LOCATION NOPLA IDEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive Typic Palecryolls
TYPICAL PEDON: Nopla silt loam, supporting a Douglas fir/pinegrass plant community, pinegrass phase, woodland; on a concave slope of 8 percent on a south aspect; about 6,280 feet elevation. (Colors are for dry soil unless otherwise noted.)
Oi--0 to 2 inches; forest litter of needles, twigs and leaves; abrupt smooth boundary. (0 to 2 inches thick)
A1--2 to 6 inches; brown (10YR 5/3) silt loam, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky and weak fine granular structure; soft, very friable, nonsticky and slightly plastic; many very fine, common fine and medium, and few coarse roots; many very fine irregular and few very fine tubular pores; 5 percent pebbles, trace of cobbles and stones; slightly acid (pH 6.4); clear smooth boundary. (2 to 8 inches thick)
A2--6 to 16 inches; brown (10YR 5/3) silt loam, dark brown (10YR 3/3) moist; moderate coarse subangular blocky structure; slightly hard, very friable, nonsticky and slightly plastic; common very fine and fine and few medium and coarse roots; many very fine tubular pores; 5 percent pebbles, trace of cobbles and stones; slightly acid (pH 6.5); clear wavy boundary. (8 to 12 inches thick)
E--16 to 26 inches; pale brown (10YR 6/3) silt loam, brown (10YR 4/3) moist; moderate very coarse subangular blocky structure; hard, very friable, nonsticky and slightly plastic; common very fine and fine and few medium and coarse roots; many very fine and few fine and medium tubular pores; 5 percent pebbles, trace of cobbles and stones; slightly acid (pH 6.1); clear wavy boundary. (4 to 30 inches thick)
Bt/E--26 to 41 inches; yellowish brown (10YR 5/4) (B material) and pale brown (10YR 6/3) (E material) gravelly silt loam, dark yellowish brown (10YR 4/4) (B material) and brown (10YR 5/3) (E material) moist; 60 percent B material and 40 percent E material; moderate coarse subangular blocky structure parting to moderate fine subangular blocky (B material) and weak fine subangular blocky (E material); hard, friable, slightly sticky and slightly plastic; common very fine, few fine and medium roots; many very fine and common fine tubular pores; common distinct clay films on rock fragments, faces of peds and lining pores of B material; few 1/4 to 3/4 inch thick lamellae; 10 percent pebbles, 5 percent cobbles, trace of stones; slightly acid (pH 6.3); gradual wavy boundary. (4 to 19 inches thick)
2Bt1--41 to 56 inches; brown (10YR 5/3) very cobbly loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure parting to weak fine subangular blocky; hard, friable, slightly sticky and moderately plastic; few very fine and fine roots; many very fine and common fine tubular pores; many distinct clay films on rock fragments and few distinct clay films on faces of peds and lining pores; many distinct uncoated silt grains on faces of peds; 25 percent pebbles, 30 percent cobbles, trace of stones; slightly acid (pH 6.2); clear smooth boundary. (5 to 20 inches thick)
3Bt2--56 to 70 inches, brown (7.5YR 5/2) silt loam, brown (7.5YR 4/2) moist; strong medium subangular blocky structure parting to moderate very fine angular blocky; hard, very friable, slightly sticky and slightly plastic; few very fine and fine roots; common fine and few medium tubular pores; few faint clay films on rock fragments, faces of peds and lining pores; many distinct uncoated silt grains on faces of peds; common 1/4 to 3/4 inch thick faint lamellae; 10 percent pebbles, trace of cobbles; slightly acid (pH 6.3); clear smooth boundary. (10 to 20 inches thick)
3Bt3--70 to 77 inches, light brown (7.5YR 6/3) silt loam, brown (7.5YR 4/3) moist; strong coarse subangular blocky structure parting to moderate fine subangular blocky; hard, friable, slightly sticky and moderately plastic; common fine and few medium tubular pores; many distinct clay films on rock fragments, on faces of peds and lining pores; 10 percent pebbles, trace of cobbles; slightly acid (pH 6.3).
TYPE LOCATION: Fremont County, Idaho; about 15 miles north of Ashton; about 2,600 feet east and 1,350 feet south of the northwest corner of sec. 24, T.11 N., R.41 E. Latitude - 44 degrees, 33 minutes, 58 seconds North; Longitude - 111 degrees, 16 minutes, 15 seconds West.
