LOCATION LEQUERICA               OR

Tentative Series
Rev. SBF/ARR/TM
04/2019

LEQUERICA SERIES

The Lequerica series consists of very deep, well drained soils that formed in mixed volcanic ash and loess over old alluvium. Lequerica soils are on footslopes and toeslopes of hills. Slopes are 0 to 8 percent. The mean annual precipitation is about 200 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Vitritorrandic Argixerolls

TYPICAL PEDON: Lequerica ashy fine sandy loam at an elevation of 1,195 meters-cropland. (Colors are for dry soil unless otherwise noted.)

Ap--0 to 13 cm; brown (10YR 5/3) ashy fine sandy loam, dark brown (10YR 3/3) moist; moderate fine granular structure; slightly hard, friable, nonsticky, nonplastic; common very fine roots; many very fine interstitial pores; 2 percent fine gravel; slightly alkaline (pH 7.4); clear smooth boundary. (3 to 39 cm thick)

AB--13 to 33 cm; brown (10YR 5/3) ashy loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; moderately hard, firm, nonsticky, nonplastic; common very fine roots; common fine tubular and very fine interstitial pores; 2 percent fine gravel; slightly alkaline (pH 7.4); clear smooth boundary. (12 to 53 cm thick)

Bt--33 to 56 cm; yellowish brown (10YR 5/4) ashy clay loam, yellowish brown (10YR 5/4) moist; strong medium angular blocky structure parting to weak thin platy structure; moderately hard, firm, moderately sticky, moderately plastic; common very fine roots; 10 percent faint clay films on all faces of peds; common fine tubular and many fine interstitial pores; slightly alkaline (pH 7.6); abrupt smooth boundary. (10 to 38 cm thick)

Btkq--56 to 73 cm; yellowish brown (10YR 5/4) extremely paragravelly ashy loam, yellowish brown (10YR 5/4) moist; weak medium subangular blocky; very hard, extremely firm, nonsticky, nonplastic; 5 percent faint clay films on all faces of peds; many very fine interstitial pores; 80 percent rounded moderately cemented durinodes; violently effervescent; slightly alkaline (pH 7.6); clear wavy boundary. (10 to 20 cm thick)

Bkq--73 to 154 cm; yellowish brown (10YR 5/4) extremely paragravelly ashy loam, brown (10YR 4/3) moist; strong medium and fine angular blocky structure; very hard, extremely firm, nonsticky, nonplastic; many very fine interstitial pores; 20 percent reddish black (2.5YR 2.5/1) manganese masses; 5 percent carbonate masses; 80 percent rounded moderately cemented durinodes; violently effervescent; slightly alkaline (pH 7.6); abrupt wavy boundary.

TYPE LOCATION: Malheur County, Oregon; Approximately 1.2 miles southeast of Arock, Oregon; about 1,280 feet south and 500 feet west of the northeast corner section 12, T. 31 S., R. 42 E.; UTM 458216 easting, 4747865 northing, zone 11, NAD83 on the USGS Arock 7.5 minute quadrangle, latitude 42 degrees, 52 minutes, 56 seconds north and longitude 117 degrees, 30 minutes, 41 seconds west, WGS84 Decimal Degrees 42.8822222 latitude, -117.5113889 longitude.

RANGE IN CHARACTERISTICS:

Soil moisture - The soil moisture control section is dry throughout in late summer and fall and moist in winter, spring; aridic moisture regime that borders on xeric.

Soil temperature - Mean annual temperature is 7 to 9 degrees C.

Mollic epipedon thickness: 25 to 51 cm, may include all or part of the Bt horizon.

Depth to durinodes: 30 to 70 cm.

Control section - Clay content - Averages 18 to 35 percent.
Rock fragments - 0 to 20 percent, mainly gravel.

A horizon
Value: 5 dry.
Chroma: 2 or 3 moist.
Reaction: Neutral through slightly alkaline.
Volcanic glass: Volcanic glass is estimated to range from 30 to 50 percent of the 0.02 to 2 mm fraction.

AB horizon
Value: 3 or 4 moist.
Chroma: 3 or 4 moist.
Texture: Loam, clay loam.
Clay content: 15 to 28 percent.
Rock fragments: 0 to 5 percent gravel.
Reaction: Neutral through slightly alkaline.
Volcanic glass: Volcanic glass is estimated to range from 30 to 50 percent of the 0.02 to 2 mm fraction.

Bt horizon
Value: 3 to 6 dry, 3 to 5 moist.
Chroma: 3 or 4 dry or moist.
Texture: Clay loam, loam.
Clay content: 20 to 35 percent.
Rock fragments: 0 to 20 percent gravel
Reaction: Neutral through slightly alkaline.
Volcanic glass: Volcanic glass is estimated to range from 10 to 30 percent of the 0.02 to 2 mm fraction.

Btkq horizon
Value: 4 or 5 dry or moist.
Clay content: 12 to 27 percent.
Rock fragments: 0 to 10 percent, gravel
Durinodes: Averages 20 to 80 percent, moderately cemented.
Volcanic glass: Volcanic glass is estimated to range from 10 to 30 percent of the 0.02 to 2 mm fraction.

Bkq horizon
Value: 6 or 7 dry, 3 to 5 moist.
Chroma: 3 or 4 moist.
Texture: Loam, fine sandy loam, sandy loam.
Clay content: 5 to 30 percent.
Rock fragments: Averages 0 to 10 percent gravel.
Durinodes: Averages 20 to 80 percent, moderately cemented.
Effervescence: Strongly effervescent through violently effervescent.
Reaction: Slightly alkaline through moderately alkaline.
Volcanic glass: Volcanic glass is estimated to range from 10 to 30 percent of the 0.02 to 2 mm fraction.

COMPETING SERIES: These are the Meadowridge (OR), Toler (WA), and Wisher soils. The Meadowridge soils do not have durinodes. The Toler soils are 50 to 100 cm to hard bedrock. The Wisher soils do not have durinodes.

GEOGRAPHIC SETTING: Lequerica soils are on footslopes and toeslopes of hills. These soils formed in mixed volcanic ash and loess over old alluvium. Slopes are 0 to 8 percent. Elevations are 1,190 to 1,200 meters. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 150 to 250 mm; mean annual temperature is about 7 to 8 degrees C, and the frost-free period is 80 to 100 days.

GEOGRAPHICALLY ASSOCIATED SOILS: This is the competing Wisher series.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained, medium runoff. Slow and very slow permeability and moderately low saturated hydraulic conductivity in the Bt horizon. Moderately rapid and rapid permeability and high saturated hydraulic conductivity in the Bkq horizon.

USE AND VEGETATION: Cropland. The present vegetation is mainly barley and alfalfa.

DISTRIBUTION AND EXTENT: Southeast Oregon; the soil is of small extent. MLRA 24 and 25.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.

SERIES PROPOSED: Malheur County, Oregon, Southern Part, 2008.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Mollic Epipedon - The zone from the soil surface to about 33 cm (Ap and AB horizons).

Argillic horizon - The zone from about 36 to 84 cm (Bt and Btkq horizons).

Vitritorrandic feature - Aridic moisture regime bordering on Xeric. Volcanic glass is 30 to 50 percent of the 0.02 to 2 mm fraction in the zone from 0 to 33 cm (Ap and AB horizons). Volcanic glass is 10 to 30 percent of the 0.02 to 2 mm fraction in the zone from 33 to 154 cm (Bt, Btkq and Bkq horizons).

Particle-size control section - The zone from 33 to 73 cm (Bt and Btkq horizons).

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National Cooperative Soil Survey
U.S.A.