LOCATION MCCOLLUM MTEstablished Series
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.