LOCATION ORO NMEstablished Series
TAXONOMIC CLASS: Clayey over loamy, smectitic over mixed, superactive, mesic Ustertic Haplargids
TYPICAL PEDON: Oro silty clay loam - rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 2 inches; brown (10YR 5/3) clay loam, brown (10YR 4/3) moist; moderate very fine granular structure; soft, very friable, slightly sticky, and slightly plastic, common very fine roots; neutral (pH 7.2); clear smooth boundary. (1 to 4 inches thick)
Bt1--2 to 8 inches; brown (7.5YR 5/3) clay, brown (7.5YR 4/3) moist; moderate medium prismatic parting to strong fine angular blocky structure; hard, very firm, very sticky and very plastic; common very fine roots; common distinct thick clay films on faces of peds; slightly alkaline (pH 7.5); clear smooth boundary. (4 to 12 inches thick)
Btss2--8 to 25 inches; brown (7.5YR 5/3) clay, brown (7.5YR 4/3) moist; strong medium angular blocky structure; very hard, very firm, very sticky and very plastic; common very fine roots; common slickensides and wedge shaped aggregates; common moderately thick clay films on faces of peds; slightly alkaline (pH 7.6); clear smooth boundary. (7 to 25 inches thick)
2Bt3--25 to 33 inches; brown (7.5YR 5/3) clay, brown (7.5YR 4/3) moist; moderate medium and fine angular blocky structure; hard, firm, sticky, and plastic; few very fine roots; common faint clay film on faces of peds; very slightly effervescent; slightly alkaline (pH 7.7); clear smooth boundary.
2Bk--33 to 39 inches; pale brown (10YR 6/3) fine sandy loam, brown (10YR 5/3) moist; moderate medium subangular blocky structure; slightly hard, firm, sticky, and plastic; few very fine tubular pores; common fine soft masses of secondary calcium carbonates; slightly effervescent; moderately alkaline (pH 7.9); clear smooth boundary.
2C--39 to 80 inches; brown (10YR 5/3) loamy fine sand, brown (10YR 4/3) moist; single grain; loose; loose, nonsticky, and nonplastic; moderately alkaline (pH 7.9).
TYPE LOCATION: Rio Arriba County, New Mexico; unsurveyed area; 36 degrees 13 minutes 25 seconds North Latitude and 107 degrees 16 minutes 13 seconds West Longitude.
RANGE IN CHARACTERISTICS:
Soil moisture: Typically dry in all parts of the moisture control section from mid-February to the end of June and are moist in some part intermittently from July to October. The SMCS is periodically moist in some parts from November to mid February. This soil is in the ustic aridic.moisture regime.
Mean annual soil temperature: 49 to 52 degrees F
Depth to lithic contact: more than 80 inches
Clay content: 35 to 50 percent, in the upper part; 5 to 25 percent in the lower part
Rock fragments: 0 to 10 percent, mainly pebbles
Depth to strongly contrasting layer: 15 to 35 inches.
Cracks are greater than 5mm wide throughout a thickness of 12 inches for some time in normal years.
A horizon:
Hue: 7.5YR or 10YR
Value: 5 or 6 dry, 3 or 4 moist
Chroma: 3 or 4 dry or moist
Bt, Btss horizon:
Hue: 7.5YR or 10YR
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 2 to 4 dry or moist
Texture: silty clay, clay or clay loam
Clay Content: 35 to 45 percent
Reaction: neutral to slightly alkaline
2Bt, 2Btk, or 2Bk horizon:
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 3 or 4 dry or moist
Texture: fine sandy loam, sandy clay loam, or loam
Clay content: 5 to 25
Reaction: slightly to moderately alkaline
Calcium carbonate equivalent: less than 15 percent
2C horizon:
Value: 5 or 6 dry, 4 or moist
Chroma: 3 or 4 dry or moist
Texture: loamy fine sand, fine sandy loam, sandy clay loam, or loam
Sand content: more than 35 percent
Clay Content: 8 to 25 percent
COMPETING SERIES: There are currently no competing series in this family.
GEOGRAPHIC SETTING: The Oro soils are on planar positions of fans and fan remnants. Slopes range from 0 to 5 percent. The soils formed in alluvium from sedimentary rock with some addition of eolian material. Mean annual temperature ranges from 47 to 53 degrees F. and mean annual precipitation ranges from 10 to 13 inches, with a marked summer maximum characterized by heavy thunderstorms of short duration. In a few areas the precipitation is higher. The frost-free season ranges from 115 to 160 days and elevation of ranges from 6,500 to 7,200 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Doakum, Starlake, and Royosa soils. Doakum soils have less than 35 percent clay in the control section. Starlake soils have natric horizons. Royosa soils lack argillic horizons.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is slow. Runoff is negligible on slopes less than 1 percent, very low on 1 to 3 percent slopes, low on 3 to 5 percent slopes.
USE AND VEGETATION: The principal use of these soils is grazing. Present vegetation is big sagebrush, blue grama, galleta, and threeawn.
DISTRIBUTION AND EXTENT: North-central New Mexico, MLRA 36. This soil is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Rio Arriba County, New Mexico, 2000
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: 0 to 2 inches. (A horizon)
Argillic horizon: 2 to 33 inches. (Bt horizon)
Ustertic features: cracks 5mm or more wide throughout a thickness of 12 inches for some time in normal years, slickensides and wedge shaped aggregates, and coefficient of linear extensibility of 6.0 or more.
ADDITIONAL DATA: Reference samples from pedon S86-NM-039-005 from Rio Arriba County, New Mexico; sample date 5/86; SSA NM8698.