LOCATION HOWCAN                  ID

Established Series
Rev. KWH/HBM
12/2022

HOWCAN SERIES

The Howcan series consists of deep and very deep, well drained soils that formed in slope alluvium and colluvium from extrusive igneous rocks on mountainsides, footslopes, and fan terraces. Permeability is moderate. Slopes are 12 to 60 percent. The mean annual precipitation is about 14 inches and the mean annual temperature is 39 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Typic Argixerolls

TYPICAL PEDON: Howcan gravelly loam on a 20 percent convex, southeast-facing slope in rangeland at 6,900 feet elevation. (Colors are for dry soil unless otherwise noted. When described on September 30, 1980, the soil was dry throughout.)

A--0 to 4 inches; dark grayish brown (10YR 4/2) gravelly loam, very dark grayish brown (10YR 3/2) moist; moderate thin platy structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and few fine roots; many very fine and fine irregular pores; 15 percent gravel; neutral (pH 7.0); gradual smooth boundary. (3 to 6 inches thick)

Bt1--4 to 10 inches; brown (10YR 5/3) gravelly loam, dark brown (10YR 3/3) moist; moderate medium and coarse subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots; many very fine tubular pores; 20 percent gravel, 10 percent cobbles; common faint films on faces of peds and lining pores; neutral (pH 7.3); gradual smooth boundary. (5 to 8 inches thick)

Bt2--10 to 30 inches; yellowish brown (10YR 5/4) very cobbly loam, dark yellowish brown (10YR 4/4) moist; moderate coarse subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine tubular pores; 25 percent gravel, 30 percent cobbles; few faint clay films on faces of peds and lining pores; neutral (pH 7.3); gradual smooth boundary. (16 to 26 inches thick)

BC--30 to 48 inches; yellowish brown (10YR 5/6) very gravelly loam, dark yellowish brown (10YR 4/4) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine roots; many very fine tubular pores; 30 percent gravel, 10 percent cobbles; neutral (pH 7.3); gradual smooth boundary. (10 to 25 inches thick)

C--48 to 60 inches; brown (7.5YR 5/4) very gravelly sandy loam, dark brown (7.5YR 3/4) moist; massive, slightly hard, friable, slightly sticky and nonplastic; common very fine and few fine irregular pores; 30 percent gravel, 20 percent cobbles; slightly effervescent; slightly alkaline (pH 7.5).

TYPE LOCATION: Custer County, Idaho; about 13 miles northwest of Mackey, Idaho; about 2,300 feet south and 100 feet east of the northwest corner of section. 4, T. 7N., R. 22E. Latitude - 43 degrees, 57 minutes, 58 seconds North; Longitude - 113 degrees, 51 minutes, 45 seconds West.

RANGE IN CHARACTERISTICS:

Average annual soil temperature - 39 to 45 degrees F.
Depth to bedrock - more than 60 inches
Solum thickness - 40 to more than 60 inches
Mollic thickness - 10 to 18 inches
Depth to base of argillic - 25 to 40 inches
Control section average: percent clay - 18 to 27
Rock fragments - 35 to 70 percent

A horizon
Value - 3 through 5 dry and 2 or 3 moist
Chroma - 2 or 3 moist and 2 through 4 dry
Reaction - neutral or slightly alkaline

Bt horizon
Hue - 7.5YR, 10YR, 2.5Y
Value - 3 through 5 dry and 2 through 4 moist
Chroma - 3 through 6 dry or moist
Texture - GR-L, GRV-L, CBV-L, CB-L, GRV-SCL, STX-L, CBX-L, STV-L
Reaction - neutral or slightly alkaline

BC horizon
Hue - 7.5YR, 10YR, 2.5Y
Value - 4 through 6 dry and 4 or 5 moist
Chroma - 3 through 6 dry or moist
Texture - GRV-L, GRX-L, CBX-L, GRV-SL, GRX-SL, CBX-SL, STX-SL
Reaction - neutral or slightly alkaline
Rock fragments - 35 to 70 percent

C horizon
Value - 3 through 6 dry or moist
Chroma - 3 through 5 dry or moist
Texture - GRV-SL, GRV-L, GRX-SL, GRX-L, CBV-SL
Reaction - neutral or slightly alkaline
Rock fragments - 35 to 70 percent

COMPETING SERIES: These are the Clanalpine, Heechee, Holmes, Horrocks, Hoskin, Pequop, Moreypeak, Suak, Valmar, Vitale and Wambolt (T) series. Clanalpine, Hoskin, Suak, Valmar, and Vitale soils are moderately deep to bedrock. Heechee soils have stones in the Bt horizon and have 25 to 35 percent clay in the particle size control section. Holmes soils have sola less than 32 inches thick. Horrocks soils have sola less than 40 inches thick. Pequop soils have the base of argillic horizons deeper than 40 inches and have average annual soil temperature of 43 to 47 degrees F. Howeypeak soils are moderately deep to a paralithic content. Wambolt soils have 27 to 35 percent clay in the particle-size control section and receive intermittent summer precipitation for 10 to 20 days cumulative.

GEOGRAPHIC SETTING: Howcan soils are on mountainsides, foothills, and fan terraces and have slopes of 12 to 60 percent. Elevations range from 4,800 to 8,000 feet. These soils formed in slope alluvium and colluvium from extrusive igneous rocks. The climate is cold and moist in winter and dry in summer. Average annual precipitation is 12 to 16 inches and average annual temperature is 37 to 43 degrees F. The frost-free period is 45 to 90 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hagenbarth, Hutchley, Justesen, and Soen soils. Hagenbarth soils are on mountains, have cryic soil temperature regimes and fine-loamy particle-size control sections. Hutchley soils are on mountains and ridges and are shallow to bedrock. Justesen soils are on fan terraces and have fine-loamy particle-size control sections. Soen soils are on toeslopes and have fine textured particle-size control section.

DRAINAGE AND PERMEABILITY: Well drained; slow and medium runoff; moderate permeability.

USE AND VEGETATION: Rangeland. Vegetation is mainly mountain big sagebrush and bluebunch wheatgrass.

DISTRIBUTION AND EXTENT: East-central Idaho. These soils are not extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon

SERIES ESTABLISHED: Custer-Lemhi Counties, Idaho, 1999.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Mollic epipedon - the zone from the surface to 10 inches (A1 and Bt1 horizons)

Argillic horizon - the zone from 4 to 30 inches (Bt1 and Bt2 horizons)

Particle-size control section - the upper 20 inches of the argillic horizon (parts of the Bt1 and Bt2 horizons)

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National Cooperative Soil Survey
U.S.A.