LOCATION RENTSAC MT+CO UT WY
Established Series
Rev. JAL/RER/EMM
04/2014
RENTSAC SERIES
The Rentsac series consists of shallow, well drained soils that formed in slope alluvium and colluvium over residuum derived from calcareous sandstone and limestone. These soils are on mountains, escarpments, bedrock-floored plains, fan remnants, and hills. Slopes are 0 to 75 percent. Mean annual precipitation is about 12 inches, and mean annual temperature is about 43 degrees F.
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Lithic Calciustepts
TYPICAL PEDON: Rentsac channery loam, in grassland (colors are for dry soil unless otherwise noted).
A--0 to 2 inches; grayish brown (10YR 5/2) channery loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; soft, very friable, slightly sticky and nonplastic; many medium and fine roots; 15 percent sandstone channers; slightly effervescent; slightly alkaline (pH 7.6); clear wavy boundary. (1 to 6 inches thick)
Bk1--2 to 7 inches; light brownish gray (10YR 6/2) channery loam, dark grayish brown (10YR 4/2) moist; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many medium and fine roots; many fine and very fine pores; 30 percent sandstone channers; disseminated lime; continuous distinct lime casts coating channers; strongly effervescent; slightly alkaline (pH 7.8); gradual wavy boundary. (3 to 7 inches thick)
Bk2--7 to 18 inches; light brownish gray (2.5Y 6/2) extremely channery loam, dark grayish brown (2.5Y 4/2) moist; weak fine and medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common medium and fine roots; many fine and very fine pores and few medium pores; 10 percent cobbles, 40 percent channers, 20 percent flagstones; disseminated lime; continuous distinct lime casts coating channers; strongly effervescent; slightly alkaline (pH 7.8); abrupt wavy boundary. (0 to 12 inches thick)
R--18+ inches; calcareous sandstone.
TYPE LOCATION: Cascade County, Montana; 500 feet north and 1,000 feet east of the SW corner of sec. 31, T. 20 N., R. 3 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 40 to 47 degrees F.
Moisture control section - between 8 inches and the lithic contact, dry in all parts between four-tenths and five-tenths of the cumulative days per year when the soil temperature at a depth of 20 inches is 41 degrees F or higher. Ustic soil moisture regime bordering on Aridic.
Depth to calcic horizon: 1 to 6 inches
Depth to lithic contact - 10 to 20 inches.
Pedons that have a particle-size control section from the soil surface to a depth of 10 to 14 inches to a lithic contact contain 35 to 60 percent total rock fragments.
Soil phases - flaggy, nonstony, very channery, extremely channery, and very gravelly.
A horizon:
Hue: 7.5YR, 10YR, or 2.5Y
Value: 5 or 6 dry; 3 or 4 moist
Chroma: 2, 3, or 4, dry or moist
Texture: loam, sandy loam, fine sandy loam
Clay content: 7 to 18 percent
Rock fragments: 0 to 60 percent gravel and channers
Reaction: pH 6.6 to 8.4
Bk1 horizon
Hue: 7.5YR, 10YR, or 2.5Y
Value: 5, 6, or 7 dry; 4 or 5 moist
Chroma: 2, 3, or 4, dry or moist
Texture: loam, sandy loam, fine sandy loam
Clay content: 7 to 18 percent
Rock fragments: 0 to 80 percent--0 to 45 percent stones and flagstones; 0 to 55 percent gravel and channers
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 6.6 to 8.4
Bk2 horizon
Hue: 7.5YR, 10YR, or 2.5Y
Value: 5, 6, or 7 dry; 4 to 6 moist
Chroma: 2, 3, 4, or 6, dry or moist
Texture: loam, sandy loam, or fine sandy loam
Clay content: 7 to 18 percent
Rock fragments: 35 to 70 percent--0 to 35 percent cobbles and flagstones; 25 to 55 percent gravel and channers
Calcium carbonate equivalent: 5 to 15 percent
Electrical conductivity: less than 4 mmhos/cm
Reaction: pH 7.4 to 8.4
R horizon - calcareous sandstone or limestone rock.
COMPETING SERIES:
Cedarknoll (UT) - has a Bw horizon
Culebra (CO) - occurs at elevations greater than 8,000 feet
Hackling (CO) - has hues of 2.5YR or 5YR
Rencot (MT) - averages more than 18 percent clay in the particle-size control section
Schoonover (CO) - averages more than 18 percent clay in the particle-size control section
GEOGRAPHIC SETTING:
Landform - mountains, escarpments, hills, bedrock-floored plains.
Elevation - 2,400 to 6,500 feet (up to 8,000 feet in Colorado, Utah, and Wyoming).
Slope - 0 to 75 percent.
Parent material - slope alluvium and colluvium over residuum derived from calcareous sandstone and limestone
Climate - long, cold winters; moist springs; warm summers.
Mean annual temperature - 38 to 45 degrees F.
Mean annual precipitation - 10 to 15 inches
Frost-free period - 80 to 135 days (60 to 155 days in parts of Colorado, Utah, and Wyoming).
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability. In Colorado these soils are somewhat excessively drained and have moderately rapid permeability.
USE AND VEGETATION: Rentsac soils are used mainly as rangeland. Potential native vegetation is mainly bluebunch wheatgrass, needleandthread, and western wheatgrass.
DISTRIBUTION AND EXTENT: The Rentsac series is extensive throughout Montana, parts of Wyoming, and the mountains of Colorado. MLRAs 32, 34A, 43B, 44B, 46, 48A, 49, and 58A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Cascade County, Montana, 1969.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Particle-size control section: 10 to 18 inches (Bk2 horizon)
Ochric epipedon: from the soil surface to a depth of 2 inches (A horizon)
Calcic horizon: from 2 to 18 inches (Bk1, Bk2)
Lithic contact: the contact with sandstone at 18 inches (R layer)
Soil interpretation records: MT0120, MT0162, MT0771, and MT1106.
Classification was changed from Lithic Ustorthents to Lithic Calciustepts 5/1999.
National Cooperative Soil Survey
U.S.A.