LOCATION AMBROSECREEK MT
Established Series
Rev. JMS/EMR/RJS
07/2013
AMBROSECREEK SERIES
The Ambrosecreek series consists of very deep, somewhat excessively drained soils that formed in alluvium from mixed sources. These soils are on stream terraces and inset fans. Slopes are 0 to 8 percent. Mean annual precipitation is about 330 mm and mean annual air temperature is about 6 degrees C.
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, frigid Aridic Haplustolls
TYPICAL PEDON: Ambrosecreek sandy loam, in rangeland on a 2 percent slope at 1,018 meters elevation (colors are for dry soil unless otherwise indicated.)
A--0 to 18 cm; grayish brown (10YR 5/2) sandy loam, very dark grayish brown (10YR 3/2) moist; moderate medium granular structure; very friable, soft, nonsticky and nonplastic; many fine and medium roots; many fine irregular and tubular pores; 5 percent gravel; neutral (pH 7.2); clear smooth boundary. (18 to 36 cm thick)
Bw--18 to 41 cm; pale brown (10YR 6/3) sandy loam, brown (10YR 4/3) moist; weak fine subangular blocky structure; very friable, soft, nonsticky and nonplastic; common fine roots; many fine irregular and tubular pores; 2 percent gravel; neutral (pH 7.0); gradual smooth boundary. (20 to 53 cm thick)
C1--41 to 71 cm; light yellowish brown (2.5Y 6/3) sandy loam, olive brown (2.5Y 4/3) moist; massive; loose, nonsticky and nonplastic; few fine roots; many fine interstitial pores; 5 percent gravel; neutral (pH 7.0); abrupt wavy boundary. (15 to 38 cm thick)
C2--71 to 127 cm; light yellowish brown (2.5Y 6/3) coarse sand, light olive brown (2.5Y 5/3) moist; single grain; loose, nonsticky and nonplastic; few fine roots; common fine interstitial pores; 10 percent gravel; neutral (pH 6.8); abrupt wavy boundary.
C3--127 to 152 cm; light yellowish brown (2.5Y 6/3) very gravelly coarse sand, light olive brown (2.5Y 5/3) moist; single grain; loose, nonsticky and nonplastic; common fine interstitial pores; 55 percent gravel; neutral (pH 6.8).
TYPE LOCATION: Stevensville topographic quadrangle, Ravalli County, Montana; 160 meters south and 463 meters east of the NW corner of section 7, T. 9 N., R. 19 W. UTM Zone 11: 726883e, 5160246n, NAD 83.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 5 to 8 degrees C
Mollic epipedon thickness - 18 to 36 cm
The coarse-loamy material contains more than 50 percent fine sand or coarser sand.
A horizon
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 2 or 3 dry or moist
Texture: sandy loam, loam or fine sandy loam
Clay content: 10 to 22 percent
Rock fragments: 0 to 15 percent--0 to 10 percent gravel, 0 to 5 percent cobbles
Reaction: pH 6.6 to 7.8
Bw horizon
Value: 5 or 6 dry; 3 or 4 moist
Chroma: 3 or 4 dry or moist
Texture: sandy loam or fine sandy loam
Clay content: 8 to 16 percent
Rock fragments: 0 to 15 percent--0 to 10 percent gravel, 0 to 5 percent cobbles
Reaction: pH 6.6 to 7.8
C1 horizon
Hue: 10YR or 2.5Y
Value: 6 or 7 dry; 4, 5 or 6 moist
Chroma: 3 or 4 dry or moist
Texture: sandy loam or loamy sand
Clay content: 4 to 12 percent
Rock fragments: 0 to 10 percent--0 to 10 percent gravel, 0 to 5 percent cobbles
Reaction: pH 6.6 to 7.8
C2 and C3 horizons
Hue: 10YR or 2.5Y
Value: 4, 5 or 6 dry; 4 or 5 moist
Chroma: 3 or 4 dry or moist
Texture: loamy fine sand, loamy sand, loamy coarse sand, coarse sand or sand
Clay content: 1 to 6 percent
Rock fragments: 10 to 65 percent--10 to 55 percent gravel, 0 to 10 percent cobbles
Reaction: pH 6.6 to 7.4
COMPETING SERIES:
Anaconda (MT) - have a calcic horizon
Chinook (MT) - have a horizon of secondary calcium carbonate accumulation
Cozberg (MT) - have a horizon of secondary calcium carbonate accumulation; have a lithologic discontinuity
Holloron (MT) - have more than 6 percent clay in the lower part of the subsoil; have more than 15 percent rock fragments in the particle-size control section
Lahood (MT) - have a horizon of secondary calcium carbonate accumulation; have a lithic contact at depths of 50 to 102 cm
Modess (MT) - have a horizon of secondary calcium carbonate accumulation; have a paralithic contact at depths of 50 to 102 cm; have a lithic contact at depths of 102 to 152 cm
Pitchstone (MT) - have a high proportion of medium, coarse, and very coarse angular sand; do not have rock fragments greater than 5 mm
Pring (CO) - have less than 15 percent rock fragments; are extremely hard at depths of 50 to 102 cm
Rhame (ND) - have a paralithic contact at depths of 50 to 102 cm
Ynot (MT) - do not have rock fragments
GEOGRAPHIC SETTING:
Landform: stream terraces and inset fans
Elevation: 980 to 1,430 meters
Slope: 0 to 8 percent
Parent material: alluvium
Climate: long, cold winters; moist springs; warm dry summers
Mean annual precipitation: 305 to 380 mm, much of which falls as snow and as spring rain
Mean annual air temperature: 4 to 7 degrees C
Frost-free period: 90 to 115 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; moderately rapid permeability to a depth of 71 cm and very rapid below.
USE AND VEGETATION: Ambrosecreek soils are used for irrigated and dryland pasture, irrigated grass hay, small grains, and minor acreages of other crops grown under irrigation.
DISTRIBUTION AND EXTENT: Ambrosecreek soils are of small extent in the valleys of western Montana. MLRA 44A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Bitterroot Valley Area, Montana, 2013; proposed in Ravalli County, Montana, 2006.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 0 to 18 cm (A horizon)
Cambic horizon - from 18 to 41 cm (Bw horizon)
Particle-size control section - from 25 to 100 cm (part of the Bw, C1 and part of the C2 horizons)
Ambrosecreek soils have a frigid temperature regime and an ustic moisture regime that borders on aridic.
National Cooperative Soil Survey
U.S.A.