LOCATION BEARPAW MT+ND SD
Established Series
Rev. NRS-JAL
01/2023
BEARPAW SERIES
The Bearpaw series consists of very deep, well drained soils that formed in till. These soils are on till plains and hills. Slopes are 0 to 15 percent. Mean annual precipitation is about 16 inches, and mean annual air temperature is about 43 degrees F.
TAXONOMIC CLASS: Fine, smectitic, frigid Vertic Argiustolls
TYPICAL PEDON: Bearpaw clay loam, in rangeland (colors are for dry soil unless otherwise noted).
A--0 to 3 inches; dark brown (10YR 4/3) loam, dark brown (10YR 3/3) moist; moderate fine and very fine granular structure; slightly hard, very friable, slightly sticky and slightly plastic, many fine roots; neutral (pH 7.0); clear smooth boundary. (2 to 7 inches thick)
Bt1--3 to 5 inches; dark grayish brown (10YR 4/2) clay loam, very dark grayish brown (10YR 3/2) moist; moderate medium prismatic structure parting to moderate fine subangular blocky; hard, friable, sticky and slightly plastic; many fine roots; common fine pores; few faint clay films on faces of peds; slightly alkaline (pH 7.6); clear smooth boundary. (0 to 3 inches thick)
Bt2--5 to 10 inches; dark grayish brown (10YR 4/2) clay loam, very dark grayish brown (10YR 3/2) moist; strong medium and fine prismatic structure parting to moderate medium and fine angular blocky; very hard, friable, sticky and plastic; common fine and very fine roots; common very fine pores; continuous faint clay films on faces of peds, 5 percent pebbles; slightly alkaline (pH 7.6); clear wavy boundary. (4 to 8 inches thick)
Bt3--10 to 16 inches, grayish brown (10YR 5/2) clay loam, dark grayish brown (10YR 4/2) moist; strong medium and fine prismatic structure parting to strong medium and fine angular blocky; very hard, friable, sticky and plastic; common fine and very fine roots; common very fine pores; continuous faint dark grayish brown (10YR 4/2) clay films on faces of peds; 5 percent pebbles; slightly alkaline (pH 7.6); clear wavy boundary. (4 to 8 inches thick)
Btk--16 to 23 inches; grayish brown (2.5Y 5/2) clay loam, dark grayish brown (2.5Y 4/2) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; very hard, friable, sticky and plastic; common fine and very fine roots; common very fine pores; few faint clay films on faces of peds; 5 percent pebbles; strongly effervescent; common fine and medium masses of lime; moderately alkaline (pH 8.0); clear wavy boundary. (5 to 8 inches thick)
Bk--23 to 39 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 medium subangular blocky; very hard, friable, sticky and plastic; few very fine roots; common fine pores; 5 percent pebbles; strongly effervescent; many fine and medium masses of lime, moderately alkaline (pH 8.4); gradual wavy boundary. (12 to 30 inches thick)
BCk--39 to 60 inches; grayish brown (2.5Y 5/2) clay loam, dark grayish brown (2.5Y 4/2) moist; weak coarse prismatic structure; very hard, firm, sticky and plastic; few very fine roots in upper part, 5 percent pebbles; strongly effervescent; few fine and medium masses of lime; moderately alkaline (pH 8.2). (0 to 25 inches thick)
TYPE LOCATION: Blaine County, Montana; 1,320 feet west and 1,200 feet south of the NE corner of sec. 8, T. 28 N., R. 22 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 41 to 47 degrees F.
Mollic epipedon thickness - 7 to 16 inches.
Depth to till - 30 to 40 inches.
Depth to Bk horizon - 10 to 20 inches.
A Bky or BCky horizon is allowed.
A or Ap horizon - Value: 3, 4, or 5 dry; 2 or 3 moist
Chroma: 2 or 3
Texture: loam or silty loam, but is typically clay loam when mixed to 6 or 7 inches.
