LOCATION FLATRON                 ID

Established Series
Rev. DFA/DMD/HBM
01/2019

FLATRON SERIES

The Flatron series consists of soils that are well drained and very shallow to bedrock. They formed in colluvium over residuum from welded tuff. They are on ridges and dipslopes. Permeability is slow. Slopes range from 2 to 20 percent. The average annual precipitation is about 380 mm, and the average annual temperature is about 8.3 degrees C.

TAXONOMIC CLASS: Clayey-skeletal, smectitic, mesic Aridic Lithic Argixerolls

TYPICAL PEDON: Flatron very gravelly loam - on a slope of 3 percent under rangeland vegetation at 1,650 meter elevation. When described on September 1979, the soil was dry throughout. (Colors are for dry soil unless otherwise noted.)

A--0 to 10 cm; grayish brown (10YR 5/2) very gravelly loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine to coarse roots; many very fine tubular pores; 25 percent gravel, 5 percent cobbles, 5 percent stones; neutral; (pH 7.0); abrupt smooth boundary. (8 to 13 cm thick)

Bt1--10 to 15 cm; brown (10YR 5/3) very cobbly clay loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; many very fine to coarse roots; common very fine tubular pores; common distinct clay films on faces of peds and lining pores; 25 percent gravel, 20 percent cobbles, 5 percent stones; neutral (pH 7.0); clear smooth boundary. (3 to 8 cm thick)

Bt2--15 to 30 cm; brown (10YR 5/3) extremely cobbly clay, dark brown (10YR 3/3) moist; strong medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few very fine and fine roots; few very fine tubular pores; common distinct clay films on faces of peds and lining pores; 35 percent gravel, 20 percent cobbles, 10 percent stones; thin carbonate coating on underside of welded tuff fragments; slightly alkaline (pH 7.6); abrupt smooth boundary. (6 to 13 inches thick)

R--30 cm; gray (10YR 6/1) welded tuff, dark gray (10YR 4/1) moist.

TYPE LOCATION: Twin Falls County, Idaho; about 7 miles east of Hollister, Idaho; about 2,100 feet south and 2,000 feet west of the northeast corner section 26, T. 12 S., R. 17 E.; USGS McMullen Basin 7.5 minute topographic quadrangle; latitude 42 degrees 21 minutes 16 seconds N and longitude 114 degrees 25 minutes 41 seconds W; WGS84 Decimal Degrees 42.3544444 latitude, -114.4280556 longitude.

RANGE IN CHARACTERISTICS:

Depth to the welded tuff - 25 to 51 cm.
Mollic epipedon - 25 to 30 cm.
Average clay percent in the control section - 50 to 60
Average annual soil temperature - 8.3 to 10.0 degrees C.
Soil moisture: Usually dry, moist in the winter and spring, dry from late June through October; xeric soil moisture regime bordering on aridic.

A horizon
Color value, moist - 2 or 3
Chroma - 2 or 3 dry or moist
Structure type - granular or platy
Organic matter content - 2 to 4 percent

Bt horizon
Color Chroma, dry or moist - 2 or 3
Structure Type - subangular blocky or angular blocky
Gravel - 20 to 40 percent
Cobbles - 20 to 25 percent
Stones - 5 to 15 percent
Texture - CBV-CL, CBV-C, CBX-CL, CBX-C

COMPETING SERIES: These are the Coelho, Longcreek, Loomer, Pioche, Ruckles and Vantage series.

Coelho, Longcreek, Loomer, and Pioche soils have less than 50 percent clay in the argillic horizon. Ruckles soils have 1 to 2 percent organic matter content in the A horizon and a mollic epipedon that is less than 25 cm thick. Vantage soils have a mollic epipedon that is less than 25 cm thick and a Btq horizon.

GEOGRAPHIC SETTING: Flatron soils are on ridges and dipslopes. The slopes range from 2 to 20 percent. The soils formed in residuum from welded tuff. Elevations are 1,525 to 1,740 meters. The average annual precipitation ranges from 360 to 410 mm. The average annual temperature is 7.2 to 8.9 degrees C. The frost free season is 100 to 110 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Nawt, Ragpie, and Stricker soils. Nawt soils are not skeletal and occur on breaks. Ragpie soils occur on the same landscape, and are loamy-skeletal. Stricker soils are loamy-skeletal, and occur on breaks.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained, medium runoff; slow saturated hydraulic conductivity.

USE AND VEGETATION: Flatron soils are used for rangeland. Native vegetation is bluebunch wheatgrass, Sandberg bluegrass, low sagebrush, and Wyoming big sagebrush.

DISTRIBUTION AND EXTENT: Flatron soils are of small extent in south central Idaho. MLRA 25.

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

SERIES PROPOSED: Twin Falls County, Idaho, 1981. The name is coined from an elevation marker.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 30 cm (A, Bt1, and Bt2 horizons).
Argillic horizon - 10 to 30 cm (Bt1 and Bt2 horizons).
Lithic contact - The boundary at 30 cm (R horizon).

Particle-size control section - The zone from the soil surface to 30 cm (The A, Bt1 and Bt2 horizons).

Classification was updated to 11th edition on 07/2011 changed from Lithic Argixerolls to Aridic Lithic Argixerolls.

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National Cooperative Soil Survey
U.S.A.