LOCATION BROWNSGULCH             MT

Established Series
JMS/RJS/EMM
11/2012

BROWNSGULCH SERIES

The Brownsgulch series are very deep, well drained soils that formed in alluvium derived from rhyolite and other moderately fine-grained igneous rocks. These soils are on alluvial fans, mountain slopes and hills. Slopes are 2 to 50 percent. Mean annual precipitation is about 406 millimeters and mean annual air temperature is about 3 degrees C.

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive Pachic Haplocryolls

TYPICAL PEDON: Brownsgulch sandy loam, in rangeland on a 28 percent slope at 1,798 meters elevation (colors are for dry soil unless otherwise indicated).

A1--0 to 15 cm; very dark grayish brown (10YR 3/2) sandy loam, very dark brown (10YR 2/2) moist; moderate fine granular structure; very friable, soft, slightly sticky and slightly plastic; many very fine and fine roots; many fine irregular pores; 8 percent gravel; moderately acid (pH 6.0); clear smooth boundary. (10 to 25 cm thick)

A2--15 to 30 cm; very dark grayish brown (10YR 3/2) gravelly sandy loam, very dark brown (10YR 2/2) moist; moderate fine granular structure; very friable, soft, slightly sticky and slightly plastic; many very fine and fine roots; many fine irregular pores; 15 percent gravel; slightly acid (pH 6.4); clear smooth boundary. (10 to 30 cm thick)

A3--30 to 51 cm; dark grayish brown (10YR 4/2) gravelly sandy loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; very friable, soft, slightly sticky and slightly plastic; many very fine and fine roots; many very fine and fine irregular pores; 20 percent gravel; neutral (pH 6.8); abrupt wavy boundary. (0 to 25 cm thick)

Bw--51 to 84 cm; brown (10YR 5/3) gravelly sandy loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; firm, slightly hard, slightly sticky and slightly plastic; many very fine and common fine roots; common fine irregular pores; 25 percent gravel; neutral (pH 6.8); abrupt wavy boundary. (15 to 110 cm thick)

C--84 to 152 cm; brown (10YR 5/3) gravelly sandy loam, brown (10YR 4/3) moist; massive; firm, hard, nonsticky and nonplastic; few fine roots; common fine irregular pores; 30 percent gravel; neutral (pH 6.8).

TYPE LOCATION: Butte South topographic quadrangle, Silver Bow County, Montana; 610 meters south and 520 meters east of the NW corner of section 26, T. 3 N., R. 8 W. UTM Zone 12: 378888e, 5093432n, NAD 83.

RANGE IN CHARACTERISTICS:
Soil temperature - 2 to 6 degrees C
Moisture control section - 20 to 60 cm
Thickness of the mollic epipedon - 40 to 75 cm thick

A1 horizon
Value: 3 or 4 dry; 2 or 3 moist
Chroma: 1 or 2 dry, or moist
Texture: loam or sandy loam
Clay content: 8 to 20 percent
Rock fragments: 0 to 25 percent--0 to 20 percent gravel, 0 to 5 percent cobbles
Reaction: pH 5.6 to 7.3

A2 and A3 horizons
Value: 3 to 5 dry; 2 or 3 moist
Chroma: 1 or 2 dry, or moist
Texture: loam or sandy loam
Clay content: 8 to 20 percent
Rock fragments: 5 to 25 percent--0 to 20 percent gravel, 0 to 5 percent cobbles Reaction: pH 6.0 to 7.6

Bw horizon
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 2 or 3, dry or moist
Texture: sandy loam, sandy clay loam, or loam
Clay content: 10 to 22 percent
Rock fragments: 10 to 25 percent--5 to 25 percent gravel, 0 to 5 percent cobbles
Reaction: pH 5.8 to 7.6

C horizon
Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 or 3, dry or moist
Texture: loam, sandy loam or sandy clay loam
Clay content: 8 to 22 percent
Rock fragments: 10 to 30 percent--15 to 30 percent gravel, 0 to 5 percent cobbles
Reaction: pH 6.0 to 7.8

COMPETING SERIES:

Aycab (NV) - is moderately deep to a paralithic contact.
Coffeepot (NV) - is deep to a paralithic contact.
Coutis (WY) - is very deep.
Earcree (ID) - is very deep.
Fleecer (MT) - has coarse sandy substrata at 66 to 132 cm.
Foxvire (NV) - have a soil temperature of 6.5 to 8 degrees C.
Gardners Fork (UT) - is very deep.
Grayhead (CO) - is deep to a paralithic contact.
Hailman (UT) - is deep to a paralithic contact.
Moonlight (ID) - has silt loam textures throughout.
Naz (ID) - is very deep.
Razorba (CO) - is very deep.
Shook (MT) - is moderately deep to a lithic contact.
Skyway (CO) - moderately deep to a lithic contact.
Taral (AK) - has an Oi horizon.
Tosp (NV) - is deep to a lithic contact.

GEOGRAPHIC SETTING:
Landform - alluvial fans, mountain slopes and hills
Elevation - 1,575 to 2,170 meters
Slope - 2 to 50 percent
Parent material - alluvium derived from rhyolite, rhyodacite, or rhyolitic tuff
Climate - long, cold winters; cold, moist springs; short, cool summers
Mean annual precipitation - 330 to 483 millimeters, much of which falls as snow and as spring rain
Mean annual air temperature - 1 to 5 degrees centigrade
Frost-free period - 50 to 70 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Nissler, Bullrey and Foxgulch soils which occur on similar landforms. Dickiepeak soils have an argillic horizon. Bullrey soils have a loamy-skeletal particle-size family. Foxgulch soils have a mollic epipedon that is less than 40 cm thick.

DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.

USE AND VEGETATION: Brownsgulch soils are used mainly for grazing. Potential native vegetation is Idaho fescue, bluebunch wheatgrass, rough fescue, prairie junegrass, big sagebrush and Rocky Mountain juniper.

DISTRIBUTION AND EXTENT: Brownsgulch soils are of small extent in the intermontane basins of central Montana. MLRA 43B.

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

SERIES ESTABLISHED: Silver Bow County, Montana, 2006.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 0 to 51 cm (A1, A2 and A3 horizons)
Cambic horizon - 51 to 84 cm (Bw horizon)
Particle-size control section - from 25 to 100 cm
Brownsgulch soils have a cryic temperature regime and an ustic moisture regime.

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National Cooperative Soil Survey
U.S.A.