LOCATION STOKES UTEstablished Series
TAXONOMIC CLASS: Fine, mixed, active, mesic Typic Natrixeralfs
TYPICAL PEDON: Stokes silt loam--irrigated cropland. (Colors are for dry soil unless otherwise noted.)
Ap--0 to 6 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; weak medium subangular blocky structure parting to weak fine granular; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots; common very fine pores; slightly effervescent; slightly alkaline (pH 7.8); abrupt smooth boundary. (3 to 8 inches thick)
A--6 to 11 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots; common very fine pores; slightly effervescent; moderately alkaline (pH 7.9); abrupt smooth boundary. (3 to 5 inches thick)
Btn--11 to 18 inches; light brownish gray (10YR 6/2) clay, dark grayish brown (10YR 4/2) moist; strong medium prismatic structure; very hard, very firm, very sticky and moderately plastic; few very fine roots; many very fine pores; dark grayish brown (10YR 4/2) and light gray (10YR 7/2) skeletans on faces of peds; continuous distinct clay films on faces of peds; strongly effervescent; 10 percent calcium carbonate equivalent; moderately alkaline (pH 8.2); clear wavy boundary. (5 to 11 inches thick)
Btkn--18 to 24 inches; very pale brown (10YR 8/2) silty clay, light brownish gray (2.5Y 6/2) moist; moderate medium subangular blocky structure; very hard, friable, moderately sticky and moderately plastic; few fine roots; few fine and very fine pores; pale brown (10YR 6/3) moist clay films on faces of peds; common fine faint brown (10YR 5/3) and pale olive (5Y 6/3) moist masses of iron accumulation; violently effervescent; 36 percent calcium carbonate equivalent; very strongly alkaline (pH 9.1); gradual wavy boundary. (6 to 12 inches thick)
Bkn--24 to 47 inches; light gray (2.5Y 7/2) silty clay loam, pale olive (5Y 6/3) and olive (5Y 5/3) moist; massive; very hard, firm, moderately sticky and moderately plastic; many very fine pores; common medium prominent brown (10YR 5/3) moist masses of iron accumulation; violently effervescent; 33 percent calcium carbonate equivalent; very strongly alkaline (pH 9.1); abrupt smooth boundary. (10 to 24 inches thick)
C--47 to 68 inches; very pale brown (10YR 7/3) silt loam, pale olive (5Y 6/3) moist; massive; very hard, friable, moderately sticky and slightly plastic; many fine and very fine pores; common medium prominent dark yellowish brown (10YR 4/6) moist masses of iron accumulation; violently effervescent; strongly alkaline (pH 8.9).
TYPE LOCATION: Box Elder County, Utah; in the Bear River Valley about 4 miles west-northwest of Corinne and about 0.25 mile north of State Highway 83; approximately 2,450 feet west and 100 feet south of the east quarter corner of section 28, T. 10 N., R. 3 W.; USGS Bear River City 7.5 minute topographic quadrangle; 41 degrees 34 minutes 18 seconds north latitude and 112 degrees 11 minutes 13 seconds west longitude, NAD83; UTM zone 12N 401037E, 4602904N, NAD83.
RANGE IN CHARACTERISTICS:
Soil moisture - The soils are usually moist in some part of the moisture control section for more than one-half of the time the soil temperature is above 41 degrees F. They are dry in all parts of the moisture control section for 60 to 90 consecutive days during the summer months; Xeric moisture regime that borders on aridic.
Mean annual soil temperature - 49 to 54 degrees F.
Mean summer soil temperature - 71 to 75 degrees F.
Ochric epipedon thickness - 6 to 13 inches.
Depth to base of natric horizon - 13 to 24 inches.
Depth to calcic horizon - 13 to 24 inches.
Particle-size control section - Clay content: 40 to 50 percent.
A horizons - Hue: 10YR or 2.5Y.
Clay content: 20 to 25 percent.
Reaction: Slightly alkaline or moderately alkaline
Btn horizon - Hue: 10YR or 2.5Y.
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 2 or 3, dry or moist.
Clay content: 40 to 50 percent.
