LOCATION PIANOHILL MTEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Typic Argiustolls
TYPICAL PEDON: Pianohill loam, in rangeland (colors are for dry soil unless otherwise noted).
A1--0 to 6 inches; grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, very friable, slightly sticky and slightly plastic; many fine and very fine roots many fine and very fine interstitial pores; 5 percent angular cobbles; slightly acid (pH 6.4); abrupt smooth boundary.
A2--6 to 10 inches; brown (10YR 5/3) loam, dark brown (10YR 3/3) moist; weak medium subangular blocky structure parting to weak fine and medium granular; soft, very friable, slightly sticky and slightly plastic, many fine and very fine roots; many fine and very fine pores; slightly acid (pH 6.2); clear smooth boundary. (Combined thickness of A horizon is 7 to 12 inches thick.)
Bw--10 to 16 inches; pale brown (10YR 6/3) loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many fine and very fine roots; many fine and very fine pores; neutral (ph 6.6); clear smooth boundary. (0 to 7 inches thick)
Bt1--16 to 21 inches; pale brown (10YR 6/3) clay loam, brown (10YR 5/3) moist; moderate medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; many fine and very fine roots; many fine and very fine pores; common faint dark yellowish brown (10YR 4/4) moist clay films on faces of peds and in pores; 5 percent angular pebbles; neutral (ph 6.6); clear smooth boundary. (4 to 9 inches thick)
Bt2--21 to 29 inches; very pale brown (10YR 7/4) loam, light yellowish brown (10YR 6/4) moist; moderate medium subangular blocky structure; soft, friable, moderately sticky and moderately plastic; common fine and very fine roots; common fine and very fine pores; few faint dark yellowish brown clay films (10YR 4/4) moist, on faces of peds and in pores; 12 percent angular pebbles; neutral (ph 6.8); clear smooth boundary. (5 to 10 inches thick)
R--29 to 60 inches; volcanic mudflow Breccia.
TYPE LOCATION: Sweet Grass County, Montana; 2,100 feet east and 800 feet north of the SW corner of sec. 23, T. 2 S., R. 15 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 to 47 degrees F.
Moisture control section - between 4 and 12 inches, moist in some or all parts from April through mid July, dry in some part less than six-tenths of the cumulative days per year when the soil temperature at a depth of 20 inches is 41 degrees or higher.
Mollic epipedon thickness - 7 to 15 inches.
Rock fragments - angular pebbles and cobbles of lahar breccia.
Depth to bedrock - 20 to 40 inches.
A transition BC horizon is allowed.
A horizons - Hue: 10YR or 2.5Y
Value: 3, 4 or 5 dry; 2 or 3 moist
Chroma: 2 or 3
Clay content: 15 to 27 percent
Rock fragments: 0 to 15 percent -- 0 to 5 percent cobbles, 0 to 10 percent pebbles
Reaction: pH 6.1 to 7.3
Bw horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 3, 4, or 5 moist
Chroma: 2, 3, or 4
Clay content: 15 to 27 percent
Rock fragments: 0 to 15 percent -- 0 to 5 percent cobbles, 0 to 10 percent pebbles
Reaction: pH 6.1 to 7.3
Bt1 horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 3 or 4
Texture: loam, clay loam
Clay content: 20 to 35 percent
Rock fragments: 0 to 15 percent--0 to 5 percent cobbles, 0 to 10 percent pebbles
Reaction: pH 6.1 to 7.3
Bt2 horizon - Hue: 10YR or 2.5Y
Value: 5, 6, or 7 dry; 4, 5, or 6 moist
Chroma: 3 or 4
Texture: loam, clay loam, sandy clay loam
Clay content: 20 to 35 percent
Rock fragments: 0 to 35 percent -- 0 to 10 percent cobbles, 0 to 25 percent pebbles
Reaction: pH 6.1 to 7.3
COMPETING SERIES:
Absarook (MT) - has a horizon of secondary calcium carbonate accumulation.
Archmesa (CO) - formed in slope alluvium and residuum from andesite; has late summer and fall precipitation peaks.
Beartooth (MT) - has loamy-skeletal material directly underlying the argillic horizon; has an Oi horizon consisting of forest litter; does not have a lithic contact at depths of 20 to 40 inches.
Bielenberg (MT) - does not have a lithic contact at depths of 20 to 40 inches; is noncalcareous throughout the profile.
Bookcliff (UT) - is calcareous at a depth of 4 inches; has hard sandstone bedrock at a depth of 40 to 60 inches.
