LOCATION HOLLORON MT
Established Series
Rev. EMR/JMS/RJS
07/2013
HOLLORON SERIES
The Holloron series consists of very deep, well drained soils formed in alluvium derived from mixed sources. These soils are on inset fans and stream terraces in intermountain valleys. Slopes are 0 to 6 percent. Mean annual precipitation is about 330 mm and mean annual temperature is about 6 degrees C.
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, frigid Aridic Haplustolls
TYPICAL PEDON: Holloron loam, in rangeland on a 2 percent slope at 1,114 meters elevation (Colors are for dry soil unless otherwise indicated).
A--0 to 32 cm; grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; soft, very friable, nonsticky, slightly plastic; common very fine and fine roots; many very fine and fine tubular pores; 3 percent gravel; neutral (pH 6.9); clear smooth boundary. (25 to 38 cm thick)
Bw--32 to 64 cm; brown (10YR 5/3) gravely loam, brown (10YR 4/3) moist; weak fine subangular blocky structure; soft, very friable, nonsticky, nonplastic; common very fine and fine roots; common fine tubular pores; 15 percent gravel; neutral (pH 6.8); gradual smooth boundary. (15 to 63 cm thick)
C--64 to 152 cm; light yellowish brown (2.5Y 6/3) very gravelly sandy loam, olive brown (2.5Y 4/3) moist; single grain; loose, nonsticky, nonplastic; few fine roots; common fine interstitial pores; 40 percent gravel and 15 percent cobbles; neutral (pH 6.9).
TYPE LOCATION: Bing topographic quadrangle, Ravalli County, Montana; 180 meters north and 90 meters west of the SE corner of section 13, T 5 N, R 21 W; UTM zone 11, 719456E, 5118397N, NAD 83.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 5 to 8 degrees C
Mollic epipedon thickness - 25 to 38 cm
A horizon
Value: 4 or 5 dry;
Chroma: 2 or 3 dry or moist
Texture: loam, silt loam or fine sandy loam
Clay content: 12 to 22 percent
Content of rock fragments: 0 to 20 percent--0 to 20 percent gravel, 0 to 10 percent cobbles
Reaction: pH 6.0 to 7.2
Bw horizon
Hue: 10YR, 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 to 4 dry or moist
Texture: loam, sandy loam or fine sandy loam
Clay content: 8 to 18 percent
Content of rock fragments: 0 to 20 percent--0 to 20 percent gravel, 0 to 10 percent cobbles
Reaction: pH 6.1 to 7.4
C horizon
Value: 6 or 7 dry; 4 or 5 moist
Chroma: 4 or 5 dry; 3 to 5 moist
Texture: sandy loam or loamy sand
Clay content: 2 to 16 percent
Content of rock fragments: 40 to 70 percent--25 to 60 percent gravel, 0 to 25 percent cobbles
Reaction: pH 6.3 to 7.8
COMPETING SERIES:
Ambrosecreek (MT) - do not have more than 6 percent clay in the lower part of the subsoil; have less than 15 percent rock fragments in the particle-size control section
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
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 20 to 35 percent rock fragments in the particle-size control section; have less than 40 percent rock fragments in the lower part of the subsoil
Pring (CO) - have less than 15 percent rock fragments; is extremely hard at a depth of 50 cm
Rhame (ND) - have a paralithic contact between depths of 50 to 100 cm
Ynot (MT) - do not have rock fragments
GEOGRAPHIC SETTING:
Landform - inset fans and stream terraces
Elevation - 975 to 1,350 meters
Slope - 0 to 6 percent
Parent material - alluvium derived from mixed sources
Climate - long, cold winters; moist springs; warm summers
Mean annual precipitation - 305 to 380 millimeters
Mean annual air temperature - 4 to 7 degrees C
Frost-free period - 90 to 115 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability to 64 cm and moderately rapid permeability below.
USE AND VEGETATION: Holloron soils are mainly used for irrigated pasture and hayland, or for dryland pasture. The vegetation is mainly bluebunch wheatgrass, needle and thread, and prairie Junegrass.
DISTRIBUTION AND EXTENT: Holloron 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, 2013; proposed in Ravalli County, Montana, 2006.
REMARKS: Diagnostic features and horizons recognized in this pedon are:
Mollic epipedon - from the surface to 32 cm (A horizon)
Cambic horizon - from 32 to 64 cm (Bw horizon)
Particle-size control section - from 25 to 100 cm (part of the A, Bw, and part of the C horizons)
Holloron soils have a frigid temperature regime and an ustic moisture regime bordering on aridic.
National Cooperative Soil Survey
U.S.A.