LOCATION UMTANUM WATentative Series
TAXONOMIC CLASS: Fine, mixed, superactive, mesic Vitrandic Argixerolls
TYPICAL PEDON: Umtanum ashy silt loam- irrigated cropland, on a 1 percent slope at an elevation of 1,760 feet. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 9 inches; very dark gray (10YR 3/1) ashy silt loam, black (10YR 2/1) moist; weak fine granular structure; slightly hard, firm, slightly sticky and slightly plastic; many very fine roots; common very fine tubular pores; NaF pH 8.5; neutral (pH 6.8); abrupt smooth boundary. (4 to 10 inches thick)
BA--9 to 16 inches; very dark gray (10YR 3/1) silty clay loam, black (10YR 2/1) moist; weak medium prismatic structure; hard, firm, moderately sticky and moderately plastic; many very fine and common fine and medium roots; common very fine tubular pores; NaF pH 8.5; neutral (pH 6.8); abrupt smooth boundary. (0 to 8 inches thick)
Bt1--16 to 19 inches; very dark gray (10YR 3/1) silty clay loam, black (10YR 2/1) moist; moderate medium prismatic structure; very hard, very firm, moderately sticky and moderately plastic; few fine and medium roots; few very fine and common medium irregular and tubular pores; few faint clay films lining pores and on faces of peds; neutral (pH 6.8); abrupt wavy boundary.
Bt2--19 to 32 inches; dark grayish brown (10YR 4/2) silty clay loam, very dark brown (10YR 2/2) moist; moderate medium prismatic structure; very hard, very firm, moderately sticky and moderately plastic; few very fine roots; few very fine irregular pores; few faint clay films lining pores and on faces of peds; neutral (pH 6.8); clear wavy boundary.
Bt3--32 to 42 inches; grayish brown (10YR 5/2) silty clay loam, very dark brown (10YR 2/2) moist; moderate medium prismatic structure; very hard, very firm, moderately sticky and moderately plastic; few very fine roots; few very fine pores; few faint clay films lining pores and on faces of peds, few coarse dark grayish brown (10YR 4/2) organic coatings on faces of peds; neutral (pH 6.8); clear wavy boundary. (Combined thickness of the Bt1, Bt2, and Bt3 horizons is 20 to 40 inches)
Bt4--42 to 48 inches; grayish brown (10YR 5/2) silty clay loam, very dark brown (10YR 2/2) moist; moderate medium prismatic structure; very hard, very firm, slightly sticky and slightly plastic; few very fine roots; few very fine irregular pores; common prominent brownish yellow (10YR 6/6) iron accumulations; common distinct clay films lining pores and on faces of peds; common coarse dark grayish brown (10YR 4/2) organic coatings on faces of peds; neutral (pH 6.8); clear wavy boundary.
Bt5--48 to 60 inches; grayish brown (10YR 5/2) silty clay loam, very dark brown (10YR 2/2) moist; moderate medium prismatic structure; very hard, very firm, slightly sticky and slightly plastic; common prominent brownish yellow (10YR 6/6) iron accumulations; few very fine roots; few very fine irregular pores; patchy distinct clay films lining pores and on faces of peds; common coarse dark grayish brown (10YR 4/2) organic coatings on faces of peds; neutral (pH 6.8); clear wavy boundary.
TYPE LOCATION: Kittitas County, Washington; about 1.5 miles south of Thorp, WA., about 700 feet east and 150 feet north of the southwest corner of section 14, T. 18 N., R. 17 E.; USGS Thorp, Washington topographic quadrangle; Latitude - 47 degrees 02 minutes 38 seconds N. and Longitude - 120 degrees 41 minutes 04 seconds W. (NAD83).[SW1]
RANGE IN CHARACTERISTICS: The average annual soil temperature at a depth of 20 inches ranges from 47 to 53 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. Depth to the uppermost limit of the irrigation-induced water table is 30 to 48 inches. The upper 7 to 12 inches has a moist bulk density of 1.10 to 1.30 g/cc; volcanic glass content of 7 to 20 percent, and Alox plus Feox of 0.4 to 0.7 percent. Organic matter is estimated to range from 3 to 5 percent. The particle-size control section has 35 to 45 percent clay and more than 15 percent fine sand or coarser. B Base saturation is more than 75 percent. The mollic epipedon is greater than 60 inches thick. These soils have an estimated moist bulk density of 1.10 to 1.30 grams per cubic centimeter.
The Ap horizon has value of 2 or 3, dry and moist, and chroma of 1 or 2, dry or moist. Reaction is slightly acid or neutral.
The BA horizon has value of 2 or 3, dry and moist, and chroma of 1 or 2, dry or moist. Texture is silty clay loam or silt loam.
The Bt1 horizon has value of 3 to 5 dry, and 2 or 3 moist, and chroma of 1 or 2, dry or moist. Texture is clay, clay loam, or silty clay loam.
The Bt2, Bt3, Bt4, and Bt5 horizons have value of 4 or 5 dry, 2 or 3 moist, and chroma of 1 or 2 dry or moist. Texture is clay, silty clay loam or clay loam.
COMPETING SERIES: This is the
Opnish series.
Opnish soils - mollic epipedon 40 to 60 inches thick; secondary calcium carbonates at a depth of 20 to 40 inches.
GEOGRAPHIC SETTING: Umtanum soils are on terraces and alluvial fans and have slopes of 0 to 5 percent. These soils formed in alluviumwith an influence of volcanic ash in the surface. Elevation is 1,500 to 2,000 feet. Climate is semiarid with warm, dry summers and cool, moist winters. The mean annual precipitation is 9 to 12 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 48 to 50 degrees F. The frost-free season is 130 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Metser, Millhouse, and Varodale series. Metser soils are on terraces and alluvial fans and are 20 to 40 inches to an extremely gravelly 2Bg horizon. Millhouse soils are on alluvial fans, are loamy-skeletal, and have greater than 45 percent rock fragments in the particle-size control section. Varodale soils are on terraces and alluvial fans, have cracks, and have more than 45 percent clay in the fine earth fraction.
DRAINAGE AND PERMEABILITY: Moderately well drained; slow runoff; moderately slow permeability. This soil has an irrigation-induced water table with its uppermost limit occurring some time between the mid-May to mid-October growing season.
USE AND VEGETATION: These soils are used for irrigated crop production and livestock grazing. Native vegetation is mainly blue bunch wheatgrass, Idaho fescue, Wyoming sagebrush and bitterbrush. When irrigated, hay, oats, wheat, corn, potatoes, and peas are among the crops grown.
DISTRIBUTION AND EXTENT: Central Washington, MLRA 8. The soil is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES PROPOSED: Kittitas County, Washington, l990. The name is coined.
REMARKS: Diagnostic horizons and features recognized in this pedon include:
Mollic epipedon (pachic) - the zone from 0 to 60 inches (all horizons)
Argillic horizon - the zone from 16 to 60 inches (Bt1, Bt2, Bt3, Bt4 and Bt5 horizons)
Redoximorphic features - the zone from 42 to 60 inches (Bt4 and Bt5 horizons) PSCS - the zone from 16 to 36 inches (the Bt1, Bt2 and part of the Bt3 horizon)
Classification revised 01/2001 from fine, mixed, mesic Pachic Argixerolls to fine, mixed, superactive, mesic Vitrandic Argixerolls.