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.