LOCATION PHILIPSBURG MT

Established Series
Rev. PEM-JJU-RJS
05/2011

PHILIPSBURG SERIES

The Philipsburg series consists of very deep, well drained soils that formed in alluvium, slope alluvium, colluvium or slide deposits derived from mixed rock sources. These soils are on stream terraces, alluvial fans, fan remnants, escarpments, hills, mountain slopes and landslides. Slopes are 0 to 60 percent. Mean annual precipitation is about 18 inches, and mean annual air temperature is about 38 degrees F.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive Calcic Argicryolls

TYPICAL PEDON: Philipsburg silt loam, in rangeland (colors are for dry soil unless otherwise noted).

A1--0 to 5 inches; dark grayish brown (10YR 4/2) silt loam, black (10YR 2/1) moist; weak fine and medium subangular blocky structure parting to weak very fine and fine granular; soft, very friable, slightly sticky and slightly plastic; many very fine and few fine roots; many very fine and fine dendritic tubular pores; 10 percent gravel; neutral (pH 6.8); clear wavy boundary.

A2--5 to 14 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak medium prismatic structure parting to moderate fine and medium granular; slightly hard, friable, slightly sticky and slightly plastic; many very fine and few fine roots; many very fine and fine dendritic tubular pores; 10 percent gravel; neutral (pH 6.7); clear wavy boundary.

Bt1--14 to 20 inches; brown (10YR 5/3), silty clay loam, brown (10YR 4/3) moist; moderate medium prismatic structure parting to moderate fine medium subangular blocky; slightly hard, friable, moderately sticky and moderately plastic; common very fine and few fine roots; common very fine and few fine dendritic tubular pores; many distinct patchy clay films on faces of peds; 10 percent gravel; neutral (pH 7.0); clear wavy boundary.

Bt2--20 to 32 inches; yellowish brown (10YR 5/4) clay loam, dark yellowish brown (10YR 4/4) moist; strong medium subangular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; common very fine and few fine roots; common very fine and few fine dendritic tubular pores; common distinct patchy clay films on faces of peds; 10 percent gravel; neutral (pH 6.8); gradual wavy boundary.

Bk1--32 to 43 inches; very pale brown (10YR 8/4), gravelly loam, very pale brown (10YR 7/4) moist; weak fine and medium subangular blocky structure parting to weak very fine and fine granular; soft, very friable, slightly sticky and slightly plastic; few very fine roots; common very fine irregular pores; 25 percent gravel; finely disseminated calcium carbonate, common fine and medium soft masses of calcium carbonate, and many distinct continuous calcium carbonate coatings on rock fragments; violently effervescent; moderately alkaline (pH 8.2); clear wavy boundary.

Bk2--43 to 60 inches; very pale brown (10YR 8/3), very gravelly sandy loam, very pale brown (10YR 7/3) moist; weak very fine and fine granular structure; soft, very friable, slightly sticky and nonplastic; few very fine roots; common very fine irregular pores; 35 percent gravel, 15 percent cobbles; finely disseminated calcium carbonate, common fine and medium soft masses of calcium carbonate, and many distinct continuous calcium carbonate coatings on rock fragments; violently effervescent; moderately alkaline (pH 8.0).

TYPE LOCATION: Beaverhead County, Montana; approximately 950 feet west and 1550 feet south of the NE corner of sec. 28, T. 4S, R. 15W; Fox Gulch topographic quadrangle; UTM 12T, 308264e, 5036779n. NAD 83.

RANGE IN CHARACTERISTICS:
Soil temperature - 35 to 42 degrees F.
Mollic epipedon thickness - 7 to 15 inches
Depth to argillic horizon - 6 to 15 inches
Depth to the calcic horizon - 20 to 39 inches

Note: Some pedons may have a Btk horizon.

