LOCATION MCCOLLUM           MT
Established Series
Rev. BDD-GLS-RJS
09/2008

MCCOLLUM SERIES


The McCollum series consists of very deep, well drained soils that formed in alluvium or glaciofluvial deposits. These soils are on dissected alluvial fans and stream terraces. Slopes are 0 to 20 percent. Mean annual precipitation is about 16 inches, and mean annual temperature is about 43 degrees F.

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, frigid Typic Haploxerolls

TYPICAL PEDON: McCollum fine sandy loam, cultivated (colors are for dry soil unless otherwise noted).

Ap--0 to 7 inches; grayish brown (10YR 5/2) fine sandy loam, very dark brown (10YR 2/2) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; many fine roots; many fine pores; neutral (pH 6.8); clear smooth boundary. (6 to 10 inches thick)

Bw1--7 to 17 inches; brown (10YR 5/3) fine sandy loam, dark brown (10YR 3/3) moist; weak medium and coarse subangular blocky structure; soft, very friable, nonsticky and nonplastic; common fine roots; common fine pores; neutral (pH 6.8); gradual boundary.

Bw2--17 to 29 inches; pale brown (10YR 6/3) fine sandy loam, brown (10YR 4/3) moist; weak coarse subangular blocky structure; soft, very friable, nonsticky and nonplastic; common fine roots; common fine pores; neutral (pH 6.8); gradual wavy boundary. (Combined thickness of the Bw1 and Bw2 horizons is 10 to 24 inches)

Bw3--29 to 60 inches; very pale brown (10YR 7/3) fine sandy loam, brown (10YR 5/3) moist; weak coarse subangular blocky structure; soft, very friable, nonsticky and nonplastic; few fine roots; few fine pores; neutral (pH 7.2)

TYPE LOCATION: Lake County, Montana; 180 feet south and 400 feet east of the NW corner of sec. 25, T. 22 N., R. 20 W.

RANGE IN CHARACTERISTICS:

Soil temperature - 42 to 47 degrees F.
Moisture control section - between 8 and 24 inches.
Mollic epipedon thickness - 10 to 20 inches.
Control section - 8 to 18 percent clay with less than 35 percent fine and coarser sand.
Some pedons have a C horizon.

Ap horizon
Hue: 10YR or 2.5Y dry or moist
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 2 or 3 dry or moist
Clay content: 8 to 18 percent
Reaction: pH 6.1 to 7.3

Bw1 horizon
Hue: 10YR or 2.5Y dry or moist
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 2 or 3 dry or moist
Clay content: 8 to 18 percent
Reaction: pH 6.1 to 7.3

Bw2 horizon
Hue: 10YR or 2.5Y dry or moist
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 or 3 dry or moist
Clay content: 8 to 18 percent
Reaction: pH 6.1 to 7.3

Bw3 horizon
Hue: 10YR or 2.5Y dry or moist
Value: 6 or 7 dry; 5 or 6 moist
Chroma: 2 or 3 dry or moist
Texture: fine sandy loam, sandy loam, or loamy fine sand
Clay content: 8 to 18 percent
Rock fragments: 0 to 60 percent gravel
Reaction: pH 6.6 to 7.8

COMPETING SERIES:

Cowers (UT) - have 20 to 30 percent gravel in the B horizon; some individual horizons have more than 20 percent clay; are calcareous at a depth of about 33 inches.
Takeuchi (ID) - have a paralithic contact of weathered granite, schist, and quartz at depths of 20 to 40 inches.

GEOGRAPHIC SETTING:

Landform- dissected alluvial fans and stream terraces.
Elevation - 2,400 to 3,300 feet.
Slope - 0 to 20 percent.
Parent material - alluvium or glaciofluvial deposits.
Climate - cold winters; moist falls and springs; dry, warm summers.
Mean annual precipitation - 14 to 19 inches, most of which falls as snow or as rain in winter, spring, and late in fall.
Mean annual temperature - 40 to 46 degrees F.
Frost-free period - 80 to 130 days.

GEOGRAPHICALLY ASSOCIATED SOILS:

DRAINAGE AND PERMEABILITY: Well drained; moderately rapid permeability.

USE AND VEGETATION: McCollum soils are used for irrigated and dryland crops and pastureland.

DISTRIBUTION AND EXTENT: McCollum soils are of small extent in the northwestern valleys of Montana. MLRA 44A.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana

SERIES ESTABLISHED: Lake County, Montana, 1991; proposed in Lake County, Montana, 1979.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 17 inches (Ap, Bw1 horizons);
Cambic horizon - 17 to 60 inches (Bw2, Bw3 horizons);
Particle-size control section - 10 to 40 inches (Bw1, Bw2, Bw3 horizons).

McCullum soils have a frigid temperature regime and a xeric moisture regime.

Soil interpretation record: MT0555.


National Cooperative Soil Survey
U.S.A.