LOCATION DUFFSON CO+UT WY
Established Series
Rev. RHM/SJJ
05/2016
DUFFSON SERIES
The Duffson series consists of moderately deep, well drained soils that formed in residuum and slope alluvium from sandstone and shale. Duffson soils are on hills, ridges, escarpments and mountainsides. Slopes are 4 to 50 percent. The mean annual precipitation is about 430mm (17 inches), and the mean annual air temperature is about 5 degrees C (41 F).
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Aridic Argiustolls
TYPICAL PEDON: Duffson loam - rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 13 cm; grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; moderate very fine granular structure; soft, very friable; 10 percent gravel; neutral (pH 6.8); clear smooth boundary. (10 to 20 cm thick)
Bt1--13 to 20 cm; brown (7.5YR 5/3) loam, dark brown (7.5YR 3/3) moist; weak medium subangular blocky structure parting to moderate very fine subangular blocky; slightly hard, very friable; few thin patchy clay films on faces of peds; 10 percent gravel; neutral (pH 6.8); clear smooth boundary. (5 to 10 cm thick)
Bt2--20 to 41 cm; brown (7.5YR 5/3) clay loam, brown (7.5YR 4/3) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; hard, friable; thin nearly continuous clay films on faces of peds; 10 percent gravel; neutral (pH 7.0); clear wavy boundary. (15 to 38 cm thick)
Btk--41 to 51 cm; light yellowish brown (10YR 6/4) loam, yellowish brown (10YR 5/4) moist; weak medium subangular blocky structure; hard, friable; few thin patchy clay films principally on vertical faces of peds; 10 percent gravel; thin visible secondary calcium carbonate occurring as coatings on gravel fragments and as small soft masses; slightly effervescent; moderately alkaline (pH 8.0); gradual wavy boundary. (8 to 13 cm thick)
Bk--51 to 76 cm; very pale brown (10YR 8/2) loam, light gray (10YR 7/2) moist; massive; hard, very friable; 10 percent gravel; visible secondary calcium carbonate occurring in finely divided forms and as coatings on gravel fragments; strongly effervescent; moderately alkaline (pH 8.2); clear smooth boundary. (13 to 64 cm thick)
R--76 cm; hard sandstone.
TYPE LOCATION: Saguache County, Colorado; NW 1/4 of Sec. 35, T. 48 N., R. 2 E.
RANGE IN CHARACTERISTICS: Thickness of the mollic epipedon ranges from 18 to 38 cm; depth to calcareous material ranges from 20 to 60 cm. Depth to the lithic bedrock ranges from 50 to 100 cm. Organic matter in the mollic epipedon ranges from 1 to 3 percent and decreases uniformly with increasing depth. The soil is 90 to 100 percent base saturated. Rock fragments range from 0 to 15 percent by volume throughout, and are mainly pebbles and cobbles.
The A horizon has hue of 2.5Y through 7.5YR, value of 4 or 5 dry, 2 or 3 moist, and chroma of 2 or 3. Usually the horizon has granular or crumb structure, but it has weak subangular blocky structure in some pedons. Texture is loam, fine sandy loam or sandy loam. Reaction is neutral or slightly alkaline.
The Bt horizon has hue of 2.5Y through 7.5YR, value of 5 or 6 dry, 3 or 4 moist, and chroma of 2 or 3. Texture is loam, clay loam or sandy clay loam. Reaction is neutral or slightly alkaline.
The Bk horizon has hue of 2.5Y through 7.5YR. Texture is loam, sandy clay loam, or fine sandy loam. It is moderately or strongly alkaline, and has 6 to 14 percent calcium carbonate equivalent. Some pedons have BCk horizons. The Bk horizon does not meet the requirements for a calcic horizon, either by thickness or carbonate content.
COMPETING SERIES: These are the Assinnibonie,
Berlake,
Bostwick,
Cheesman,
Crittenden,
Eapa,
Evanot,
Evanston,
Jarre,
Joplin,
Kenilworth,
Kevin,
Marmarth,
Peyton,
Reicess,
Sugakool,
Telstad,
Turret, and
Udecide series, all of which have bedrock deeper than 100 cm, except Cheesman, Marmarth and Udecide. Cheesman, Marmarth and Udecide soils have a paralithic contact at depths of 50 to 100 cm.
GEOGRAPHIC SETTING: Duffson soils are on upland hills, ridges, escarpments and mountainsides. Slope ranges from 4 to 50 percent. Elevation ranges from 2,200-2,900 meters (7,200-9,500 ft.). The soils formed in parent material weathered from sandstone and interbedded shale. At the type location the average annual precipitation is about 430mm (17 inches), but it ranges from 350-460mm (14-18 inches), with peak periods of precipitation occurring in the spring and summer. The mean annual air temperature (MAAT) ranges from 4.0 to 6.0 degrees C (39-43F). The mean annual soil temperature (MAST) ranges from 6.0 to 8.0 degrees C (43-47F). The average summer soil temperature is 17 degrees C (62F). The frost-free season typically ranges from 60 to 90 days, but may extend slightly lower or higher by 10 days in some areas.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Corpening and
Spring Creek soils, both of which have a lithic contact at a depth of less than 50cm.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; moderate or moderately slow permeability. (Ksat 5-10-15 um/sec or 1.5-3-5 um/sec)
USE AND VEGETATION: These soils are used principally as rangeland. Native vegetation is mainly Big sagebrush, Arizona fescue, Western wheatgrass, and Needlegrass.
DISTRIBUTION AND EXTENT: Western and central Colorado, southern Wyoming, and northern Utah. MLRA 47 and 48A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Gunnison County, Colorado, 1975.
REMARKS: Diagnostic features recognized in this pedon.
Mollic epipedon; The zone from 0 to 20 cm, (A, Bt1)
Argillic horizon; The zone from 20 to 51 cm, (Bt2, Btk)
Secondary carbonates; The zone from 41 to 76 cm, (Btk, Bk) (not calcic)
Lithic Contact; 76 cm, R.
National Cooperative Soil Survey
U.S.A.