LOCATION BAVDARK MT
Established Series
Rev. GAR-KTS-JCK
12/2022
BAVDARK SERIES
The Bavdark series consists of very deep, well drained soils that formed in alluvium and colluvium derived from gneiss and schist. These soils are on alluvial fans, stream terraces, hills, mountain slopes, and drainageways. Slopes are 4 to 50 percent. Mean annual precipitation is about 530 mm, and the mean annual air temperature is about 2 degrees C.
TAXONOMIC CLASS: Fine-loamy, mixed, superactive Pachic Argicryolls
TYPICAL PEDON: Bavdark coarse sandy loam, in rangeland (Colors are for dry unless otherwise noted).
A--0 to 25 cm; dark gray (10YR 4/1) coarse sandy loam, black (10YR 2/1) moist; weak medium granular structure; soft, very friable, slightly sticky and slightly plastic; common very fine and fine and few medium roots; many very fine and common fine and medium pores; 5 percent gravel; slightly acid (pH 6.2); clear smooth boundary. (20 to 30 cm thick)
AB--25 to 46 cm; dark gray (10YR 4/1) sandy clay loam, very dark gray (10YR 3/1) moist; moderate medium granular structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and few fine and medium roots; many very fine, common fine and few medium pores; 5 percent gravel; slightly acid (pH 6.4); clear smooth boundary. (15 to 36 cm thick)
Bt1--46 to 76 cm; dark grayish brown (10YR 4/2) sandy clay loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; hard, very friable, moderately sticky and moderately plastic; few very fine, fine and medium roots; many very fine, common fine and few medium pores; common faint clay films on faces of peds and lining pores; 5 percent gravel; slightly acid (pH 6.4); clear wavy boundary.
Bt2--76 to 107 cm; brown (10YR 5/3) sandy clay loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; hard, very friable, moderately sticky and slightly plastic; few very fine, fine and medium roots; many very fine, common fine and few medium pores; common faint clay films on faces of peds and lining pores; 5 percent gravel; slightly acid (pH 6.2); clear wavy boundary. (Combined thickness of Bt horizons is 46 to 86 cm).
C--107 to 152 cm; brown (10YR 5/3) coarse sandy loam; brown (10YR 4/3) moist; massive; slightly hard, very friable, nonsticky and nonplastic; few very fine and fine roots; many very fine, common fine and few medium pores; 10 percent gravel; slightly acid (pH 6.2).
TYPE LOCATION: Gallatin County, Montana; 274 meters north and 701 meters west of the SE corner of section 33 T.3S.,R.3E.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 2 to 4 degrees C
Mean summer soil temperature - 11 to 14 degrees C
Mollic epipedon thickness - 46 to 114 cm
Depth to top of argillic horizon - 36 to 50 cm
A horizon
Value: 3 or 4 dry; 2 or 3 moist
Texture: coarse sandy loam, sandy loam, loam
Clay content: 12 to 25 percent
Rock fragments: 5 to 30 percent--5 to 25 percent gravel, 0 to 5 percent cobbles, 0 to 5 percent stones
Reaction: pH 6.1 to 7.3
AB horizon
Value: 3 or 4 dry; 2 or 3 moist
Chroma: 1 or 2; dry or moist
Texture: coarse sandy loam, sandy clay loam
Clay content: 12 to 25 percent
Rock fragments: 5 to 25 percent--5 to 20 percent gravel, 0 to 5 percent cobbles
Reaction: pH 6.1 to 7.3
Bt1 horizon
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 2 to 4; dry or moist
Texture: sandy clay loam, clay loam
Clay content: 22 to 35 percent
Rock fragments: 5 to 25 percent--5 to 20 percent gravel, 0 to 5 percent cobbles
Reaction: pH 6.1 to 7.3
Bt2 horizon
Value: 5 or 6 dry; 3 or 4 moist
Chroma: 3 or 4; dry or moist
Texture: sandy clay loam, clay loam
Clay content: 22 to 35 percent
