LOCATION SIRREF UTEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic, frigid Typic Argiustolls
TYPICAL PEDON: Sirref loam--woodland. (Colors are for air-dry soil unless otherwise stated.)
A--0 to 3 inches; reddish brown (5YR 4/3) loam, dark reddish brown (5YR 3/2) moist; moderate medium granular structure that parts to weak medium subangular blocky; soft, friable; many very fine and fine, common medium roots; common fine tubular pores; 8 percent pebbles, 4 percent cobbles, 1 percent stones; mildly alkaline (pH 7.7); clear wavy boundary. (3 to 14 inches thick)
Bt1--3 to 9 inches; reddish brown (5YR 4/4) gravelly clay loam, dark reddish brown (5YR 3/3) moist; moderate medium subangular blocky structure; hard, firm, sticky and plastic; common very fine, fine, and medium roots; common fine tubular pores; few thin clay films on faces of peds; 15 percent pebbles, 5 percent cobbles, 2 percent stones; mildly alkaline (pH 7.7); clear wavy boundary. (2 to 7 inches thick)
Bt2--9 to 15 inches; reddish brown (5YR 4/4) gravelly clay, reddish brown (5YR 3/3) moist; strong coarse subangular blocky structure that parts to strong medium subangular blocky; very hard, very firm, sticky and plastic; common fine and medium roots; few fine tubular pores; many thick clay films on faces of peds and lining pores; 20 percent pebbles, 20 percent cobbles, 3 percent stones; mildly alkaline (pH 7.8); gradual wavy boundary. (0 to 10 inches thick)
Bt3--15 to 33 inches; yellowish red (5YR 4/6) very gravelly clay, reddish brown (5YR 4/4) moist; strong coarse angular blocky structure that parts to strong medium angular blocky; extremely hard, very firm, very sticky and very plastic; few fine and medium roots; few fine tubular pores; continuous thick clay films on faces of peds and lining pores; 30 percent pebbles, 20 percent cobbles, 5 percent stones; mildly alkaline (pH 7.8); clear wavy boundary.
(13 to 27 inches thick)
Btk--33 to 48 inches; yellowish red (5YR 4/6) extremely cobbly clay, yellowish red (5YR 5/6) moist; strong medium angular blocky structure; extremely hard, very firm, very sticky and very plastic; few fine and medium roots; common fine tubular pores; many thick clay films on faces of peds and lining pores; 35 percent pebbles, 35 percent cobbles, 5 percent stones; strongly calcareous; carbonates are in few soft masses and coatings on rock fragments moderately alkaline (pH 7.9); abrupt wavy boundary. (8 to 20 inches thick)
Bk--48 to 60 inches; pink (7.5YR 7/4) very cobbly clay loam, brown (7.5YR 5/4) moist; massive; soft, firm, sticky and plastic; few fine roots; 25 percent pebbles, 25 percent cobbles, 5 percent stones, strongly calcareous; carbonates are in common fine soft masses and coatings on rock fragments; moderately alkaline (pH 8.4).
TYPE LOCATION: San Juan County, Utah about 2 miles north of LaSal Guard Station; 2,300 feet south and 150 feet west of the northeast corner of sec. 10, T. 28 S, R. 25 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 42 to 47 degrees F. and the mean summer soil temperature at a depth of 20 inches is 60 to 62 degrees F. These soils are continuously moist in some part of the moisture control section for at least 90 consecutive days during the time the soil temperature at 20 inches is 41 degrees F. or higher. The mollic epipedon is 11 to 15 inches thick. Depth to the upper boundary of the Bt2 is 3 to 14 inches. Rock fragments range from 35 to 50 percent in the upper 20 inches of the Bt and clay averages 35 to 45 percent.
The A horizon has hue of 5YR or 7.5YR, value of 3 to 4 dry, 2 or 3 moist, and chroma of 2 or 3. This horizon is neutral and mildly alkaline.
The Bt horizon has hue of 5YR or 7.5YR, value of 4 or 5 dry, 3 to 5 moist, and chroma of 2 to 6. The upper part of the Bt is gravelly or very gravelly clay and very gravelly clay loam with 35 to 45 percent clay. The lower part is very cobbly clay, extremely stony sandy clay loam and extremely cobbly clay with 30 to 50 percent clay. The upper part of the Bt is 35 to 50 percent rock fragments and lower part is 50 to 70 percent rock fragments. It is noncalcareous in the upper part and slightly calcareous to strongly calcareous in the lower part. This horizon is neutral to moderately alkaline.
COMPETING SERIES: These are the Kolob and Showalter series. Kolob series are noncalcareous throughout. Showalter series are not moist for as long a period when the soil temperature at 20 inches is 41 degrees F. or higher.
GEOGRAPHIC SETTING: Sirref soils are on glacial outwash fans and mountain slopes. Elevations range from 8,200 to 9,000 feet. These soils formed in alluvium from diorite and mixed sedimentary rocks. Mean annual is 39 to 42 degrees F. and the average annual precipitation is 18 to 25 inches. The freeze-free period is 60 to 90 days. GEOGRAPHICALLY ASSOCIATED SOILS: These are Falcon, Flygare, Herm, Tomasaki, Tukuhnik and Skylick soils. The Falcon soils have bedrock at 10 to 20 inches. Herm, Tomasaki, Tukuhnik and Skylick soils are not skeletal. Flygare and Skylick soils have cryic temperature regimes.
DRAINAGE AND PERMEABILITY: Well drained, slow permeability; slow to medium runoff.
USE AND VEGETATION: Used mainly for rangeland and wildlife habitat. The natural plant community is mountain big sagebrush, serviceberry, birchleaf moutainmahogany, muttongrass, needleandthread, brome grass and bluegrass.
DISTRIBUTION AND EXTENT: Southeastern Utah. The series is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Canyonlands Area, Parts of Grand and San Juan Counties, Utah, 1983. Name was coined.