LOCATION DAPOIN CO

Established Series
Rev. WSH/CRP/JCK
05/2017

DAPOIN SERIES

The Dapoin series consists of very deep, well drained soils that formed in alluvium, colluvium or slide deposits derived from shale. These soils are on alluvial fans, fan remnants, mountain slopes, landslides, drainageways and swales. Slopes are from 0 to 25 percent. Mean annual precipitation is about 558 mm, and mean annual temperature is about 5.5 degrees C.

TAXONOMIC CLASS: Fine, smectitic, frigid Vertic Haplustolls

TYPICAL PEDON: Dapoin clay loam, on a southwest facing, simple 10 percent slope in rangeland at an elevation of 2,475 meters (colors are for dry soil unless otherwise noted).

A1--0 to 10 cm; dark brown (10YR 3/3) clay loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and moderately plastic; slightly alkaline (pH 7.4); clear smooth boundary. (8 to 15 cm thick)

A2--10 to 33 cm; dark grayish brown (10YR 4/2) clay loam, very dark grayish brown (10YR 3/2) moist; moderate fine subangular blocky structure; hard, friable, moderately sticky and moderately plastic; slightly alkaline (pH 7.4); clear smooth boundary. (18 to 25 cm thick)

Bw--33 to 46 cm; grayish brown (2.5Y 5/2) clay, dark grayish brown (2.5Y 4/2) moist; weak coarse subangular blocky structure; very hard, firm, moderately sticky and moderately plastic; slightly alkaline (pH 7.4); clear smooth boundary. (13 to 20 cm thick)

BCk1--46 to 74 cm; light olive brown (2.5Y 5/4) clay, olive brown (2.5Y 4/4) moist; massive; extremely hard, very firm, moderately sticky and moderately plastic; finely disseminated carbonates; strongly effervescent; slightly alkaline (pH 7.8); clear wavy boundary.

BCk2--74 to 81 cm; light brownish gray (2.5Y 6/2) paragravelly clay loam, light olive brown (2.5Y 5/4) moist; massive; extremely hard, very firm, slightly sticky and moderately plastic; finely disseminated carbonates; 20 percent paragravel; violently effervescent; moderately alkaline (pH 8.4); clear wavy boundary.

BCk3--81 to 97 cm; light brownish gray (2.5Y 6/2) paragravelly clay, light olive brown (2.5Y 5/4) moist; massive; extremely hard, very firm, moderately sticky and moderately plastic; finely disseminated carbonates; 25 percent paragravel; violently effervescent; moderately alkaline (pH 8.4); clear wavy boundary.

BCk4--97 to 112 cm; light yellowish brown (2.5Y 6/4) clay loam, light olive brown (2.5Y 5/4) moist; massive, extremely hard, very firm, moderately sticky and moderately plastic; finely disseminated carbonates; violently effervescent; moderately alkaline (pH 8.4); clear wavy boundary.

BCk5--112 to 150 cm; light gray (2.5Y 7/2) clay loam, olive (5Y 5/3) moist; massive; extremely hard, very firm, slightly sticky and moderately plastic; finely disseminated carbonates; 10 percent paragravel; violently effervescent; moderately alkaline (pH 8.4). (combined thickness of BCk horizons is 90 to 117 cm or more)

TYPE LOCATION: Dolores County, Colorado; about 24 kilometers north of Dolores, Colorado; located about 244 meters north and 152 meters west of the southeast corner, sec. 29, T. 40 N., R. 14 W.; Willow Springs USGS quad; lat. 37 degrees 41 minutes 34 seconds N. and long. 108 degrees 24 minutes 37 seconds W., NAD 27

RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 5 to 8 degrees C
Mean summer soil temperature - 16 to 19 degrees C
Mollic epipedon thickness - 25 to 40 cm
Depth to secondary calcium carbonate - 38 to 50 cm

A horizon
Hue: 2.5Y or 10YR
Value: 3 to 5 dry; 2 or 3 moist
Chroma: 1 to 3, dry or moist
Texture: clay loam or clay
Clay content: 28 to 50 percent
Rock fragments: 0 to 5 percent channers
Reaction: 7.4 to 7.8

Bw horizon
Hue: 2.5Y or 10YR
Value: 3 or 5 dry; 2 or 3 moist
Chroma: 1 to 3, dry or moist
Texture: clay or clay loam
Clay content: 35 to 50 percent
Rock fragments: 0 to 5 percent channers
Reaction: 7.4 to 7.8

Bk horizons
Hue: 5Y to 10YR
Value: 5 to 7 dry; 4 or 5 moist
Chroma: 2 to 4, dry or moist
Texture: clay or clay loam
Clay content: 35 to 50 percent
Rock fragments: 0 to 25 percent channers; 0 to 25 percent paragravel
Calcium carbonate equivalent: 5 to 15 percent
Reaction: 8.0 to 8.4

COMPETING SERIES:
Frazer (MT) - do not have horizons of secondary calcium carbonate accumulation
Lipke (MT) - do not have horizons of secondary calcium carbonate accumulation above 65 cm; are moderately acid to neutral in the upper part of the subsoil
Moreau (ND) - have a paralithic contact at depths of 50 to 100 cm

GEOGRAPHIC SETTING:
Parent material: alluvium, colluvium or slide deposits
Landform: alluvial fans, fan remnants, mountain slopes, landslides, drainageways and swales
Slopes: 0 to 25 percent
Elevation: 2,200 to 2,800 meters
Mean annual air temperature: 4.0 to 6.0 degrees C.
Mean annual precipitation: 455 to 635 mm
Frost-free period: 70 to 100 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bradfield, Coulterg, Narraguinnep, Pagoda and Gladlow soils.

DRAINAGE AND PERMEABILITY: Well drained; moderately slow to slow permeability.

USE AND VEGETATION: Dapoin soils are used for livestock grazing and wildlife habitat. Principal native vegetation is western wheatgrass, Letterman's needlegrass, mountain big sagebrush, Saskatoon serviceberry, muttongrass, slender wheatgrass, Gambel oak, and Arizona fescue.

DISTRIBUTION AND EXTENT: Dapoin soils are of small extent in southwestern Colorado. MLRA 36, 48A.

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

SERIES ESTABLISHED: San Miguel Area, Colorado, Parts of Dolores, Montrose, and San Miguel Counties, 1987.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 0 to 33 cm (A1 and A2 horizons)
Secondary calcium carbonate accumulation - from 46 to 150 cm (Bk1, Bk2, Bk3, Bk4, and Bk5 horizons)
Particle-size control section - from 25 to 100 cm (part of the A2, Bw, Bk1, Bk2, Bk3 and part of the Bk4 horizon)

Dapoin soils have a frigid temperature regime and an ustic moisture regime.

National Cooperative Soil Survey
U.S.A.