LOCATION SILVA NMEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, mesic Ustic Calciargids
TYPICAL PEDON: Silva loam - rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 2 inches; brown (10YR 5/3) loam, dark brown (10YR 3/3) moist; weak fine granular structure; soft, very friable; many fine roots; common fine interstitial pores; slightly alkaline (pH 7.6); clear smooth boundary. (0 to 3 inches thick)
Bt1--2 to 10 inches; brown (7.5YR 5/4) clay loam, dark brown (7.5YR 3/4) moist; moderate medium subangular blocky structure; hard, friable, sticky and plastic; common fine roots; common fine tubular pores; thin patchy clay films on peds; slightly alkaline (pH 7.6); clear wavy boundary. (4 to 12 inches thick)
Bt2--10 to 18 inches; light brown (7.5YR 6/4) clay loam, brown (7.5YR 4/4) moist; moderate medium subangular blocky structure; hard, friable, sticky and plastic; common fine roots; common fine tubular pores; thin patchy clay films on peds; slightly calcareous; moderately alkaline (pH 8.0); clear wavy boundary. (4 to 16 inches thick)
Bk--18 to 33 inches; light brown (7.5YR 6/4) clay loam, brown (7.5YR 5/4) moist; weak medium subangular blocky structure; hard, friable, sticky and plastic; few fine roots; common fine interstitial pores; strongly calcareous, with few medium faint lime masses; moderately alkaline (pH 8.2); clear wavy boundary. (10 to 20 inches thick)
Ck--33 to 60 inches; very pale brown (10YR 7/4) clay loam, yellowish brown (10YR 5/4) moist; massive; hard, friable, sticky and plastic; few fine roots; few very fine interstitial pores; 10 percent angular caliche coated basalt cobbles; strongly calcareous, lime finely divided with few medium soft masses and threads of lime; moderately alkaline (pH 8.4).
TYPE LOCATION: Taos County, New Mexico; 0.35 mile east and 200 feet north of SW corner of section 22, T.28 N., R.10E.
RANGE IN CHARACTERISTICS:
Soil moisture regime: The soils have an aridic moisture regime that borders on an ustic regime. Th moisture control section is moist for 15 continuous days or less immediately after the soil temperature reaches 41 degrees F. in the spring.
Thickness of the solum: 30 to 40 inches
Gravel content in the control section: 0 to 15 percent
Depth to the calcic horizon: 30 to 40 inches
Where the A horizon or the A and upper part of the B horizon has color of a mollic epipedon, it is either too thin or too low in organic carbon to meet the requirements for a mollic epipedon
A horizon
Hue: 7.5YR or 10YR
Value: 5 or 6 dry, 3 through 5 moist
Chroma: 3 or 4
Texture: loam or fine sandy loam
Consistence: soft or slightly hard
B2t horizon
Hue: 7.5YR or 10YR
Value: 3 through 6
Chroma: 3 or 4
Texture: clay loam, silty clay loam, or clay
Clay content: more than 35 percent
C horizon
Value: 6 through 8 dry, 5 or 6 moist
Chroma: 2 through 4
Texture: loam or clay loam
COMPETING SERIES: These are the Alesna, Hano, Keeseha, and Poley series.
GEOGRAPHIC SETTING: Silva soils are on upland fans and ridges and have slopes of 0 to 10 percent. Elevations range from 6,500 to 7,500 feet. The soils formed in moderately fine textured calcareous alluvial and eolian sediments. The average annual precipitation is about 11 to 13 inches of which approximately 8 inches falls during the period from May through October as intense thunderstorms. The remainder occurs during the period of November through April mainly as snow. The average annual temperature is about 46 to 48 degrees F. The frost-free season is 125 to 135 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Petaca, Hernandez, and Prieta soils. Petaca and Prieta soils have basalt at depths of 10 to 20 inches. Hernandez soils have a calcic horizon.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; slow permeability.
USE AND VEGETATION: The soils are used for range, wildlife habitat, irrigated cropland, and urbanization. Native vegetation is mainly big sagebrush, western wheatgrass, blue grama, galleta, fourwing saltbush, broom snakeweed, and threeawn.
DISTRIBUTION AND EXTENT: North central New Mexico. MLRAs 36 & 51. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Taos County, New Mexico, 1977.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 0 to 2 inch (A horizon)
Argillic horizon - the zone from 2 to 18 inches (Bt horizons)
Calcic horizon - the zone from 18 to 60 inches (Bk, Ck horizon)
Classified according to Soil Taxonomy Second Edition, 1999
The classification was changed from fine, mixed, superactive, mesic Ustic Haplargids to fine, mixed, superactive, mesic Ustic Calciargids in 2003