LOCATION LOBAT NM+CO
Established Series
Rev. MWR-TWH-KLS
02/2018
LOBAT SERIES
The Lobat series consists of very deep, well drained, moderately slowly permeable soils that formed in colluvium from igneous and metamorphic rocks. Lobat soils are on mountain footslopes. Slopes are 15 to 60 percent. The mean annual air temperature is about 4.4 degrees C., and mean annual precipitation is about 635 mm.
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Udic Haplustalfs
TYPICAL PEDON: Lobat gravelly loam - forested. (Colors are for dry soils unless otherwise noted.)
Oi--0 to 3 cm; slightly decomposed organic matter (0 to 8 cm thick).
A--3 to 18 cm; brown (10YR 5/3) gravelly loam, dark brown (10YR 3/3) moist; moderate fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; few coarse and medium and many fine and very fine roots; common fine and very fine interstitial pores; 5 percent cobbles and 15 percent gravel; slightly acid; clear wavy boundary. (10 to 15 cm thick)
E--18 to 51 cm; pink (7.5YR 7/4) gravelly clay loam, brown (7.5YR 5/4) moist; weak fine and medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common medium, fine and very fine roots; common fine tubular pores; 5 percent cobbles and 15 percent gravel; slightly acid; gradual wavy boundary. (0 to 33 cm thick)
Bt--51 to 122 cm; light brown (7.5YR 6/4) gravelly clay loam, brown (7.5YR 4/4) moist; moderate fine and medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few fine and very fine roots; common fine tubular pores; common moderately thick clay films on faces of peds; 10 percent cobbles and 20 percent gravel; slightly acid; gradual wavy boundary. (61 to 97 cm thick)
C--122 to 155 cm; pink (7.5YR 7/4) gravelly sandy clay loam, brown (7.5YR 5/4) moist; massive; hard, firm, slightly sticky and slightly plastic; few fine roots; common fine tubular pores; 5 percent cobbles and 15 percent gravel; neutral.
TYPE LOCATION: Rio Arriba County, New Mexico; about 8 kilometers east and 2 kilometers south of Chama, NM; West Fork Rio Brazos USGS quadrangle; New Mexico state plane coordinates 652,944 meters north and 130,741 meters east; Lat. 36 degrees, 53 minutes, 14 seconds N.; Long. 106 degrees, 29 minutes, 35 seconds W.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature: 5.4 to 7.7 degrees C.
Depth to the base of the argillic (Bt) horizon: 86 to 127 cm
Particle-size control section (weighted average):
Clay content: 27 to 34 percent
A horizon
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 2 or 3; dry or moist
Rock fragment content: 5 to 20 percent cobbles and 15 to 20 percent gravel.
Reaction (pH): 6.1 to 7.3
E horizon (where present)
Value: 6 or 7 dry; 4 or 5 moist
Chroma: 2 to 4, dry or moist
Rock fragment content: 5 to 10 percent cobbles and 10 to 25 percent gravel.
Reaction (pH): 6.1 to 7.3
Bt horizon
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 to 4, dry or moist
Rock fragment content: 5 to 10 percent cobbles and 10 to 20 percent gravel.
Reaction (pH): 6.1 to 7.3
C horizon
Value: 6 or 7 dry
Rock fragment content: 0 to 5 percent cobbles and 5 to 15 percent gravel
Reaction (pH): 6.1 to 7.3
COMPETING SERIES:
Eaglecreek (MT) - are moderately deep to lithic contact
GEOGRAPHIC SETTING:
Landform - mountain slopes
Elevation - 2,500 to 2,990 meters
Slopes - 15 to 60 percent
Parent material - colluvium derived from igneous and metamorphic rocks
Mean annual air temperature - 4.4 to 6.1 degrees C.
Mean annual precipitation - 560 to 710 mm
Frost-free period - 70 to 90 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; very high runoff; moderately slow permeability.
USE AND VEGETATION: Lobat soils are used mainly for wood production and wildlife habitat. The present vegetation is aspen, Douglas fir, white fir with scattered Ponderosa pine and Colorado blue spruce.
DISTRIBUTION AND EXTENT: North-central New Mexico, south-central Colorado. LRR D, E; MLRA 36, 48A. The series is of moderate extent.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Rio Arriba County, New Mexico, 1989. The series name is taken from a nearby railroad depot.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Argillic horizon - 51 to 119 cm (Bt horizon)
Particle-size control section - 51 to 101 cm (upper 50 cm of the Bt horizon)
Lobat soils have a frigid temperature regime and are in an ustic soil moisture regime bordering on udic.
National Cooperative Soil Survey
U.S.A.