A1, A2 horizons
Hue: 7.5YR or 10YR; dry or moist
Value: 2 to 5 dry; 2 or 3 moist
Chroma: 1 to 3; dry or moist
Texture: loam, silt loam or clay loam
Clay content: 18 to 30 percent
Rock fragments: 0 to 30 percent--0 to 25 percent gravel, 0 to 10 percent cobbles
Reaction: pH 6.1 to 7.3

Bt1, Bt2 horizons
Hue: 7.5YR or 10YR; dry or moist
Value: 4 to 6 dry; 3 to 5 moist
Chroma: 2 to 4; dry or moist
Texture: loam, clay loam or silty clay loam
Clay content: 25 to 35 percent
Sand content: less than 40 percent sand
Rock fragments: 0 to 35 percent--0 to 35 percent gravel, 0 to 10 percent cobbles
Reaction: pH 6.6 to 7.8

Btk horizon (where present)
Hue: 7.5YR or 10YR; dry or moist
Value: 4 to 6 dry; 3 to 5 moist
Chroma: 2 to 4; dry or moist
Texture: loam, clay loam or silty clay loam
Clay content: 25 to 35 percent
Sand content: less than 40 percent sand
Rock fragments: 0 to 35 percent--0 to 35 percent gravel, 0 to 10 percent cobbles
Calcium carbonate equivalent: 3 to 10 percent
Reaction: pH 7.8 to 8.2

Bk1, Bk2 horizons
Hue: 10YR or 2.5Y; dry or moist
Value: 6 to 8 dry; 5 to 7 moist
Chroma: 2 to 4; dry or moist
Texture: sandy loam, loam or clay loam
Clay content: 12 to 35 percent
Rock fragments: 10 to 50 percent--10 to 35 percent gravel, 0 to 15 percent cobbles
Calcium carbonate equivalent: 15 to 25 percent
Reaction: pH 7.9 to 8.4

COMPETING SERIES:
Accola (MT) - have an O horizon
Elispring (MT) - are moderately deep to a lithic contact
Gebson (CO) - have an aridic moisture subclass
Glentivar (CO) - have an aridic moisture subclass
Madigan (MT) - are moderately deep to a lithic contact
Michelson (MT) - have a buried Bt horizon
Monida (ID) - have a xeric soil moisture regime
Morset (CO) - are drier in the moisture control section for longer periods of time
Northorn (UT) - have an udic soil moisture regime
Oro Fino (MT) - have sandy-skeletal material at depths of 40 to 60 inches

GEOGRAPHIC SETTING:
Landform - stream terraces, alluvial fans, fan remnants, escarpments, hills, mountain slopes and landslides
Elevation - 5,500 to 8,000 feet
Slope - 0 to 60 percent
Parent material - alluvium, slope alluvium, colluvium or slide deposits derived from mixed rock sources
Climate - long, cold winters; cold, moist springs; short, cool summers
Mean annual precipitation - 14 to 24 inches
Mean annual air temperature - 34 to 40 degrees F.
Frost-free period - 30 to 70 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Adel, Bridger, Maciver and Tiban series. Adel soils have mollic epipedon more than 40 mm thick and lack argillic horizons. Bridger soils have more than 35 percent clay in the argillic horizons and lack a calcic horizon. Maciver soils have loamy-skeletal argillic horizons. Tiban soils have a loamy skeletal control section, and lack both argillic and calcic horizons.

DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.

USE AND VEGETATION: Philipsburg soils are primarily used for rangeland and wildlife habitat. The potential native vegetation is mainly rough fescue, Idaho fescue, bluebunch wheatgrass, prairie junegrass, mountain brome, Parry's danthonia, sticky geranium, sedum (stoneseed), western yarrow, milkvetch, shrubby cinquefoil, and mountain big sagebrush.

DISTRIBUTION AND EXTENT: Philipsburg soils are of moderate extent in southwestern Montana. MLRAs - 43B, 44B.

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

SERIES ESTABLISHED: Granite County, Montana, 1972. Type location moved to Jefferson County, Montana, 1993. Type location moved to Beaverhead County, Montana, 2005.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 14 inches (A horizons)
Argillic horizon - from 14 to 32 inches (Bt1, Bt2 horizons)
Calcic horizon - from 32 to 60 inches (Bk1, Bk2 horizons)
Particle-size control section - from 14 to 32 inches (Bt1, Bt2 horizons)

Philipsburg soils have a cryic temperature regime and an ustic moisture regime.

ADDITIONAL DATA: Soil interpretation record - MT0525.

National Cooperative Soil Survey
U.S.A.