Structure: Weak to strong, fine to coarse prismatic or columnar.
Reaction: Moderately alkaline or strongly alkaline.
Exchangeable sodium: 15 to 50 percent.
Sodicity (SAR): 13 to 30.
Calcium carbonate equivalent: 5 to 10 percent.
Effervescence: Strongly effervescent or violently effervescent.
Other features: The interior of some peds is noneffervescent.
Btkn horizon - Hue: 10YR or 2.5Y.
Value: 7 or 8 dry.
Clay content: 40 to 50 percent.
Structure: Weak or moderate medium prismatic or moderate medium subangular blocky.
Reaction: Strongly alkaline or very strongly alkaline.
Exchangeable sodium: 25 to 85 percent.
Sodicity (SAR): 20 to 50.
Calcium carbonate equivalent: 25 to 35 percent.
Redoximorphic features: Common fine faint to distinct masses of iron accumulation with chroma of 3.
Bkn horizon - Hue: 10YR through 5Y.
Value: 5 through 8 dry, 4 through 6 moist.
Chroma: 2 through 4, dry or moist.
Exchangeable sodium: 25 to 85 percent.
Sodicity (SAR): 20 to 50.
Calcium carbonate equivalent: 20 to 30 percent.
Redoximorphic features: Few to many, distinct to prominent masses of iron accumulation at depths of 16 to 30 inches.
C horizon - Hue: 7.5YR through 5Y.
Calcium carbonate equivalent: 10 to 20 percent.
Other features: Lacustrine deposits with rock structure of fine laminae.
COMPETING SERIES: This is the Payson series. Payson soils have ochric epipedons 2 to 6 inches thick and have calcic horizons at depths of 9 to 13 inches.
GEOGRAPHIC SETTING: Stokes soils occur on low lake terraces and lake plains. They formed in lacustrine deposits derived from mixed sources, the surface of which may have been reworked by wind and water. Slopes are 0 to 1 percent. Elevations range from 4,200 to 4,270 feet. The climate is dry subhumid. The mean annual precipitation is 14 to 16 inches. The mean annual temperature is 47 to 52 degrees F. The frost-free period is 130 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Airport, Greenson, and Lasil soils. Airport soils are fine-silty and have mollic epipedons. Greenson soils are fine-silty, have mollic epipedons, and do not have natric horizons. Lasil soils are fine-silty.
DRAINAGE AND PERMEABILITY: Moderately well drained; medium surface runoff; slow permeability (moderately low or moderately high saturated hydraulic conductivity). Endosaturation is present with an apparent seasonal high water table between 3.5 and 5 feet (deep free water occurrence class) between April and September. Cumulative annual duration class is Common.
USE AND VEGETATION: Stokes soils are used mostly for irrigated and nonirrigated cropland and some rangeland. The native vegetation in rangeland is mainly black greasewood, Wyoming big sagebrush, Nuttall's saltbush, annual mustard, prickly lettuce, and other annuals.
DISTRIBUTION AND EXTENT: Northwestern Utah. These soils are not extensive with about 5,400 acres of the series mapped to date. MLRA 28A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona.
SERIES ESTABLISHED: Box Elder County (Eastern Part), Utah, 1969.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 11 inches (Ap and A horizons).
Natric horizon - The zone from 11 to 24 inches (Btn and Btkn horizons).
Calcic horizon - The zone from 18 to 47 inches (Btkn and Bkn horizons).
Endosaturation feature - The condition of ground water with an upper boundary between 42 and 60 inches at certain times during normal years (parts of the Bkn and C horizons).
Particle-size control section - The zone from 11 to 24 inches (Btn and Btkn horizons).
The revision of April 2005 updated the taxonomic class from Fine, mixed, active, mesic Aquic Natrixeralfs based on the depth to the seasonal high saturation of more than 30 inches.
ADDITIONAL DATA: The typical pedon at the series type location has partial characterization data by the Soils Laboratory from Utah State University (USU) Logan, UT and is published on pages 214-215, Table 9 of the Soil Survey of Box Elder County, Utah, Eastern Part. The pH values in the typical pedon are from saturated paste.