LOCATION TOMBEALL IDEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Cumulic Haploxerolls
TYPICAL PEDON: Tombeall silt loam -- on an nearly level slope at 815 feet elevation in a cultivated field. When described on September 4, 1985, the soil was moist to 35 inches and saturated below. (Colors are for dry soil unless otherwise stated).
Ap--0 to 7 inches; dark grayish brown (10YR 4/2) silt loam, black (10YR 2/1) moist; moderate medium and fine granular structure; hard, firm, slightly sticky and slightly plastic; many fine and very fine roots; common fine, very fine, and medium tubular pores; 5 percent gravel; neutral (pH 7.2); clear smooth boundary.
A1--7 to 17 inches; dark grayish brown (10YR 4/2) silt loam, black (10YR 2/1) moist; weak medium prismatic structure parting to weak medium subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; common fine and very fine roots; common very fine, fine, and medium tubular pores; 5 percent gravel; neutral (pH 7.2); clear smooth boundary.
A2--17 to 28 inches; dark grayish brown (10YR 4/2) sandy loam, very dark grayish brown (10YR 3/2) moist; common fine distinct strong brown (7.5YR 4/6) moist mottles; weak coarse prismatic structure; slightly hard, friable, slightly sticky and nonplastic; common fine and very fine roots; common very fine, fine, and medium tubular pores; 5 percent gravel; neutral (pH 7.2); abrupt smooth boundary. (combined thickness of the A horizons is 20 to 35 inches)
2C1--28 to 35 inches; brown (10YR 4/3) very gravelly sandy loam, very dark grayish brown (10YR 3/2) moist; common fine distinct strong brown (7.5YR 4/6) moist mottles; massive; slightly hard, very friable, nonsticky and nonplastic; few very fine roots; many very fine and fine irregular pores; 40 percent gravel, 10 percent cobbles; neutral (pH 7.2); gradual smooth boundary. (2 to 14 inches thick)
2C2--35 to 60 inches; grayish brown (10YR 5/2) extremely gravelly sandy loam, very dark grayish brown (10YR 3/2) moist; massive; slightly hard, very friable, nonsticky and nonplastic; many fine and very fine irregular pores; 60 percent gravel, 20 percent cobbles; neutral (pH 7.0).
TYPE LOCATION: Nez Perce County, Idaho; about 1 mile south of Spalding, about 1,250 feet south and 100 feet east of the northwest corner of section 26, T. 36 N., R. 4 W. Latitude - 46 degrees, 26 minutes, 20 seconds north; Longitude - 116 degrees, 48 minutes, 40 seconds west. USGS quadrangle - Lapwai.
RANGE IN CHARACTERISTICS:
Thickness of mollic epipedon - 20 to 35 inches Depth to mottles - 12 to 30 inches Depth to seasonal water table - 12 to 30 inches Solum thickness - 20 to 35 inches Average annual soil temperature - 54 to 56 degrees F
Particle-size control section (weighted averages) Clay content - 11 to 16 percent Coarse fragment content - 15 to 35 percent
A horizon Value - 3 or 4 dry, 2 or 3 moist Chroma -1 or 2, dry or moist Reaction - neutral or mildly alkaline
A2 and A3 horizons Value - 3 or 4 dry, 2 or 3 moist Chroma - 1 or 2, dry or moist Textures - SIL, SL, L Gravel content - 0 to 15 percent Clay content - 15 to 20 percent Reaction - neutral or mildly alkaline
2C1 horizon Value - 3 or 4 dry Chroma - 2 or 3, dry or moist Textures - GRV-SL, GRV-L Coarse fragment content - 40 to 60 percent Reaction - neutral or mildly alkaline
2C2 horizon Value - 3 through 5 dry Chroma - 2 or 3, dry or moist Textures - GRX-SL, GRX-L Coarse fragment content - 65 to 90 percent Reaction - neutral or mildly alkaline
COMPETING SERIES: These are the Coxlake, Endersby, Evans, Lapwai(T), Leavenworth, Narcisse, Okanogan, Patit Creek, Pleasant View, Plinco(T), Poween, Redola, and Threecreeks(T) series. Coxlake and Narcisse soils have annual soil temperatures of 47 to 50 degrees F., and have less than 20 percent coarse fragments in the lower control section. Endersby, Evans, Lapwai, Leavenworth, Okanogan, and Patit Creek soils lack redoximorphic concentrations above 30 inches. Lapwai and Pleasant View soils are calcareous in the lower part of the control section. Plinco and Threecreeks soils have average annual soil temperature of less than 54 degrees F. Poween soils have less than 15 percent coarse fragments in the control section and are moderately or strongly alkaline throughout. Redola soils are calcareous throughout.
GEOGRAPHIC SETTING: Tombeall soils are on low terraces and floodplains. Slopes range from 0 to 4 percent. These soils formed in loamy alluvium from mixed sources over gravelly alluvium from basalt. Elevations range from 800 to 1,200 feet. The average annual precipitation is 16 to 22 inches, the average annual temperature is 52 to 54 degrees F, and the frost-free period is 160 to 190 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Lapwai series and the Bridgewater series. Bridgewater soils are well drained, loamy-skeletal, and are on higher terraces. Lapwai soils are on higher terraces.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow runoff; moderate permeability. These soils are subject to rare or occasional periods of flooding.
USE AND VEGETATION: These soils are used for cropland and pasture. Native vegetation is mainly willow, tufted hairgrass, sedge, slender wheatgrass, and cinquefoil.
DISTRIBUTION AND EXTENT: This soil is of small extent in north central Idaho.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Nez Perce County, Idaho 1995.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon (Cumulic feature) - The zone from the surface to 35 inches (the Ap, A1, and A2 horizons).
Particle-size control section - The zone from 10 to 40 inches (part of the A1, the A2, the 2C1, and part of the 2C2 horizons).