LOCATION ORWIG WAEstablished Series
TAXONOMIC CLASS: Sandy, isotic, frigid Vitrandic Dystroxerepts
TYPICAL PEDON: Orwig sandy loam - woodland. (Colors are for dry soil unless otherwise stated.)
Oe--2 inches to 0; dark brown (10YR 3/3) moist; loose, partially decomposed organic litter composed of needles, leaves, twigs, bark, and cones; abrupt smooth boundary. (1/2 to 3 inches thick)
E--0 to 1/4 inch; light gray (2.5Y 7/2) very fine sandy loam (volcanic ash) grayish brown (2.5Y 5/2) moist, weak very fine granular structure; soft, very friable, nonsticky and nonplastic; common roots, slightly acid (pH 6.4) abrupt smooth boundary. (1 to 1 inch thick)
Bw1--1/4 to 4 inches; light yellowish brown (10YR 6/4) sandy loam, dark yellowish brown (10YR 4/4) moist; weak fine and medium granular structure; soft, very friable, slightly sticky and nonplastic; many very fine, fine, common medium, and few coarse roots; few very fine and fine discontinuous pores; slightly acid dark yellowish brown (10YR 4/4) moist; weak fine and medium granular structure; soft, very friable, slightly sticky and nonplastic; many very fine, fine, common medium, and few coarse roots; few very fine and fine discontinuous pores; slightly acid (pH 6.2); clear wavy boundary. (3 to 6 inches thick)
Bw2--4 to 9 inches; light yellowish brown (10YR 7/4) sandy loam, dark yellowish brown (10YR 4/4) moist; weak fine and medium granular structure; soft, very friable, slightly sticky and nonplastic; many very fine, fine, few medium and coarse roots; few very fine and fine discontinuous pores; slightly acid (pH 6.2); clear wavy boundary. (4 to 6 inches thick)
BC--9 to 18 inches; very pale brown (10YR 7/4) sandy loam, yellowish brown (10YR 5/4) moist; weak fine and medium subangular blocky structure; soft, very friable, slightly sticky and nonplastic; many very fine, fine, and few medium and coarse roots; few very fine and fine discontinuous pores; 5 percent angular granitic pebbles; slightly acid (pH 6.4); clear wavy boundary. (6 to 10 inches thick)
C1--18 to 27 inches; very pale brown (10YR 8/3) loamy sand, pale brown 910YR 6/3) moist; common fine and medium distinct stainings of strong brown (7.5Y
C2--27 to 60 inches; very pale brown (10YR 8/3) gravelly sand, pale brown (10YR 6/3) moist; few fine and medium distinct stainings of strong brown (7.5YR 5/6) moist; single grain; loose; few very fine and fine roots; 15 percent angular granitic pebbles; slightly acid (pH 6.4).
TYPE LOCATION: Pend Oreille County, Washington; 1,200 feet west and 1,800 feet south of the northeast corner of section 11, T. 35 N., R. 42 E., WM.
RANGE IN CHARACTERISTICS: The soil is moist in all horizons but is dry in all parts between 8 and 24 inches for 60 to 75 consecutive days following the summer solstice. The mean annual soil temperature at 20 inches ranges from 45 to 47 degrees F. Weighted average of angular, granitic pebbles in the control section range from 5 to 20 percent. Sand in the control section is dominantly angular and granitic. The soil is slightly acid or neutral throughout.
The E horizon, when present has hue of 2.5Y or 10YR, value of 6 or 7 when dry, 4 or 5 when moist, and chroma of 1 or 2 dry and moist..
The Bw has value of 6 or 7 dry, 3 through 5 moist, and chroma of 3 or 4 dry or moist. It has very fine to medium subangular blocky structure. Pebble content ranges from 0 to 10 percent.
The BC horizon has value of 7 or 8 dry, 5 or 6 moist, and chroma of 3 or 4 dry or moist. It is sandy loam or loamy sand. Angular granitic pebbles range from 5 to 10 percent.
The C horizon has hue of 10YR or 2.5Y, value of 7 or 8 dry, 5 or 6 moist, and chroma of 2 through 4 dry or moist. Texture is sand, gravelly sand, or loamy sand. Angular granitic pebbles range from 10 to 25 percent. It has few to common fine and medium distinct stainings in most pedons.
COMPETING SERIES: This is the Kaniksu and the similar Inkler, Merkel, Scrabblers, and Thout series. Inkler, Merkel, and Thout soils are loamy-skeletal. Kaniksu soils have rounded pebbles of mixed lithology and dominantly rounded sand grains of mixed lithology in the particle-size control section. Scrabblers soils have a mantle of volcanic ash 7 to 14 inches thick with 30 to 60 percent volcanic glass and acid-oxalate of 1.0 to 2.0 percent.
GEOGRAPHIC SETTING: Orwig soils are on outwash terraces and terrace escarpments at elevations of 2,000 to 4,500 feet. Slopes are smooth or undulating and range from 0 to 65 percent. Average annual precipitation is 25 to 35 inches. Average annual air temperature is 44 degrees F., average frost-fee season (32F) is 75 to 105 days, average growing season (28F) is 90 to 110 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bonner, Kegel, Kiehl, Manley, Mobate, Moscow, Newbell, and the competing Merkel soils. Bonner soils are coarse-loamy over sandy or sandy-skeletal. Kegel soils have a mollic epipedon. Kiehl soils are sandy-skeletal. Manley soils are medial over loamy-skeletal and are cryic. Merkel and Newbell soils are loamy-skeletal. Mobate soils are loamy-skeletal and are 10 to 20 inches deep. Moscow soils are coarse-loamy and are 20 to 40 inches deep.
DRAINAGE AND PERMEABILITY: Well drained; slow to very rapid runoff; moderately rapid permeability.
USE AND VEGETATION: Used for grazable woodland, watershed, wildlife habitat, and recreation. Overstory vegetation includes Douglas-fir, ponderosa pine, lodgepole pine with an understory of rose, Oregonn-grape, kinnikinnick, pachystima, snowberry, strawberry, and pinegrass.
DISTRIBUTION AND EXTENT: Northeastern Washington. Series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Pend Oreille County Area, Washington, 1981.
REMARKS: Diagnostic horizons and features recognized in this pedon are an ochric epipedon from the mineral surface to 9 inches and a cambic horizon from 9 to 18 inches. The upper 9 inches of this pedon is estimated to have 5 to 20 percent volcanic glass and acid-oxalate extractable aluminum plus one-half of the acid-oxalate extractable iron of 0.4 to 1.0 percnet. This descriptions reflects a change in classification due to Andisols Order from Sandy, mixed, frigid Typic Xerochrepts to Sandy, mixed, frigid Vitrandic Xerochrepts.