LOCATION ACKNA WATentative Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Vitrandic Argixerolls
TYPICAL PEDON: Ackna ashy loam - irrigated pasture, on a 2 percent slope at an elevation of 1,600 feet. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 8 inches; brown (10YR 4/3) ashy loam, very dark brown (10YR 2/2) moist; moderate medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many very fine and few medium roots; many very fine irregular pores; 5 percent gravel; neutral (pH 6.9); abrupt smooth boundary. (4 to 10 inches thick)
A--8 to 18 inches; brown (10YR 4/3) ashy loam, very dark grayish brown (10YR 3/2) moist; moderate medium prismatic structure; hard, friable, slightly sticky and slightly plastic; many very fine and few medium roots; many very fine irregular, common very fine tubular and few fine tubular pores; 5 percent gravel; neutral (pH 6.9); clear wavy boundary. (8 to 13 inches thick)
2BAt--18 to 28 inches; brown (10YR 5/3) loam, dark brown (10YR 3/3) moist; moderate coarse prismatic structure parting to moderate medium subangular blocky; hard, firm, slightly sticky and slightly plastic; common very fine roots; many very fine irregular and very fine tubular, and few fine tubular pores; few faint pressure faces on peds and few faint clay bridging in pores; 10 percent gravel; 25 percent very coarse cylindrical cicada cast; neutral (pH 7.0); clear wavy boundary. (8 to 17 inches thick)
3Bt1--28 to 42 inches; dark yellowish brown (10YR 4/4) extremely gravelly sandy clay loam; dark brown (10YR 3/3) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots; many very fine irregular and common very fine tubular pores; few faint pressure faces on peds, common faint clay bridging in pores and common distinct clay films on rock fragments; 45 percent gravel, 15 percent cobbles and 5 percent stones; neutral (pH 7.0).
3Bt2--42 to 55 inches; dark yellowish brown (10YR 4/4) extremely gravelly sandy loam, dark brown (10YR 3/3) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; few very fine roots; many very fine irregular pores; common distinct clay films on rock fragments and common faint clay bridging of sand grains; 40 percent gravel, 20 percent cobbles and 5 percent stones; neutral (pH 6.9). (Combined thickness of 3Bt horizon is 20 to 36 inches)
4C--55 to 60 inches; yellowish brown (10YR 5/4) extremely gravelly loamy sand; brown (10YR 4/3) moist; single grain; loose; pockets of extremely gravelly coarse sand; 45 percent gravel, 20 percent cobbles and 10 percent stones; neutral (pH 6.9).
TYPE LOCATION: Kittitas County, Washington; about 2.5 miles west of Ellensburg; about 2,100 feet west and 1,900 feet south of the northeast corner of section 32, T. 18 N., R. 18 E.; USGS Ellensburg North, Washington topographic quadrangle; Latitude - 47 degrees 00 minutes 33 seconds N. and Longitude - 120 degrees 36 minutes 40 seconds W. (NAD83).
RANGE IN CHARACTERISTICS: The average annual soil temperature at a depth of 20 inches ranges from 47 to 54 degrees F. These soils are usually moist but are dry in the moisture control section for 90 to 100 consecutive days following the summer solstice. Thickness of the mollic epipedon is 25 to 35 inches and includes part of the argillic horizon. The upper 15 to 23 inches has an estimated bulk density of 1.15 to 1.40 grams per cubic centimeter, volcanic glass content of 15 to 25 percent, acid oxalate extractable aluminum plus one-half of acid oxalate extractable iron of .25 to .40 percent, and 15-bar water retention of 5 to 10 percent for air-dried samples. The particle-size control section has 25 to 35 percent clay and averages 15 percent or more fine sand or coarser and 35 to 50 percent rock fragments by volume. Organic matter is estimated to range from 1 to 3 percent in the Ap and A horizons. Depth to an extremely gravelly 3Bt horizon ranges from 20 to 40 inches. Depth to a 4C horizon is 40 to 60 inches.
The Ap horizon has value of 3 or 4 dry, and chroma of 2 or 3 dry, 1 or 2 moist. Reaction is slightly acid or neutral.
The A horizon has value of 3 or 4 dry, 2 or 3 moist, and chroma of 2 or 3 dry, 1 or 2 moist. Texture is ashy loam or ashy silt loam.
