LOCATION BOISE IDEstablished Series
The Boise series consists of very deep, somewhat excessively drained soils with moderately rapid permeability that formed in alluvium from granitic rocks. Slopes range from 3 to 8 percent in valleys and canyons. The average annual precipitation is about 13 inches and the average annual temperature is about 51 degrees F.
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Cumulic Ultic Haploxerolls
TYPICAL PEDON: Boise coarse sandy loam -- on a slightly convex south-facing slope of 6 percent, in irrigated hayland at 2,760 feet elevation. When described on October 3, 1994, the soil was moist throughout. (Colors are for air-dry soil unless otherwise stated.)
Ap1--0 to 3 inches; dark grayish brown (10YR 4/2) coarse sandy loam, very dark brown (10YR 2/2) moist; moderate fine and medium platy structure parting to weak fine and medium granular; slightly hard, very friable, nonsticky and nonplastic; many very fine and fine, common medium, few coarse roots; many very fine and fine, few medium irregular pores; 10 percent fine gravel; slightly acid (pH 6.5); abrupt smooth boundary.
Ap2--3 to 7 inches; dark grayish brown (10YR 4/2) coarse sandy loam, very dark brown (10YR 2/2) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; common very fine, fine and medium, few coarse roots; common very fine and fine, few medium irregular and tubular pores; 10 percent fine gravel; slightly acid (pH 6.5); clear smooth boundary.
A--7 to 15 inches; dark grayish brown (10YR 4/2) fine gravelly coarse sandy loam, very dark gray (10YR 3/1) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; common very fine, fine and medium, few coarse roots; common very fine and fine, few medium irregular and tubular pores; 15 percent fine gravel; moderately acid (pH 5.8); clear wavy boundary. (combined A horizon is 12 to 22 inches thick)
Bw--15 to 28 inches; grayish brown (10YR 5/2) fine gravelly coarse sandy loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; hard, friable, nonsticky and nonplastic; common very fine and fine, few medium roots; few very fine and fine tubular pores; 15 percent fine gravel; moderately acid (pH 5.8); clear smooth boundary. (10 to 18 inches thick)
BC--28 to 36 inches; brown (10YR 5/3) very gravelly coarse sandy loam, dark brown (10YR 3/3) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; common very fine and fine, few medium roots; few very fine and fine tubular pores; 30 percent gravel, 15 percent cobbles, 5 percent stones; moderately acid (pH 6.0); clear wavy boundary. (0 to 12 inches thick)
C1--36 to 53 inches; pale brown (10YR 6/3) very gravelly loamy coarse sand, brown (10YR 4/3) moist; massive; soft, very friable, nonsticky and nonplastic; few very fine, fine and medium roots; few very fine and fine irregular pores; 50 percent gravel; slightly acid (pH 6.1); clear smooth boundary. (10 to 24 inches thick)
C2--53 to 60 inches; pale brown (10YR 6/3) extremely gravelly loamy coarse sand, brown (10YR 4/3) moist; single grain; loose; few very fine and fine roots; few very fine and fine irregular pores; 70 percent gravel; slightly acid (pH 6.2).
TYPE LOCATION: Boise County, Idaho; about 1/2 mile north of Horseshoe Bend; 1,000 feet north and 500 feet west of the southeast corner of section 22, T.7 N., R.2 E.; USGS Horseshoe Bend Quadrangle; Latitude - 43 degrees, 55 minutes, 31 seconds N. and Longitude - 116 degrees, 11 minutes, 49 seconds W.; NAD 83.
RANGE IN CHARACTERISTICS:
Mollic epipedon thickness - 20 to 40 inches
Base saturation (10 and 30 inches) - 50 to 75 percent
Particle-size control section - 5 to 35 percent rock fragments; 8 to 18 percent clay
Moisture control section - moist less than 90 consecutive days when the soil temperature is greater than 47 degrees F.
Average annual soil temperature - 52 to 53 degrees F.
A horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 1 through 3 dry or moist
Rock fragments - 5 to 15 percent gravel
Reaction - moderately acid through neutral
Bw horizon
Chroma - 2 or 3 dry or moist
Texture - SL or COSL
Clay content - 10 to 18 percent
Rock fragments - 5 to 25 percent gravel
Reaction - moderately acid or slightly acid
C horizon
Chroma - 3 or 4 dry or moist
Texture - COSL or LCOS
Clay content - 3 to 10 percent
Rock fragments - 0 to 5 percent stones, 0 to 15 percent cobbles, 35 to 75 percent gravel and 35 to 75 percent total
Reaction - moderately acid or slightly acid
COMPETING SERIES: These are the Cloudyway and Staircase series. Cloudyway soils typically have O horizons and are dry 60 to 90 consecutive days following the summer solstice (xeric soil moisture regime). Staircase soils have redox features above 60 inches (moderately well drained) and are dry 60 to 90 consecutive days following the summer solstice (xeric soil moisture regime).
GEOGRAPHIC SETTING: Boise soils are gently or moderately sloping on alluvial fans in valleys and canyons at elevations of 2,550 to 3,350 feet. Slopes range from 3 to 8 percent. These soils formed in alluvium from granitic rocks. The average annual precipitation ranges from 13 to 15 inches. The average annual temperature ranges from 50 to 51 degrees F. Frost-free period is 140 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bissell, Jasseek, and Piercepark soils. These soils have argillic horizons. Bissell soils are on fan remnants, Jasseek soils are on relict lake terraces and Piercepark soils are on hill footslopes.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; slow runoff; moderately rapid permeability.
USE AND VEGETATION: Boise soils are used mainly for irrigated hayland/pastureland. Some areas are used for rangeland. Native vegetation is basin big sagebrush, antelope bitterbrush, bluebunch wheatgrass and Thurber needlegrass.
DISTRIBUTION AND EXTENT: Southwestern Idaho. MLRA11. Boise 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: Boise soils originally had class II or III stoniness, but the surface stones and cobbles have been removed in most places to allow for cultivation.
Diagnostic horizons and features recognized in this pedon:
Mollic epipedon - zone from 0 to 36 inches (Ap1, Ap2, A, Bw and BC horizons)
Irregular decrease in organic carbon content - zone from 15 to 60 inches (Bw, BC, C1 and C2 horizons)
Particle-size control section - zone from 10 to 40 inches
Soil moisture regime - aridic bordering on xeric
These soils are drier than other Xerolls in the region under similar precipitation due to low AWC, exposure and extended period of high evapotranspiration.