LOCATION KENNEWICK WA+OREstablished Series
TAXONOMIC CLASS: Coarse-silty, mixed, superactive, calcareous, mesic Xeric Torriorthents
TYPICAL PEDON: Kennewick silt loam grassland. (Colors are for dry soil unless otherwise noted. All textures are apparent field textures).
A--0 to 2 inches; grayish brown (10YR 5/2) silt loam, dark grayish brown (10YR 4/2) moist; weak thin platy structure; soft, friable, nonsticky and slightly plastic; many roots; few vesicular pores; strong effervescence; moderately alkaline (pH 8.2); abrupt smooth boundary. (1 to 10 inches thick)
C1--2 to 12 inches; light gray (2.5Y 7/2) silt loam, grayish brown (2.5Y 5/2) moist; massive, finely laminated; slightly hard, friable, slightly sticky and slightly plastic; common roots; few fine tubular pores; violent effervescence, moderately alkaline (pH 8.4); gradual wavy boundary. (4 to 15 inches thick)
C2--12 to 19 inches; light gray (2.5Y 7/2) silt loam, grayish brown (2.5Y 5/2) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; thinly laminated; few roots; few fine tubular pores; violent effervescence; moderately alkaline (pH 8.4); abrupt wavy boundary. (4 to 14 inches thick)
C3--19 to 32 inches; light brownish gray (10YR 6/2) silt loam, dark gray (10YR 4/1) moist; massive; hard, firm, slightly sticky and slightly plastic; strong thin laminations; few fine tubular pores; disseminated and segregated mycelial lime; violent effervescence; strongly alkaline (pH 8.5); gradual wavy boundary. (8 to 15 inches thick)
C4--32 to 40 inches; light gray (2.5Y 7/2) silt loam, grayish brown (2.5Y 5/2) moist; massive; hard, firm, slightly sticky and slightly plastic; strong thin laminations; few fine tubular pores; disseminated and segregated mycelial lime; violent effervescence; strongly alkaline (pH 8.8); gradual wavy boundary. (5 to 18 inches thick)
C5--40 to 49 inches; light brownish gray (2.5Y 6/2) silt loam, dark grayish brown (2.5Y 4/2) moist; massive; hard, firm, slightly sticky and slightly plastic; moderate thin laminations; few fine tubular pores; disseminated and segregated mycelial lime; violent effervescence; strongly alkaline (pH 8.8); abrupt wavy boundary. (0 to 15 inches thick)
C6--49 to 62 inches; light brownish gray (2.5Y 6/2) silt loam, dark grayish brown (2.5Y 4/2) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; violent effervescence; moderately alkaline (pH 8.3).
TYPE LOCATION: Benton County, Washington; 100 feet north and 400 feet west of Olympia St. and West 36th Ave. intersection, south of Kennewick, Washington; SE1/4 NE1/4 NE1/4, sec. 14, T. 8 N., R. 29 E., W.M.
RANGE IN CHARACTERISTICS: Average annual soil temperature at a depth of 20 inches ranges from 52 to 56 degrees F. These soils are usually dry in all parts between depths of 4 and 12 inches. The particle-size control section is dominated by silt loam or very fine sandy loam and averages 2 to 10 percent clay and 5 to 15 percent fine sand or coarser. After the upper 7 inches of the soil is mixed, the entire soil is calcareous and it is moderately or strongly alkaline. Some pedons have vertical or diagonal clastic dikes ranging from a a fraction of an inch wide cut vertically or diagonally through the soil in many pedons. The calcium carbonate equivalent ranges from 1 to 15 percent throughout.
The A horizon has hue of 10YR or 2.5Y, value of 5, 6, or 7 dry, 3 through 5 moist and chroma of 2 or 3 moist and dry. It is slightly alkaline or moderately alkaline.
The C horizon has hue of 10YR or 2.5Y value of 5 through 8 dry, 4, 5, or 6 moist and chroma of 1, 2, or 3 moist and dry. In some pedons below 40 inches it is very gravelly sand or extremely gravelly coarse sand.
COMPETING SERIES: These are the Linoyer, Pocatello, Ritzcal, and Wheeler series. Linoyer soils particle-size control section has 10 to 18 percent clay; lack visible secondary carbonates in the series control section
Pocatello soils lack hard and firm laminated silt loam layers above 40 inches; has 5 to 15 percent hard krotovinas (cicada) in Bk horizon
Ritzcal soils lack hard and firm laminated silt loam layers above 40 inches in particle-size control section
Wheeler soils have 15 to 23 percent calcium carbonate in particle-size control section.
GEOGRAPHIC SETTING: Kennewick soils occur dominantly on terraces and terrace escarpments, in addition to foot slopes in some areas. Elevation is 300 to 1,600 feet. Slopes are 0 to 60 percent. The soils formed in lacustrine sediments. Some areas have glacial outwash or flood deposits between 40 and 60 inches. They are in an arid climate with warm, dry summers and cool, moist winters. The average annual precipitation is 6 to 9 inches. The average January temperature is 29 degrees F. The average July temperature is 72 degrees F. and average annual temperature is 50 to 54 degrees F. The frost-free season is 130 to 210 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Finley, Royal, Taunton, Wahluke, and Warden soils on terraces. Taunton soils have a duripan. Finley soils are loamy-skeletal. Royal and Warden soils have a cambic horizon. Wahluke soils have weakly cemented lenses in the particle-size control section.
DRAINAGE AND PERMEABILITY: Well-drained; very slow to rapid runoff; moderately slow or moderate permeability.
USE AND VEGETATION: Irrigated crop production and domestic livestock grazing. Native vegetation is bluebunch wheatgrass, needleandthread, Wyoming big sagebrush, balsamroot, Sandberg bluegrass, spiny hopsage, winterfat, Indian ricegrass, and bottlebrush squirreltail.
DISTRIBUTION AND EXTENT: South-central Washington; MLRA 7.Series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Benton County, Washington, 1971.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon zone from 0 to 2 inches
Aridic soil moisture regime
Free carbonates in all parts of the pedon.