LOCATION BUCKHORSE NMEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Calcidic Argiustolls
TYPICAL PEDON: Buckhorse coarse sandy loam--on a toeslope of an erosional fan remnant sloping 7 percent to the southeast at 6,730 feet elevation--rangeland. (Colors are for dry soil unless otherwise noted. When described, the soil was moist from 1 to 3 inches and otherwise dry throughout.)
A--0 to 4 inches; brown (7.5YR 4/3) coarse sandy loam, dark brown (7.5YR 3/2) moist; weak medium platy structure parting to moderate fine granular; soft, very friable, slightly sticky and nonplastic; many very fine roots; few very fine irregularly shaped pores; 10 percent gravel; strongly effervescent; moderately alkaline (pH 8.2); abrupt smooth boundary. (2 to 4 inches thick)
Bt--4 to 11 inches; brown (7.5YR 4/3) coarse sandy loam, dark brown (7.5YR 3/2) moist; moderate medium prismatic structure parting to weak coarse subangular blocky; soft, very friable, slightly sticky and nonplastic; few medium, few fine, and common very fine roots; few fine and few very fine tubular pores; few distinct clay films on faces of peds and few faint clay films on faces of peds and lining pores; 10 percent gravel; strongly effervescent, secondary calcium carbonate segregated as very few irregularly shaped coats on rock fragments; moderately alkaline (pH 8.3); clear smooth boundary. (5 to 8 inches thick)
Btk1--11 to 22 inches; brown (7.5YR 5/3) loam, brown (7.5YR 4/2) moist; moderate medium prismatic structure parting to weak coarse subangular blocky; slightly hard, very friable, slightly sticky and slightly plastic; few coarse, few medium, few fine, and common very fine roots; common very fine tubular pores; few faint clay films on faces of peds and lining pores; 10 percent gravel; violently effervescent, secondary calcium carbonate segregated as common fine and medium irregularly shaped coats on faces of peds and on rock fragments; moderately alkaline (pH 8.4); clear wavy boundary. (4 to 16 inches thick)
Btk2--22 to 37 inches; light brown (7.5YR 6/3) loam, brown (7.5YR 4/3) moist; weak medium prismatic structure parting to moderate coarse subangular blocky; slightly hard, friable, moderately sticky and slightly plastic; few coarse, few medium, common fine and common very fine roots; few fine and common very fine tubular pores; few faint clay films on faces of peds and lining pores; 5 percent gravel; violently effervescent, secondary calcium carbonate segregated as common fine irregularly shaped coats on faces of peds and on rock fragments; strongly alkaline (pH 8.6); clear wavy boundary. (0 to 16 inches thick)
Bk--37 to 49 inches; light brown (7.5YR 6/4) fine sandy loam, brown (7.5YR 4/4) moist; moderate coarse subangular blocky structure; slightly hard, very friable, slightly sticky and nonplastic; few medium, few fine, and few very fine roots; few fine and common very fine tubular pores; 5 percent gravel; violently effervescent, secondary calcium carbonate segregated as few fine and medium irregularly shaped coats on rock fragments and on faces of peds; strongly alkaline (pH 8.6); clear smooth boundary. (6 to 18 inches thick)
BCk--49 to 61 inches; light brown (7.5YR 6/4) sandy loam, brown (7.5YR 4/4) moist; weak coarse subangular blocky structure; soft, very friable, slightly sticky and nonplastic; few fine and few very fine roots; few fine and few very fine tubular pores; 10 percent gravel; strongly effervescent, secondary calcium carbonate segregated as very few fine irregularly shaped coats on rock fragments; moderately alkaline (pH 8.4); clear wavy boundary. (8 to 26 inches thick)
C--61 to 83 inches; light brown (7.5YR 6/4) gravelly coarse sand, brown (7.5YR 4/4) moist; single grain; loose, nonsticky and nonplastic; few very fine roots; few strata of loam and sandy loam; 20 percent gravel; slightly effervescent; moderately alkaline (pH 8.2).
TYPE LOCATION: Santa Fe County, New Mexico; about 2.5 miles north of Agua Fria; 900 feet east and 700 feet south of the northwest corner of section 20, T.17N., R.9E.; USGS Agua Fria 7.5 minute topographic quadrangle; Latitude 35 degrees 41 minutes 42 seconds North and Longitude 106 degrees 0 minutes 55 seconds West, NAD 27.
RANGE IN CHARACTERISTICS:
Soil moisture - Typically, the soil moisture control section is moist in all parts during the 60 days following the winter solstice. It is moist in some part less than 40 percent and moist in all parts less than 25 percent of the time when the soil temperature at 20 inches is above 41 degrees F. The soils are driest in May and June. The soil moisture regime is ustic bordering on aridic.
Mean annual soil temperature - 49 to 52 degrees F.
Depth to base of mollic epipedon - 7 to 19 inches
Depth to calcareous material - 0 to 8 inches
Depth to base of argillic horizon - 15 to 38 inches
Depth to calcic horizon - 7 to 11 inches
Lithology of rock fragments: granite, gneiss, and schist.
