)
2C1--29 to 45 inches; light yellowish brown (2.5Y 6/3) very gravelly sand, olive brown (2.5Y 4/3) moist; single grain; loose; calcium carbonate coats on undersides of gravel; strongly effervescent; 55 percent subrounded gravel; moderately alkaline (pH 8.3); abrupt smooth boundary.
2C2--45 to 63 inches; pale brown (10YR 6/3) very gravelly sand, brown (10YR 4/3) moist; single grain; loose; calcium carbonate coats on undersides of gravel; strongly effervescent; 35 percent subrounded gravel; moderately alkaline (pH 8.3); clear smooth boundary.
2C3--63 to 80 inches; pale yellow (2.5Y 7/3) sand, light olive brown (2.5Y 5/3) moist; single grain; loose; calcium carbonate coats on undersides of gravel; strongly effervescent; 5 percent subrounded gravel; moderately alkaline (pH 8.4).
TYPE LOCATION: Brookings County, South Dakota; located about 1075 feet east and 115 feet south of the NW corner of sec. 25, T. 111 N., R. 51 W; BRUCE, S. DAK. topographic quadrangle; lat. 44 degrees 23 minutes 55 seconds N and long. 96 degrees 54 minutes 18 seconds W., NAD27.
RANGE IN CHARACTERISTICS: The depth to sand and gravel ranges from 20 to 40 inches. Thickness of the mollic epipedon ranges from 16 to 30 inches. Depth to calcium carbonate ranges from 17 to 40 inches.
The A horizon has hue of 10YR, value of 3 or 4 and 2 or 3 moist, and chroma of 1 moist and 1 or 2 dry, but some pedons have chroma of 2 moist below the Ap horizon. It typically is loam but is sandy loam or silt loam in some pedons. It is moderately acid to neutral.
The Bw horizon has hue of 7.5YR, 10YR, or 2.5Y; value of 3 to 5 and 2 to 4 moist; and chroma of 1 to 4. It is loam, silt loam, sandy loam, or clay loam averaging between 18 and 30 percent clay. It ranges from slightly acid to slightly alkaline.
Some pedons have a buried horizon.
Some pedons have a BC or Bk horizon less than 5 inches thick.
The 2C horizon has hue of 7.5YR, 10YR, or 2.5Y; value of 4 to 7 and 3 to 6 moist; and chroma of 2 to 4. It is sand, coarse sand, loamy sand or their gravelly or very gravelly analogues. Thin strata of finer textures are in some pedons. It is slightly alkaline or moderately alkaline.
COMPETING SERIES: These are the Fordville, Spottswood, and Vang series. Fordville soils do not have soil saturation in the series control section. Spottswood soils have soil saturation above a depth of 40 inches. Vang soils have 50 percent or more coarse shale fragments within depth of 20 to 40 inches.
GEOGRAPHIC SETTING: Fordtown soils are on flood plains. They formed in loamy alluvium over stratified sand and gravel. Slopes are plane or convex and range from 0 to 2 percent. Elevations range from 1000 to 2350 feet. Mean annual precipitation is 20 to 24 inches. The frost-free period is 120 to 140 days. Mean annual air temperature ranges from 40 to 45 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are Allivar, Divide, Marysland, Renwash and Spottswood soils. The Allivar soils have less than 18 percent clay in the upper part of the series control section and are on slightly high positions on the landscape. Divide and Marysland soils have a calcic horizon within 16 inches. The Divide, Marysland, and Spottswood soils are in slightly concave and lower parts of the landscape. Renwash soils are less than 20 inches to sand and gravel and are slightly higher on the landscape.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is very low. Permeability is moderate in the upper part and very rapid in the underlying material. A seasonal high water table is at a depth of 3.5 to 6 feet from March to June in most years.
USE AND VEGETATION: Most areas are cultivated to corn and hay. Native grasses are big bluestem, little bluestem, needlegrass, western wheatgrass, and blue grama.
DISTRIBUTION AND EXTENT: Northeastern South Dakota (MLRA 102A). The series is of minor extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Brookings County, South Dakota, 1995.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of about 21 inches (Ap, A, and Bw1 horizons); cambic horizon - the zone from about 21 to 29 inches (Bw2 horizon).