LOCATION POLUMAR IDEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Calcic Pachic Haplocryolls
TYPICAL PEDON: Polumar gravelly silt loam on a 55 percent north slope at 5,800 feet elevation. When described on September 24, 1993, the soil was dry throughout. (Colors are for air dry soil unless otherwise noted.) There are stones on the soil surface that are 30 to 60 feet apart.
A1--0 to 6 inches; dark grayish brown (10YR 4/2) gravelly silt loam, very dark brown (10YR 2/2) moist; moderate medium and coarse granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and common fine to coarse roots; many very fine and few fine irregular pores; 25 percent gravel and 5 percent cobbles; slightly alkaline (pH 7.6); clear smooth boundary.
A2--6 to 11 inches; grayish brown (10YR 5/2) gravelly silt loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine to coarse roots; common very fine and few fine tubular and common very fine irregular pores; 15 percent gravel and 5 percent cobbles; slightly alkaline (pH 7.8); clear irregular boundary.
A3--11 to 18 inches; grayish brown (10YR 5/2) very cobbly silt loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine to coarse roots; common very fine irregular and few very fine and fine tubular pores; 15 percent gravel, 35 percent cobbles, and 5 percent stones; slightly alkaline (pH 7.8); clear wavy boundary. (combined thickness of A horizons is 15 to 25 inches)
Bk--18 to 22 inches; brown (10YR 5/3) very cobbly silt loam, dark brown (10YR 3/3) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine to medium roots; common very fine and few fine tubular pores; slightly effervescent (10 percent calcium carbonate equivalent); disseminated carbonate and few fine irregularly shaped carbonate masses; 10 percent gravel, 35 percent cobbles, and 10 percent stones; moderately alkaline (pH 8.0); abrupt wavy boundary.
Bkq1--22 to 28 inches; pale brown (10YR 6/3) extremely cobbly loam, brown (10YR 4/3) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine and few medium roots; common very fine irregular and few fine tubular pores; strongly effervescent (20 percent calcium carbonate equivalent); disseminated carbonate and common fine irregularly shaped carbonate masses; carbonate coats on bottoms of rock fragments; a few rock fragments have silica coats; 10 percent gravel, 35 percent cobbles, and 15 percent stones; moderately alkaline (pH 8.2); gradual irregular boundary.
Bkq2--28 to 46 inches; light brownish gray (10YR 6/2) extremely cobbly loam, dark grayish brown (10YR 4/2) moist; weak medium and coarse subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common very fine to coarse roots; common very fine irregular and few fine tubular pores; violently effervescent (25 percent calcium carbonate equivalent); disseminated carbonate and common fine irregularly shaped carbonate masses; carbonate coats on bottoms of rock fragments; a few rock fragments have silica coats; 10 percent gravel, 30 percent cobbles, and 20 percent stones; moderately alkaline (pH 8.2); abrupt irregular boundary. (combined thickness of Bk horizons is 25 to 35 inches)
R--46 inches; limestone.
TYPE LOCATION: Franklin County, Idaho; about 3 miles southeast of Thatcher; about 2,450 feet west and 650 feet north of the southeast corner of section 9, T. 12 S., R. 41 E.; 42 degrees, 23 minutes, 20 seconds north latitude and 111 degrees, 40 minutes, 15 seconds west longitude, NAD27.
RANGE IN CHARACTERISTICS:
Profile:
Thickness of mollic epipedon - 18 to 35 inches
Depth to calcic horizon - 15 to 25 inches
Depth to lithic contact - 40 to 60 inches
Average annual soil temperature - 41 to 44 degrees F.
Soil moisture regime: Xeric
Particle-size control section:
Clay content average - 14 to 18 percent (total clay)
Rock fragments average - 35 to 70 percent
A horizons:
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Reaction - slightly alkaline or moderately alkaline
Bk and Bkq horizons:
Hue - 7.5YR or 10YR
Value - 5 through 7 dry, 3 through 5 moist
Chroma - 2 or 3 dry, 2 through 4 moist
Texture - CBV-SIL, CBV-L, and CBX-L
Clay content - 12 to 18 percent (total clay)
Rock fragment content - 10 to 25 percent gravel, 30 to 45 percent cobbles, 10 to 25 percent stones
Calcium carbonate equivalent - upper part: 1 to 15 percent, lower part: 15 to 30 percent
COMPETING SERIES: These are the
Eganroc,
Firading (T),
Levengood,
Meegernot,
Raynoldson,
Spearhead, and
Stoneman (T) series.
Eganrock soils are very deep.
Firading soils are moderately deep to a lithic contact.
Levengood soils are very deep and have average annual soil temperatures of 36 to 41 degrees F.
Meegernot soils have 20 to 26 percent clay in the particle size control section and are very deep.
Raynoldson soils are very deep and have average annual soil temperature of 37 to 40 degrees F.
Spearhead soils are more moist with probable udic moisture regime.
Stoneman soils are very deep and are dominated by stones in the particle-size control section.
GEOGRAPHIC SETTING: Polumar soils are on mountain slopes at elevations of 5,500 to 6,700 feet. They formed in colluvium and residuum from limestone. Slopes are 25 to 70 percent. The average annual precipitation ranges from 16 to 20 inches. The average annual air temperature is 40 to 43 degrees F. The frost free period is 60 to 75 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ireland, Manila, and Povey soils. Ireland soils are on convex slopes on similar landscape positions as Polumar soils. Ireland soils are moderately deep to bedrock and have a mollic epipedon less than 20 inches thick. Manila soils are on terraces and hills below Polumar soils. Manila soils have a fine particle-size control section and slow permeability. Povey soils are on north facing slopes above Polumar soils. Povey soils are leached free of accumulations of calcium carbonate.
DRAINAGE AND PERMEABILITY: Well drained; rapid runoff; moderate permeability.
USE AND VEGETATION: Polumar soils are used for rangeland. The potential natural vegetation is mountain big sagebrush and bluebunch wheatgrass.
DISTRIBUTION AND EXTENT: Southeastern Idaho. LRR B; MLRA 13. This series is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Franklin County, Idaho, 1994. The name is coined.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from the surface to 22 inches (A1, A2, A3, and Bk horizons)
Calcic horizon - the zone from 22 to 46 inches (the Bkq1 and Bkq2 horizons)
Particle-size control section - the zone between 10 and 40 inches (part of the A2, the A3, Bk, Bkq1, and part of the Bkq2 horizons)