LOCATION BURNT FORK MT
Established Series
Rev. EMR/JMS/RJS
10/2012
BURNT FORK SERIES
The Burnt Fork series consists of very deep, well drained soils formed in alluvium and colluvium. These soils are on fan remnants, eroded fan remnants, and escarpments in intermountain valleys. Slopes are 0 to 45 percent. Mean annual precipitation is about 368 mm and mean annual temperature is about 6 degrees C.
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, frigid Typic Haplustolls
TYPICAL PEDON: Burnt Fork loam, in rangeland on a 2 percent slope at 1,118 meters elevation (Colors are for dry soil unless otherwise indicated).
A--0 to 25 cm; grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; moderate coarse granular structure; friable, slightly hard, slightly sticky and slightly plastic; common very fine and fine roots; many very fine and fine tubular pores; slightly alkaline (pH 7.4); clear smooth boundary. (18 to 36 cm thick)
Bw--25 to 46 cm; light brownish gray (10YR 6/2) loam, dark grayish brown (10YR 4/2) moist; moderate medium subangular blocky structure; friable, hard, slightly sticky and slightly plastic; common very fine and fine roots; common fine tubular pores; 5 percent gravel; slightly alkaline (pH 7.4); clear smooth boundary. (15 to 40 cm thick)
Bk1--46 to 61 cm; light brownish gray (10YR 6/2) fine sandy loam, dark grayish brown (10YR 4/2) moist; moderate medium subangular blocky structure; friable, slightly hard, nonsticky and nonplastic; common very fine and fine roots; common fine irregular pores; 5 percent gravel; few fine distinct calcium carbonate masses in the matrix; strongly effervescent, moderately alkaline (pH 8.0); gradual smooth boundary.
Bk2--61 to 104 cm; pale brown (10YR 6/3) fine sandy loam, brown (10YR 4/3) moist; moderate fine subangular blocky structure; friable, slightly hard, nonsticky and nonplastic; few very fine roots; common fine irregular pores; 5 percent gravel and 5 percent cobbles; common fine carbonate masses and weakly cemented carbonate nodules in the matrix; violently effervescent; moderately alkaline (pH 8.2); clear smooth boundary. (combined thickness of Bk horizons 25 to 100 cm)
BCk--104 to 152 cm; very pale brown (10YR 7/3) very gravelly fine sandy loam, brown (10YR 5/3) moist; single grain; soft, very friable, nonsticky and nonplastic; few fine roots; common fine irregular pores; 30 percent gravel and 10 percent cobbles; few distinct carbonate coats on bottom surfaces of rock fragments; strongly effervescent; moderately alkaline (pH 8.0).
TYPE LOCATION: Corvallis topographic quadrangle, Ravalli County, Montana; 520 meters north and 460 meters east of the SW corner section 35, T 7 N, R 20 W; UTM zone 11, 725902E, 5133487N, NAD 83.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 5 to 8 degrees C
Mollic epipedon thickness - 18 to 36 cm
Depth to cambic horizon - 18 to 36 cm
Depth to calcic horizon - 33 to 76 cm
A horizon
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 2 or 3 dry or moist
Clay content: 12 to 24 percent
Rock fragments: 0 to 45 percent; 0 to 25 percent gravel, 0 to 30 cobbles, 0 to 5 percent stones
Reaction: pH 6.6 to 7.8
Bw horizon
Value: 5 or 6 dry
Chroma: 2 or 3 dry or moist
Texture: loam or fine sandy loam
Clay content: 12 to 22 percent
Rock fragments: 0 to 10 percent; 0 to 10 percent gravel, 0 to 5 percent cobbles
Reaction: pH 6.8 to 7.8
Bk horizon(s)
Value: 6 to 8 dry; 4 to 6 moist
Chroma: 2 to 4 dry or moist
Texture: fine sandy loam, sandy loam, or loam
Clay content: 8 to 18 percent
Rock fragments: 0 to 35 percent; 0 to 30 percent gravel, 0 to 10 percent cobbles
Calcium carbonate equivalent: 15 to 40 percent
Reaction: pH 8.0 to 8.4
BCk horizon
Hue: 10YR or 2.5 Y
Value: 6 or 7 dry; 4 to 6 moist
Chroma: 2 to 4 dry or moist
Texture: fine sandy loam or sandy loam
Clay content: 4 to 16 percent
Rock fragments: 35 to 60 percent; 20 to 50 percent gravel, 0 to 15 percent cobbles
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.9 to 8.2
COMPETING SERIES:
Baggs (MT) - do not have a calcic horizon; do not have more than 15 percent rock fragments
Baxton (MT) - do not have a calcic horizon; have a paralithic contact at depths of 50 to 102 cm and a lithic contact at depths of 102 to 152 cm
Belain (MT) - do not have a calcic horizon; have a lithic contact at depths of 50 to 102 cm
Chincap (WY) - do not have a calcic horizon; have a lithic contact at depths of 50 to 102 cm
Hopley (MT) - do not have a calcic horizon; have a paralithic contact at depths of 102 to 152 cm
Kalispell (MT) - contain more than 45 percent silt in the upper part of the subsoil; do not have rock fragments
Losttrail (MT) - do not have a calcic horizon; contain more than 80 percent sand in the lower part of the subsoil
Mott (ND) - do not have a calcic horizon; do not have more than 10 percent rock fragments
Relan (MT) - do not have a cambic or a calcic horizon; have hues redder than 10YR
Tally (MT) - do not have a calcic horizon; do not have more than 15 percent rock fragments
Tinytown (CO) - do not have a calcic horizon; have angular granite rock fragments; have hues redder than 10YR
Unaweep (CO) - do not have a calcic horizon; do not have more than 10 percent rock fragments; have hues redder than 10YR
Vebar (ND) - do not have a calcic horizon; have a paralithic contact at depths of 50 to 102 cm
Victor (MT) - do not have a cambic or a calcic horizon; have more than 80 percent sand in the lower part of the subsoil
Weedzunit (MT) - do not have a calcic horizon; have a lithic contact at depths of 50 to 102 cm
GEOGRAPHIC SETTING:
Landform - fan remnants, eroded fan remnants, and escarpments
Elevation - 975 to 1,830 meters
Slope - 0 to 45 percent
Parent material - alluvium and colluvium
Climate: long, cold winters; moist springs; warm summers
Mean annual precipitation - 330 to 432 millimeters
Mean annual air temperature - 4 to 7 degrees C
Frost-free period - 95 to 120 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability to a depth of 46 cm and moderately rapid below.
USE AND VEGETATION: Burnt Fork soils are used as rangeland, irrigated pasture and hayland. Native vegetation is bluebunch wheatgrass, needle and thread and prairie Junegrass.
DISTRIBUTION AND EXTENT: Burnt Fork soils are of small extent in the intermountain valleys of southwest Montana. MLRA 44A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Bitterroot Valley Area, Montana, 1952. The name is taken from a local creek.
REMARKS: Diagnostic features and horizons recognized in this pedon are:
Mollic epipedon - from the surface to 25 cm (A horizon)
Cambic horizon - from 25 to 46 cm (Bw horizon)
Calcic horizon - from 46 to 152 cm (Bk1, Bk2, BCk horizons)
Particle-size control section - from 25 to 100 cm (Bw, Bk1, part of the Bk2 horizon).
Burnt Fork soils have a frigid temperature regime and an ustic moisture regime.
National Cooperative Soil Survey
U.S.A.