LOCATION ROBROOST UT

Established Series
Rev. JMD/RLM
04/2011

ROBROOST SERIES

The Robroost series consists of very deep, well drained, moderately permeable soils that formed in mixed alluvium and eolian deposits from gypsiferous sandstone and shale on alluvial fans and plains. Slopes range from 2 to 15 percent. The average annual precipitation is about 6 inches and mean annual air temperature is about 50 degrees F.

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Typic Calcigypsids

TYPICAL PEDON: Robroost fine sandy loam, rangeland. (Colors are for air-dry soil unless otherwise noted.)

A--0 to 5 inches; light reddish brown (5YR 6/3) fine sandy loam, reddish brown (5YR 4/4) moist; weak thin platy structure; soft, very friable, few fine roots; few fine pores; strongly effervescent; carbonates are disseminated; moderately alkaline (pH 8.2); clear wavy boundary. (2 to 5 inches thick)

By--5 to 10 inches; light reddish brown (5YR 6/3) loam, reddish brown (5YR 5/3) moist; weak fine prismatic structure parting to weak, medium and fine subangular blocky; slightly hard, very friable, slightly plastic; few fine and medium roots; few fine pores; strongly effervescent; carbonates are disseminated; few thin veins and streaks of gypsum; moderately alkaline (pH 8.2); clear wavy boundary. (0 to 16 inches thick)

Byk1--10 to 30 inches; light reddish brown (5YR 6/3) loam, reddish brown (5YR 5/3) moist; weak coarse prismatic structure; slightly hard, very friable, slightly plastic; few fine and very few medium roots; few fine pores; many medium and large gypsum veins and splotches; strongly effervescent; carbonates are disseminated and in veins; moderately alkaline (pH 8.2); gradual wavy boundary. (20 to 40 inches thick)

Byk2--30 to 60 inches; light reddish brown (5YR 6/3) loam, reddish brown (5YR 5/3) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; very few medium and fine roots; few fine pores; common gypsum veins and splotches; strongly effervescent; carbonates are in veins and fine splotches; moderately alkaline (pH 8.2).

TYPE LOCATION: Wayne County, Utah; 3 miles south, 1 mile east of Hanksville, Utah; NE 1/4, sec. 34, T. 28., R. 11 E.

RANGE IN CHARACTERISTICS:

Soil moisture: usually dry in all parts of the moisture control section 50 to 75 percent of the time that the soil temperature at a depth of 20 inches exceeds 41 degrees F. and driest in May and June. Typic aridic soil moisture regime.

Mean annual soil temperature: 52 to 59 degrees F.

Depth to gypsic horizon: 2 to 32 inches

Total carbonates plus gypsum: 40 percent or less (by weight)

Depth to calcic horizon: 2 to 18 inches

Percent calcium carbonates: 5 to 24 percent

Percent gypsum: 5 to 32 percent

Clay content in the particle-size control section: less than 18 percent clay.

Other features: Some pedon contains Bw, Bk or Cy horizons

A horizon
Hue: 5YR, 7.5YR
Value: 5 or 6, dry or moist
Chroma: 3 to 6, dry or moist
Reaction: slightly alkaline to strongly alkaline.

By horizon
Hue: 5YR, 7.5YR
Value: 5 to 7, dry or moist
Chroma: 3 to 6, dry or moist
Texture: fine sandy loam, very fine sandy loam, sandy loam, loam
Reaction: slightly alkaline to strongly alkaline
Calcium carbonates equivalent: 3 to 15 percent
Percent gypsum: 10 to 35 percent

Byk horizon
Hue: 5YR, 7.5YR
Value: 4 to 8, dry or moist
Chroma: 3 to 6, dry or moist
Texture: fine sandy loam, very fine sandy loam, sandy loam, loam
Calcium carbonate equivalent: 8 to 30 percent
Percent gypsum: 5 to 30

Bk horizon (when present)
Hue: 5YR, 7.5YR
Value: 4 to 7, dry or moist
Chroma: 3 to 6, dry or moist
Texture: fine sandy loam, very fine sandy loam, loam
Calcium carbonate equivalent: 8 to 35 percent
Gypsum percent: 0 to 3 percent
Reaction: slightly alkaline or moderately alkaline

Cy horizon (when present)
Other features: Usually contains parachanners or paragravels from underlying bedrock and the gypsum are usually weathering from parent material.
Gypsum percent: 5 to 35 percent
Reaction: slightly alkaline to strongly alkaline.

COMPETING SERIES: These are the Brimhall (NM) and Peagre (CO) series. Brimhall soils have 10YR and 2.5Y hues and bedrock at 40 to 60 inches. Peagre soils have bedrock at 20 to 40 inches.

GEOGRAPHIC SETTING: Robroost soils are on alluvial fans and plains at elevations of 4,000 to 5,000 feet. Slopes are 2 to 15 percent. The soils formed in coarse textured alluvial and eolian deposits from gypsiferous sandstone and shale. The mean annual air temperature is 50 to 57 degrees F. and the average annual precipitation is 5 to 10 inches. The precipitation is fairly well distributed throughout the year. There is a slight increase during August, September and October, with the driest months being May and June. The average frost free period is 145 to 160 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Chipeta and Goblin and Mussentuchit soils. Chipeta and Goblin soils have paralithic contacts at less than 20 inches. Mussentuchit soils have a paralithic contact at 20 to 40 inches. These soils are on shale hills.

DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderate permeability.

USE AND VEGETATION: These soils are used mainly for livestockgrazing and wildlife habitat. Potential native vegetation is galleta, alkali sacaton, shadscale, Mormon-tea and winterfat.

DISTRIBUTION AND EXTENT: Southeastern Utah. The soils of this series are moderately extensive. MLRA is 35.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona

SERIES ESTABLISHED: Henry Mountains Area, Parts of Garfield, Kane and Wayne Counties, Utah, 1985. Named after Robbers Roost. A historical setting in the survey area.

REMARKS: Diagnostic horizon and features recognized in this pedon are:

Ochric epipedon - the zone from 0 to 5 inches (A horizon)

Gypsic horizon - the zone from 5 to 60 inches (By, Byk1, Byk2)

Calcic horizon - the zone from 10 to 60 inches (Byk1 and Byk2)

Additional Data: NSSL data numbers; S82UT 037 006 and S84UT 015 008.

Soils classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Eleventh Edition, 2010

Revisions and updted competing series section 2/08 DWD

Updated for the correlation of the Emery Area, Utah, April 2011

National Cooperative Soil Survey
U.S.A.