LOCATION OHWILER                 CO+NM

Established Series
Rev. JPP/TWH/KLS
04/2018

OHWILER SERIES


The Ohwiler series consists of very deep, well drained soils that formed in slope alluvium derived from mixed sources, mostly sandstone and shale. Ohwiler soils are on mountain slopes and mountain valleys. Slopes range from 3 to 30 percent. Mean annual precipitation is about 559 mm and the mean annual temperature is about 5.6 degrees C.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Pachic Argiustolls

TYPICAL PEDON: Ohwiler loam, on a southwest facing, simple, 20 percent slope in grassland at an elevation of 2,530. (Colors are for dry soil unless otherwise noted.) Described on September 10, 1985.

A1--0 to 20 cm; dark grayish brown (10YR 4/2) loam, very dark brown (10YR 2/2) moist; moderate fine granular structure; soft, very friable, nonsticky and nonplastic; many fine and very fine roots; many fine pores; neutral (pH 6.8); clear smooth boundary.

A2--20 to 38 cm; dark grayish brown (10YR 4/2) loam, very dark brown (10YR 2/2) moist; weak medium subangular blocky structure parting to moderate medium granular; soft, very friable, slightly sticky and nonplastic; many fine and very fine roots; many fine pores; neutral (pH 6.8); clear smooth boundary. (combined thickness of A1, A2 - 18 to 60 cm)

Bt1--38 to 76 cm; dark grayish brown (10YR 4/2) clay loam, very dark grayish brown (10YR 3/2) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; common distinct clay films on faces of peds; few fine roots; few fine pores; neutral (pH 7.0); gradual smooth boundary.

Bt2--76 to 102 cm; grayish brown (10YR 5/2) clay loam, very dark grayish brown (10YR 3/2) moist; weak coarse prismatic structure parting to moderate medium subangular blocky; hard, firm, sticky and plastic; common distinct clay films on faces of peds; 5 percent gravel; neutral (pH 7.0); gradual wavy boundary. (combined thickness of the Bt1, Bt2 - 35 to 130 cm)

BC--102 to 132 cm; brown (10YR 5/3) loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; 10 percent gravel; neutral (pH 7.2); gradual wavy boundary. (0 to 36 cm thick)

C--132 to 152 cm; pale brown (10YR 6/3) loam, brown (10YR 4/3) moist; massive; slightly hard, very friable, nonsticky and nonplastic; 10 percent gravel; neutral (pH 7.0).

TYPE LOCATION: La Plata County, Colorado; about 24 kilometers northeast of Durango; located about 488 meters east and 732 meters north of the southwest corner of Sec. 16, T. 37 N., R. 8 W.; Hermosa USGS quad; Lat. 37 degrees, 28 minutes, 20 seconds, N. and Long. 107 degrees, 45 minutes, 24 seconds, W., NAD 27.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature: 5.6 to 7.8 degrees C.
Mean summer soil temperature: 15.0 to 17.2 degrees C.
Thickness of the mollic epipedon: 41 to 114 cm

Particle-size control section:
Clay content: 24 to 35 percent
Rock fragment content: 0 to 15 percent, mostly sandstone gravel and cobble

A horizon
Hue: 10YR or 2.5Y
Value: 3 to 5 dry, 2 or 3 moist
Chroma: 1 to 3, dry or moist
Rock fragments: 0 to 15 percent, mainly sandstone gravel and cobble
Reaction (pH): 6.1 to 7.3

Bt horizon(s)
Hue: 10YR to 2.5Y
Value: 3 to 6 dry, 2 to 5 moist
Chroma: 1 to 4, dry or moist
Texture: loam, clay loam, or sandy clay loam with 20 to 60 percent sand and less than 35 percent being fine or coarser sand
Rock fragments: 0 to 15 percent, mainly sandstone gravel and cobble
Reaction (pH): 6.1 to 7.3

C horizon (if present)
Hue: 10YR or 2.5Y
Value: 4 to 6 dry, 3 to 5 moist
Chroma: 2 to 6, dry or moist
Texture: loam or clay loam
Reaction (pH): 6.1 to 8.0

COMPETING SERIES:
Bowbells (ND) - have secondary calcium carbonate accumulation
Cambern (AZ) - are moderately deep to lithic contact
Carfall (MT) - have horizons of sandy loam or loamy sand below the argillic horizon
Center Creek (UT) - have a lithologic discontinuity with skeletal materials
Chugcreek (WY) - are moderately deep to lithic contact; formed in granite
Detra (UT) - are deep to lithic contact
Fiesta (NM) - have calcium carbonate accumulation; have hues redder than 10YR
Flaxton (ND) - have a lithologic discontinuity
Gordo (AZ) - are deep to paralithic contact; have a lithologic discontinuity; have calcium carbonate accumulation
Hereford (AZ) - have secondary calcium carbonate accumulation
Hesperus (CO) - have redoximorphic concentrations and endosaturation at depths below 100 cm
Jaythree (NM) - have more than 35 percent fine and coarser sands
Lacycreek (MT) - have a lithologic discontinuity
Pachel (MT) - have secondary calcium carbonate accumulation
Schauson (UT) - are bordering on an aridic moisture regime
Shermap (CO) - have a mollic epipedon thickness of less than 60 cm
Southbaldy (CO) - are moderately deep to lithic contact
Todacheene (NM) - have a lithologic discontinuity; have hues redder than 10YR
Tschicoma (NM) - have igneous extrusive rock fragments; formed in dacite, latite, and ryolitic tuff
Weed (CO) - have secondary calcium carbonate accumulation

GEOGRAPHIC SETTING:
Landform - mountain slopes and mountain valleys
Elevation - 2,070 to 2,590 meters
Slopes - 3 to 30 percent
Parent material - slope alluvium derived from mixed sources, mostly sandstone and shale
Mean annual air temperature - 4.4 to 7.2 degrees C.
Mean annual precipitation - 457 to 635 mm
Precipitation pattern - wettest months are July and August, while the driest months are May and June, however soils are still moist from snowmelt during these months.
Frost-free period - 80 to 100 days

GEOGRAPHICALLY ASSOCIATED SOILS: None listed.

DRAINAGE AND PERMEABILITY: Well drained, low to moderate runoff, moderately slow permeability

USE AND VEGETATION: These soils are used principally for livestock grazing, irrigated cropland, and wildlife habitat. Native vegetation is Arizona fescue, Parry oatgrass, needlegrass, mountain brome, Gambel oak, basin big sagebrush, bluegrass, and western wheatgrass.

DISTRIBUTION AND EXTENT: Southwest Colorado and northern New Mexico, LRR D, E; MLRA 36, 48A; moderate extent.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana

SERIES ESTABLISHED: Jicarilla Apache Area, New Mexico, 2000. The series was proposed in La Plata County, Colorado, Animas-Dolores Soil Survey Area. The name is from a mountain in the area.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon, Pachic feature: 0 to 102 cm (A1, A2, Bt1, and Bt2 horizons)
Argillic horizon: 38 to 102 cm (Bt1 and Bt2 horizons)
Particle-size control section: 38 to 88 cm (Bt1 and part of the Bt2 horizons)

Ohwiler soils have a frigid temperature regime and are in an ustic soil moisture class with a typic subclass.


National Cooperative Soil Survey
U.S.A.