LOCATION HOFFMANVILLE MTEstablished Series
TAXONOMIC CLASS: Clayey over sandy or sandy-skeletal, smectitic over mixed, calcareous, frigid Typic Ustifluvents
TYPICAL PEDON: Hoffmanville silty clay - cultivated. (Colors are of dry soil unless otherwise stated)
Ap--0 to 8 inches; grayish brown (2.5Y 5/2) silty clay, dark grayish brown (2.5Y 4/2) moist; moderate medium angular blocky structure parting to moderate coarse granular; very hard, firm, very sticky and very plastic; common very fine roots throughout; slightly effervescent throughout (HCI, 1 normal); slightly alkaline; abrupt smooth boundary. (5 to 10 inches thick)
C1--8 to 20 inches; light brownish gray (2.5Y 6/2) stratified silty clay loam and silty clay, dark grayish brown (2.5Y 4/2) moist; massive; very hard, firm, very sticky and very plastic; stratifications 1 to 2 mm thick; common very fine roots throughout; common fine irregular masses of lime pedogenic throughout; slightly effervescent throughout (HCI, 1 normal); moderately alkaline; abrupt smooth boundary. (10 to 35 inches thick)
C2--20 to 26 inches; light brownish gray (2.5Y 6/2) stratified silty clay, dark grayish brown (2.5Y 4/2) moist; massive; very hard, firm, very sticky and very plastic; stratifications 1 to 2 mm thick; few very fine roots throughout; common fine irregular masses of lime pedogenic throughout and common fine carbonate threads pedogenic throughout; strongly effervescent throughout (HCI, 1 normal); moderately alkaline; abrupt smooth boundary.
2C3--26 to 41 inches; light brownish gray (2.5Y 6/2) stratified loamy fine sand, dark grayish brown (2.5Y 4/2) moist; massive; soft, very friable, slightly sticky and nonplastic; stratifications 1 to 2 mm thick; few very fine roots throughout; few fine irregular masses of lime; slightly effervescent throughout (HCI, 1 normal); moderately alkaline; clear smooth boundary.
2C4--41 to 50 inches; light brownish gray (2.5Y 6/2) stratified fine sandy loam; dark grayish brown (2.5Y 4/2) moist; massive; soft, very friable, slightly sticky and slightly plastic; stratifications 1 to 2 mm thick; few very fine roots throughout; common fine irregular dark yellowish brown (10YR 4/6) iron concretions pedogenic throughout; slightly effervescent throughout (HCI, 1 normal); moderately alkaline; abrupt smooth boundary.
3C5--50 to 61 inches; grayish brown (2.5Y 5/2) stratified silty clay and silty clay loam, dark grayish brown (2.5Y 4/2) moist; massive; very hard, firm, very sticky and very plastic; stratifications 1 to 2 mm thick; common fine irregular masses of lime pedogenic throughout; common fine irregular dark yellowish brown (10YR 4/6) iron concretions pedogenic throughout; strongly effervescent throughout (HCI, 1 normal); moderately alkaline; abrupt smooth boundary.
4C6--61 to 80 inches; light brownish gray (2.5Y 6/2) stratified fine sandy loam and silt loam, grayish brown (2.5Y 5/2) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; stratifications 1 to 2 mm thick; common fine irregular dark yellowish brown (10YR 4/6) iron concretions pedogenic throughout; slightly effervescent throughout (HCI, 1 normal); moderately alkaline.
TYPE LOCATION: Richland County, Montana, 180 north and 200 feet east of the southwest corner, sec. 24, T. 26 N., R. 59 E.
RANGE IN CHARACTERISTICS: The soil has hue of 2.5Y, 5Y or 10YR; value of 5 or 6 dry, 4 or 5 moist, and chroma is 1 to 3 throughout the soil. Average texture of the upper C horizons is silty clay or silty clay loam with thin strata of loam and silt loam in some pedons. The 2C horizon typically occurs at depths of 24 to 36 inches but ranges from 20 to 40 inches. It is loamy fine sand or fine sand containing up to 35 percent gravel. Textures below a depth of 40 inches are fine sand, loamy fine sand, fine sandy loam, silt loam, silty clay loam or silty clay.
COMPETING SERIES: There are no competing series in the same family.
GEOGRAPHIC SETTING: Hoffmanville soils are on nearly level and gently sloping or undulating floodplains and low terraces. The soils formed in calcareous, clayey alluvium deposited over sandy alluvium that is gravelly in some areas. Mean annual air temperature is 40 degrees to 45 degrees F., mean January temperature is 8 to 25 degrees F., and mean July temperature is 65 degrees to 70 degrees F. Average annual precipitation is 10 to 16 inches. The frost-free period is 105 to 135 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Banks, Havrelon, Lohler, Ridgelawn and Trembles soils. Banks soils have sandy control sections. Havrelon, Lohler and Trembles soils have fine-loamy, fine, and coarse-loamy control sections respectively. Ridgelawn soils have fine-loamy over sandy or sandy-skeletal control sections.
DRAINAGE AND PERMEABILITY: Well-drained; slow runoff; slow permeability. Some areas are subject to occasional flooding.
USE AND VEGETATION: Hoffmanville soils are used mainly as dry farmed and irrigated cropland. Sugar beets, corn silage, alfalfa, and small grains are the main crops. Some areas are used as rangeland. Native vegetation is mainly wheatgrasses, rosebush, snowberry, and silver sagebrush with a sparse overstory of cottonwood and green ash trees in some places.
DISTRIBUTION AND EXTENT: Eastern Montana. The series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Richland County, Montana, 1973.
REMARKS: Diagnostic horizons and features recognized in this pedon are: Ochric epipedon - the zone from the surface of the soil to a depth of 8 inches (Ap horizon); Irregular decrease in organic carbon - stratifications in the 8 to 80 inch zone (C1, C2, 2C3, 2C4, 3C5 and 4C6 horizons).