LOCATION SECO NMEstablished Series
TAXONOMIC CLASS: Very-fine, mixed, superactive, frigid Vertic Argiustolls
TYPICAL PEDON: Seco clay loam--in rangeland on an east facing slope of 2 percent at an elevation of 8,350 feet. (Colors are for dry soils unless otherwise noted.)
A--0 to 3 inches; grayish brown (10YR 5/2) clay loam, very dark grayish brown (10YR 3/2) moist; moderate medium and thick platy structure; slightly hard, friable, sticky and plastic; common very fine and fine roots; common fine irregular pores; slightly acid (pH 6.4); clear smooth boundary. (2 to 4 inches thick)
Bt-- 3 to 11 inches; dark grayish brown (10YR 4/2) clay, very dark brown (10YR 2/2) moist; strong very fine and fine subangular blocky structure; very hard, very firm, very sticky and very plastic; many prominent clay films coating faces of peds; neutral (pH 7.2); abrupt wavy boundary.
Btss--11 to 23 inches; brown (7.5YR 4/2) clay, dark brown (7.5YR 3/2) moist; moderate fine and medium prismatic structure parting to strong fine angular blocky; extremely hard, extremely firm, very sticky and very plastic; common very fine and fine roots; few fine tubular pores; many prominent clay films coating faces of peds; common slickensides and pressure faces; cracks less than 1/4 inch wide extend from 11 to 28 inches; slightly alkaline (pH 7.4); gradual irregular boundary. (The combined thickness of the Bt horizons is 19 to 58 inches.)
Btkss--23 to 58 inches; brown (7.5YR 4/4) clay, dark brown (7.5YR 3/4) moist; moderate medium angular blocky structure; extremely hard, extremely firm, very sticky and very plastic; few very fine and fine roots; few fine tubular pores; many prominent clay films coating faces of peds; common fine and medium distinct dark grayish brown (10YR 4/2) and very dark grayish brown (10YR 3/2) moist redox depletions; common slickensides and pressure faces; calcium carbonate is segregated as few fine soft masses and as coats on soft weathered basalt pebbles; matrix is noneffervescent, soft masses and coats are strongly effervescent; 2 percent soft weathered basalt pebbles; slightly alkaline (pH 7.8); clear wavy boundary. (0 to 35 inches thick)
2BCg--58 to 70 inches; light yellowish brown (2.5Y 6/3) clay, light olive brown (2.5Y 5/3) moist; massive; extremely hard, extremely firm, very sticky and very plastic; very few very fine roots; very few very fine irregular pores; common fine and medium prominent brown (7.5YR 5/4) and brown (7.5YR 4/4) moist redox concentrations; few fine soft white noneffervescent masses; slightly alkaline (pH 7.4). (0 to 12 inches thick)
TYPE LOCATION: McKinley County, New Mexico; Marquez Quadrangle; about 4.6 miles west-northwest of Marquez, New Mexico; 107 degrees 20 minutes 23 seconds west longitude, 35 degrees 22 minutes 27 seconds north latitude.
RANGE IN CHARACTERISTICS:
Soil Moisture: The SMCS is usually moist, in some part, for more than 90 cumulative days from May through October. It is usually dry, in all parts, for less than 90 cumulative days during the same period. It is continuously moist in some part November through April. The period of maximum precipitation is July through October. The soil is driest during May and June. Typic ustic moisture regime.
Soil Temperature: 42 to 47 degrees F
Particle size control section: 60 to 80 percent clay
Mollic epipedon: 15 to 30 inches thick
Depth to secondary calcium carbonate (when present): 20 to 50 inches with less than 5 percent calcium carbonate equivalent.
Depth to cracks, slickensides, and pressure faces: 8 to 22 inches
Redoximorphic features:
Depth: 20 to 50 inches
Size: fine or medium
Contrast: distinct or prominent
Hue: 7.5YR or 10YR
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 2 to 4 dry or moist
A horizon
Hue: 7.5YR or 10YR
Value: 4 or 5 dry
Chroma: 2 or 3 dry
Reaction: slightly acid or neutral
Bt horizon
Hue: 5YR, 7.5YR, or 10YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 2 to 4 dry, 0 to 4 moist
Texture: clay or silty clay
Reaction: neutral to moderately alkaline
Btss horizon
Hue: 5YR, 7.5YR, or 10YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 2 to 4 dry, 0 to 4 moist
Texture: clay or silty clay
Reaction: neutral to moderately alkaline
Salinity: 0 to 2 mmhos/cm
Btk horizon (may be absent)
Hue: 7.5YR or 10YR
Value: 4 or 5 dry, 3 or 4 moist
Reaction: slightly or moderately alkaline
Calcium carbonate equivalent: 1 to 5 percent
Salinity: 0 to 2 mmhos/cm
2BC horizon (may be absent)
Value: 4 to 6 dry, 4 or 5 moist
Chroma: 2 or 3 moist
Salinity: 0 to 2 mmhos/cm
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: The Seco soils formed in alluvium and slope alluvium derived from basalt (associated with the Mt. Taylor and Mesa Chivato volcanic fields) and are on valley floors and edges of playas. Slopes are 0 to 5 percent. Elevations range from 8,000 to 8,400 feet. The mean annual temperature is 40 to 45 degrees F., and the mean annual precipitation is 16 to 20 inches. The frost free period is 90 to 110 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Chivato soils on playas; and the Canoneros and Montillo soils on lava plateaus and cinder cones. The Chivato soils lack argillic horizons and have cracks extending to the surface. The Canoneros and Montillo soils are shallow and moderately deep to basalt, respectively.
DRAINAGE AND PERMEABILITY: Moderately well drained, high to very high runoff, and very slow permeability.
USE AND VEGETATION: This series is used for rangeland. The present vegetation is fringed sage, cinquefoil, broom snakeweed, Arizona fescue, bottlebrush squirreltail, and blue grama.
DISTRIBUTION AND EXTENT: West central, New Mexico; MLRA 35, LRR-D. This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona.
SERIES ESTABLISHED: McKinley County Area, New Mexico; McKinley County and Parts of Cibola and San Juan Counties, 2001.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: The zone from 0 to 23 inches. (A, Bt, and Btss horizons)
Argillic horizon: The zone from 3 to 58 inches. (Bt, Btss, and the Btkss horizons)
Vertic features: The presence of cracks, slickensides and pressure faces from 11 to 58 inches. (Btss and Btkss horizons)
Redoximorphic features: The zone from 23 to 70 inches. (Btkss and 2BC horizons)
Mineralogy class was changed from smectitic to mixed, and superactive cation exchange activity class was added in December 2000.
Classified according to Soil Taxonomy Second Edition, 1999.