LOCATION AHREN WAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Andic Haploxerepts
TYPICAL PEDON: Ahren loam - woodland. (Colors are for dry soil unless otherwise stated.)
Oe--1 1/2 inches to 0; partially decomposed needles, leaves, twigs, bark, and cones; abrupt smooth boundary. (1 to 3 inches thick)
Bw1--0 to 4 inches; yellowish brown (10YR 5/4) loam, dark yellowish brown (10YR 3/4) moist; weak fine and medium granular structure; soft, very friable, slightly sticky, slightly plastic and weakly smeary; many fine and medium common coarse roots; many fine and medium common coarse pores; 5 percent pebbles; neutral (ph 7.0); clear wavy boundary.
Bw2--4 to 12 inches yellowish brown (10YR 5/4) loam, dark yellowish brown (10YR 3/4) moist; weak fine and medium granular structure; soft, very friable, slightly sticky, slightly plastic, and weakly smeary; many fine and medium, and few coarse roots; many fine and medium, and few coarse pores; 10 percent pebbles; neutral (ph 7.0); clear wavy boundary. (combined thickness of the Bw horizon is 7 to 14 inches)
2Bw3--12 to 20 inches; light brownish gray (2.5Y 6/2) gravelly loam, dark grayish brown (2.5Y 4/2) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many fine and medium and few coarse roots; many fine and medium and few coarse pores; 20 percent pebbles; strongly effervescent; moderately alkaline (ph 8.4); clear wavy boundary. (6 to 12 inches)
2Bw4--20 to 30 inches; light brownish gray (2.5Y 6/2) gravelly silty clay loam, dark grayish brown (2.5Y 4/2) moist; moderate fine and medium subangular blocky structure; slightly hard, firm, sticky and plastic; common fine and medium and few coarse roots; common fine and medium and few coarse pores; 25 percent pebbles; strongly effervescent; moderately alkaline (ph 8.4); clear wavy boundary. (6 to 12 inches thick)
2Bw5--30 to 40 inches; light brownish gray (2.5Y 6/2) gravelly silty clay loam; dark grayish brown (2.5Y 4/2) moist; moderate fine and medium subangular blocky structure; hard, firm, sticky and plastic; common fine and medium and few coarse roots; common fine and medium and few coarse pores; 30 percent pebbles; strongly effervescent; moderately alkaline (ph 8.4); clear wavy boundary. (6 to 12 inches thick)
2C--40 to 60 inches; light brownish gray (2.5Y 6/2) gravelly silty clay loam, very dark grayish brown (2.5Y 3/2) moist; massive; hard, firm, sticky and plastic; few fine, medium and coarse roots; few fine, medium and coarse pores; 35 percent pebbles; strongly effervescent; strongly alkaline (ph 8.6).
TYPE LOCATION: Stevens County, Washington; 2,900 feet east and 400 feet south of NW corner of sec. 19, T.39 N.,R. 41 E., WM.
RANGE IN CHARACTERISTICS: The soil is usually moist in all horizons, but is dry in all parts between depths of 4 and 12 inches for 45 to 60 consecutive days during summer and fall. Mean annual soil temperature is 45 to 47 degrees F. The mantle of volcanic ash and loess is 7 to 14 inches thick. The particle size control section has 15 to 35 percent rock fragments by volume. The depth to the 2Bw horizon ranges from 10 to 13 inches.
The A horizon, when present, has chroma of 2 or 3 moist. Texture is loam or silt loam. A thin E horizon fromed in younger volcanic ash is at the surface in some pedons.
The Bw horizon has hue of 10 YR or 7.5YR, value of 5 or 6 dry, 3 or 4 moist and chroma of 3 or 4 moist or dry. Pedons having chroma of 3 have value of 6 dry or 4 moist. It is loam or silt loam. This horizon has 1 to 10 percent rock fragments. It is neutral or mildly alkaline.
The 2Bw horizon has hue of 10 YR, 2.5Y or 5Y, value of 5 or 6 dry, 3 or 4 moist and chroma of 3 or 4 moist or dry. It is loam, clay loam, or silty clay loam with 15 to 35 percent rock fragments. It is slightly to strongly alkaline.
The 2C horizon has hue of 10YR, 2.5Y, or 5Y, value of 5 to 7 when dry and 3 to 5 when moist, and chroma of 2 or 3 when dry or moist. Texture is gravelly or very gravelly; loam, clay loam, or silty clay loam with 15 to 50 percent rock fragments.
COMPETING SERIES: This is the Smackout series. Smackout soils are not calcareous in the Particle-size control section.
GEOGRAPHIC SETTING: Ahren soils are on glaciated foothills and mountains at elevations of 1,800 to 3,800 feet. Slopes are 0 to 65 percent. The soils formed in a mantle of volcanic ash and loess over glacial till from dark colored shaly rock and limestone. The climate is characterized by dry summers and cold, moist winters. Average annual precipitation is 22 to 32 inches. Mean annual temperature is 43 to 45 degrees F. The growing season (28F) is about 90 to 110 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Aits, Huckleberry, Leadpoint, and Waits and the competing Smackout soils. Aits and Waits soils have a coarse-loamy control section. Belzar, Huckleberry, and Leadpoint soils have bedrock at a depth of 20 to 40 inches. Leadpoint soils also have a mollic epipedon and more than 35 percent coarse fragments in the control section.
DRAINAGE AND PERMEABILITY: Well drained; very slow to very rapid runoff; moderately slow permeability.
USE AND VEGETATION: Used mainly for woodland, grazed woodland, and some dryland crops. Land vegetation is mainly Douglas-fir, western larch, western redcedar, western hemlock, grand fir, lodgepole pine and western white pine with an understory of pinegrass, Rocky mt. maple, huckleberry, rose, common snowberry, Oregongrape, creambush oceanspray, pachystima, mallow ninebark, kinnikinnick, thimbleberry, western hazel and ceanothus.
DISTRIBUTION AND EXTENT: Northeastern Washington and possibly northern Idaho. The series is small in extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Stevens County, Washington, l978.
REMARKS: Diagnostic horizons and features recognized in this pedon are an ochric epipedon from the mineral surface to 4 inches and a cambic horizon from 4 to 40 inches. The upper 12 inches is estimated to have a moist bulk density of less than 1.0 g/cc and acid-oxalate extractable aluminum plus one-half of the acid-oxalate extractable iron of more than 1.0 percent.