LOCATION OWINZA IDEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Xeric Natrargids
TYPICAL PEDON: Owinza silt loam - on a slope of 1 percent under rangeland vegetation at 4,000 feet elevation. When described on October 23, 1980, the soil profile was dry throughout. (Colors are for dry soil unless otherwise noted.)
A--0 to 4 inches; very pale brown (10YR 7/3) silt loam, brown (10YR 4/3) moist; strong medium platy structure; soft, very friable, slightly sticky and slightly plastic; few very fine, fine, and medium roots; common fine, medium and coarse vesicular pores; neutral (pH 6.9); abrupt smooth boundary. (1 to 5 inches thick)
Btn1--4 to 10 inches; yellowish brown (10YR 5/4) clay, yellowish brown (10YR 5/4) moist; strong medium columnar structure; extremely hard, very firm, very sticky and very plastic; few very fine, fine, and medium roots; few very fine tubular pores; many prominent clay films on faces of peds and in pores; slightly effervescent; moderately alkaline (pH 8.0); clear wavy boundary. (3 to 8 inches thick)
Btn2--10 to 16 inches; very pale brown (10YR 7/3) clay, brown (10YR 5/3) moist; moderate medium angular blocky structure; very hard, firm, very sticky and very plastic; few very fine, fine, and medium roots; few very fine tubular pores; many prominent clay films on faces of peds and in pores; strongly effervescent (8 percent calcium carbonate); moderately alkaline (pH 8.4); abrupt smooth boundary. (6 to 10 inches thick)
Bk1--16 to 23 inches; white (10YR 8/2) silty clay loam, pale brown (10YR 6/3) moist; massive; very hard, firm, sticky and plastic; few very fine, fine and medium roots; few very fine tubular pores; violently effervescent (17 percent calcium carbonate); moderately alkaline (pH 8.2); abrupt smooth boundary. (7 to 10 inches thick)
2Bk2--23 to 41 inches; very pale brown (10YR 7/3) loam, brown (10YR 5/3) moist; massive; very hard, friable, slightly sticky and slightly plastic; few very fine tubular pores; 5 percent gravel; violently effervescent (17 percent calcium carbonate); moderately alkaline (pH 8.2); abrupt smooth boundary. (7 to 10 inches thick)
2Bk3--41 to 63 inches; very pale brown (10YR 8/3) loam, light yellowish brown (10YR 6/4) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few very fine tubular pores; 10 percent gravel; violently effervescent (52 percent calcium carbonate); moderately alkaline (pH 8.4).
TYPE LOCATION: Jerome County, Idaho; about 11 miles northeast of Hazelton, Idaho, in the southeast 1/4, southeast 1/4, southeast 1/4, section 21, T. 8 S., R. 21 E.
RANGE IN CHARACTERISTICS:
Depth to bedrock - more than 60 inches
Secondary lime - 12 to 21 inches
Control section
Clay content average - 39 to 48 percent (less than 15 percent coarser than very fine sand)
SAR - 20 to 40 percent
Average annual soil temperature - 52 to 42 degrees F
A horizon
Value - 6 or 7 dry, 3 through 5 moist
Chroma - 2 or 3 dry or moist
pH - neutral or mildly alkaline
Btn horizon
Value - 5 through 7 dry, 4 or 5 moist
Chroma - 3 or 4 dry or moist
Texture - C, CL
Structure Type - subangular, blocky, angular blocky or columnar
pH - mildly alkaline or moderately alkaline
Bk1 and 2Bk2 horizons
Value - 6 through 8 dry, 4 through 6 moist
Chroma - 2 through 4 dry or moist
Texture - SICL, L or GR-L
Gravel - 0 to 20 percent
Cobbles - 0 to 5 percent
pH - moderately alkaline or strongly alkaline
COMPETING SERIES: These are the Birflat (T), Bullion, Chappuis (T), Couch, Kiesel, Standish, Tomera, and Valcrest (T) series. Bullion soils have hues redder than 5YR. Chappuis and Standish are not well drained. Couch have stratified layers immediately below the Bt at depths of less than 40 inches. Kiesel have a water table at 3 to 4 feet in the spring, and are moderately well drained. Tomera are not effervescent in the upper part of the Bt, and are more than 30 inches deep to the base of the Bt. Birflat soils have more than 15 percent medium and fine sand in the control section.
GEOGRAPHIC SETTING: Owinza soils are in depressions on terraces. The slope ranges from 1 to 3 percent. The soils formed in alluvium from mixed sources. Elevations are 3,500 to 4,500 feet. The average annual precipitation ranges from 9 to 11 inches. The average annual temperature is 49 to 52 degrees F. The frost free season is 120 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are Banbury Paulville, and Power soils. Banbury, Paulville, and Power soils occur on upper terraces. Banbury soils are shallow to basalt bedrock. Paulville soils are fine-loamy. Power soils are fine-silty.
DRAINAGE AND PERMEABILITY: Well drained, slow runoff; very slow permeability.
USE AND VEGETATION: Owinza soils are used for rangeland. Native vegetation is bluebunch wheatgrass, Sandberg bluegrass, pepperweed, threetip sagebrush, and Wyoming big sagebrush.
DISTRIBUTION AND EXTENT: Owinza soils are of moderate extent in south central Idaho.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Jerome County, Idaho, 1992.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 4 inches
Argillic horizon - 4 to 16 inches
Natric feature - Salinity of 20 to 40 in argillic horizon
Name was changed from Milner.