LOCATION ZBART MTEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, nonacid, frigid Aridic Lithic Ustorthents
TYPICAL PEDON: Zbart very channery loam, in rangeland (colors are for dry soil unless otherwise noted).
A--0 to 7 inches; dark grayish brown (2.5Y 4/2) very channery loam, dark olive gray (5Y 3/2) moist (colors are lithochromic); moderate fine granular structure; slightly hard, very friable, slightly sticky and nonplastic; common very fine and fine roots; common very fine and fine pores; 5 percent flagstones and 40 percent channers; slightly acid (pH 6.4); clear wavy boundary. (5 to 8 inches thick)
R--7 inches; gray (5Y 5/1) hard fractured shale.
TYPE LOCATION: Jefferson County, Montana; 50 feet south and 925 feet west of the northeast corner of sec. 36, T. 2 N., R. 3 W.
RANGE IN CHARACTERISTICS:
Annual soil temperature - 42 to 46 degrees F.
Moisture control section - between the surface and 7 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 bedrock - 5 to 10 inches.
The colors of the A horizon are lithochromic; the horizon is not mollic. A thin transition horizon is allowed.
A horizon - Value: 4 or 5 dry
Clay content: 15 to 27 percent
Rock fragments: 35 to 60 percent-- 0 to 15 percent flagstones, 35 to 50 percent channers
Reaction: pH 6.1 to 7.3
COMPETING SERIES:
Ashbon (MT) - has lithic contact of granite at 10 to 20 inches; has O horizons.
Ashbray (MT) - has a lithic contact of granite at 12 to 20 inches.
Valto (CO) - has a lithic contact of sandstone at 6 to 20 inches; is very stony throughout.
GEOGRAPHIC SETTING:
Landform - escarpments, ridges, interfluves and sideslopes of hills.
Elevation - 3,800 to 5,000 feet.
Slope- 4 to 70 percent.
Parent material - residuum from hard fractured shale or argillite.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 10 to 14 inches.
Mean annual air temperature - 40 to 44 degrees F.
Frost-free period - 90 to 115 days.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained, moderate permeability.
USE AND VEGETATION: Zbart soils are primarily used for rangeland. The potential native vegetation is mainly bluebunch wheatgrass, blue grama, needleandthread, skunkbush sumac, rubber rabbitbrush, Rocky Mountain juniper, phlox, and widely scattered limber pine.
DISTRIBUTION AND EXTENT: Zbart soils are of small extent in southwestern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Jefferson County, Montana, 1998.
REMARKS: Soil interpretation record: MT1592. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 7 inches (A horizon); a particle-size control section from the surface to 7 inches (A horizon); lithic contact to hard fractured shale at 7 inches (R horizon). Zbart soils have a frigid temperature regime and an ustic moisture regime bordering on aridic.