LOCATION ROBOLATA NMEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, frigid Pachic Argiustolls
TYPICAL PEDON: Robolata loam--pastureland on a convex surface of 1 percent slope at an elevation of 7,880 feet. (Colors are for dry soils unless otherwise noted.)
A--0 to 6 inches; reddish brown (5YR 4/3) loam, dark reddish brown (5YR 3/3) moist; moderate thin platy structure; soft, very friable, slightly sticky and nonplastic; many very fine and fine roots; slightly alkaline (pH 7.6); abrupt smooth boundary. (2 to 9 inches thick)
Bt1--6 to 12 inches; reddish brown (5YR 4/3) loam, dark reddish brown (5YR 3/3) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and nonplastic; many very fine, fine, and few medium roots; common very fine and few fine irregular pores; few wormcasts; common distinct clay films on faces of peds; slightly alkaline (pH 7.6); abrupt wavy boundary.
Bt2--12 to 20 inches; dark reddish brown (5YR 3/3) clay, dark reddish brown (5YR 3/2) moist; strong medium angular blocky structure; very hard, very firm, sticky and plastic; common very fine, fine, and few medium roots; common very fine and few medium irregular pores; many prominent clay films on faces of peds; 1 percent sandstone pebbles; slightly alkaline (pH 7.6); abrupt wavy boundary.
2Bt3--20 to 30 inches; dark red (2.5YR 3/6) clay loam, dark reddish brown (2.5YR 3/4) moist; strong medium angular blocky structure; very hard, very firm, sticky and plastic; common very fine and fine roots; few very fine irregular pores; few very fine and fine manganese concretions; many prominent clay films on faces of peds; 1 percent sandstone pebbles; slightly alkaline (pH 7.8); clear wavy boundary. (The combined thickness of the Bt horizons is 6 to 15 inches thick)
2Btk--30 to 50 inches; red (2.5YR 5/6) sandy clay loam, red (2.5YR 4/6) moist; weak fine subangular blocky structure; hard, firm, slightly sticky and non plastic; few very fine roots; few very fine irregular pores; few faint clay films on faces of peds and bridging sand grains; 12 percent sandstone pebbles; slightly effervescent; few very fine masses of calcium carbonate; 6 percent calcium carbonate equivalent; slightly alkaline (pH 7.8); clear wavy boundary. (20 to 40 inches thick)
2BC--50 to 70 inches; red (2.5YR 5/6) very gravelly sandy loam, red (2.5YR 4/6) moist; weak very fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; few very fine roots; 55 percent sandstone pebbles; slightly effervescent; calcium carbonate is disseminated; slightly alkaline (pH 7.8). (0 to 20 inches thick)
TYPE LOCATION: McKinley County, New Mexico; about 0.5 mile south of Page, New Mexico; Page Quadrangle; 2050 feet south and 100 feet west of the northeast corner of section 32, T. 13 N., R. 15 W.; 108 degrees 26 minutes 28 seconds west longitude, 35 degrees 18 minutes 56 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: 35 to 50 percent clay
Thickness of the mollic epipedon: 16 to 26 inches
Depth to secondary carbonates: 20 to 40 inches
A horizon
Hue: 5YR or 7.5YR
Chroma: 2 or 3
Bt horizon
Hue: 2.5YR or 5YR
Value: 3 or 4 dry
Chroma: 2 to 6
Textures: loam, clay loam, or clay
Rock fragments: 0 to 5 percent sandstone pebbles
Btk horizon
Hue: 2.5YR or 5YR
Value: 3 or 4 moist
Chroma: 4 or 6
Textures: sandy clay loam, loam, clay loam, or clay
Rock fragments: 0 to 25 percent sandstone pebbles
Reaction: slightly to moderately alkaline
BC horizon
Hue: 2.5YR or 5YR
Value: 3 or 4 moist
Chroma: 4 or 6
Textures: fine sandy loam, very gravelly sandy loam, gravelly loam, or loam
Rock fragments: 0 to 55 percent sandstone pebbles
Reaction: slightly to moderately alkaline
COMPETING SERIES: These are the Bandarito (CO), Encicado (NM), Gaines (NM), Seeprid (UT), and Telephono (NM) series. Bandarito soils have hue 10YR and yellower. Encicado soils have a discontinuity with clayey-skeletal materials in the subsoil. Gaines and Seeprid soils have lithic contacts within 60 inches. Telephono soils have lithic contacts within 40 inches.
GEOGRAPHIC SETTING: The Robolata soils formed in alluvium and stream alluvium derived from mixed sources and are on stream terraces on valley floors. Slopes are 1 to 5 percent. Elevations range from 7,700 to 8,000 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 Cinnadale, Heckly, Ligocki, Polich and Zuni soils. Cinnadale and Heckly are shallow and moderately deep soils on hills and ridges. Ligocki soils lack a mollic epipedon and are on fan remnants. Polich soils are somewhat poorly drained on flood plains. The Zuni soils are moderately deep on mountain sideslopes.
DRAINAGE AND PERMEABILITY: Well drained, high runoff, and slow permeability. These soils occasionally flood during spring runoff.
USE AND VEGETATION: This series is used for livestock grazing. The present vegetation is western wheatgrass, muttongrass, blue grama, bottlebrush squirreltail, broom snakeweed, fringed sagewort, and lupine.
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 and Pachic feature: The zone from 0 to 20 inches. (A, Bt1, and Bt2 horizons)
Argillic horizon: The zone from 6 to 50 inches. (Bt1, Bt2, 2Bt3, and 2Btk horizons)
Classified according to Soil Taxonomy Second Edition, 1999.