The 2BAt horizon has value of 4 or 5 dry, and chroma of 2 or 3, dry or moist.
The 3Bt horizons have value of 4 or 5 dry and chroma of 3 or 4 dry. The 3Bt1 horizon is extremely gravelly clay loam, extremely gravelly loam or extremely gravelly sandy clay loam. The 3Bt2 is extremely gravelly clay loam, extremely gravelly sandy clay loam, or extremely gravelly sandy loam.
The 4C horizon has value of 5 or 6 dry, 3 or 4 moist, and chroma of 3 or 4 dry. It is extremely gravelly loamy sand, extremely gravelly sand, or extremely gravelly coarse sand.
COMPETING SERIES: These are the Blint, Brysill (T), Bunselmeier, Cubhill, Hehe, Hovelton, Lainand, Leidl, McDaniel, Millhouse (T), Nint (T), Norod, Setill (T), and Skooker soils. Blint, Hovelton, Leidl, Nint, and Norod soils are less than 40 inches to a lithic contact. Brysill and Bunselmeier soils have greater than 35 percent rock fragments throughout the BA and argillic horizon. In addition, Bunselmeier soils are 40 to 60 inches to unweathered cinders. Cubhill soils have horizons with greater than 25 percent rock fragments of glacial till origin in the 2AB horizon and greater than 35 percent throughout argillic horizon, and has a mollic epipedon 15 to 25 inches thick. Hehe soils are 20 to 40 inches to weathered bedrock. Lainand soils are 40 to 60 inches to a lithic contact. McDaniel soils have an argillic horizon that extends to 60 inches or more and are dry for 75 to 95 consecutive days. Millhouse soils have 20 to 25 percent clay in the particle-size control section and are 20 to 40 inches to an extremely gravelly loamy sand 3C horizon. Skooker soils are 40 to 60 inches to a paralithic contact. The Setill soils are not competing however have a similar classification except for isotic mineralogy and they are 25 to 35 inches to compact glacial till 3Btd horizons.
GEOGRAPHIC SETTING: Ackna soils are on outwash terraces and alluvial fans and have slopes of 0 to 5 percent. These soils formed in alluvium and loess with an influence of volcanic ash in the surface. Elevation is 1,400 to 2,500 feet. Climate is semiarid with warm, dry summers and cool, moist winters. The mean annual precipitation is 9 to 13 inches. The average January temperature is about 25 degrees F. and the average July temperature is about 69 degrees F. The mean annual temperature is 46 to 52 degrees F. The frost-free season is 130 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Brysill soils and the Brickmill, Nack, Nanum, Opnish and Vanderbilt soils. Brysill soils are on alluvial fans. Brickmill soils are on alluvial fans, are moderately well drained, and have horizons with greater than 35 percent rock fragments above argillic and throughout argillic horizon. Nack soils are on alluvial fans and are moderately or strongly alkaline. Nanum and Opnish soils are on alluvial fans and have more than 35 percent clay in the particle-size control section. Vanderbilt soils are on terraces and alluvial fans and have less than 5 percent rock fragments in the particle-size control section.
DRAINAGE AND PERMEABILITY: Well drained, slow runoff; moderately slow permeability.
USE AND VEGETATION: These soils are used for irrigated cropland, livestock grazing and wildlife habitat. Native vegetation is bluebunch wheatgrass, Idaho fescue, Wyoming sagebrush and bitterbrush.
DISTRIBUTION AND EXTENT: Kittitas County, Washington; MLRA 8. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES PROPOSED: Kittitas County, Washington, l997. The name is coined.
REMARKS: Diagnostic horizons and features recognized in this pedon include:
Mollic epipedon (pachic) - the zone from 0 to 28 inches (Ap, A and 2BAt horizons)
Argillic horizon - the zone from 18 to 55 inches (2BAt Lakedale-Wisconsin Age soil member, 3Bt1 and 3Bt2 horizons)
PSCS - the zone from 18 to 38 inches (2BAt and part of the 3Bt1 horizon) with a weighted average of 38 percent rock fragments.
Vitrandic feature - the zone from 0 to 18 inches (Ap and A horizons)
Soil moisture - xeric bordering aridic.