Rock fragments: 5 to 25 percent--5 to 20 percent gravel, 0 to 5 percent cobbles
Reaction: pH 6.1 to 7.3
C horizon
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 3 or 4; dry or moist
Texture: coarse sandy loam, sandy clay loam
Clay content: 12 to 25 percent
Rock fragments: 10 to 30 percent--10 to 20 percent gravel, 0 to 10 percent cobbles
Reaction: pH 6.1 to 7.3
COMPETING SERIES:
Bachus (WY) - have a lithic contact at depths of 50 to 100 cm
Benteen (MT) - have a lithic contact at depths of 50 to 100 cm
Brushtop (ID) - have a paralithic contact at depths of 50 to 100 cm; have a xeric moisture regime
Clayburn (UT) - have an udic moisture regime
Croydon (UT) - have a lithic contact at depths of 100 to 152 cm
Crystalbutte (ID) - have a lithologic discontinuity; have a xeric moisture regime
Davtone (CO) - have hues redder than 10YR throughout the subsoil
Dehana (ID) - have a lithologic discontinuity
Demast (ID) - have a a lithic contact at depths of 100 to 152 cm
Dranburn (ID) - have an udic moisture regime
Dranyon (ID) - have hues redder than 10YR in the upper part of the subsoil; have an udic moisture regime
Echemoor (WY) - have a paralithic contact at depths of 50 to 100 cm
Hagenbarth (ID) - have a xeric moisture regime
Hoopgobel (ID) - have a paralithic contact at depths of 50 to 100 cm
Longway (ID) - have a lithologic discontinuity; have a xeric moisture regime
Lostminer (UT) - have a horizon of secondary calcium carbonate accumulation; have a lithic contact at depths of 50 to 100 cm
Millerlake (WY) - have horizons of secondary calcium carbonate accumulation
Odark (MT) - do not have an AB horizon
Senchert (UT) - have a lithic contact at depths of 50 to 100 cm; have an udic moisture regime
Southmount (ID) - have a lithologic discontinuity
Poodle (NV) - have a paralithic contact at depths of 50 to 100 cm
Stubbs (WY) - have a horizon of secondary calcium carbonate accumulation; have a paralithic contact at depths of 50 to 100 cm
Thulepah (NV) - have a lithologic discontinuity
Vadnais (ID) - have a lithic contact at depths of 50 to 100 cm
Winu (NV) - have a lithic contact at depths of 50 to 100 cm
GEOGRAPHIC SETTING:
Landform - alluvial fans, stream terraces, hills, mountain slopes, and drainageways
Elevation - 1,500 to 2,300 meters
Slope - 4 to 50 percent
Parent material - alluvium and colluvium derived from gneiss and schist
Climate - long, cold winters; cool, moist springs; short summers
Mean annual precipitation - 430 to 600 mm
Mean annual air temperature - 1 to 4 degrees C
Frost-free period - 50 to 70 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability to a depth of 107 cm and moderately rapid below.
USE AND VEGETATION: Bavdark soils are used mainly for rangeland and wildlife habitat. Potential native vegetation may include Idaho fescue, Richardson needlegrass, Columbia needlegrass, mountain brome, lupine, and sticky geranium.
DISTRIBUTION AND EXTENT: Bavdark soils are moderately extensive in central and southwestern Montana. MLRA 43B.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Gallatin County, Montana, 1997.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 0 to 107 cm (A, AB, Bt1 and Bt2 horizons)
Argillic horizon - from 46 to 107 cm (Bt1 and Bt2 horizons)
Particle size control section - from 46 to 96 cm (Bt1 and part of Bt2 horizons)
Bavdark soils have a cryic temperature regime and an ustic moisture regime.
Horizon designation for the AB horizon and similarity between this soil and the competing Odark series needs to be investigated across the extent of the series.
Additional Data: Soil interpretations record: MT1419.
National Cooperative Soil Survey
U.S.A.