LOCATION ROMBERG CO

Established Series
Rev. JWH/DKR/TWH
10/2012

ROMBERG SERIES

The Romberg series consists of very deep, well drained soils that formed in colluvium and alluvium derived from sandstone and shale. Romberg soils are in canyons and on hills, structural benches, and alluvial fans. Slopes range from 6 to 50 percent. Mean annual precipitation is about 12 inches and the mean annual temperature is about 51 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Ustic Haplargids

TYPICAL PEDON: Romberg very stony loam, on a northeast facing, 50 percent slope in pinyon-juniper woodland at an elevation of 6,240 feet. (Colors are for dry soil unless otherwise noted.) The surface is partially covered by 10 percent gravel, 5 percent cobbles, and 10 percent stones.

A--0 to 2 inches; brown (7.5YR 4/4) very stony loam, dark brown (7.5YR 3/4) moist; moderate medium and coarse granular structure; soft, very friable, slightly sticky and slightly plastic; 15 percent gravel, 5 percent cobbles, and 30 percent stones; neutral (pH 7.2); clear wavy boundary. (1 to 8 inches thick)

BA--2 to 5 inches; brown (7.5YR 4/4) very stony clay loam, dark brown (7.5YR 3/4) moist; weak medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; 15 percent gravel, 5 percent cobbles, and 30 percent stones; slightly alkaline (pH 7.5); clear wavy boundary. (0 to 8 inches thick)

Bt--5 to 11 inches; brown (7.5YR 5/4) very stony clay loam, brown (7.5YR 4/4) moist; weak medium and coarse subangular blocky structure; very hard, firm, moderately sticky and moderately plastic; common distinct discontinuous clay films on faces of peds; 15 percent gravel, 5 percent cobbles, and 30 percent stones; violently effervescent; moderately alkaline (pH 8.2); gradual wavy boundary. (4 to 12 inches thick)

Btk--11 to 20 inches; light brown (7.5YR 6/4) very stony clay loam, brown (7.5YR 4/4) moist; weak medium and coarse subangular blocky structure; very hard, firm, moderately sticky and moderately plastic; many distinct continuous clay films on faces of peds and in pores; 15 percent gravel, 5 percent cobbles, and 30 percent stones; few medium soft masses of calcium carbonate; strongly effervescent; moderately alkaline (pH 8.2); clear wavy boundary. (4 to 18 inches thick)

Bk1--20 to 35 inches; brown (7.5YR 5/4) very stony clay loam, brown (7.5YR 4/4) moist; weak fine and medium subangular blocky structure; very hard, firm, moderately sticky and moderately plastic; 15 percent gravel, 5 percent cobbles, and 30 percent stones; common medium soft masses of calcium carbonate; slightly effervescent; moderately alkaline (pH 8.4); clear wavy boundary. (4 to 18 inches thick)

Bk2--35 to 48 inches; brown (7.5YR 5/4) very stony clay loam, brown (7.5YR 4/4) moist; weak medium subangular blocky structure; very hard, firm, moderately sticky and moderately plastic; 15 percent gravel, 5 percent cobbles, and 30 percent stones; few fine soft masses of calcium carbonate; violently effervescent; slightly alkaline (pH 7.6); clear wavy boundary. (0 to 20 inches thick)

Bk3--48 to 60 inches; brown (10YR 5/3) very stony clay loam, brown (10YR 4/3) moist; massive; very hard, firm, moderately sticky and slightly plastic; 15 percent gravel, 5 percent cobbles, and 30 percent stones; common fine soft masses of calcium carbonate; violently effervescent; moderately alkaline (pH 8.4). (0 to 20 inches thick)

TYPE LOCATION: Montezuma County, Colorado; about 12 miles northwest of Cortez; located about 1,770 feet east and 1,950 feet north of the southwest corner of sec. 30, T. 37 N., R. 17 west.; Woods Canyon, CO USGS quad; lat. 37 degrees 25 minutes 57 seconds N. and long. 108 degrees 46 minutes 00 seconds W., NAD27

RANGE IN CHARACTERISTICS:
Soil moisture regime: aridic bordering on ustic
Soil temperature regime: mesic
Mean annual soil temperature: 47 to 53 degrees F
Surface rock fragments: 20 to 90 percent
Depth to secondary calcium carbonate: 3 to 40 inches

Particle-size control section:
Clay content:18 to 35 percent

A horizon:
Hue: 7.5YR to 2.5Y
Value: 3 to 5 dry, 3 or 4 moist
Chroma: 2 or 4
Rock fragments: 15 to 70 percent
Calcium carbonate equivalent: 0 to 5 percent
Reaction: neutral or slightly alkaline

Bt horizon:
Hue: 7.5YR to 2.5Y
Value: 5 or 6 (4 or 5 moist)
Chroma: 2 to 4
Texture: loam or clay loam
Rock fragments: 35 to 55 percent
Calcium carbonate equivalent: 1 to 15 percent
Reaction: slightly or moderately alkaline

Bk horizon:
Hue: 7.5YR or 10YR
Value: 5 or 6 (4 or 5 moist)
Chroma: 3 to 5
Texture: loam or clay loam
Rock fragments: 35 to 70 percent
Calcium carbonate equivalent: 1 to 15 percent
Reaction: slightly or moderately alkaline

COMPETING SERIES: These are the Elements, Saemo, Sed, and the Tacan series. A potential competitor that does not yet have CEA class assigned is the Sed series. Elements soils do not have free secondary carbonates. Saemo soils do not have visible secondary carbonates and have loamy coarse sands in a C horizon. Sed soils are moderately deep. Tacan soils are redder than 7.5YR in the control section and lack horizons of carbonate accumulation.

GEOGRAPHIC SETTING:
Parent material: colluvium and alluvium derived from sandstone and shale
Landform: canyons, hills, structural benches, and alluvial fans
Slopes: 6 to 50 percent
Elevation: 5,400 to 6,800 feet
Mean annual temperature: 50 to 52 degrees F
Mean annual precipitation: 10 to 14 inches
Precipitation is fairly evenly distributed throughout the year with July and August being slightly wetter and June being slightly dryer.
Frost-free period: 120 to 170 days

GEOGRAPHICALLY ASSOCIATED SOILS: This is the Crosscan series. Crosscan soils are shallow to soft bedrock.

DRAINAGE AND PERMEABILITY: well drained, medium to very high runoff, moderate and moderately slow permeability

USE AND VEGETATION: Romberg soils are used mainly as wildlife habitat. Potential native vegetation is twoneedle pinyon, Utah juniper, mountain mahogany, common snowberry, Utah serviceberry, western wheatgrass, galleta, and muttongrass.

DISTRIBUTION AND EXTENT: Southwest Colorado. LRR D, MLRA 36. This series is of moderate extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana

SERIES ESTABLISHED: Bridger Area, Carbon County, Montana. 1971.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: The zone from 0 to 2 inches. (A horizon)
Argillic horizon: The zone from 5 to 20 inches. (Bt and Btk horizons)
Particle-size control section: The zone from 5 to 20 inches. (Bt and Btk horizons)

Taxonomic version: Classified according to Keys to Soil Taxonomy, Tenth Edition, 2006.

The type location was moved to Cortez Area, Colorado in 1996 due to Montana no longer recognizing mesic temperature regime.

National Cooperative Soil Survey
U.S.A.