LOCATION TREVINO IDEstablished Series
TAXONOMIC CLASS: Loamy, mixed, superactive, mesic Lithic Xeric Haplocambids
TYPICAL PEDON: Trevino silt loam -- on a 3 percent northwest-facing slope at 2,780 feet elevation in rangeland. (Colors are for air-dry soil unless otherwise noted.)
A--0 to 3 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; weak thin and very thin platy structure parting to weak very fine granular; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and fine and few coarse roots; many very fine interstitial and tubular pores; neutral (pH 7.2); abrupt smooth boundary. (0 to 4 inches thick)
AB--3 to 5 inches; pale brown (10YR 6/3) silt loam, dark grayish brown (10YR 4/2) moist; weak medium subangular blocky structure parting to weak very fine and fine granular; hard, very friable, slightly sticky and slightly plastic; common very fine and fine, and few medium and coarse roots; common very fine pores; slightly alkaline (pH 7.4); clear smooth boundary. (0 to 3 inches thick)
Bw--5 to 10 inches; pale brown (10YR 6/3) silt loam, brown (10YR 4/3) moist; weak medium prismatic structure parting to weak medium and fine subangular blocky; hard, very friable, slightly sticky and slightly plastic; few thin clay films on vertical faces of peds and in channels; common very fine and fine, few medium and coarse roots; many very fine tubular pores; noneffervescent except for few pieces from the underlying Bkq horizon; slightly alkaline (pH 7.6); abrupt smooth boundary. (3 to 8 inches thick)
Bkq1--10 to 13 inches; very pale brown (10YR 7/3) silt loam, brown (10YR 5/3) moist; weak medium and fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few fine to coarse roots; many very fine tubular pores; 5 percent gravel, few hard nodules of soil material; few chips or fragments of hard, firm, weakly cemented soil material; strongly effervescent; moderately alkaline (pH 8.2); clear smooth boundary. (2 to 6 inches thick)
Bkq2--13 to 18 inches; white (10YR 8/2) light loam, pale brown (10YR 6/3) moist; massive; soil material in coarse lenses or plates; matrix is soft, very friable, nonsticky and slightly plastic; few discontinuous very thin (less than 1 mm) dense cemented lenses; roots matted on top of the lenses, with soil in immediate area very pale brown (10YR 8/3) and brown (10YR 5/3) moist; few very hard, firm nodules or (cicada) krotovinas; 10 percent gravel; moderately calcareous with thin lime coats on the nodules and rock fragments; moderately alkaline (pH 8.3); clear wavy boundary. (0 to 6 inches thick)
2R--18 inches; basalt; lime-coated on upper boundary.
TYPE LOCATION: Canyon County, Idaho; about 4 miles north of Melba; 27 feet north of the northwest corner of the power substation, 208 feet north of the power line, and 350 feet west of road; 475 feet west and 1,950 feet south of the NE corner of section 11, T. 1 N., R. 2 W.; USGS Melba Quadrangle; (Latitude - 43 degrees, 26 minutes, 21 seconds N. and Longitude - 116 degrees, 32 minutes, 04 seconds W.).
RANGE IN CHARACTERISTICS
Average annual soil temperature - 47 to 56 degrees F.
Depth to bedrock - 8 to 20 inches
Depth to calcium carbonate - 8 to 18 inches
Particle-size control section
Clay content - 10 to 18 percent
Sand content - more than 15 percent coarser than VFS
Rock fragments - 0 to 35 percent including gravel, cobbles and stones
A and AB horizons
Value - 4 through 7 dry, 3 through 5 moist
Chroma - 2 or 3 dry or moist
Reaction - neutral through moderately alkaline
Bw horizon
Value - 5 through 7 dry, 3 through 5 moist
Chroma - 2 through 4 dry or moist
Texture - SIL, L or VFSL
Rock fragments - 0 to 35 percent
Reaction - neutral through moderately alkaline
Bkq horizon
Value - 6 through 8 dry, 4 through 7 moist
Chroma - 2 through 4 dry or moist
Texture - SIL, L or FSL
Rock fragments - 0 to 35 percent
Calcium carbonate equivalent - 5 to 15 percent
Reaction - slightly alkaline through strongly alkaline
COMPETING SERIES: These are the Calzacorta (T), Slayton and Starbuck series. Slayton soils are moderately coarse textured in the control section, contain pumice, and have sandy tuff or breccia bedrock above depth of 20 inches. Calzacorta and Starbuck soils lack Bkq horizons. Calzacorta soils have 18 to 35 percent clay in the particle-size control section.
GEOGRAPHIC SETTING: Trevino soils are on basalt plains, buttes, terraces, and terrace side slopes and plug domes, lava flow lobes, pressure ridges and tumuli on shield volcanoes and lava plains. Elevations are 2,000 to 5,400 feet. The soils formed in loess and weathered volcanic ash mixed with alluvium and colluvium from basalt. Slopes are 0 to 30 percent. The climate is semiarid with hot, dry summers and cool, moist winters. Average annual precipitation is 7 to 12 inches, average annual temperature is 45 to 54 degrees F., and the frost free season is 110 to 160 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Minidoka, Portneuf and Scism series all of which lack bedrock above 20 inches. These soils occur on the same landscape.
DRAINAGE AND PERMEABILITY: Well drained, slow through rapid runoff; moderate permeability.
USE AND VEGETATION: Used mostly for rangeland and wildlife habitat. Some minor areas are irrigated and used for small grains, corn, beans, hay, and pasture. Potential vegetation in the natural plant community is Wyoming big sagebrush, Thurber needlegrass, and bluebunch wheatgrass.
DISTRIBUTION AND EXTENT: Southern Idaho; MLRA 11. The series is extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Canyon County, Idaho, 1973.
REMARKS: Diagnostic horizons and other features recognized in this pedon are:
Ochric epipedon - The zone from 0 to 5 inches (A and AB horizons)
Cambic horizon - The zone from 3 to 13 inches (AB and Bw horizons)
Particle-size control section - The zone from 10 to 18 inches.
Lithic contact - The boundary at approximately 18 inches
Soil moisture regime - aridic bordering xeric
Geographic setting - terms used throughout MLRA 11 to identify the setting of this soil are quite varied although all equate to the same landscape. There will be further investigation from an MLRA project level as to the accepted terms for use.
The classification of this pedon has been revised as of 4/00 from loamy, mixed, mesic Lithic Xerollic Camborthids to loamy, mixed, superactive, mesic Lithic Xeric Haplocambids based on revisions to Soil Taxomony.
The term silty alluvium used in this series concept infers a localized influence on the mixed loess and weathered volcanic ash soil mantle by overland flow of running water.