LOCATION HATWAI IDEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Typic Natrixerolls
TYPICAL PEDON: Hatwai silt loam -- on a convex northwest facing slope of 6 percent at 1,780 feet elevation in a cultivated field. When described on September 14, 1982, the soil was dry to 26 inches and moist below. (Colors are for dry soil unless otherwise stated).
Ap1--0 to 4 inches; dark grayish brown (10YR 4/2) silt loam, black (10YR 2/1) moist; weak medium subangular blocky structure parting to weak medium granular; soft, friable, slightly sticky and slightly plastic; common very fine and fine roots; many very fine tubular pores; slightly acid (pH 6.1); abrupt smooth boundary.
Ap2--4 to 13 inches; dark grayish brown (10YR 4/2) silt loam, black (10YR 2/1) moist; weak medium and thick platy structure; hard, firm, slightly sticky and slightly plastic; common very fine and fine roots; many very fine tubular pores; slightly acid (pH 6.2); clear smooth boundary. (Combined thickness of the Ap horizons is 4 to 13 inches)
E--13 to 21 inches; brown (10YR 5/3) silt loam, dark brown (10YR 4/3) moist; weak medium and coarse subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine roots; many very fine and fine tubular pores; slightly alkaline (pH 7.5); abrupt smooth boundary. (0 to 8 inches thick)
Btn--21 to 26 inches; brown (10YR 4/3) silt loam, dark brown (10YR 3/3) moist; strong medium and coarse prismatic structure; very hard, firm, moderately sticky and moderately plastic; common very fine and fine roots; many very fine and fine tubular pores; few distinct dark grayish brown (10YR 4/2) clay films on faces of peds; common distinct skeletans on faces of peds; common very dark grayish brown (10YR 3/2) organic matter coats on faces of peds; moderately alkaline (pH 8.0); clear smooth boundary. (4 to 15 inches thick)
Btkn--26 to 36 inches; brown (10YR 5/3) silt loam, dark brown (10YR 4/3) moist; weak medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; many very fine and fine roots; many very fine and fine tubular pores; common distinct clay films on faces of peds; few distinct skeletans on faces of peds; few organic coats on faces of peds; strongly effervescent; lime in many fine seams and filaments; strongly alkaline (pH 8.8); clear smooth boundary. (0 to 14 inches thick)
Btk--36 to 50 inches; brown (10YR 5/3) silt loam, dark yellowish brown (10YR 4/4) moist; weak medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; few very fine and fine roots; many very fine and fine tubular pores; few distinct patchy clay films on faces of peds; strongly effervescent; lime in common fine seams and filaments; strongly alkaline (pH 9.0); gradual smooth boundary. (8 to 18 inches thick)
Btkb--50 to 66 inches; yellowish brown (10YR 5/4) silt loam, dark yellowish brown (10YR 4/4) moist; moderate fine and medium prismatic structure; hard, friable, moderately sticky and moderately plastic; many very fine and fine tubular pores; common distinct discontinuous clay films lining pores; slightly effervescent; lime disseminated and in few fine filaments; strongly alkaline (pH 8.6).
TYPE LOCATION: Nez Perce County, Idaho; about 5 miles east of the Lewiston Orchards, about 2,575 feet south and 2,600 feet east of the northwest corner of section 15, T.35 N., R. 4 W. Latitude - 46 degrees, 22 minutes, 38 seconds N.; Longitude - 116 degrees, 49 minutes, 20 seconds W. USGS quadrangle - Lapwai.
RANGE IN CHARACTERISTICS:
Thickness of mollic epipedon - 10 to 18 inches (less than 1 percent organic matter below 18 inches) Depth to natric horizon - 15 to 21 inches Depth to secondary carbonates - 20 to 35 inches Days dry in moisture control section - 75 to 90 Average annual soil temperature - 51 to 54 degrees F.
A horizon Value - 4 or 5 dry, 2 or 3 moist Chroma - 1 or 2, dry or moist Reaction - slightly acid or neutral
E horizon Value - 5 or 6 dry Reaction - neutral or slightly alkaline
Btn horizon Value - 5 or 6 dry, 3 or 4 moist Chroma - 3 or 4, dry or moist Textures - SIL, SICL Clay content - 22 to 34 percent Sodium absorption ratio - 13 to 20 Exchangeable sodium - 30 to 55 percent Reaction - moderately alkaline or strongly alkaline
Btkn horizon Value - 5 or 6 dry, 3 or 4 moist Chroma - 3 or 4, dry or moist Textures - SIL, SICL Clay content - 22 to 34 percent Sodium absorption ratio - 20 to 40 Exchangeable sodium - 30 to 55 percent Reaction - moderately alkaline or strongly alkaline
Btk and Btkb horizons Value - 5 or 6 dry, 4 or 5 moist Chroma - 3 or 4, dry or moist Textures - SIL, SICL Clay content - 16 to 30 percent Reaction - moderately alkaline through very strongly alkaline
COMPETING SERIES: These are the Fridlo and Spofford series. Fridlo soils have average annual soil temperature of less than 51 degrees F. Spofford soils are dry for 90 to 105 days.
GEOGRAPHIC SETTING: Hatwai soils are on hills on plateaus and canyons at elevations of 1,500 to 2,200 feet. Slopes range from 1 to 65 percent. These soils formed in loess. The average annual temperature ranges from 49 to 52 degrees F., with an average annual precipitation of 15 to 18 inches. The average frost-free period is from 150 to 170 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Broadax and Bryden series. Broadax soils do not have natric horizons and are on concave slopes and north and east facing slopes. Bryden soils are moderately deep to a duripan and are on convex south and west facing slopes.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; slow permeability.
USE AND VEGETATION: These soils are used for cropland. Potential natural vegetation is mainly bluebunch wheatgrass, Idaho fescue, arrowleaf balsamroot, and silky lupine.
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, 1996.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from the surface to 13 inches (the Ap1 and Ap2 horizons).
Natric horizon - the zone from 21 to 36 inches (Btn and Btkn horizons).
Secondary carbonate accumulation - the zone from 26 to 66 inches (the Btkn, Btk and Btkb horizons).
Particle-size control section - the zone from 21 to 40 inches (Btn, Btkn, and part of the Btk horizons).
ADDITIONAL DATA: See NSSL Pedon No. 83P 193.