Clay content: 20 to 35 percent
Rock fragments: 0 to 20 percent--0 to 5 percent cobbles; 0 to 15 percent pebbles
Reaction: pH 6.1 to 7.8
Bt1 horizon - Value: 4 or 5 dry; 3 or 4 moist
Chroma: 2 or 3
Texture: clay, clay loam or loam
Clay content: 27 to 50 percent
Rock fragments: 0 to 20 percent--0 to 5 percent cobbles; 0 to 15 percent pebbles
Reaction: pH 6.1 to 7.8
Bt2 horizon - Value: 4 or 5 dry; 3 or 4 moist
Chroma: 2 or 3
Texture: clay loam or clay
Clay content: 35 to 50 percent
Rock fragments: 0 to 20 percent--0 to 5 percent cobbles; 0 to 15 percent pebbles
Reaction: pH 6.6 to 7.8
Bt3 horizon - Value: 5 or 6 dry
Chroma: 2 or 3
Texture: clay loam or clay
Clay content: 35 to 50 percent
Rock fragments: 0 to 20 percent--0 to 5 percent cobbles; 0 to 15 percent pebbles
Reaction: pH 6.6 to 7.8
Btk horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 or 3
Texture: clay loam or clay
Clay content: 35 to 45 percent
Rock fragments: 0 to 20 percent--0 to 5 percent cobbles; 0 to 15 percent pebbles
EC -- 0 to 4 mmhos/cm
SAR -- 0 to 5
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.4 to 8.4
Bk horizon - Hue: 10YR, 2.5Y, or 5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 or 3
Texture: clay loam, silty clay loam, or clay
Clay content: 30 to 45 percent
Rock fragments: 0 to 20 percent--0 to 5 percent cobbles; 0 to 15 percent pebbles
Calcium carbonate equivalent: 5 to 15 percent
EC -- 0 to 4 mmhos/cm
SAR -- 0 to 5
Reaction: pH 7.4 to 8.4
BCk horizon - Hue: 2.5Y or 5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 or 3
Texture: clay loam, silty clay loam, or clay
Clay content: 30 to 45 percent
Rock fragments: 0 to 20 percent--0 to 5 percent cobbles; 0 to 15 percent pebbles
Bulk density: 1.55 and greater
Calcium carbonate equivalent: 1 to 10 percent
EC -- 0 to 8 mmhos/cm
SAR -- 0 to 13
Gypsum: 1 to 5 percent
Reaction: pH 7.4 to 9.0
Some pedons have a BCky horizon.
COMPETING SERIES:
Absarokee (MT) - have a paralithic contact at depths of 20 to 40 inches.
Acree (CO) - have hues of 5YR and redder.
Brolliar (AZ) - are medium acid and have iron and manganese oxide concretions throughout the profile.
Danvers (MT) - have a calcic horizon.
Delson (CO) - do not have horizons of secondary carbonates.
Herm (CO) - do not have horizons of secondary carbonates.
Morapos (CO) - did not form in till that has a moist bulk density of 1.55 or greater above a depth of 40 inches; formed in residuum from shale or in loess.
Nortez (CO) - have a lithic contact at a depth of 20 to 40 inches.
Peninsula (CO) - has a calcic horizon.
Pramiss (CO) - have a paralithic contact at a depth of 20 to 40 inches.
Regent (ND) - have a paralithic contact at a depth of 20 to 40 inches.
Reget (WY) - have a paralithic contact at a depth of 20 to 40 inches.
Ricot (CO) - have a lithological discontinuity in the control section.
Wyola (MT) - did not form in till that has a moist bulk density of 1.55 or greater above a depth of 40 inches; did not form in till.
Tamaneen (MT) - did not form in till that has a moist bulk density of 1.55 or greater above a depth of 40 inches; formed in alluvium.
Tomasaki (UT) - do not have a calcic horizon.
Tukuhnik (UT) - have hues redder than 10YR throughout and have a lithic contact at a depth of 40 to 60 inches.
Work (MT) - did not form in till that has a moist bulk density of 1.55 or greater above a depth of 40 inches; formed in alluvium.
GEOGRAPHIC SETTING:
Landform - till plains or hills.
Elevation - 1650 to 3800 feet.
Slopes - 0 to 15 percent.
Parent material - clay loam glacial till.
Mean annual precipitation - 13 to 19 inches.
Mean annual temperature - 40 to 45 degrees F. (in South Dakota ranges to 34 degrees F.).
Frost-free period - 90 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS:
DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability through the Bk horizon and slow permeability in the underlying till.
USE AND VEGETATION: Bearpaw soils are used for dryland crops and as rangeland. Potential native vegetation is mainly western wheatgrass, bluebunch wheatgrass, needleandthread, green needlegrass, and perennial forbs.
DISTRIBUTION AND EXTENT: Bearpaw soils are moderately extensive on the till plains in northern and north-central Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Blaine County, Montana, 1976.
REMARKS: Soil interpretations records: MT0139, MT1130. Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from the soil surface to 10 inches (A, Bt1, and Bt2 horizons); and an argillic horizon and particle-size control section from 3 to 16 inches (Bt1, Bt2, and Bt3 horizons); horizons of secondary carbonate from 16 to 60 inches (Btk, Bk, BCk horizons).
National Cooperative Soil Survey
U.S.A.