LOCATION EMMONS                  CO

Established Series
Rev. WSH-GB-KLS
03/2023

EMMONS SERIES

The Emmons series consists of deep, well drained soils formed in colluvium and glacial drift derived from mixed sources. Emmons soils are on the sides of mesas and pediments. Slopes are 2 to 20 percent. The mean annual precipitation is about 380 mm and the mean annual air temperature is about 7 degrees C.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Aridic Calciustolls

TYPICAL PEDON: Emmons very cobbly loam - rangeland. (Colors are for dry soil unless otherwise noted.)

Oe--0 to 3 cm; partially decomposed organic material.

A1--3 to 16 cm; grayish brown (10YR 5/2) very cobbly loam, dark brown (10YR 3/3) moist; moderate medium granular structure; hard, friable, slightly sticky and slightly plastic; 5 percent gravel and 40 percent cobbles; strongly effervescent; slightly alkaline (pH 7.8); clear smooth boundary. (8 to 18 cm thick)

A2--16 to 41 cm; brown (10YR 4/3) cobbly clay loam, dark brown (10YR 3/3) moist; moderate fine subangular blocky structure; slightly hard, friable, sticky and plastic; 10 percent gravel and 5 percent cobbles; slightly effervescent; slightly alkaline (pH 7.6); clear wavy boundary. (20 to 30 cm thick)

Bk1--41 to 77 cm; light brownish gray (10YR 6/2) cobbly clay loam, grayish brown (10YR 5/2) moist; strong fine subangular blocky structure; very hard, very firm, sticky and plastic; 10 percent gravel and 5 percent cobbles; violently effervescent (22 percent calcium carbonate equivalent); moderately alkaline (pH 8.2); clear wavy boundary. (30 to 50 cm thick)

Bk2--77 to 156 cm; light gray (10YR 7/2) cobbly clay loam, brown (10YR 4/3) moist; strong fine subangular blocky structure; extremely hard, very firm, slightly sticky and plastic; 10 percent gravel and 5 percent cobbles; violently effervescent (23 percent calcium carbonate equivalent); moderately alkaline (pH 8.2).

TYPE LOCATION: San Miguel County, Colorado; about 260 meters south and 120 meters east of the northwest corner, Sec. 18, T. 43 N., R. 14 W.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature--7 to 8 degrees C
Mean summer soil temperature--15 to 19 degrees C
Soil moisture control section--dry for 15 consecutive days from May 15 to July 15 when the soil temperature at 50 cm is greater than 5 degrees C. It is not dry in all parts of the moisture control section for as long as 45 consecutive days following the summer solstice to October 20, nor for as long as 90 cumulative days during this period.

Mollic epipedon--18 to 38 cm
Depth to the calcic horizon--20 to 50 cm
Calcium carbonate equivalent--15 to 30 percent in the calcic horizon
Rock fragment content of the A horizon--0 to 45 percent

Particle-size control section:
Clay content--27 to 35 percent
Sand content--15 to 35 percent fine sand and coarser
Rock fragment content--0 to 15 percent gravel and cobbles

A horizon
Hue--2.5Y through 10YR
Value--4 or 5 dry; 2 or 3 moist
Chroma--2 or 3

Bw horizon, when present
Hue--2.5Y through 10YR
Value--5 or 6 dry; 4 or 5 moist
Chroma--3 or 4

Bk1 horizon
Hue--2.5Y through 10YR
Value--4 through 8 dry; 2 through 6 moist
Chroma--2 or 3

Bk2 horizon
Hue--2.5Y through 10YR
Value--6 through 8 dry; 4 through 6 moist
Chroma--2 or 3

COMPETING SERIES: These are the Rothican, Rothiemay, and Zinzer series. Rothican soils have 18 to 27 percent clay in their particle-size control section. Rothiemay soils are moist in some parts of the soil moisture control section from May 15 to July 15. Zinzer soils have 35 to 60 percent fine sand and coarser in the particle-size control section.

GEOGRAPHIC SETTING:
Landform--mesa side slopes and pediments
Elevation--2075 to 2500 meters
Slope--2 to 20 percent
Parent material--colluvium and glacial drift derived from mixed sources
Mean annual precipitation--330 to 430 mm; evenly distributed pattern throughout the year with over 50 percent coming as snow.
Mean annual air temperature--6 to 8 degrees C
Frost-free period --80 to 110 days

GEOGRAPHICALLY ASSOCIATED SOILS: None listed.

DRAINAGE AND PERMEABILITY: Well drained; medium to very rapid runoff; moderately slow permeability.

USE AND VEGETATION: These soils are used for livestock grazing and wildlife habitat. Principal native vegetation is pinon pine, Utah juniper, Rocky Mountain juniper, Gambel oak, serviceberry, and Indian ricegrass.

DISTRIBUTION AND EXTENT: Emmons soils are of small extent in southwestern Colorado and northeastern Utah; MLRAs 34B and 48A.

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

SERIES ESTABLISHED: Roosevelt-Duchesne Area, Utah, 1949

REMARKS:
Particle-size control section--25 to 100 cm (part of the A2, all of Bk1 and part of the Bk2 horizons)

Emmons soils have a frigid temperature regime and an ustic soil moisture regime, bordering on aridic.

Converted to metric and O horizons were updated to start at zero. Competing series section was not updated. 01/2023

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National Cooperative Soil Survey
U.S.A.