LOCATION NORTHCASTLE IDEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Typic Durixerolls
TYPICAL PEDON: Northcastle loam -- on a 5 percent south-facing slope under native rangeland at 5,320 feet elevation. (When described on August 3, 1978, the soil was slightly moist throughout. Colors are for air dry soil unless otherwise stated.)
A1--0 to 7 inches; dark grayish brown (10YR 4/2) loam, very dark brown (10YR 2/2) moist; moderate medium subangular blocky structure; slightly hard, very friable, slightly plastic; many very fine and fine roots; common very fine and fine vesicular and interstitial pores; slightly acid (pH 6.2); abrupt smooth boundary. (2 to 7 inches thick)
A2--7 to 16 inches; dark grayish brown (10YR 4/2) loam, very dark grayish brown (10YR 3/2) moist; strong medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and fine roots; common very fine and fine vesicular and interstitial pores; 10 percent gravel; slightly acid (pH 6.3); clear smooth boundary. (0 to 9 inches thick)
Bt--16 to 34 inches; yellowish brown (10YR 5/4) gravelly clay loam, dark yellowish brown (10YR 3/4) moist; strong fine prismatic structure parting to moderate very fine subangular blocky; hard, friable, slightly sticky and slightly plastic; common very fine and few fine roots; common very fine tubular pores; many moderately thick clay films on faces of peds; 25 percent gravel; slightly acid (pH 6.1); clear wavy boundary. (14 to 34 inches thick)
Bqm--34 to 60 inches; white (10YR 8/2) to very pale brown (10YR 7/4) continuous indurated duripan; massive; extremely hard, very firm, brittle; 50 percent gravel; clear smooth boundary. (5 to 26 inches thick)
C--60 to 72 inches; very pale brown (10YR 7/3) gravelly sandy loam, dark brown (10YR 3/3) moist with common medium strong brown (7.5YR 5/6) mottles; massive; very hard, friable; many very fine interstitial pores; 20 percent gravel; slightly acid (pH 6.4).
TYPE LOCATION: Owyhee County, Idaho; about 7 miles north of Triangle; 500 feet west and 100 feet north of the southeast corner of section 29, T. 6 S., R. 2 W.
RANGE IN CHARACTERISTICS:
Mollic epipedon thickness - 7 to 16 inches
Depth to duripan - 21 to 40 inches
Average annual soil temperature - 43 to 47 degrees F.
Average summer soil temperature - 63 to 67 degrees F.
A horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 1 to 3 dry or moist
Reaction (pH) - slightly acid or neutral
Coarse fragments - 0 to 10 percent
Bt horizon
Value - 5 to 7 dry, 2 to 4 moist
Chroma - 3 or 4 dry or moist
Texture - SCL, CL, or GR-CL
Clay content - 24 to 35 percent
Reaction (pH) - slightly acid or neutral
Coarse fragments - 0 to 25 percent
C horizon
Value - 5 to 8 dry, 3 to 6 moist
Chroma - 3 or 4 dry or moist
Texture - GR-LS, GR-SL, LS, or SL
Coarse fragments - 0 to 30 percent
Reaction (pH) - slightly acid through moderately alkaline
COMPETING SERIES: These are the Chayson and Ibola series. Chayson soils are mildly or moderately alkaline in the argillic horizon and have secondary calcium carbonate below a depth of 8 to 27 inches. Ibola soils have duripans 1 to 4 inches thick.
GEOGRAPHIC SETTING: Northcastle soils occur on nearly level to gently sloping fans and stream terraces at elevations of 5,000 to 5,900 feet. Slopes range from 1 to 8 percent. These soils formed in mixed alluvium from volcaniclastic and tuffaceous material. The climate is cool and moist in the winter, and hot and dry in the summer. Average annual precipitation is 12 to 16 inches, and average annual temperature is 41 to 45 degrees F. The frost-free period is 70 to 95 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Blackwell, Bluecreek, Paynecreek, and Yatahoney series. Blackwell and Paynecreek soils lack duripans. Bluecreek and Yatahoney soils have greater than 35 percent clay in the control section. Blackwell soils are on lower alluvial bottomlands. Bluecreek, Paynecreek, and Yatahoney soils are on similar landscape positions or on higher terraces and fans.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderately slow permeability. The layers below the duripan are commonly wet for short periods in spring.
USE AND VEGETATION: Northcastle soils are used mainly for rangeland and wildlife habitat. The dominant natural vegetation is basin big sagebrush, Idaho fescue, bluebunch wheatgrass, and Sandberg bluegrass.
DISTRIBUTION AND EXTENT: Southwestern Idaho. Northcastle soils are of small extent.
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:
Mollic epipedon - zone 0 to 16 inches (A1 and A2 horizons)
Argillic horizon and particle-size control section - zone 16 to 34 inches (Bt horizon)
Duripan - zone 34 to 60 inches (Bqm horizon)
The superactive cation exchange activity class was added in 03/2003 to the taxonomic classification by the National Soil Survey Center on request of the Reno MLRA office, without review of the soil series property data. The remainder of this document has not been updated.