Volcanic glass content: 70 to 90 percent in the coarse silt plus sand fraction
Particle-size control section (weighted averages)
Silicate clay content: 8 to 18 percent
Sand content: 35 to 65 percent
Fine sand and coarser content: more than 35 percent
Rock fragment content: 0 to 15 percent gravel
Mica content: 1 to 3 percent (by grain count)
Organic matter content - 1 to 3 percent in the mollic epipedon
Reaction - neutral to moderately alkaline in the surface and in the upper part of the subsoil; moderately alkaline to strongly alkaline in the lower part of the subsoil and in the upper part of the substratum; slightly alkaline to strongly alkaline in the lower part of the substratum.
Salinity, mmhos/cm - 0 to 1 in the surface and subsoil; 0 to 2 in the substratum
Sodicity, SAR - 0 to 1 in the surface and subsoil; 0 to 4 in the substratum
A horizon
Value: 4 or 5 dry
Chroma: 2 or 3, dry or moist
Rock fragments: 5 to 15 percent gravel
Bt horizon
Value: 4 or 5 dry
Chroma: 2 or 3, dry or moist
Texture: coarse sandy loam, sandy loam, or loam
Btk horizons
Value: 5 or 6 dry, 3 or 4 moist
Chroma: 3 or 4 dry, 2 through 4 moist
Texture: loam or sandy loam
Calcium carbonate equivalent: 5 to 15 percent
Bk horizons
Value: 5 through 7 dry, 4 or 5 moist
Chroma: 3 or 4, dry or moist
Texture: fine sandy loam, sandy loam, or loam
Rock fragments: 0 to 15 percent gravel
Calcium carbonate equivalent: 5 to 15 percent
Other features: some pedons have thin subhorizons with texture of gravelly loam or gravelly sandy loam.
BCk horizon
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 3 or 4, dry or moist
Texture: sandy loam, coarse sandy loam, or gravelly sandy loam
Rock fragments: 5 to 20 percent gravel
Calcium carbonate equivalent: 5 to 10 percent
Other features: some pedons have thin subhorizons with texture of very gravelly coarse sandy loam or very gravelly loamy coarse sand.
C horizons
Value: 5 through 7 dry, 4 or 5 moist
Chroma: 3 or 4 dry, 3, 4, or 6 moist
Texture: stratified gravelly coarse sand to loam
Rock fragments: 5 to 20 percent gravel
Calcium carbonate equivalent: 0 to 10 percent
Other features: some pedons have buried horizons with weak, discontinuous cementation by secondary silica or up to 15 percent calcium carbonate equivalent.
COMPETING SERIES: There are currently no competing series.
GEOGRAPHIC SETTING: Buckhorse soils are on toeslopes of erosional fan remnants. They formed in alluvium derived from Precambrian granite, gneiss, and schist, and from Tertiary granitic sandstone, fanglomerate, and mudstone. Slopes are 2 to 8 percent. Elevation ranges from 5,700 to 7,900 feet. The mean annual precipitation is 13 to 15 inches with about 45 percent falling as rain from high-intensity convective thunderstorms between July and September. The mean annual air temperature is 47 to 50 degrees F. The frost-free period is 140 to 160 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Altazano, Encantado, and Tanoan soils. Altazano soils are coarse-loamy, have stratified alluvial mantles, and occur on adjacent, frequently flooded inset fans. Encantado soils are sandy-skeletal, have calcic horizons, and occur on shoulders and backslopes of erosional fan remnants. Tanoan soils are coarse-loamy, have ochric epipedons and calcic horizons, and occur on shoulders and footslopes of erosional fan remnants.
DRAINAGE AND PERMEABILITY: Well drained; medium surface runoff; moderately rapid permeability in the subsoil and in the upper part of the substratum, and moderately rapid or rapid permeability in the lower part of the substratum.
USE AND VEGETATION: Buckhorse soils are used for urban development, livestock grazing, and recreation. The historic climax vegetation is blue grama, galleta, ring muhly, black grama, and broom snakeweed. The ecological site is Loamy(R036XB112NM).
DISTRIBUTION AND EXTENT: Buckhorse soils are of small extent on the southeastern Espanola Basin part of the Basin and Range province in northcentral New Mexico. The MLRA is 36.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Santa Fe County, New Mexico; Santa Fe Area Soil Survey Update; 2008. Buckhorse is a coined name derived from the name Buckman, its region of origin. This series was originally proposed as Buckmen in 1996, and changed to Buckhorse in 2006.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to a depth of about 11 inches. (A and Bt horizons)
Argillic horizon - The zone from 4 to about 37 inches. (Bt, Btk1, and Btk2 horizons)
Calcic horizon - The zone from 11 to about 49 inches. (Btk1, Btk2, and Bk horizons)
ADDITIONAL DATA: The series type location has been sampled for the Soil Survey Laboratory (SSL), Lincoln, NE, as soil survey sample number S94NM-049-001. Reference analyses such as particle-size distribution, organic carbon content, and cation exchange capacity were performed.