LOCATION NAWT                    ID

Established Series
Rev. DDL/DA/GHL/MD
01/2023

NAWT SERIES

The Nawt series consists of deep, well drained soils that formed in colluvium and residuum from welded tuff and volcanic ash. Nawt soils are on breaks. They have slopes of l5 to 75 percent. Permeability is slow. The average annual precipitation is about 330 mm, and the average annual air temperature is about 8.9 degrees C.

TAXONOMIC CLASS: Fine, smectitic, mesic Ultic Palexerolls

TYPICAL PEDON: Nawt extremely stony loam--on an east-facing slope of 50 percent under native rangeland vegetation at 1,510 meter elevation. (Colors are for dry soil unless otherwise stated.) When described on August 20, l977, the soil profile was slightly moist in the A horizon and dry below.

A--0 to 13 cm; brown (10YR 5/3) extremely stony loam, dark brown (10YR 3/3) moist; moderate fine platy structure parting to weak fine granular; soft, very friable, slightly sticky and slightly plastic; many fine and very fine roots; many very fine tubular pores; 30 percent stones, 5 percent cobbles and 30 percent gravel; neutral (pH 7.2); abrupt smooth boundary. (8 to 28 cm thick)

Bt1--13 to 25 cm; brown (10YR 5/3) gravelly clay, dark brown (10YR 3/3) moist; moderate fine or medium subangular blocky structure; hard, firm, very sticky and very plastic; many fine and very fine roots; many very fine tubular pores; many distinct clay films on faces of peds and in pores; l5 percent gravel; neutral (pH 7.2); clear smooth boundary. (13 to 23 cm thick)

Bt2--25 to 46 cm; brown (7.5YR 5/4) gravelly clay, brown (7.5YR 4/4) moist; strong medium subangular blocky structure parting to weak medium prismatic; very hard, firm, very sticky and very plastic; common fine and very fine roots; common very fine tubular pores; many distinct clay films on faces of peds and in pores; 5 percent cobbles, 20 percent gravel; neutral (pH 7.2); clear smooth boundary. (23 to 36 cm thick)

Bt3--46 to 91 cm; light yellowish brown (10YR 6/4) stony clay, brown (7.5YR 5/4) moist; moderate medium subangular blocky structure; very hard, very firm, moderately sticky and moderately plastic; common fine and very fine roots; common very fine tubular pores; common faint clay films on faces of peds and in pores; 5 percent stones, 5 percent cobbles, and 10 percent gravel; slightly alkaline (pH 7.4); clear smooth boundary. (20 to 48 cm thick)

Bk--91 to 114 cm; very pale brown (10YR 7/4) very gravelly clay loam, yellowish brown (10YR 5/4) moist; moderate medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few very fine roots; few very fine tubular pores; 10 percent cobbles and 45 percent gravel; strongly effervescent in veins; carbonate segregated in common rounded fine filaments; moderately alkaline (pH 8.4); clear smooth boundary. (25 to 50 cm thick)

Cr--114 to 157 cm; brown (7.5YR 4/2) decomposing carbonate coated vesicular welded tuff, dark reddish brown (5YR 3/3) moist.

TYPE LOCATION: Twin Falls County, Idaho; about 8 miles east of Hollister, Idaho; about 2,350 feet north and 1,430 feet east of the southwest corner, section 24, T. 12 S., R. 17 E.; USGS McMullen Basin 7.5 minute topographic quadrangle; latitude 42 degrees 22 minutes 00 seconds N and longitude 114 degrees 24 minutes 54 seconds W; WGS84 Decimal Degrees 42.3666667 latitude, -114.4150000 longitude.

RANGE IN CHARACTERISTICS:

Average annual soil temperature - 8.9 to 11.1 degrees C.
Mollic epipedon thickness - 25 to 46 cm.
Depth to base of argillic horizon - 75 to 100 cm
Clay content of control section - 40 to 50 percent.
Rock fragments in control section - 10 to 30 percent.
Depth to bedrock - 100 to 152 cm
Base saturation in upper 30 inches - 65 to 75 percent.
Soil Moisture: This soil is usually moist, but is dry for 45 to 70 consecutive days during the late summer and autumn. Typic xeric moisture regime.
A horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist

Bt horizon
Hue - 10YR or 7.5YR
Value - 5 or 6 dry, 3 or 4 moist
Chroma - 3 or 4 dry or moist
Texture - GR-SIC, GR-C, OR ST-C

Bk horizon
Value - 6 or 7 dry, 4 or 5 moist
Chroma - 3 or 4 dry or moist
Texture - GR-L, GR-SIL, OR GRV-CL
Calcium carbonate equivalent - 5 to 15 percent

COMPETING SERIES: This is the Driscoll series. Driscoll soils are slightly to medium acid, have E horizons above the argillic horizon and have an average annual precipitation of 560 to 610 mm.

GEOGRAPHIC SETTING: Nawt soils are on breaks. They have slopes of l5 to 75 percent. They formed in colluvium and residuum from welded tuff and volcanic ash. Elevations are 1,310 to 1,830 meters. Average annual precipitation is 300 to 410 mm. Average annual temperature is 8.3 to 10.0 degrees C. The frost free season is about l00 to 110 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Doodlelink,
Flatron, Gosinta, Rogerson, Schnipper, and Stricker soils. Doodlelink soils occur on the same landscape, but on higher, cooler, wetter exposures, are Pachic and skeletal. Flatron soils occur on ridges and dipslopes, and are shallow to bedrock. Gosinta soils occur on terraces, and are fine-loamy. Rogerson and Schnipper soils occur on terraces and toeslopes. Rogerson soils are shallow to a hardpan. Schnipper soils are moderately deep to a hardpan. Stricker soils lack an argillic horizon, and are skeletal.

DRAINAGE AND PERMEABILITY: Well drained, medium or rapid runoff; slow permeability.

USE AND VEGETATION: Nawt soils are used for rangeland. Native vegetation is bluebunch wheatgrass and Wyoming big sagebrush.

DISTRIBUTION AND EXTENT: South central Idaho. The series is of moderate extent. MLRA 25.

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

SERIES PROPOSED: Twin Falls County, Idaho, l977. Named is coined.

REMARKS: Base saturation: 0 to 13 cm - 76 percent; 13 to 25 cm - 69 percent; 25 to 46 cm - 70 percent; 46 to 86 cm - 69 percent.

Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0to 25 cm (A and Bt1 horizons)
Abrupt textural change - The boundary at 13 cm (A and Bt1 horizons)

Argillic horizon - 13 to 91 cm (Bt1, Bt2 and Bt3 horizons).
Paralithic contact - 114 cm (The boundary at the top of the Cr horizon).

Particle-size control section - The zone from 13 to 63 cm (The Bt1, Bt2 and part of the Bt3 horizons).

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National Cooperative Soil Survey
U.S.A.