LOCATION LOCKDOWN ID

Established Series
Rev. ALH/RWL
07/2012

LOCKDOWN SERIES

The Lockdown series consists of deep, well drained soils with very slow permeability that formed in alluvium from tuff and volcaniclastic sediments. Slopes range from 4 to 15 percent in foothills. The average annual precipitation is about 15 inches and the average annual temperature is about 50 degrees F.

TAXONOMIC CLASS: Fine, smectitic, mesic Chromic Calcixererts

TYPICAL PEDON: Lockdown clay loam -- on a linear southeast-facing slope of 13 percent, in rangeland at 3,255 feet elevation. The surface has cracks .2 to 1.5 inches wide and 4 to 10 inches apart. When described on November 1, 1995, the soil was dry to 12 inches and slightly moist below. (Colors are for air-dry soil unless otherwise stated.)

A--0 to 1 inch; grayish brown (2.5Y 5/2) clay loam, dark grayish brown (2.5Y 4/2) moist; weak thin platy structure parting to strong very fine and fine granular; slightly hard, friable, very sticky and very plastic; few very fine and fine roots; common very fine and fine, few medium irregular pores; 5 percent gravel, 5 percent cobbles; neutral (pH 7.2); abrupt smooth boundary. (1 to 2 inches thick)

Bt--1 to 3 inches; grayish brown (2.5Y 5/2) clay, dark grayish brown (2.5Y 4/2) moist; weak coarse platy structure parting to moderate fine and medium angular blocky; hard, firm, very sticky and very plastic; few very fine and fine roots; common very fine and fine tubular pores; cracks 5 mm to 2.5 cm wide; common distinct clay films on faces of peds and in pores; 5 percent fine gravel; neutral (pH 7.1); clear wavy boundary. (2 to 10 inches thick)

Btss1--3 to 15 inches; dark grayish brown (10YR 4/2) clay, very dark grayish brown (10YR 3/2) moist; moderate coarse prismatic structure parting to moderate fine and medium angular blocky; very hard, very firm, very sticky and very plastic; few very fine and fine roots; few very fine tubular pores; cracks 2 to 15 mm wide; many prominent clay films on faces of peds and in pores; common intersecting slickensides and few wedge-shaped aggregates; 5 percent fine gravel; neutral (pH 7.2); gradual wavy boundary.

Btss2--15 to 22 inches; dark grayish brown (10YR 4/2) clay, very dark grayish brown (10YR 3/2) moist; weak coarse prismatic structure parting to moderate medium and coarse angular blocky; very hard, very firm, very sticky and very plastic; few very fine and fine roots; few very fine tubular pores; cracks 2 to 10 mm wide; many prominent clay films on faces of peds and in pores; few intersecting slickensides and wedge-shaped aggregates; neutral (pH 7.2); clear wavy boundary. (combined Btss - 12 to 20 inches thick)

Btk1--22 to 27 inches; grayish brown (2.5Y 5/2) clay, dark grayish brown (2.5Y 4/2) moist; moderate medium angular blocky structure; very hard, firm, very sticky and very plastic; few very fine roots; few very fine and fine tubular pores; cracks less than 5 mm wide; common prominent clay films on faces of peds and in pores; common fine and medium strongly effervescent seams and masses of segregated calcium carbonate; neutral (pH 7.3); clear wavy boundary.

Btk2--27 to 41 inches; light brownish gray (2.5Y 6/2) clay loam, grayish brown (2.5Y 5/2) moist; moderate fine and medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; few very fine and fine tubular pores; common distinct clay films on faces of peds and in pores; violently effervescent; slightly alkaline (pH 7.6); gradual wavy boundary. (combined Btk - 4 to 20 inches thick)

Bk--41 to 53 inches; light brownish gray (2.5Y 6/2) clay loam, grayish brown (2.5Y 5/2) moist; massive; slightly hard, friable, moderately sticky and moderately plastic; few very fine tubular pores; violently effervescent; slightly alkaline (pH 7.8); abrupt smooth boundary. (6 to 18 inches thick)

Cr--53 to 60 inches; slightly fractured tuff with seams of calcium carbonates.

