LOCATION NIGHTHAWK WAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Calcidic Haploxerolls
TYPICAL PEDON: Nighthawk extremely stony loam, range. (Colors are for dry soil unless otherwise noted.)
A1--0 to 4 inches; grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; slightly hard, friable, slightly sticky, slightly plastic; many roots; 3 percent stones, 5 percent gravel; neutral (pH 7.0); abrupt smooth boundary. (3 to 5 inches thick)
A2--4 to 8 inches; grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; weak thick platy and weak coarse prismatic structure; slightly hard, friable, slightly sticky and slightly plastic; many roots; few fine pores; 3 percent stones, 5 percent gravel; neutral (pH 7.2); clear smooth boundary. (3 to 5 inches thick)
Bw1--8 to 13 inches; brown (10YR 5/3) gravelly loam, dark brown (10YR 3/3) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many roots; few medium pores; 25 percent gravel; slightly alkaline (pH 7.4); clear smooth boundary. (4 to 6 inches thick)
Bw3--13 to 22 inches; light yellowish brown (10YR 6/4) very gravelly loam, brown (10YR 4/3) moist; massive slightly hard, friable, slightly sticky and slightly plastic; common roots; few medium pores; 55 percent gravel; slightly alkaline (pH 7.6); abrupt wavy boundary. (8 to 10 inches thick)
Bk1--22 to 32 inches; pale yellow (2.5Y 7/4) very gravelly loam, light olive brown (2.5Y 5/4) moist; massive; hard, friable, slightly sticky and slightly plastic; common roots; few medium pores; 1 percent stones and cobbles, 55 percent gravel; thick calcium carbonate coatings on undersides of gravel, stones, and cobbles; strongly effervescent; moderately alkaline (pH 8.0); abrupt wavy boundary. (9 to 11 inches thick)
Bk2--32 to 60 inches; pale yellow (2.5Y 8/4) very gravelly coarse sandy loam, light yellowish brown (2.5Y 6/4) moist; massive; hard, friable, nonsticky and nonplastic; weakly cemented in 60 percent gravel; thin and thick calcium carbonate coatings on gravel, cobbles, and stones; numerous threads and masses of calcium carbonate; violently effervescent; moderately alkaline (pH 8.4).
TYPE LOCATION: Okanogan County, Washington; 100 feet east and 5 feet south of the NW corner of the SW1/4 NE1/4 section 13, T.37N., R.26E., WM.
RANGE IN CHARACTERISTICS: The mean annual temperature is 48 to 54 degrees F. The soils are neutral to moderately alkaline. Depth to secondary carbonates is 18 to 40 inches. Solum thickness is 18 to 26 inches. Rock fragments in the soil range from 5 to 60 percent and average 35 to 50 percent in the particle size control section.
The A horizon has value of 4 or 5 dry and 2 or 3 moist.
The Bw horizon has value of 5 or 6 dry and 3 or 4 moist. It is silt loam, loam or gravelly or very gravelly silt loam or loam.
The Bk horizon has hue of 2.5Y or 10YR, value of 6 through 8 dry, 5 or 6 moist, and chroma of 2 through 4 moist and dry. It is very gravelly coarse sandy loam, very gravelly loam, stony sandy loam or stony loam.
COMPETING SERIES: This is the Peshastin series. Peshastin soils average more than 50 percent rock fragments in the control section.
GEOGRAPHIC SETTING: Nighthawk soils are on nearly level to steep topography st elevations of 700 to 2,500 feet. They formed in glacial till of mixed mineralogy over indurated shaley metasediments. These soils occur in a continental climate. The annual precipitation is 8 to 11 inches; the mean annual temperature is 50 degrees F.; and the frost free season ranges from 145 to 178 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cashmont, Conconully, Newbon, and Vallan soils. Cashmont, Conconully, and Newbon soils have coarse, loamy control sections. Vallan soils have a lithic contact within 20 inches of the surface.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderate permeability.
USE AND VEGETATION: Irrigated orchards, hay, pasture, and range. Native vegetation is Sandberg bluegrass, dropseed, needlegrass, and threeawn grass.
DISTRIBUTION AND EXTENT: North central Washington. The series is moderately extensive.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Okanagan County, Washington, 1972.
REMARKS: These soils were classified as Brown soils.