LOCATION LANARK IDEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive Pachic Argicryolls
TYPICAL PEDON: Lanark silt loam, grass. (Colors are for dry soil unless otherwise noted.)
A1--0 to 2 inches; grayish brown (10YR 5/2) silt loam, very dark brown (10YR 2/2) (very dark grayish brown 10YR 3/2, crushed) moist; moderate very fine granular structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and fine roots; common very fine and fine tubular pores; neutral (pH 6.8); abrupt smooth boundary. (0 to 4 inches thick)
A2--2 to 7 inches; dark grayish brown (10YR 4/2) (dark brown 10YR 4/3, crushed) silt loam, very dark brown (10YR 2/2) (very dark grayish brown 10YR 3/2, crushed) moist; moderate fine and medium granular and weak fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots; common very fine and fine tubular pores; neutral (pH 7.0); gradual smooth boundary. (4 to 10 inches thick)
A3--7 to 14 inches; brown (10YR 5/3) silt loam, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure; hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots; common very fine and fine tubular pores; neutral (pH 7.2); gradual smooth boundary. (5 to 10 inches thick)
Bt1--14 to 28 inches; brown (10YR 5/3) heavy silt loam, dark brown (10YR 3/3) moist; weak medium and coarse subangular blocky structure; hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots; common very fine and fine tubular pores; faint patchy clay films in some channels; few uncoated silt particles on peds; neutral (pH 7.2); abrupt wavy boundary. (6 to 16 inches thick)
Bt2--28 to 41 inches; brown (10YR 5/3) (pale brown 10YR 6/3, crushed) light silty clay loam, dark brown (10YR 4/3) moist; weak fine prismatic structure that parts to moderate medium and fine subangular blocky; hard, friable, sticky and plastic; few very fine tubular pores; faint patchy clay films on peds and thin and medium nearly continuous ones on many pores; few uncoated silt particles on peds; slightly alkaline (pH 7.8); gradual smooth boundary. (10 to 15 inches thick)
Bk1--41 to 54 inches; pale brown (10YR 6/3) heavy silt loam, brown (10YR 4/3) moist; weak medium and fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few very fine roots; many very fine and fine tubular pores; thin patchy clay films in few pores; moderately calcareous, few fine veins and spots of calcium carbonate; moderately alkaline (pH 8.1); clear wavy boundary. (5 to 15 inches thick)
Bk2--54 to 66 inches; very pale brown (10YR 7/3) silt loam, brown (10YR 5/3) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; few very fine roots; many very fine and fine tubular pores; strongly calcareous, many fine veins and spots of calcium carbonate; moderately alkaline (pH 8.4).
TYPE LOCATION: Bingham County, Idaho; 2,300 feet south and 1,980 feet east of the NW corner sec. 12, T. 3 S., R. 41 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature ranges from 35 degrees to 43 degrees F., and the mean summer temperature at a depth of 20 inches ranges from 55 degrees to 59 degrees F. The soils are usually moist. The solum is 25 to 50 inches thick. The mollic epipedon is 16 to 30 inches thick. The profile is noncalcareous to a depth of 40 to 60 inches.
The A horizon when mixed to 7 inches has value of 4 or 5 dry, 2 or 3 moist, and chroma of 2 or 3. It has weak to moderate granular to weak subangular blocky structure. This horizon has 3.5 to 5.5 percent organic matter having a C:N ratio of 10 to 13. It ranges in pH from 6.5 to 7.4
The Bt horizon has value of 5 or 6 dry, 3 or 4 moist, and chroma of 2 through 4. It is heavy silt loam or light silty clay loam and averages 24 to 30 percent clay and less than 15 percent particles coarser than very fine sand. It ranges in pH from 6.6 to 7.8.
COMPETING SERIES: These are the Bozeman an Robana series. Bozeman soils are calcareous below a depth of 20 to 40 inches. Robana soils have sola thicker than 50 inches and lack a Cca horizon.
GEOGRAPHIC SETTING: The soils formed in deep loess in mountain slopes and fans at elevations of 5,800 to 7,000 feet. Slopes range from 0 to 45 percent. The subhumid continental climate has a mean annual precipitation of 14 to 18 inches including 3 to 6 feet of snowfall, and an average frost-free season of 30 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Steelton and Enochville soils. Steelton soils are less than 20 inches deep over basalt. Enochville soils are noncalcareous and have mottles due to wetness in or immediately below the A1 horizon.
DRAINAGE AND PERMEABILITY: Well drained; medium or rapid runoff; moderate permeability.
USE AND VEGETATION: Used for nonirrigated small grains and range. The principal native plants are Idaho fescue, streambank wheatgrass, Columbia needlegrass, Nevada bluegrass, and geranium.
DISTRIBUTION AND EXTENT: The series is moderately extensive in the loessal uplands of southeastern Idaho and western Wyoming.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Star Valley Area, Lincoln County, Wyoming, 1941.
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