LOCATION BRUNELDA MTEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Torrertic Haplustepts
TYPICAL PEDON: Brunelda silty clay, grassland (colors are for dry soil unless otherwise noted).
A--0 to 1 inch; light brownish gray (2.5Y 6/2) silty clay loam, grayish brown (2.5Y 5/2) moist; moderate very fine granular structure; slightly hard, friable, sticky and plastic; many very fine roots; slightly effervescent; moderately alkaline (pH 8.2); abrupt smooth boundary. (1 to 3 inches thick)
Bw--1 to 6 inches; light brownish gray (2.5Y 6/2) silty clay, grayish brown (2.5Y 5/2) moist; moderate medium angular blocky structure parting to moderate fine and very fine angular blocky; hard, firm, sticky and plastic; many very fine roots; many very fine pores; few fine masses of lime in lower part; strongly effervescent; moderately alkaline (pH 8.2); abrupt smooth boundary. (0 to 7 inches thick)
Byz1--6 to 13 inches; light brownish gray (2.5Y 6/2) silty clay, grayish brown (2.5Y 5/2) moist; moderate coarse prismatic structure parting to moderate medium angular blocky; very hard, firm, very sticky and very plastic; common very fine roots; common very fine pores; many fine masses of gypsum and other salts; slightly effervescent; mildly alkaline (pH 7.8); clear smooth boundary. (5 to 10 inches thick)
Byz2--13 to 40 inches; grayish brown (2.5Y 5/2) clay, dark grayish brown (2.5Y 4/2) moist; massive; very hard, very firm, very sticky and very plastic; few very fine roots; common very fine pores; common fine masses of gypsum and other salts; strongly alkaline (pH 8.8); gradual smooth boundary. (10 to 30 inches thick)
BC--40 to 60 inches; grayish brown (2.5Y 5/2) clay, dark grayish brown (2.5Y 4/2) moist; massive; very hard, very firm, very sticky and very plastic; few very fine pores; mildly alkaline (pH 7.6).
TYPE LOCATION: Rosebud County, Montana; 2,640 feet east and 1,500 feet north of the SW corner of sec. 23, T. 11 N., R. 35 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 43 to 47 degrees F.
Moisture control section - between 4 and 12 inches, 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.
Depth to Byz1 horizon - 1 to 10 inches.
Depth to Byz2 horizon - 10 to 20 inches.
The chroma of 1 in the Byz2 and BC horizons is lithochromic from parent materials.
A horizon - Value: 5 or 6 dry, 4 or 5 moist
Chroma: 2 or 3
Texture: silty clay loam, silty clay, or clay
Clay content: 35 to 50 percent
Reaction: pH 7.4 to 8.4
Bw horizon - Value: 5 or 6 dry, 4 or 5 moist
Chroma: 2 or 3
Texture: silty clay or clay
Clay content: 40 to 50 percent
EC: less than 4 mmhos/cm
Reaction: pH 7.9 to 8.4
Byz1 horizon - Value: 5 or 6 dry, 4 or 5 moist
Chroma: 2 or 3
Texture: silty clay or clay
Clay content: 45 to 60 percent
EC: 4 to 8 mmhos/cm
Salt: 1 to 2 percent
Gypsum: 15 to 25 percent
SAR: 10 to 25
Reaction: pH 7.4 to 9.0
Byz2 horizon - Hue: 2.5Y or 10YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 1, 2, or 3
Texture: silty clay or clay
Clay content: 45 to 60 percent
EC: 16 to 24 mmhos/cm
Salt: 1 to 2 percent
Gypsum: 1 to 5 percent
SAR: 25 to 45
Reaction: pH 7.4 to 9.0
This horizon remains moist in some part throughout the growing season. Iron stains, 10YR 5/4 through 5/8 moist, are present in some pedons.
BC horizon - Hue: 2.5Y or 10YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 1, 2, or 3
Texture: silty clay or clay
Clay content: 45 to 60 percent
EC: 16 to 30 mmhos/cm
Salt: 1 to 2 percent
Gypsum: 1 to 2 percent
SAR: 25 to 45
Reaction: pH 7.4 to 8.4
Some part of this horizon remains moist throughout the growing season. Iron stains, 10YR 5/4 through 5/8 moist, are present in some pedons.
COMPETING SERIES:
Kobase (MT) - does not have a gypsic horizon; has horizons of secondary calcium carbonate accumulation.
Megonot (MT) - does not have a gypsic horizon; has a horizon of secondary carbonate accumulation; has a paralithic contact at depths of 20 to 40 inches.
Nunemaker (MT) - has a horizon of secondary calcium carbonate accumulations; has a lithologic discontinuity at a depth of 16 to 20 inches; does not have a gypsic horizon.
Teigen (MT) - does not have a gypsic horizon; has a very strongly acid particle-size control section.
Welter (MT) - has an E horizon; does not have a gypsic horizon; has a paralithic contact at a depth of 20 to 40 inches.
Zatoville (MT) - has a paralithic contact above a depth of 60 inches.
GEOGRAPHIC SETTING:
Landform - sedimentary plains.
Elevation - 2,800 to 3,300 feet.
Slope- 1 to 8 percent.
Parent material - semiconsolidated shale.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 10 to 14 inches.
Mean annual temperature - 41 to 45 degrees F.
Frost-free period - 115 to 125 days.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Brunelda soils are used mainly for rangeland. Potential native vegetation is mainly western wheatgrass, thickspike wheatgrass, Montana wheatgrass, green needlegrass, and Nuttall saltbush.
DISTRIBUTION AND EXTENT: Brunelda soils are of moderate extent in southeastern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Rosebud County, Montana, 1981.
REMARKS: Soil interpretations record: MT0735. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 7 inches (mixed) (A, Bw, Byz1 horizons); a gypsic horizon from 6 to 13 inches (Byz1 horizon); a particle-size control section from 10 to 40 inches (Byz1, Byz2 horizons). Brunelda soils have a frigid temperature regime and an ustic moisture regime that borders on aridic.
ADDITIONAL DATA: Laboratory sample S81MT-087-579.