LOCATION BONILLA SDEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Pachic Haplustolls
TYPICAL PEDON: Bonilla loam - on slightly concave slope of 1 percent in a cultivated field. When described the soil was moist throughout. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 8 inches; very dark gray (10YR 3/1) loam, black (10YR 2/1) moist; weak fine granular structure; slightly hard, friable; moderately acid; abrupt smooth boundary.
A--8 to 13 inches; very dark gray (10YR 3/1) loam, black (10YR 2/1) moist; weak medium subangular blocky structure parting to weak fine granular; slightly hard, friable; moderately acid; clear wavy boundary. (Combined thickness of the A horizon is 7 to 15 inches.)
Bw1--13 to 29 inches; dark gray (10YR 4/1) clay loam, very dark brown (10YR 2/2) moist; weak medium prismatic structure parting to weak medium subangular blocky; hard, friable, slightly sticky and slightly plastic; slightly acid; gradual wavy boundary.
Bw2--29 to 35 inches; grayish brown (2.5Y 5/2) clay loam, dark grayish brown (2.5Y 4/2) moist; few fine distinct yellowish brown (10YR 5/6) redox concentrations and black (10YR 2/1) iron and manganese stains; weak medium prismatic structure parting to weak medium subangular blocky; hard, friable, slightly sticky and slightly plastic; neutral; clear wavy boundary. (Combined thickness of the Bw horizon is 13 to 30 inches.)
Bk1--35 to 42 inches; light brownish gray (2.5Y 6/2) clay loam, dark grayish brown (2.5Y 4/2) moist; few fine distinct yellowish brown (10YR 5/6) redox concentrations and very dark brown (10YR 2/2) iron and manganese stains; weak medium prismatic structure parting to weak medium subangular blocky; hard, friable, slightly sticky and slightly plastic; common fine accumulations of carbonate; strong effervescence; slightly alkaline; gradual wavy boundary.
Bk2-- 42 to 47 inches; light brownish gray (2.5Y 6/2) clay loam, grayish brown (2.5Y 5/2) moist; common fine distinct light olive brown (2.5Y 5/6) redox concentrations and gray (2.5Y 6/1) redox depletions; weak medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common fine and medium accumulations of carbonate; strong effervescence; slightly alkaline; gradual wavy boundary. (Combined thickness of the Bk horizon is 0 to 35 inches.)
C--47 to 60 inches; light yellowish brown (2.5Y 6/4) and light gray (5Y 7/1) clay loam, olive brown (2.5Y 4/4) and gray (5Y 5/1) moist; few fine distinct very dark brown (10YR 2/2) iron and manganese stains; massive; hard, friable, slightly sticky and slightly plastic; common fine accumulations of carbonate; strong effervescence; slightly alkaline.
TYPE LOCATION: Turner County, South Dakota; about 1 mile east and 5 1/2 miles south of Marion; 115 feet west and 1,420 feet north of the southeast corner of sec. 5, T. 98 N., R. 54 W.
RANGE IN CHARACTERISTICS: The depth to carbonates ranges from 20 to 40 inches. Thickness of the mollic epipedon ranges from 20 to 40 inches and it extends into or through the Bw horizon. The control section averages between 18 and 30 percent clay.
The A horizon has value of 3 or 4 and 2 or 3 moist, and chroma of 1 or 2. It is loam, fine sandy loam or silt loam. It ranges from moderately acid to neutral.
The Bw horizon has hue of 10YR or 2.5Y, value of 4 to 6 and 2 to 4 moist, and chroma of 1 to 3. It typically is mottled within the lower part. It typically is loam or clay loam and ranges from slightly acid to slightly alkaline.
The Bk horizon has 10YR, 2.5Y, or 5Y hue; value of 6 or 7 and 4 or 5 moist; and chroma of 1 to 3. It typically is loam or clay loam but is silt loam, or light silty clay loam in some pedons. It has common to many accumulations of carbonate. It ranges from neutral to moderately alkaline.
The C horizon has 10YR, 2.5Y, or 5Y hue; value of 6 or 7 and 4 or 5 moist; and chroma of 1 to 4. It typically is loam or clay loam and in some pedons it is stratified loam, silt loam, or fine sandy loam, with lenses 1 to 10 inches thick of clay loam, silty clay loam, or loamy sand. It is slightly or moderately alkaline. The C horizon has few to many, distinct or prominent mottles. It typically has few to many accumulations of carbonate. Visible gypsum is common in the lower part.
COMPETING SERIES: These are the Davis, Table Mountain and Whiskey soils in the same family. Davis soils do not have mottles above depths of 40 inches. Table Mountain soils are dry more than 1/2 the time the soil temperature is 41 degrees F. or higher. Whiskey soils are intermittently moist in some part of the soil moisture control section during July-September and December-February.
GEOGRAPHIC SETTING: Bonilla soils are nearly level to gently sloping in drainageways, swales, flats and foot slopes of the glacial till plains. Surfaces are plane to slightly concave and slope gradients typically are 2 percent or less, but range from 0 to 6 percent. Bonilla soils formed in loam or clay loam glacial till. The mean annual air temperature ranges from 45 to 52 degrees F, and the mean annual precipitation ranges from 18 to 26 inches. Growing season is about 135 to 165 days; average growing season precipitation ranges from 14 to 20 inches; and growing degree days are about 2700 to 3500.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the Blendon, Clarno, Crossplain, Davison, Ethan, Hand, Henkin, Prosper, and Tetonka soils. Blendon soils are on similar landscapes and have a coarse-loamy control section. Clarno, Ethan, Hand, and Henkin soils are on higher convex slopes. Clarno, Ethan, Hand, and Henkin soils have mollic epipedons less than 20 inches thick. In addition, Ethan soils have carbonates at or near the surface and Henkin soils have a coarse-loamy control section. Crossplain and Tetonka soils are in swales and depressions, have a fine textured series control section, and are more poorly drained. Davison soils are on slight rises near swales or depressions and have a calcic horizon within 16 inches of the surface. Prosper soils have an argillic horizon and are on similar landscapes as the Bonilla soils.
DRAINAGE AND PERMEABILITY: Moderately well drained. Surface runoff is neglible to medium depending on slopes. Permeability is moderate in the solum and is moderately slow or moderate in the underlying material. Seasonal water table typically is at depths of 3 to 4 feet for short periods in the spring of some years.
USE AND VEGETATION: Most areas are cultivated. Corn, oats, soybeans, grain sorghum, tame grass, and alfalfa are the main crops. Native vegetation is mainly big bluestem, green needlegrass, needleandthread, western wheatgrass, sideoats grama, little bluestem, leadplant, sedges, and forbs.
DISTRIBUTION AND EXTENT: East-central and southeastern South Dakota. It is of large extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Spink County, South Dakota, 1955.
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 29 inches (Ap, A, Bw1, horizon).