LOCATION HANN IDEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Vertic Argixerolls
TYPICAL PEDON: Hann silt loam -- on a northwest-facing slope of 33 percent at 3,960 feet elevation in rangeland. When described on October 25, 1994, the soil was dry throughout. (Colors are for air-dry soil unless otherwise noted.)
A--0 to 3 inches; very dark grayish brown (10YR 3/2) silt loam, very dark brown (10YR 2/2) moist; strong medium platy structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine and fine irregular pores; neutral (pH 6.8); clear smooth boundary. (2 to 10 inches thick)
Bt1--3 to 6 inches; dark grayish brown (10YR 4/2) silty clay loam, very dark brown (10YR 2/2) moist; moderate fine subangular blocky structure; hard, friable, moderately sticky and moderately plastic; many very fine and fine, few medium and coarse roots; many very fine, fine and medium tubular pores; few distinct clay films on faces of peds and in pores; cracks 5 to 15 mm wide; neutral (pH 6.7); clear smooth boundary. (3 to 24 inches thick)
Bt2--6 to 13 inches; brown (10YR 4/3) silty clay, dark brown (10YR 3/3) moist; moderate medium and coarse prismatic structure parting to strong fine subangular blocky; very hard, firm, very sticky and very plastic; common very fine and fine roots; common very fine and fine tubular pores; few distinct clay films on faces of peds and in pores; cracks 1 to 5 mm wide; neutral (pH 6.8); gradual wavy boundary. (6 to 10 inches thick)
Bt3--13 to 25 inches; brown (10YR 5/3) silty clay, dark brown (10YR 3/3) moist; moderate coarse prismatic structure; very hard, firm, very sticky and very plastic; common very fine and fine roots; common very fine and fine tubular pores; common prominent clay films on faces of peds and in pores; neutral (pH 6.7); clear wavy boundary. (5 to 20 inches thick)
Bt4--25 to 44 inches; yellowish brown (10YR 5/4) silty clay loam, dark yellowish brown (10YR 3/4) moist; weak coarse subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common very fine and fine roots; common very fine and fine tubular pores; common distinct clay films on faces of peds and in pores; neutral (pH 6.9); gradual wavy boundary. (0 to 20 inches thick)
Bt5--44 to 72 inches; light yellowish brown (10YR 6/4) silty clay loam, dark yellowish brown (10YR 3/4) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine roots; common very fine and fine tubular pores; common faint clay films on faces of peds and in pores; neutral (pH 6.9).
TYPE LOCATION: Boise County, Idaho; about 6 miles west of Banks; 800 feet south and 2,600 feet east of the northwest corner of section 20, T.9 N., R.2 E.; USGS Dry Buck Valley Quadrangle; Latitude - 44 degrees, 06 minutes, 25 seconds N. and Longitude - 116 degrees, 14 minutes, 46 seconds W.; NAD 83.
RANGE IN CHARACTERISTICS:
Mollic epipedon thickness - 20 to 40 inches
Depth to bedrock - greater than 60 inches
Particle-size control section - 35 to 45 percent clay; 0 to 15 percent rock fragments
Moisture control section - dry 60 to 90 consecutive days following the summer solstice
Average annual soil temperature - 47 to 53 degrees F.
A horizon
Value - 3 through 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Rock fragments - 0 to 5 percent gravel, 0 to 15 percent cobbles, 0 to 5 percent stones and 0 to 20 percent total
Reaction - slightly acid or neutral
Bt1 horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Texture - SIL or SICL
Clay content - 25 to 40 percent
Rock fragments - 0 to 5 percent gravel
Cracks - 5 to 15 mm wide
Reaction - moderately acid through neutral
Bt2 and Bt3 horizons
Hue - 10YR or 7.5YR
Value - 4 or 5 dry, 3 or 4 moist
Chroma - 3 or 4 dry or moist
Texture - C or SIC
Clay content - 40 to 55 percent
Rock fragments - 0 to 15 percent gravel
Cracks - 0 to 10 mm wide
Slickensides - none through common
Reaction - moderately acid through neutral
Bt4 and Bt5 horizons (when present)
Hue - 10YR or 7.5YR
Value - 4 through 6 dry, 3 or 4 moist
Chroma - 3 or 4 dry or moist
Texture - SIL or SICL
Clay content - 25 to 35 percent
Rock fragments - 0 to 15 percent gravel
Reaction - neutral or slightly alkaline
COMPETING SERIES: These are the Ayette, Darow, Forsgren, Gimmi, Karney, Kuck, McDesh, Montour, Tub and Ukiah series. Ayette soils are 40 to 60 inches deep to a paralithic contact and have a mollic epipedon 10 to 20 inches thick. Darow, Gimmi, Karney, Kuck and Ukiah soils are moderately deep to a paralithic contact. Forsgren soils are calcareous at depths of 40 to 55 inches. McDesh soils are 20 to 40 inches deep to a lithic contact. Montour soils are calcareous at depths above 40 inches. Tub soils have secondary carbonates at a depth of 18 to 37 inches.
GEOGRAPHIC SETTING: Hann soils are on fan remnants, structural benches, hill slopes, and butte escarpments at elevations of 2,600 to 5,250 feet. These soils formed in colluvium and alluvium from lacustrine deposits. Slopes range from 2 to 50 percent. The average annual precipitation is 14 to 22 inches and the average annual temperature is 45 to 51 degrees F. The frost-free period is 90 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Breadloaf, Doubledia, Hillcreek, Hovelton and Shafer soils. Breadloaf soils are on hills and moderately deep to a Cr horizon. Doubledia soils are on hills and fan remnants and deep to a Cr horizon. Hillcreek soils are on hills and fan remnants and fine-loamy. Hovelton soils are on hills and moderately deep to bedrock. Shafer soils are on structural benches and moderately deep to bedrock.
DRAINAGE AND PERMEABILITY: Well drained; medium to very rapid runoff; slow permeability.
USE AND VEGETATION: The Hann soils are used mainly for rangeland. Small areas are used for irrigated hayland/pasture. Native vegetation is xeric big sagebrush, bluebunch wheatgrass and Idaho fescue.
DISTRIBUTION AND EXTENT: West-central Idaho. MLRA 10. Hann soils are of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Boise County Area, Idaho, Parts of Ada and Boise Counties, 2005.
REMARKS: Diagnostic horizons and features recognized in this soil:
Mollic epipedon - zone from the soil surface to 25 inches (A, Bt1, Bt2 and Bt3 horizons)
Argillic horizon - zone from 3 to 72 inches (Bt horizons)
Particle-size control section - zone from 3 to 23 inches
Linear extensibility - 6.0 or more in the zone from the soil surface to 25 inches (assumed)
Soil moisture regime - xeric