Burtoner (MT) - has a paralithic contact above the lithic contact.
Clancy (MT) - has a lithic contact at a depth of 40 to 60 inches.
Clasoil (MT) - does not have a lithic contact above a depth of 60 inches.
Dooley (MT) - does not have a lithic contact at depths of 20 to 40 inches.
Doughty (MT) - does not have a lithic contact above 60 inches.
Empedrado (CO) - does not have a lithic contact at depths of 20 to 40 inches.
Fairfield (MT) - does not have a lithic contact at depths of 20 to 40 inches; has a calcic horizon at depths of 9 to 11 inches.
Farnuf (MT) - does not have a lithic contact at depths of 20 to 40 inches.
Farside (MT) - does not have a lithic contact above 60 inches.
Felor (SD) - does not have a lithic contact at depths of 20 to 40 inches.
Greenway (SD) - does not have a lithic contact at a depth of 20 to 40 inches.
Gurney (SD) - has horizons of secondary calcium carbonate accumulation; has hue redder than 10YR in the argillic horizon; formed in residuum derived from calcareous sandstone.
Hangdo (UT) - does not have a lithic contact at a depth of 20 to 40 inches.
Hoppers (MT) - has a paralithic contact above the lithic contact.
Hyalite (MT) - does not have a lithic contact at a depth of 20 to 40 inches; has a sandy-skeletal discontinuity above a depth of 40 inches.
Jeffcity (MT) - has horizons of secondary calcium carbonate accumulation.
Kokoruda (MT) - does not have a lithic contact at a depth of 20 to 40 inches.
Livona (ND) - does not have a lithic contact at a depth of 20 to 40 inches.
Martinsdale (MT) - does not have a lithic contact at a depth of 20 to 40 inches.
Maudlin (CO) - dry in all parts for 45 or more consecutive days after July 15; formed in materials derived from hard sandstone.
Meagher (MT) - does not have a lithic contact at a depth of 20 to 40 inches.
Moen (CO) - has hue of 7.5YR in the lower part of the argillic horizon; formed in residuum and colluvium derived from volcanic materials.
Moento (CO) - formed in alluvium from sandstone; has peak precipitation in July and August.
Placerton (MT) - has a lithic contact between 40 and 60 inches.
Reeder (ND) - has a paralithic contact between 20 and 40 inches.
Reedwest (MT) - has a paralithic contact at 20 to 40 inches.
Snakejohn (UT) - has a lithic contact at 40 to 60 inches.
Sponseller (AZ) - does not have a lithic contact at a depth of 20 to 40 inches.
Tragmon (CO) - does not have a lithic contact at a depth of 20 to 40 inches.
Trazuni (NM) - does not have a lithic contact at a depth of 20 to 40 inches.
Ulrant (WY) - does not have a lithic contact at a depth of 20 to 40 inches.
Vida (MT) - does not have a lithic contact at a depth of 20 to 40 inches.
Watne (MT) - does not have a lithic contact.
Watrous (ND) - has a horizon of secondary calcium carbonate accumulation.
Williams (ND) - does not have a lithic contact at a depth of 20 to 40 inches.
Yegen (MT) - does not have a lithic contact at a depth of 20 to 40 inches.
GEOGRAPHIC SETTING:
Landform - lahars; hills; structural benches.
Elevation - 4,200 to 6,000 feet.
Parent material - residuum and colluvium from volcanic mudflow breccia.
Slope - 0 to 35 percent.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 15 to 19 inches, most of which falls during spring and early summer.
Mean annual air temperature - 39 to 45 degrees F.
Frost-free period - 90 to 120 days.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Pianohill soils are used mainly for rangeland. Potential native vegetation is mainly Idaho fescue, Columbia needlegrass, prairie junegrass, bluebunch wheatgrass, big sagebrush, and fringed sagewort.
DISTRIBUTION AND EXTENT: Pianohill soils are of moderate extent in South Central Montana.
MLRA OFFICE RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Sweet Grass County Area, Montana, 2000.
REMARKS: Soil Interpretations Record: MT1489. Diagnostic horizons and features recognized in this pedon are:
a mollic epipedon from 0 to 10 inches (A1 and A2 horizons); a cambic horizon from 10 to 16 inches (Bw horizon); an argillic horizon from 16 to 29 inches (Bt1 and Bt2 horizons); and a lithic contact at 29 inches (R horizon). Pianohill soils have a frigid temperature regime and an ustic moisture regime.