LOCATION LAPWAI IDEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Cumulic Haploxerolls
TYPICAL PEDON: Lapwai silt loam -- on a 1 percent slope at 820 feet elevation in a cultivated field. When described on September 4, 1985 the soil was dry to 58 inches and moist below. (Colors are for dry soil unless otherwise stated).
Ap--0 to 9 inches; dark grayish brown (10YR 4/2) silt loam, very dark gray (10YR 3/1) moist; weak coarse granular structure parting to moderate fine granular; hard, firm, sticky and slightly plastic; many very fine and fine roots; many very fine and common fine tubular pores; neutral (pH 6.8); abrupt smooth boundary. (5 to 10 inches thick)
Bw1--9 to 16 inches; grayish brown (10YR 5/2) silt loam, very dark gray (10YR 3/1) moist; weak fine and medium prismatic structure; slightly hard, friable; sticky and slightly plastic; many very fine and fine and common medium roots; many very fine and common fine tubular pores; neutral (pH 7.0); gradual smooth boundary.
Bw2--16 to 28 inches; brown (10YR 5/3) silt loam, very dark grayish brown (10YR 3/2) moist; weak medium prismatic structure; soft, very friable, slightly sticky and nonplastic; common very fine, fine, and medium roots; common very fine, fine, and medium tubular pores; neutral (pH 7.1); gradual smooth boundary. (combined thickness of the Bw1 and Bw2 horizons is 14 to 30 inches)
Bw3--28 to 35 inches; pale brown (10YR 6/3) loam, dark brown (10YR 3/3) moist; weak coarse prismatic structure; soft, very friable, nonsticky and nonplastic; common very fine, fine, and medium roots; common very fine and fine tubular pores; neutral (pH 7.3); abrupt wavy boundary. (5 to 10 inches thick)
2Bk--35 to 60 inches; brown (10YR 5/3) very gravelly sandy loam, dark brown (10YR 3/3) moist; single grain; loose; common very fine roots; many very fine through coarse irregular pores; 30 percent gravel, 20 percent cobbles; secondary lime deposits on all surfaces; strongly effervescent (2 percent calcium carbonate equivalent); moderately alkaline (pH 8.0).
TYPE LOCATION: Nez Perce County, Idaho; about 1 mile south of Spalding; about 1,250 feet south and 50 feet west of the northeast corner of section 27, T. 36 N., R. 4 W.; USGS Lapwai topographic quadrangle; Latitude - 46 degrees, 26 minutes, 20 seconds N.; Longitude - 116 degrees, 48 minutes, 43 seconds W.
RANGE IN CHARACTERISTICS
Thickness of mollic epipedon - 20 to 30 inches Depth to secondary carbonates - 30 to 40 inches Average annual soil temperature - 53 to 55 degrees F Hazard of flooding - rare
Particle-size control section (weighted averages) Clay content - 10 to 18 percent Coarse fragment content - 2 to 25 percent
A horizon Value - 2 or 3 moist Chroma - 2 or 3 dry, 1 through 3 moist Reaction - neutral or slightly alkaline
Bw horizon Value - 3 through 6 dry, 2 or 3 moist Chroma - 2 or 3 dry, 1 through 3 moist Textures - SIL, L, GR-L Clay content - 10 to 20 percent Coarse fragment content - 0 to 20 percent Reaction - neutral or slightly alkaline
2Bk horizon Textures - GRV-SL, GRV-L Coarse fragment content - 35 to 50 percent Calcium carbonate equivalent - 1 to 5 percent
COMPETING SERIES: These are the Coxlake, Endersby, Evans, Leavenworth, Narcisse, Okanogan, Patit Creek, Pleasant View, Plinco(T), Poween, Redola, Threecreeks(T), and Tombeall(T) series. Coxlake, Endersby, Narcisse, Patit Creek, Plinco, and Tombeall soils are noncalcareous throughout. Endersby, Narcisse, Plinco, and Tombeall soils have redoximorphic concentrations above 60 inches. Evans and Leavenworth soils do not have very gravelly textures in the lower part of the series control section. Okanogan, Poween, and Threecreeks soils do not have a Bk horizon above 40 inches. Pleasant View soils have a Bk horizon with 12 to 25 percent calcium carbonate equivalent. Redola soils are calcareous throughout.
GEOGRAPHIC SETTING: Lapwai soils are on stream terraces. Slopes range from 1 to 4 percent. These soils formed in loamy alluvium from mixed sources over gravelly alluvium predominantly from basalt. Elevations are 750 to 1,200 feet. Average annual precipitation is 16 to 20 inches, average annual temperature is 51 to 53 degrees F., and the frost free period is 160 to 185 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Chard and Tombeall soils. Chard soils are on higher dissected terraces and do not have a thick mollic epipedon. Tombeall soils are on lower terraces and floodplains, do not have a Bk horizon, and have redoximorphic concentrations within 60 inches.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderate permeability; rare flood hazard in winter and spring.
USE AND VEGETATION: These soils are used for cropland, hayland and pasture. Main crops are wheat, barley, and peas. Native vegetation is mainly bluebunch wheatgrass, wildrye, slender wheatgrass, and woods rose.
DISTRIBUTION AND EXTENT: North central Idaho. This soil is of small extent.
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 - The zone from the surface to 28 inches (Ap, Bw1, and Bw2 horizons).
Cambic horizon - The zone from 28 to 35 inches (Bw3 horizon).
Accumulations of secondary carbonates - The zone from 35 to 60 inches (2Bk horizon).
Particle-size control section - The zone from 10 to 40 inches (most of the Bw1, the Bw2, Bw3, and part of the 2Bk horizons).