LOCATION BLACKLEAF               MT

Established Series
Rev. GFB-PEM-RJS
06/2011

BLACKLEAF SERIES

The Blackleaf series consists of shallow, well drained soils that formed in colluvium and/or residuum derived from hard sandstone or igneous rock. These soils are on cuestas, hills, mountain slopes, ridges or structural benches. Slopes are 4 to 60 percent. Mean annual precipitation is about 12 inches, and mean annual air temperature is about 40 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Lithic Haplustalfs

TYPICAL PEDON: Blackleaf very channery sandy loam, in rangeland (Colors are for dry soil unless otherwise noted).

A--0 to 4 inches; light brownish gray (2.5Y 6/2) very channery sandy loam, olive brown (2.5Y 4/3) moist; weak fine and medium subangular blocky structure parting to weak fine granular; soft, very friable, slightly sticky and nonplastic; common very fine and few fine roots; common very fine and fine interstitial pores; 40 percent channers; neutral (pH 7.2); clear smooth boundary. (3 to 6 inches thick)

Bt--4 to 8 inches; brown (10YR 5/3) very channery sandy clay loam, brown (10YR 4/3) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slighty sticky and slightly plastic; common very fine and few fine roots; common very fine and fine tubular and interstitial pores; common faint clay films bridging sand grains and on faces of peds; 40 percent channers; slightly alkaline (pH 7.4); clear smooth boundary. (3 to 8 inches thick)

Bk--8 to 13 inches; light yellowish brown (2.5Y 6/3) extremely channery loam, light olive brown (2.5Y 5/3) moist; weak fine granular structure; soft, very friable, slightly sticky and slightly plastic; common very fine and few fine roots; common very fine and fine tubular and interstitial pores; 55 percent channers, 15 percent flagstones; disseminated calcium carbonate; common distinct calcium carbonate casts on underside of coarse fragments; strongly effervescent; slightly alkaline (pH 7.7); clear smooth boundary. (1 to 5 inches thick)

R--13 inches; hard fractured sandstone.

TYPE LOCATION: Beaverhead County, Montana; 600 feet south and 700 feet west of the NE corner of sec. 32, T. 4 S., R. 9 W. Glen topographic quadrangle. Lat. 45 degrees 27 minutes 03 seconds N.; Long. 112 degrees 43 minutes 59 seconds W.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 38 to 44 degrees F.
Depth to argillic horizon - 3 to 7 inches
Depth to lithic contact - 10 to 20 inches

A horizon
Hue: 10YR or 2.5Y; dry or moist
Value: 5 or 6 dry; 4 moist
Chroma: 2 to 4; dry or moist
Texture: sandy loam, loam or sandy clay loam
Clay content: 10 to 25 percent
Rock fragments: 20 to 60 percent--20 to 40 percent channers or gravel, 0 to 20 percent flagstones or cobbles
Reaction: pH 6.6 to 7.4

Bt horizon
Hue: 10YR or 2.5Y; dry or moist
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 to 4; dry or moist
Texture: sandy clay loam, clay loam or loam
Clay content: 20 to 35 percent
Rock fragments: 35 to 70 percent--35 to 50 percent channers or gravel, 0 to 20 percent flagstones or cobbles
Reaction: pH 6.6 to 7.4

Bk horizon
Hue: 10YR or 2.5Y; dry or moist
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 to 4; dry or moist
Texture: loam or sandy loam
Clay content: 18 to 27 percent
Rock fragments: 35 to 80 percent--35 to 60 percent channers or gravel, 0 to 20 percent flagstones or cobbles
Calcium carbonate equivalent: 1 to 5 percent
Reaction: pH 7.4 to 8.4

COMPETING SERIES:
Brickner (MT) - does not have secondary calcium carbonate accumulation
Jagon (UT) - have Btk horizons
Sanchez (NM) - does not have secondary calcium carbonate accumulation
Tolex (MT) - does not have secondary calcium carbonate accumulation
Wetmore (CO) - does not have secondary calcium carbonate accumulation

GEOGRAPHIC SETTING:
Landform - cuestas, hills, mountain slopes, ridges or structural benches
Elevation - 5,000 to 6,500 feet
Slope - 4 to 60 percent
Parent material - colluvium and/or residuum derived from hard sandstone or igneous rock
Climate - long, cold winters; moist springs; warm summers
Mean annual precipitation - 10 to 14 inches
Mean annual air temperature - 37 to 43 degrees F.
Frost-free period - 70 to 105 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Twinadams and Thunderhead soils. The Twinadams soilsare moderately deep and loamy-skeletal. The Thunderhead soilsare moderately deep and fine-loamy. These soils occur on similar landforms as the Blackleaf soils.

DRAINAGE AND PERMEABILITY: Well drained, moderate permeability.

USE AND VEGETATION: Blackleaf soils are primarily used for rangeland. The potential native vegetation is bluebunch wheatgrass, big sagebrush, winter fat, fringed sagewort, prickly pear cactus, blue gramma, needle and thread, and rubber rabbitbrush.

DISTRIBUTION AND EXTENT: Blackleaf soils are of small extent in southwestern Montana. MLRAs - 43B, 44B, 46.

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

SERIES ESTABLISHED: Beaverhead County, Montana, 2001.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 4 inches (A horizon)
Argillic horizon - from 4 to 8 inches (Bt horizon)
Particle-size control section - from 0 to 13 inches (A, Bt and Bk horizons)
Hard sandstone bedrock at 13 inches (R horizon)

Blackleaf soils have a frigid temperature regime and an ustic moisture regime bordering on aridic.

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National Cooperative Soil Survey
U.S.A.