LOCATION POVIRT IDEstablished Series
TAXONOMIC CLASS: Fine, smectitic, calcareous, frigid Vertic Epiaquepts
TYPICAL PEDON: Povirt silty clay loam--on a nearly level slope at 4,965 feet elevation--nonirrigated cropland. (When described on June 5, 1986, the soil was moist below four inches. Colors are for dry soil unless otherwise noted.)
Ap--0 to 10 inches; light brownish gray (10YR 6/2) silty clay loam, brown (10YR 5/3) moist; moderate medium subangular blocky structure; slightly hard, firm, very sticky and very plastic; 0.5 inch wide cracks that extend through the horizon; few very fine roots; common very fine tubular pores; slightly effervescent; moderately alkaline (pH 7.9); abrupt smooth boundary. (6 to 12 inches thick)
Bg--10 to 20 inches; light brownish gray (10YR 6/2) silty clay, dark grayish brown (10YR 4/2 ) moist; strong medium and coarse subangular blocky structure; hard, firm, very sticky and very plastic; 0.5 inch wide cracks that extend through the horizon; few fine roots; common very fine tubular pores; few fine, prominent reddish brown (2.5YR 5/4) masses of iron accumulation; slightly effervescent; moderately alkaline (pH 8.3); clear wavy boundary. (8 to 12 inches thick)
Bkng1--20 to 27 inches; light brownish gray (10YR 6/2) silty clay, dark grayish brown (10YR 4/2 ) moist; strong medium prismatic structure; very hard, very firm, very sticky and very plastic; 0.3 inch wide cracks that extend to base of horizon; few very fine roots; common very fine tubular pores; few fine prominent reddish brown (2.5YR 5/4) masses of iron accumulation; secondary carbonates segregated in few fine masses; slightly effervescent; strongly alkaline (pH 8.6); clear wavy boundary. (4 to 12 inches thick)
Bkng2--27 to 45 inches; very pale brown (10YR 7/3) silty clay, grayish brown (10YR 5/2) moist; strong medium subangular blocky structure; very hard, very firm, very sticky and very plastic; few very fine roots; common very fine tubular pores; few fine prominent red (2.5YR 5/6) masses of iron accumulation; secondary carbonates segregated in common coarse masses; slightly effervescent; strongly alkaline (pH 8.8); clear wavy boundary. (12 to 24 inches thick)
Bkng3--45 to 60 inches; light gray (10YR 7/1) silty clay, grayish brown (10YR 5/2) moist; strong medium and coarse subangular blocky structure; very hard, very firm, very sticky and very plastic; common very fine tubular pores; many fine prominent red (2.5YR 5/6) masses of iron accumulation; secondary carbonates segregated in many coarse masses; slightly effervescent; strongly alkaline (pH 8.8).
TYPE LOCATION: Oneida County, Idaho; about 14 miles southwest of Malad City in Pocatello Valley; approximately 1,700 feet south and 600 feet east of the northwest corner of section 3, T. 16 S., R 34 E.; USGS Grover Canyon 7.5 minute topographic quadrangle; 42 degrees 03 minutes 40 seconds north latitude and 112 degrees 28 minutes 36 seconds west longitude, NAD27.
RANGE IN CHARACTERISTICS:
Soil moisture - Usually saturated for 1 to 3 months in the spring during most years.
Mean annual soil temperature - 44 to 47 degrees F.
Ochric epipedon thickness - 7 to 12 inches.
Particle-size control section - Clay content: Averages 40 to 60 percent.
Cracks- Extend from the soil surface to between 20 to 30 inches deep, 0.3 to 1 inch wide, and 15 to 40 inches long.
Linear extensibility (LE) - 6 to 9 cm.
Ap horizon - Value: 5 through 7 dry, 4 through 6 moist.
Chroma: 1 through 3, dry or moist
Bg horizon - - Value: 6 or 7 dry, 4 through 6 moist.
Chroma: 1 or 2, dry or moist.
Clay content: 27 to 50 percent.
Effervescence: Slightly effervescent or strongly effervescent.
Bkng horizons - Value: 6 or 7 dry, 4 through 6 moist.
Chroma: 1 or 2, dry or moist.
Clay content: 40 to 60 percent.
Reaction: Moderately alkaline or strongly alkaline.
Sodicity (SAR): 10 to 30.
Calcium carbonate equivalent: 5 to 20 percent.
COMPETING SERIES: There are currently no other series in this family.
GEOGRAPHIC SETTING: Povirt soils are on relict lakebeds. These soils formed in lacustrine deposits derived from limestone, sandstone, quartzite, and tuff. Slopes are 0 to 2 percent. Elevations range from 4,900 to 5,200 feet. The mean annual precipitation is 14 to 18 inches, the mean annual temperature is 42 to 45 degrees F., and the frost-free period is 80 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bothwell, Buckboard, and Elevator soils. These soils have less than 35 percent clay in the particle-size control section, are not usually saturated for 1 to 3 months in the spring during most years, and are on lake terraces.
DRAINAGE AND PERMEABILITY: Poorly drained; negligible surface runoff; very slow permeability (low or moderately low saturated hydraulic conductivity). These soils are susceptible to frequent ponding for very long duration from April through June with water up to 1 foot deep. Episaturation is present with a seasonal perched water table between the soil surface and 1.5 feet (very shallow or shallow free water occurrence classes) between April and June. Cumulative annual duration class is Transitory. These soils are susceptible to rare flooding year-round.
USE AND VEGETATION: Povirt soils are used mainly for nonirrigated cropland. The crops are small grains such as wheat and barley.
DISTRIBUTION AND EXTENT: Southern Idaho. These soils are not extensive with about 1,400 acres of the series mapped to date. MLRA 28A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: Oneida County Area, Idaho, 1994.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 10 inches (Ap horizon).
Cambic horizon - The zone from 10 to 20 inches (Bg horizon).
Aquic conditions - The conditions of episaturation, reduction, and redoximorphic features between the soil surface and 18 inches at certain times during normal years (Ap horizon and part of the Bg horizon).
Identifiable secondary carbonates - The zone from 20 to 60 inches (Bkng1, Bkng2, and Bkng3 horizons).
Particle-size control section - The zone from 10 to 40 inches (Bg and Bkng1 horizons and part of the Bkng2 horizon).