LOCATION WILTON NDEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, frigid Pachic Haplustolls
TYPICAL PEDON: Wilton silt loam - near crest of broad low rise of l percent slope in cultivated field. (Colors are for dry soil unless otherwise stated)
Ap--0 to 8 inches; dark grayish brown (10YR 4/2) silt loam, very dark brown (10YR 2/2) moist; weak medium subangular blocky structure parting to moderate fine granular; slightly hard, very friable; slightly sticky and slightly plastic; common roots, neutral; abrupt smooth boundary. (Combined A horizons 5 to 12 inches thick)
Bw1--8 to 13 inches; dark grayish brown (10YR 4/2) silt loam, very dark brown (10YR 2/2) moist; moderate medium prismatic structure parting to weak medium subangular blocky; slightly hard; very friable, slightly sticky and slightly plastic; many fine roots; common fine pores; neutral; clear wavy boundary.
Bw2--13 to 18 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; slightly hard, very friable, slightly sticky and slightly plastic; common fine roots; common fine pores; faint clay films on some vertical faces of peds; very dark brown (10YR 2/2) moist coatings on peds; neutral; gradual wavy boundary.
Bw3--18 to 27 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; moderate medium prismatic structure parting to weak medium subangular blocky; slightly hard, very friable, slightly sticky and slightly plastic; common fine roots; common fine pores; slight effervescence in spots; slightly alkaline; clear wavy boundary. (Combined Bw horizons 10 to 30 inches thick)
2Bk1--27 to 36 inches; light brownish gray (2.5Y 6/2) clay loam, dark grayish brown (2.5Y 4/2) moist; weak coarse prismatic structure parting to weak coarse and medium subangular blocky; hard, friable, sticky and plastic; few fine roots; common fine pores; about 5 percent coarse fragments; strong effervescence, carbonates in many medium and few large masses; slightly alkaline; gradual wavy boundary.
2Bk2--36 to 60 inches; light brownish gray (2.5Y 6/2) clay loam, olive brown (2.5Y 4/3) moist; few fine prominent strong brown (7.5YR 5/6) redox concentrations; massive; hard, friable, sticky and plastic; few roots; about 5 percent coarse fragments; strong effervescence, carbonates in common masses; moderately alkaline.
TYPE LOCATION: McLean County, North Dakota; about 2 1/2 miles east of Riverdale; 1,600 feet east and 300 feet north of southwest corner, sec. 31, T. 147 N., R. 83 W.
RANGE IN CHARACTERISTICS: Depth to the finer textured 2Bk horizon is 20 to 40 inches. The silty loess mantle contains less than 15 percent fine or coarser sand and more than 18 percent clay. The mollic epipedon ranges from 16 inches to more than 30 inches in thickness and commonly includes most of the Bw horizon.
The A horizon has hue of 10YR, value of 3 to 5 and 2 or 3 moist, and chroma of 2. It is silt loam. It is slightly acid or neutral.
The Bw horizon has hue of 10YR or 2.5Y, value of 4 or 5 and 2 to 4 moist, and chroma of 2 to 4. It is silt loam with 18 to 27 percent clay and less than 15 percent fine or coarser sand. It is neutral or slightly alkaline. Faces of peds are coated with faint clay films in some pedons, but the soil does not have an argillic horizon. The lower part of the Bw horizon extends into the underlying till in some pedons.
The 2Bk horizon has hue of 2.5Y or 5Y, value of 5 to 7 dry and 4 or 5 moist, and chroma of 2 to 4. It is loam or clay loam till containing 2 to 10 percent by volume gravel and stones. It is slightly alkaline or moderately alkaline. It has few through many masses of carbonates. Some pedons have a 2C horizon below the 2Bk horizon.
COMPETING SERIES: These are the Grassna and Makoti series. These soils do not have loam or clay loam till horizons within depths of 40 inches.
GEOGRAPHIC SETTING: Wilton soils are on level to gently rolling uplands. Slope gradients typically are 1 to 6 percent but range from 0 to 9 percent. The soil formed in a silty loess mantle overlying loam or clay loam till. Mean annual air temperature ranges from 39 to 45 degrees F, and mean annual precipitation ranges from 13 to 18 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing
Grassna soils and the
Linton,
Mandan,
Temvik and
Williams soils. Grassna, Linton and Mandan soils are in areas where the silty loess mantle is more than 40 inches thick. Grassna soils are in concave swales. Temvik soils commonly are on adjacent slightly steeper slopes or slightly convex positions. Linton and Temvik soils have mollic epipedons less than 16 inches thick. Mandan soils are coarse-silty.
Williams soils are on nearby till plains, typically on higher lying parts of the landscape. They have argillic horizons.
DRAINAGE AND PERMEABILITY: Well drained. Slow or medium runoff. Permeability is moderate in the silty loess mantle and moderately slow in the underlying till.
USE AND VEGETATION: Soils are mainly cropped to small grains, flax and corn. Some areas are used for hay and pasture. Native vegetation was western wheatgrass, green needlegrass, bearded wheatgrass, prairie junegrass, needleandthread and a variety of forbs.
DISTRIBUTION AND EXTENT: Central North Dakota and possibly north-central South Dakota adjacent to the Missouri River. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: McLean County, North Dakota, 1974.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of 27 inches (Ap, Bw1, Bw2, and Bw3 horizons).