TYPE LOCATION: Ada County, Idaho; about 2 miles east of the Old Idaho State Penitentiary in Boise; 2,550 feet south and 2,450 feet west of the northeast corner of section 17, T.3 N., R.3 E.; USGS Lucky Peak Quadrangle; (Latitude - 43 degrees, 35 minutes, 51 seconds N. and Longitude - 116 degrees, 07 minutes, 23 seconds W.)

RANGE IN CHARACTERISTICS:
Depth to calcium carbonates - 20 to 30 inches
Depth to paralithic contact - 40 to 60 inches
Surface cracks - 5 mm to 5 cm wide; open from July through October in most years
Moisture control section - dry 60 to 90 consecutive days following the summer solstice
Average annual soil temperature - 51 to 52 degrees F.

A horizon
Hue - 10YR or 2.5Y
Chroma - 1 or 2 dry or moist
Clay content - 30 to 40 percent
Rock fragment content - 0 to 15 percent
(0 to 5 cobbles, 0 to 10 gravel)

Bt horizon
Hue - 10YR or 2.5Y
Value - 5 or 6 dry
Chroma - 1 or 2 dry or moist
Texture - SICL, CL or C
Clay content - 35 to 45 percent
Rock fragment content - 0 to 5 percent gravel

Btss horizon
Hue - 10YR or 2.5Y
Value - 4 through 6 dry, 3 or 4 moist
Chroma - 2 or 3 dry or moist
Texture - SIC or C
Clay content - 40 to 50 percent
Rock fragment content - 0 to 5 percent gravel
Wedge-shaped aggregates - few to common (oriented 10 to 45 degrees from horizontal)
Reaction (pH) - neutral or slightly alkaline

Btk horizon
Hue - 10YR through 5Y
Value - 5 through 7 dry, 4 through 6 moist
Chroma - 2 through 4 dry or moist
Texture - C or CL
Clay content - 30 to 45 percent
Rock fragment content - 0 to 5 percent gravel
Calcium carbonate equivalent - 5 to 20 percent
Reaction (pH) - neutral or slightly alkaline

Bk horizon
Hue - 10YR through 5Y
Value - 5 through 7 dry, 4 through 6 moist
Chroma - 2 through 4 dry or moist
Structure - massive or subangular blocky
Texture - CL or L
Clay content - 25 to 35 percent
Rock fragment content - 0 to 15 percent gravel
Calcium carbonate equivalent - 15 to 25 percent
Reaction (pH) - slightly or moderately alkaline

COMPETING SERIES: There are no other series listed with this classification. Brifox (T) soils are similar, but have an average annual soil temperature less than 47 degrees F.

GEOGRAPHIC SETTING: Lockdown soils are moderately to strongly sloping on structural benches at elevations of 2,900 to 3,300 feet. Slopes range from 4 to 15 percent. These soils formed in alluvium from tuff and volcaniclastic sediments. The climate is cool and moist in the winter and warm and dry in the summer. Average annual precipitation is 15 to 16 inches. Average annual temperature is 49 to 50 degrees F. The frost-free period is 130 to 140 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Castlerock and Shafer soils. Castlerock soils have an aridic soil moisture regime, do not have cracks to the surface and are on convex landscape positions. Shafer soils are 20 to 40 inches deep, are noncalcareous and on similar landscape positions.

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

USE AND VEGETATION: Lockdown soils are used mainly for rangeland. The dominant natural vegetation is biscuitroot.

DISTRIBUTION AND EXTENT: Southwestern Idaho. MLRA 10. Lockdown soils are not extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon

SERIES ESTABLISHED: Ada County, Idaho, 2012.

REMARKS: Diagnostic horizons and features recognized in this pedon:
Chromic colors - value 4 moist throughout upper 12 inches
Calcic horizon - zone 27 to 53 inches (Btk2 and Bk horizons)
Cracks - 2 mm to 4 cm wide extending from the surface to 27 inches.
Paralithic contact - at 53 inches (Cr horizon)
Particle-size control section - zone 10 to 40 inches
Soil moisture regime - xeric

National Cooperative Soil Survey
U.S.A.