LOCATION ROUNDOR MT
Established Series
Rev. BDD-JAL-EMM
01/2014
ROUNDOR SERIES
The Roundor series consists of moderately deep, well drained soils that formed in calcareous materials derived from weakly consolidated sandy and silty sedimentary beds or in alluvium over the sedimentary beds. These soils are on escarpments, sedimentary plains, hills and strath terraces. Slopes are 0 to 60 percent. Mean annual precipitation is about 17 inches, and mean annual temperature is about 42 degrees F.
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Typic Calciustolls
TYPICAL PEDON: Roundor loam, grassland (colors are for dry soil unless otherwise noted).
A--0 to 5 inches; dark grayish brown (10YR 4/2) loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many fine and few medium roots; many fine vesicular pores; about 5 percent gravel; slightly effervescent; slightly alkaline (pH 7.4); clear smooth boundary. (5 to 10 inches thick)
Bw--5 to 12 inches; brown (10YR 5/3) clay loam, dark brown (10YR 4/3) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; hard, friable, moderately sticky and slightly plastic; common fine roots; common fine and very fine pores; 5 percent gravel with common distinct lime coats on undersides; strongly effervescent; slightly alkaline (pH 7.6); clear smooth boundary. (5 to 12 inches thick)
Bk1--12 to 26 inches; pale brown (10YR 6/3) clay loam, brown (10YR 5/3) moist; weak coarse prismatic structure parting to weak medium subangular blocky; hard, friable, slightly sticky and slightly plastic; common fine roots; common very fine pores; 5 percent gravel; common medium and fine masses of lime; violently effervescent; moderately alkaline (pH 7.9); clear wavy boundary. (6 to 16 inches thick)
2Bk2--26 to 31 inches; very pale brown (10YR 7/3) silt loam, pale brown (10YR 6/3) moist; stratified parting to weak medium granular structure; hard, friable, slightly sticky and slightly plastic; few fine roots; 10 percent soft shale fragments; common fine masses of lime; violently effervescent; moderately alkaline (pH 8.2); clear wavy boundary. (4 to 8 inches thick)
Cr--31 to 60 inches; very pale brown (10YR 7/3) semiconsolidated shale; pale brown (10YR 6/3) moist; strongly effervescent; strongly alkaline (pH 8.8).
TYPE LOCATION: Teton County, Montana; 1,650 feet south and 450 feet west of the NE corner of sec. 12, T. 24 N., R. 7 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 41 to 47 degrees F.
Moisture control section - between 4 and 12 inches.
Mollic epipedon thickness - 7 to 12 inches (may include the upper part of the Bw horizon).
Control section - 20 to 35 percent clay and 0 to 15 percent rock fragments or soft shale fragments.
Depth to bedrock - 20 to 40 inches.
Calcic horizon - 15 to 35 percent calcium carbonate equivalent.
A horizons
Hue - 2.5Y, 7.5YR, or 10YR
Value - 4 or 5 dry; 2 or 3 moist
Chroma - 2 or 3, dry or moist
Texture - loam or silt loam
Clay content - 18 to 27 percent
Rock fragments - 0 to 35 percent--0 to 15 percent cobbles, 0 to 30 percent gravel
Reaction - pH 6.6 to 8
Bw horizon
Hue - 2.5Y, 7.5YR, or 10YR
Value - 4, 5, or 6 dry; 3, 4, or 5 moist
Chroma - 2 or 3, dry or moist
Texture - loam, silt loam, clay loam, or silty clay loam
Clay content - 20 to 35 percent
Rock fragments - 0 to 15 percent either rounded gravel or soft shale fragments
Reaction - pH 7.4 to 8.4
Bk horizons
Hue - 2.5Y, 7.5YR, or 10YR
Value - 5, 6, or 7 dry; 4, 5, or 6 moist
Chroma - 2, 3 or 4, dry or moist
Texture - loam, silt loam, fine sandy loam, or clay loam
Clay content - 20 to 35 percent
Rock fragments - 0 to 15 percent total - 0 to 15 percent either rounded gravel or soft shale fragments, 0 to 3 percent cobbles
Calcium carbonate equivalent - 15 to 35 percent
Reaction - pH 7.9 to 8.4
Cr horizon - soft, sandy, or silty sedimentary beds. Some pedons have thin layers of soft sandstone or semiconsolidated mudstone in the bedrock.
COMPETING SERIES:
Beanlake (MT) - is very deep.
Ipano (MT) - has a lithic contact at 20 to 40 inches.
Kiev (MT) - is very deep.
Minnimaud (UT) - has a paralithic contact at 40 to 60 inches.
Mudcree (UT) - has 15 to 35 percent coarse fragments in the particle-size control section.
Osote (UT) - is very deep.
Zahl (ND) - is very deep.
GEOGRAPHIC SETTING:
Landform - strath terraces, sedimentary plains, hills and escarpments.
Elevation - 3,800 to 6,000 feet.
Slope - 0 to 60 percent.
Parent material - calcareous materials derived from weakly consolidated sandy and silty sedimentary beds or in alluvium over the sedimentary beds.
Climate - long, cold winters; cool, moist springs; and warm, dry summers.
Mean annual precipitation - 13 to 19 inches.
Mean annual temperature - 38 to 45 degrees F.
Frost-free period - 70 to 125 days.
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; slow or medium runoff; moderately slow permeability.
USE AND VEGETATION: Roundor soils are used mainly for nonirrigated cropland and rangeland. Potential native vegetation is mainly rough fescue, bluebunch wheatgrass, green needlegrass, needleandthread, western wheatgrass, Idaho fescue, forbs, and shrubs.
DISTRIBUTION AND EXTENT: Roundor soils are of moderate extent in north central Montana. MLRAs 43B, 46 and 48A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Choteau-Conrad Area, parts of Teton and Pondera Counties, Montana, 1991; proposed in Choteau-Conrad Area, Montana, 1980.
REMARKS: Soil interpretation record: MT0460.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon (mixed) - the zone from the surface to 7 inches (A and Bw horizons)
Cambic horizon - the zone from 5 to 12 inches (Bw horizon)
Horizons of lime accumulation from 12 to 31 inches (Bk1 and 2Bk2 horizons)
Particle-size control section - the zone from 10 to 31 inches (Bw, Bk1, and 2Bk2 horizons to 3Cr horizon at depth of 31 inches).
Roundor soils have a frigid temperature regime and an ustic moisture regime.
National Cooperative Soil Survey
U.S.A.