LOCATION NICHOLFLAT              ID

Established Series
Rev. DBJ/ALH/CLM
09/2019

NICHOLFLAT SERIES

The Nicholflat series consists of shallow to a duripan, well drained soils with slow permeability that formed in mixed alluvium from extrusive rocks and volcanic ash. Nicholflat soils are on alluvial flats with slopes of 1 to 8 percent. The average annual precipitation is about 14 inches, and the average annual temperature is about 44 degrees F.

TAXONOMIC CLASS: Clayey, smectitic, frigid, shallow Abruptic Durixeralfs

TYPICAL PEDON: Nicholflat silt loam -- on a east-facing slope of 4 percent, in native rangeland at 5,585 feet elevation. (When described on August 1, 1979, the soil was dry to 7 inches and slightly moist from 7 to 18 inches. Colors are for air dry soil unless otherwise stated.)

E--0 to 3 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; moderate fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine, common fine, and few medium roots; common very fine and fine vesicular pores; 5 percent gravel; slightly acid (pH 6.3); clear smooth boundary. (2 to 5 inches thick)

BE--3 to 7 inches; light brownish gray (10YR 6/2) silt loam, dark brown (10YR 3/3) moist; light gray (10YR 7/2) skeletans coating faces of peds; moderate very fine angular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and fine, few medium and coarse roots; common very fine tubular pores; 5 percent gravel; moderately acid (pH 6.0); abrupt smooth boundary. (3 to 7 inches thick)

Bt--7 to 18 inches; yellowish brown (10YR 5/4) clay, dark yellowish brown (10YR 4/4) moist; strong fine columnar structure parting to strong fine angular blocky; extremely hard, very firm, sticky and plastic; common very fine, few fine roots; few very fine tubular pores; continuous thick clay films on faces of peds and in pores; 5 percent gravel; slightly acid (pH 6.1); abrupt smooth boundary. (7 to 11 inches thick)

Bkqm--18 to 40 inches; thin white (10YR 8/1) continuous indurated laminar cap over very pale brown (10YR 8/3) strongly cemented duripan, yellow (10YR 7/6) moist; massive; very hard, very firm, brittle; 15 percent gravel; slight effervescence; clear smooth boundary. (10 to 40 inches thick)

Bqm--40 to 60 inches; very pale brown (10YR 8/4) strongly cemented duripan, light yellowish brown (10YR 6/4) moist; massive; brittle; 10 percent gravel.

TYPE LOCATION: Owyhee County, Idaho; about 6 1/2 miles west and 1/2 mile north of Riddle; 2,700 feet north of the southwest corner of section 28, T. 12 S., R. 2 E.

RANGE IN CHARACTERISTICS:

Depth to abrupt textural change - 5 to 12 inches
Depth to duripan - 14 to 20 inches
Rock fragments - 0 to 10 percent, mostly fine gravel
Average annual soil temperature - 45 to 47 degrees F.
Average summer soil temperature - 65 to 67 degrees F.

A horizon
Value - 6 or 7 dry, 3 or 4 moist
Chroma - 2 or 3 dry or moist
Reaction (pH) - moderately acid through neutral

Bt horizon
Value - 4 to 6 dry, 3 to 5 moist
Chroma - 3 to 6 dry or moist
Clay content - 40 to 50 percent
Rock fragments - 0 to 20 percent gravel
Reaction (pH) - slightly acid or neutral

Bqm horizon
Value - 7 or 8 dry, 5 to 7 moist
Chroma - 3 to 6 dry or moist
Structure - massive or platy
Effervescence - none or slightly effervescent in upper part

COMPETING SERIES: These are the Furshur and Ponina series. Furshur soils formed in residuum and have bedrock above 40 inches under the duripan. Ponina soils have an abrupt textural change at a depth of 2 to 5 inches and average 50 to 60 percent clay in the Bt horizon.

GEOGRAPHIC SETTING: Nicholflat soils occur on nearly level to gently sloping alluvial flats at elevations of 5,300 to 5,600 feet. Slopes range from 1 to 8 percent. These soils formed in mixed alluvium from extrusive rocks and volcanic ash. The climate is cool and moist in the winter and hot and dry in the summer. Average annual precipitation is 13 to 15 inches, and average annual temperature is 43 to 45 degrees F. The frost-free period is 70 to 90 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bluecreek, and Yatahoney soils. They do not have abrupt textural changes and are deeper than 20 inches. Bluecreek soils are on lower alluvial terraces and Yatahoney soils are on higher, slightly convex landscape positions.

DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; slow permeability.

USE AND VEGETATION: Nicholflat soils are used mainly for rangeland and wildlife habitat. The dominant natural vegetation is low sagebrush, Idaho fescue, bluebunch wheatgrass, and Sandberg bluegrass.

DISTRIBUTION AND EXTENT: Southwestern Idaho. Nicholflat soils are not extensive.

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

SERIES ESTABLISHED: Owyhee County Area, Idaho, 1992.

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

Ochric epipedon - zone 0 to 7 inches (E and BE horizons)

Abrupt textural change - at 7 inches, estimated 20% clay increase within 1 inch (upper boundary of Bt horizon)

Argillic horizon and particle-size control section - zone 7 to 18 inches (Bt horizon)

Duripan - zone 18 to 60 inches (Bkqm and Bqm horizons)

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National Cooperative Soil Survey
U.S.A.