LOCATION ANINTO IDEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic, frigid Typic Palexerolls
TYPICAL PEDON: Aninto very gravelly silty clay loam--on an east-facing slope of 20 percent under rangeland vegetation at 5,500 feet elevation. (Colors are for air dry soil unless otherwise stated. When described on September 26, l979, the soil profile was slightly moist throughout.)
A--0 to 6 inches; brown (10YR 5/3) very gravelly silty clay loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine, fine, and medium roots; many very fine and fine tubular pores; 40 percent gravel; slightly acid (pH 6.1); abrupt smooth boundary. (3 to 12 inches thick)
Bt1--6 to 13 inches; brown (10YR 4/3) very gravelly clay, dark brown (10YR 3/3) moist; moderate fine angular blocky structure; very hard, very firm, very sticky and very plastic; common very fine, fine, and medium roots; common very fine and fine tubular pores; many distinct clay films on faces of peds and in pores; 40 percent gravel; slightly acid (pH 6.3); clear smooth boundary. (4 to 10 inches thick)
Bt2--13 to 26 inches; brown (10YR 4/3) very gravelly silty clay, brown (7.5YR 4/4) moist; moderate medium prismatic structure parting to moderate medium angular blocky; very hard, very firm, very sticky and very plastic; common very fine and fine roots; few very fine and fine tubular pores; many prominent clay films on faces of peds and in pores; 40 percent gravel; slightly acid (pH 6.2); gradual wavy boundary. (8 to 15 inches thick)
Bt3--26 to 41 inches; yellowish brown (10YR 5/4) extremely gravelly silty clay, brown (7.5YR 4/4) moist; moderate medium angular blocky structure; very hard, very firm, very sticky and very plastic; common very fine and fine roots; few very fine and fine tubular pores; common distinct clay films on faces of peds and in pores; 70 percent gravel; neutral (pH 6.9); clear smooth boundary. (13 to 18 inches thick)
2Btk--41 to 56 inches; dark yellowish brown (10YR 4/4) clay, brown (10YR 4/3) moist; moderate medium angular blocky structure; very hard, very firm, very sticky and very plastic; common very fine and fine roots; few very fine and fine tubular pores; common distinct clay films on faces of peds and in pores; slightly effervescent; (10 percent calcium carbonate equivalent) carbonates occur in few, fine, irregularly shaped filaments or threads; neutral (pH 7.2); abrupt smooth boundary. (15 to 20 inches thick)
2Bk--56 to 70 inches; brown (7.5YR 5/4) clay loam, brown (7.5YR 4/4) moist; massive; hard, firm, very sticky and very plastic; few very fine and fine roots; few very fine and fine tubular pores; slightly effervescent (11 percent calcium carbonate equivalent); carbonates occur in few, fine, irregularly shaped soft masses; mildly alkaline (pH 7.4).
TYPE LOCATION: Twin Falls County, Idaho; about 17 miles southeast of Rogerson, Idaho; in the northwest 1/4, southeast 1/4, southeast 1/4 of sec. 25, T. 16 S., R. 17 E.
RANGE IN CHARACTERISTICS:
Depth to bedrock - more than 60 inches
Mollic epipedon thickness - 10 to 15 inches
Average clay content in control section - 45 to 59 percent
Average annual soil temperature - 43 to 45 degrees F.
Average summer soil temperature - 60 to 62 degrees F.
Abrupt textural change - there is a minimum of 15 percent absolute clay increase between the A and Bt horizon in 2.5 cm or at least a 20 percent absolute increase in 7.5 cm.
A horizon
Hue - 10YR or 7.5YR
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Clay content - 15 to 35 percent
Coarse fragments
Gravel - 5 to 45 percent
Cobbles - 0 to 5 percent
Stones - 0 to 10 percent
Reaction - slightly acid to mildly alkaline
Bt horizon
Hue - 7.5YR or 10YR
Value - 4 through 6 dry, 3 through 5 moist
Chroma - 3 or 4 dry or moist
Texture - GRV-C, GRV-SIC, GRX-SIC, FLV-C, CB-C, STX-SCL, GRX-C
Clay content - 30 to 59 percent - clay content less than 40 percent occurs in the lower part of the argillic horizon out of the textural control section
Coarse fragments - 40 to 75 percent
Reaction - slightly acid to moderately alkaline
2Bk horizon
Hue - 10YR or 7.5YR
Value - 5 through 8 dry, 4 through 7 moist
Chroma - 3 through 6
Texture - L, CL, GR-L
Percent clay - 20 to 39 percent clay
Reaction - mildly alkaline or moderately alkaline
COMPETING SERIES: These are the Amboat (T), Boneyard (T), Durfee, Ebic, and Ziram series. Amboat soils have an average annual soil temperature of 41 to 43 degrees F., and a Bt2 horizon that averages 60 to 85 percent clay, and 60 to 85 percent stones. Boneyard soils lack an abrupt boundary between the A and B horizons, and have 35 to 45 percent clay in the control section. Durfee soils have argillic horizons that extend to depths of more than 60 inches and lack discontinuities in the lower part of the profile. Ebic soils are moderately deep to bedrock. Ziram soils have secondary carbonates at 16 to 27 inches, and a soil reaction that is mildly alkaline or moderately alkaline.
GEOGRAPHIC SETTING: Aninto soils are on fan terraces and terrace sideslopes. The slope ranges from 1 to 30 percent. The soils formed in alluvium from mica schist, quartzite, and welded tuff. Elevations are 5,500 to 6,500 feet. The average annual precipitation ranges from 12 to 16 inches. The average annual temperature is 42 to 44 degree F. The frost free season is 70 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bancy (T), Chayson, Forvic (T), Oshone (T), and Zola soils. Bancy soils are shallow to a hardpan and occur on terraces. Chayson, Forvic, and Oshone soils are moderately deep to a hardpan, and occur on terraces. Zola soils are fine-loamy, moderately well drained, and occur on lower alluvial terraces.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; very slow permeability.
USE AND VEGETATION: Aninto soils are used for rangeland. Native vegetation is bluebunch wheatgrass, low sagebrush, mountain big sagebrush, and Idaho fescue.
DISTRIBUTION AND EXTENT: Aninto soils are of moderate extent in south central Idaho.
MLRA OFFICE RESPONSIBLE: Reno, Nevada
SERIES ESTABLISHED: Cassia County, Idaho, l986.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from the surface to 13 inches (A and Bt1 horizons).
Argillic horizon - the zone from 6 to 56 inches (Bt1, Bt2, Bt3, and 2Btk horizons).
Palexeroll feature - has a clay increase of greater than 15 percent absolute within a distance of 2.5 cm at the upper boundary of the argillic horizon and has a clayey particle size class.
Particle size control section - the upper 20 inches of the argillic horizon (Bt1 and Bt2 horizons).
Moisture regime - Xeric.