RANGE IN CHARACTERISTICS:
Mollic epipedon thickness - 10 to 20 inches
Depth to argillic horizon - 24 to 40 inches
Clay content in the particle-size control section, weighted average - 18 to 27 percent
Rock fragments in the particle-size control section, weighted average - 5 to 35 percent
Reaction - moderately acid to neutral
Volcanic glass content - 5 to 30 percent in the 0.02 to 2.0 mm fraction
Ammonium oxalate extractable Al plus Fe - 0.1 to 1.0 percent
Phosphate retention - 20 to 50 percent
Base saturation - 60 to 100 percent
Mean annual soil temperature - 37 to 42 degrees F.
Mean summer soil temperature - 42 to 46 degrees F.
Moisture control section - between 4 and 12 inches; dry throughout the moisture control section for 30 to 45 consecutive days during the four months following the summer solstice
A horizons
Hue - 7.5YR or 10YR
Value - 3 to 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
E horizons
Hue - 7.5YR or 10YR
Value - 6 or 7 dry, 4 or 5 moist
Chroma - 3 or 4 dry or moist
Texture, less than 2 mm fraction - SIL or L
Clay content - 7 to 14 percent
Rock fragments - 0 to 30 percent
Pebbles - 0 to 20 percent
Cobbles - 0 to 5 percent
Stones - 0 to 5 percent
Bt/E horizon
Hue - 7.5YR or 10YR
Value - E material - 6 or 7 dry, 4 or 5 moist
B material - 5 or 6 dry, 3 or 4 moist
Chroma - 3 or 4 dry or moist
Texture, less than 2 mm fraction - SIL or L
Clay - 16 to 27 percent
Rock fragments - 5 to 25 percent
Pebbles - 5 to 25 percent
Cobbles - 0 to 10 percent
Stones - 0 to 5 percent
Percentage of E material ranges from 15 to 50 percent
Percentage of B material ranges from 50 to 85 percent
2Bt horizon
Hue - 7.5YR or 10YR
Value - 4 to 6 dry, 3 or 4 moist
Chroma - 2 to 4 dry or moist
Texture, less than 2 mm fraction - L or CL
Clay - 20 to 35 percent
Rock fragments - 20 to 60 percent
Pebbles - 10 to 30 percent
Cobbles - 10 to 40 percent
Stones - 0 to 5 percent
3Bt horizons
Hue - 7.5YR or 10YR
Value - 4 to 6 dry, 3 or 4 moist
Chroma - 2 to 4 dry or moist
Texture, less than 2 mm fraction - SIL or L
Clay - 18 to 27 percent
Rock fragments - 5 to 35 percent
Pebbles - 5 to 35 percent
Cobbles - 0 to 20 percent
Stones - 0 to 5 percent
COMPETING SERIES: This is the Alpon series. Alpon soils average 27 to 35 percent clay in the upper 20 inches of the argillic horizon.
GEOGRAPHIC SETTING: The Nopla soils occur on shield volcanos and ground moraines. Slopes are from 2 to 15 percent. The soil formed in local alluvium derived from loess, volcanic ash and igneous rocks. Elevations range from 6,000 to 7,000 feet. The mean annual precipitation is about 20 to 30 inches. The mean annual air temperature is about 35 to 40 degrees F. The frost-free season is 30 to 70 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Koffgo and Vadnais series. Koffgo soils occur on adjacent volcanic shields and plateaus. They have ochric epipedons over cambic horizons and greater than 35 percent rock fragments throughout the particle-size control section. Vadnais soils occur on adjacent basalt plains. They are less than 24 inches deep to the top of the argillic horizon and are 20 to 40 inches deep over hard bedrock.
DRAINAGE AND PERMEABILITY: Well drained; slow to moderate runoff; moderately slow permeability.
USE AND VEGETATION: Nopla soils are used for recreation, woodland, wildlife habitat and livestock grazing. The potential native vegetation is a Douglas fir/pinegrass plant association, pinegrass phase.
DISTRIBUTION AND EXTENT: Southeastern Idaho. The soil is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Targhee National Forest, Fremont County, Idaho, 1997.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from the mineral soil surface to 14 inches (the A1 and A2 horizons)
Argillic horizon - the zone from 24 to 75 inches (the Bt/E, 2Bt1, 3Bt2, and 3Bt3 horizons)
Particle-size control section - the zone from 24 to 44 inches (the Bt/E and portion of the 2Bt1 horizon)
Moisture regime - udic