LOCATION DEMAST ID+MT

Established Series
Rev. WJL/RJE/EMM
12/2022

DEMAST SERIES

The Demast series consists of deep, well drained soils on mountain slopes. They formed in material weathered mainly from basalt and other closely related volcanic rocks. Permeability is moderately slow. Slopes are 10 to 80 percent. The average annual precipitation is about 20 inches, and the average annual air temperature is about 38 degrees F.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive Pachic Argicryolls

TYPICAL PEDON: Demast loam, rangeland; on a 25 percent north facing slope at 6,200 feet elevation. (Colors are for dry soil unless otherwise noted.)

A1--0 to 2 inches; very dark grayish brown (10YR 3/2) loam, black (10YR 2/1) moist; strong medium and coarse granular structure; slightly hard, very friable, slightly sticky and slightly plastic; few fine roots; many very fine irregular pores; moderately acid (pH 5.7); abrupt smooth boundary. (2 to 6 inches thick)

A2--2 to 15 inches; dark brown (10YR 3/3) loam, very dark brown (10YR 2/2) moist; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common fine, medium and coarse roots; common very fine tubular pores; 10 percent gravel; moderately acid (pH 5.7); clear smooth boundary. (9 to 18 inches thick)

Bt1--15 to 22 inches; brown (7.5YR 4/3) gravelly loam, dark brown (7.5YR 3/3) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common fine, medium and coarse roots; many very fine tubular pores; few faint clay films on faces of peds and in pores; 15 percent gravel; moderately acid (pH 5.7); clear wavy boundary. (5 to 10 inches thick)

Bt2--22 to 33 inches; brown (7.5YR 4/4) cobbly loam, dark brown (7.5YR 3/3) moist; moderate medium subangular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; common fine, medium and coarse roots; many very fine tubular pores; few faint clay films on faces of peds and in pores; 10 percent stones, 15 percent cobbles and 5 percent gravel; moderately acid (pH 5.6); clear wavy boundary. (8 to 17 inches thick)

Bt3--33 to 41 inches; reddish brown (5YR 4/4) gravelly clay loam, dark reddish brown (5YR 3/4) moist; moderately coarse subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few fine and medium roots; many very fine tubular pores; common distinct clay films on faces of peds; 5 percent cobbles and 25 percent gravel; moderately acid (pH 6.0); gradual wavy boundary. (6 to 12 inches thick)

Cr--41 to 52 inches; highly weathered latite with small amounts of soil material similar to the Bt3 horizon. (0 to 12 inches thick)

R--52 inches; latite.

TYPE LOCATION: Elmore County, Idaho; 19 miles northeast of Mountain Home; about 2,500 feet south and 300 feet west of the northeast corner of section 19, T. 2 S., R. 10 E.

RANGE IN CHARACTERISTICS:

Average annual soil temperature - 37 to 43 degrees F.
Depth to bedrock - 40 to more than 60 inches
Mollic epipedon thickness - 30 to 50 inches
Reaction in profile - neutral to moderately acid
Depth to argillic horizon - 10 to 30 inches

A horizon
Value - 3 or 4 dry, 2 or 3 moist
Chroma - 1 to 3 dry or moist

Bt horizons
Hue - 5YR to 10YR
Value - 3 to 6 dry, 2 to 4 moist
Chroma - 3 or 4 dry or moist
Texture - loam or clay loam
Rock fragments - 20 to 40 percent (Averages less than 35 percent)
Clay content - 22 to 30 percent

C horizons present in some pedons.

COMPETING SERIES:
Bachus (WY) - has a lithic contact at 20 to 40 inches.

Bavdark (MT) is very deep.

Benteen (MT) - has a lithic contact at 20 to 40 inches.

Brushtop (ID) - does not have a lithic contact.

Clayburn (UT) - has a udic moisture regime.

Croydon (UT) - has an E horizon.

Crystalbutte (ID) - has 25 to 35 percent coarse fragments in the particle-size control section; has a 2Bt horizon.

Davtone (CO) - has hues of 5YR or redder in the Bt horizon.

Dehana (ID) - has a mollic epipedon more than 35 inches thick; formed in alluvium or colluvium from welded rhyolitic tuff, latite and volacanic ash.

Dranburn (ID) - has silty clay loam Bt horizon with more than 45 percent silt.

Dranyon (ID) - depth to argillic horizon is less than 10 inches; allows bedrock at 40 inches or more.

Echemoor (WY) - has a paralithic contact at 20 to 40 inches.

Hagenbarth (ID) - is very deep.

Longway (ID) - is very deep.

Lostminer (UT) - has a lithic contact at 20 to 40 inches.

Hoopgobel (ID) has a paralithic contact at 20 to 40 inches.

Millerlake (WY) - has horizons of secondary carbonate accumulation.

Odark (MT) - is very deep.

Senchert (UT) - has a lithic contact at 20 to 40 inches.

Southmount (ID) - has redox concentrations at 18 to 40 inches; is moderately well drained.

Poodle (NV) - has a paralithic contact at 20 to 40 inches.

Stubbs (WY) - has a paralithic contact at 20 to 40 inches; has calcareous material at 15 to 36 inches.

Thulepah (NV) - has 2Bt horizons; has mean annual soil temperature of 43 to 47 degrees F.

Vadnais (ID)- has a lithic contact at 20 to 40 inches; has a xeric moisture regime.

Winu (NV) - has a lithic contact at 24 to 40 inches.

GEOGRAPHIC SETTING: The soils are principally on steep and very steep northerly mountain slopes at elevations of 4,000 to 8,000 feet. Most slopes are between about 30 and 50 percent, but the slopes range from 10 to 80 percent. The soils formed in material weathered from basalt and other closely related volcanic rocks. The climate is cool subhumid and has an average annual precipitation of 18 to 25 inches, including 8 to 12 feet of snowfall. Average annual temperature is 35 to 41 degrees F. Frost-free season is about 60 to 80 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Elkcreek, Gaib and Klicker soils. Elkcreek soils are moderately deep and occur on shoulders and south-facing slopes. Gaib soils have basalt bedrock at depths of less than 20 inches and are on ridges. Klicker soils are skeletal and have a cryic soil temperature regime and are on landscape positions similar to Demast soils.

DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; moderately slow permeability.

USE AND VEGETATION: Nearly all is used for rangeland. The potential natural vegetation is a rather dense growth of mountain big sagebrush, snowberry, Idaho fescue, Junegrass, beardless wheatgrass, Stipa spp. chokecherry, lupine, and widely spaced Douglas-fir and/or alpine fir.

DISTRIBUTION AND EXTENT: The series is moderately extensive in southern and western Idaho and in central Montana. MLRA 43B.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana

SERIES ESTABLISHED: Owyhee County, Idaho, 1972.

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

Mollic epipedon - the zone from 0 to 33 inches (A1, A2, Bt1 and Bt2 horizons).

Argillic horizon - the zone from 22 to 41 inches (the Bt2 and Bt3 horizons).

Particle-size control section - the zone from 22 to 40 inches (the Bt2 and part of the Bt3 horizons).

National Cooperative Soil Survey
U.S.A.