LOCATION PERLA ID+NVEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Aridic Argixerolls
TYPICAL PEDON: Perla very stony loam, rangeland. (Colors are for air-dry soil unless otherwise stated.)
A1--0 to 4 inches; grayish brown (10YR 5/2) very stony loam, very dark grayish brown (10YR 3/3) moist; weak thin platy structure parting to moderate fine granular; slightly hard, friable, slightly sticky and slightly plastic; common fine roots; many fine pores; neutral (pH 6.6); clear wavy boundary. (3 to 9 inches thick)
A2--4 to 9 inches; grayish brown (10YR 5/2) very stony loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; common fine roots; many fine pores; slightly acid (pH 6.5); abrupt wavy boundary. (0 to 6 inches thick)
BA--9 to 13 inches; grayish brown (10YR 5/2) very stony clay loam, very dark grayish brown (10YR 3/2) moist; weak medium and very fine subangular blocky structure; slightly hard, friable, sticky and plastic; common fine roots; many very fine pores; slightly bleached silty specks on faces of peds; slightly acid (pH 6.4); abrupt wavy boundary. (0 to 5 inches thick)
Bt1--13 to 18 inches; grayish brown (10YR 5/2) stony clay, very dark grayish brown (10YR 3/2) moist; strong medium prismatic structure; very hard, very firm, very sticky and very plastic; few fine roots along vertical cracks; few fine pores; continuous prominent clay films on all faces of peds; upper part has thin bleached silty specks on faces of peds; slightly acid (pH 6.2); clear irregular boundary. (4 to 8 inches thick)
Bt2--18 to 21 inches; pale brown (10YR 6/3) stony clay, dark brown (10YR 4/3) moist; strong fine and very fine angular blocky structure; very hard, very firm, very sticky and very plastic; few fine roots; few very fine pores; slightly darker colored continuous distinct clay films on all faces of peds; slightly acid (pH 6.2); abrupt wavy boundary. (3 to 8 inches thick)
Bt3--21 to 25 inches; pale brown (10YR 6/3) very stony clay loam, dark yellowish brown (10YR 4/4) moist; moderate very fine subangular blocky structure; hard, firm, sticky and plastic; few fine roots; few fine pores; prominent clay films on rock fragments; moderately acid (pH 6.0); abrupt wavy boundary. (0 to 10 inches thick)
R--25 inches; somewhat decomposed, grading to unweathered, rhyolitic tuff or rhyolite.
TYPE LOCATION: Gem County, Idaho; about 12 miles southeast of Emmett and 2 miles southeast of Pearl; 600 feet north and 1,000 feet west of the southeast corner of the northeast 1/4 of section 36, T. 6 N., R. 1 E.
RANGE IN CHARACTERISTICS:
Mollic epipedon thickness - 10 to 20 inches
Depth to bedrock - 20 to 40 inches
Average annual soil temperature - 47 to 54 degrees F.
Clay content control section - 35 to 50 percent (average)
A horizon
Hue - 7.5YR or 10YR
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Rock fragments - 0 to 35 percent
Reaction (pH) - moderately acid to neutral
Bt horizon
Hue - 7.5YR or 10YR
Value - 5 or 6 dry, 3 to 5 moist
Chroma - 2 through 4 dry or moist
Texture - SICL, SIC, C, CL, GR-C, GR-CL, ST-C, or ST-CL
Clay content - 35 to 55 percent
Rock fragments - 0 to 35 percent
Reaction (pH) - moderately acid to neutral
Btb horizons are present in some pedons
COMPETING SERIES: These are the Brownscombe, Bucklake, Cagle, Correco, Holmzie, Northmore, Schoer, Sherar, Simpson, Wicup and Zymans series. The Brownscombe, Cagle, Holmzie, Sherar, and Wicup soils are moderately deep to a paralithic contact. Bucklake soils have less than 35 percent clay in the upper part of the argillic horizon. Correco, Northmore, Schoer, and Simpson soils are very deep. Zymans soils are deep to a paralithic contact.
GEOGRAPHIC SETTING: Perla soils are on basalt plains, buttes, structural benches, tablelands, foothills, and mountains at elevations of 3,000 to 5,800 feet. Slopes range from 0 to 60 percent. These soils formed in alluvium, colluvium, and loess from extrusive rocks and volcanic ash. The climate has dry, hot summers and cool, moist winters. Average annual precipitation ranges from 10 to 13 inches and average annual temperature ranges from 45 to 52 degrees F. The frost-free period is 80 to 145 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dishner, Glasgow, and Aikman series. Dishner soils have E horizons and are 10 to 20 inches deep to sandstone. Glasgow soils have light colored A horizons and Btk horizons. Aikman soils have deep cracks and hues of 2.5YR or 5YR.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; slow permeability.
USE AND VEGETATION: These soil are used mainly for rangeland and wildlife habitat. The dominant natural vegetation is bluebunch wheatgrass, Sandberg bluegrass, and big sagebrush. Cheatgrass and medusahead wildrye are presently common.
DISTRIBUTION AND EXTENT: Southwestern Idaho and northern California. These soils are moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Gem County, Idaho, 1962.
REMARKS: Diagnostic horizons and other features recognized in this pedon:
Mollic epipedon - zone 0 to 18 inches (A1, A2, BA, and Bt1)
Argillic horizon and particle-size control section - zone 13 to 25 inches (Bt1, Bt2, and Bt3)