LOCATION MAHOGANY WY
Tentative Series
Rev. DMM-DP-RJS
02/2016
MAHOGANY SERIES
The Mahogany series consists of deep, well drained soils that formed in colluvium over residuum weathered from black slate. These soils are on mountain slopes and scarp slopes. Slopes are 4 to 50 percent. Mean annual precipitation is about 425 mm and mean annual air temperature is about 1.0 degree C.
TAXONOMIC CLASS: Fine, smectitic Vertic Haplocryalfs
TYPICAL PEDON: Mahogany clay loam, in rangeland (colors are for dry soil unless otherwise noted).
A--0 to 13 cm; gray (2.5Y 5/1), clay loam, very dark gray (2.5Y 3/1), moist; strong fine granular structure; slightly hard, friable, slightly sticky, slightly plastic; many very fine roots; many fine interstitial pores; moderately acid (pH 6.0); clear smooth boundary. (7 to 15 cm thick)
Bt1--13 to 26 cm; gray (5Y 5/1), clay loam, very dark gray (5Y 3/1), moist; strong medium subangular blocky structure; moderately hard, firm, moderately sticky, moderately plastic; many very fine roots; common fine tubular pores; 40 percent faint clay films on all faces of peds; slightly acid (pH 6.3); clear smooth boundary. (10 to 25 cm thick)
Bt2--26 to 46 cm; gray (5Y 5/1), clay, very dark gray (5Y 3/1), moist; moderate medium prismatic structure; moderately hard, firm, very sticky, very plastic; common very fine roots; common fine tubular pores; 60 percent faint clay films on all faces of peds; neutral (pH 6.9); clear smooth boundary. (20 to 50 cm thick)
Btk--46 to 92 cm; gray (5Y 5/1), clay, very dark gray (5Y 3/1), moist; weak coarse prismatic structure; moderately hard, firm, very sticky, very plastic; few fine roots; common fine tubular pores; 10 percent faint clay films on all faces of peds; 5 percent fine irregular carbonate masses; slightly effervescent; moderately alkaline (pH 8.4); gradual smooth boundary. (40 to 60 cm thick)
BCk--92 to 120 cm; gray (5Y 5/1), clay loam, very dark gray (5Y 3/1), moist; weak coarse prismatic structure; moderately hard, firm, moderately sticky, moderately plastic; common fine tubular pores; 10 percent faint clay films on all faces of peds; 5 percent fine irregular carbonate masses; 5 percent channers; slightly effervescent; moderately alkaline (pH 8.0); abrupt wavy boundary. (20 to 35 cm thick)
R--120 cm; indurated black slate bedrock.
TYPE LOCATION: Sublette County, Wyoming; USGS Coal Creek, Wyoming topographic quadrangle; 42 degrees 18 minutes 28.00 seconds north latitude and 110 degrees 31 minutes 19.00 seconds west longitude.
RANGE IN CHARACTERISTICS:
Soil temperature - 1.0 to 3.5 degrees C.
Ochric epipedon thickness - 7 to 15 cm
Depth to argillic horizon - 7 to 15 cm
Depth to lithic contact - 100 to 150 cm
Depth to secondary calcium carbonate - 40 to 75 cm
A horizon
Hue: 2.5Y or 5Y; dry or moist
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 1 or 2; dry or moist
Clay content: 27 to 35 percent
Rock Fragments: 0 to 5 percent channers
Reaction: pH 5.6 to 6.0
Bt1, Bt2 horizons
Hue: 2.5Y or 5Y; dry or moist
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 1 or 2; dry or moist
Texture: clay, clay loam
Clay content: 35 to 60 percent
Rock Fragments: 0 to 5 percent channers
Reaction: pH 6.1 to 7.3
Btk horizon
Hue: 2.5Y or 5Y; dry or moist
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 1 or 2; dry or moist
Texture: clay, clay loam
Clay content: 38 to 50 percent
Rock Fragments: 0 to 5 percent channers
Calcium carbonate equivalent: 2 to 5 percent
Reaction: pH 7.9 to 8.4
BCk horizon
Hue: 2.5Y or 5Y; dry or moist
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 1 or 2; dry or moist
Texture: clay, clay loam
Clay content: 33 to 45 percent
Rock Fragments: 5 to 15 percent channers
Calcium carbonate equivalent: 2 to 5 percent
Reaction: pH 7.9 to 8.4
COMPETING SERIES:
Bridgerton (WY) - have an udic soil moisture regime
Conwaycreek (WY) - are very deep
Doolittle (MT) - are moderately deep to a paralithic contact
Fossilbutte (WY) - are very deep
Goldhill (ID) - have a xeric soil moisture regime
Harkness (ID) - have an udic soil moisture regime
Herd (UT) - have an udic soil moisture regime
Sledrunner (WY) - are very deep
GEOGRAPHIC SETTING:
Landform - mountain slopes, scarp slopes
Elevation - 2,275 to 2,600 meters.
Slope - 4 to 50 percent.
Parent Material - colluvium over residuum weathered from slate.
Climate - long, cold winters; cool, moist springs; short, cool summers.
Mean annual precipitation - 375 to 500 mm with peak periods of precipitation occurring during the spring.
Mean annual air temperature - 0.5 to 3.0 degrees C.
Frost-free period - 10 to 40 days.
GEOGRAPHICALLY ASSOCIATED SOILS: none listed.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained, Ksat 0.01-1.5 um/sec.
USE AND VEGETATION: Mahogany soils are primarily used for rangeland. The potential native vegetation is mainly letterman's needlegrass, early sagebrush, flowery phlox, Sandberg bluegrass, bluebunch wheatgrass, and stemless mock goldenweed.
DISTRIBUTION AND EXTENT: Mahogany soils are of small extent in southwestern Wyoming. MLRA 46.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Sublette County, Wyoming, 2013. The series name is derived from a local landmark.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 13 cm (A horizon)
Argillic horizon - 13 to 92 cm (Bt1, Bt2, Btk horizons)
Secondary carbonates - 46 to 120 cm (Btk, BCk horizons)
Lithic contact - 120 cm (R horizon)
Estimated linear extensibility (0 to 100 cm) - 6.0 to 8.0 cm
Particle-size control section - 13 to 63 cm (Bt1, Bt2, part of Btk horizons)
Mahogany soils have a cryic temperature regime and an ustic moisture regime.
National Cooperative Soil Survey
U.S.A.