LOCATION TRICON NMEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, mesic Petrocalcic Paleustolls
TYPICAL PEDON: Tricon silt loam, rangeland. (Colors are for dry soil unless otherwise stated.)
A1--0 to 7 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; slightly hard, very friable, slightly sticky; many very fine and common fine roots; neutral (pH 6.8); clear smooth boundary. (4 to 8 inches thick)
B21t--7 to 13 inches; dark brown (10YR 4/3) heavy clay loam, dark brown (10YR 3/3) moist; weak fine prismatic structure parting to fine subangular blocky; hard, firm, sticky; common very fine roots; few very fine and fine pores; few thin clay films on faces of peds; mildly alkaline (pH 7.8); clear smooth boundary. (4 to 10 inches thick)
B22t--13 to 23 inches; brown (10YR 5/3) heavy clay loam, brown (10YR 4/3) moist; weak fine prismatic structure parting to moderate fine subangular blocky; very hard, firm, slightly sticky; common very fine roots; few very fine and fine pores; few thin patchy clay films on faces of peds; fine rounded soft lime masses, few caliche fragments 1/2 to 3/4 inch in diameter; matrix is usually noncalcareous in upper part of this horizon and calcareous in lower part; moderately alkaline (pH 8.1); gradual smooth boundary. (5 to 15 inches thick)
B3ca--23 to 33 inches; light brown (7.5YR 6/4) clay loam, brown (7.5YR 4/4) moist; moderate fine subangular blocky structure; very hard, firm, slightly sticky; few very fine and fine pores; calcareous; medium irregular lime occurring as filaments or threads; moderately alkaline (pH 7.9); abrupt wavy boundary. (5 to 12 inches thick)
Ccam--33 to 34 inches; pinkish white (7.5YR 8/2), continuous across a pedon; 25 percent is indurated with lamination on the surface; remainder can be chipped with a spade.
TYPE LOCATION: San Miguel County, New Mexico; 3 1/4 miles on Maes Road from junction of State Highway 104; 668 feet WNW from Maes Road along fence, then 1,060 feet SSW; T.16N., R.20E.
RANGE IN CHARACTERISTICS: Solum thickness and depth to the petrocalcic horizon are 20 to 40 inches. These soils are normally noncalcareous to depths of 8 to 20 inches. These soils have a ustic moisture regime bordering aridic.
The A horizon has hue of 10YR or 7.5YR and chroma of 2 or 3 moist. It is typically silt loam but includes loam and light clay loam. This horizon has weak or moderate structure.
The B horizon has hue of 10YR or 7.5YR, value of 4 or 5 dry, 3 or 4 moist, and chroma of 2 through 4. It ranges from heavy clay loam through light clay and heavy silty clay loam. This horizon has moderate or strong structure.
The petrocalcic (Ccam) horizon has a wavy upper boundary and is continuous across a pedon without cracks. Fifty percent of this horizon is weakly cemented (can be chipped with a spade) and 50 percent is indurated. A laminar surface occurs on 25 percent of this horizon.
COMPETING SERIES: These are the Crews, Slaughter, and Stegall series in other families. Crews and Slaughter soils have petrocalcic horizons at depths of less than 20 inches. Slaughter and Stegall soils have a thermic temperature regime.
GEOGRAPHIC SETTING: Tricon soils are typically on broad upland plains. Elevation is 5,000 to 7,000 feet. Slopes dominantly range from 0 to 3 percent but range to 5 percent near some of the drainageways. The soils formed in old alluvium and eolian sediments. Purgatoire and Dakota sandstone are commonly beneath the petrocalcic horizon at an unknown depth. The climate is semiarid continental. The average annual temperature is 50 to 58 degrees F. The Thornthwaite P-E Index is about 29. The frost free season is about 140 to 180 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bernal, Crews, Dioxice, Partri, Pastura, and Travessilla soils. Bernal, Crews, Pastur, and Travessilla soils are shallower than 20 inches. Also, Pastura and Travessilla soils lack argillic horizons. Dioxice soils lack a petrocalcic horizon, and Patri soils lack a petrocalcic horizon within 40 inches.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; slow permeability.
USE AND VEGETATION: Used primarily as native rangeland. The principal vegetation is blue grama, buffalograss, western wheatgrass, ring muhly, galleta, snakeweed, and sideoats grama.
DISTRIBUTION AND EXTENT: Central and northeastern New Mexico. This soil is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: San Miguel County, New Mexico, 1973.
REMARKS: The type location was moved from Torrance County to San Miguel County, New Mexico, to locate the central concept of the series near the center of its geographic distribution in New Mexico.