LOCATION PILABO NM

Established Series
Rev: WRJ/DPK/RJA
12/2014

PILABO SERIES

The Pilabo series consists of deep, well drained, moderately permeable soils that formed in colluvium and alluvium. These soils are on dipslopes of hogbacks, escarpments, hills, and cuestas and have slopes ranging from l5 to 35 percent. Mean annual temperature is about 59 degrees F., and mean annual precipitation is about 9 inches.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, thermic Ustic Haplocambids

TYPICAL PEDON: Pilabo very cobbly loam--on a convex, west facing cuesta dipslope of 2l percent--rangeland (colors are for dry soil unless otherwise noted).

A--0 to 3 inches; brown (10YR 4/3) very cobbly loam, dark brown (10YR 3/3) moist; moderate fine granular structure; soft, very friable, nonsticky and slightly plastic; few fine and very fine roots; l0 percent stones, 30 percent cobbles and 20 percent gravel; slightly effervescent; slightly alkaline; clear smooth boundary (1 to 4 inches thick).

Bw1--3 to 11 inches; brown (10YR 4/3) very cobbly loam, very dark grayish brown (10YR 3/2) moist; weak fine and very fine subangular blocky structure; slightly hard, very friable, nonsticky and slightly plastic; common very fine roots; 30 percent cobbles and 25 percent gravel; slightly effervescent; slightly alkaline; abrupt wavy boundary (6 to l2 inches thick).

Bw2--11 to 17 inches; brown (10YR 5/3) very cobbly loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common medium and few fine roots; l0 percent stones, 30 percent cobbles and l5 percent gravel; strongly effervescent; lime disseminated and segregated as few fine filaments; slightly alkaline; clear wavy boundary (6 to l0 inches thick).

Bk1--17 to 35 inches; pale brown (10YR 6/3) very cobbly loam; brown (10YR 4/3) moist; massive; slightly hard, friable, nonsticky and slightly plastic; few medium and common very fine roots; 40 percent cobbles and l5 percent gravel; violently effervescent; lime disseminated and segregated as common fine soft masses, fine filaments, seams and as pendants on the undersides of rock fragments; moderately alkaline; gradual wavy boundary (6 to 25 inches thick).

Bk2--35 to 60 inches; light yellowish brown (10YR 6/4) very gravelly loam, dark yellowish brown (10YR 4/4) moist; massive; soft, very friable, slightly sticky and slightly plastic; few fine roots; 5 percent cobbles and 35 percent gravel; strongly effervescent; calcium carbonate disseminated and segregated as common fine filaments and as pendants on the undersides of rock fragments; slightly alkaline.

TYPE LOCATION: Socorro County, New Mexico; 14 miles southwest of Socorro; on the Pedro Armendaris Grant No. 34; 1,300 feet east and 550 feet south of the NW corner, sec. 1, T. 6S., R. 2W., (projected).

RANGE IN CHARACTERISTICS:

Soil moisture: Typically parts of the moisture control section are moist during December and January and for short periods during July, August and September after summer convective storms. Ustic aridic soil moisture regime.

Rock fragments in the particle-size control section: average 35 to 60 percent by volume.

A horizon
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 2 to 4, dry or moist
Rock fragments: 35 to 60 percent by volume
Clay content: 18 to 24 percent

Bw horizon
Value: 3 to 5 dry, 3 or 4 moist
Chroma: 2 to 4, dry or moist
Rock fragments by volume: 5 to 10 percent stones, 15 to 30 percent cobbles, 15 to 20 percent gravel
Clay content: 18 to 27 percent
Calcium carbonate equivalent: 7 to 12 percent

Bk horizon
Value: 6 or 7 dry, 4 to 6 moist
Chroma: 2 to 4, dry or moist
Rock fragments by volume: 20 to 40 percent cobbles, 15 to 20 percent gravel
Calcium carbonate equivalent: 10 to 14 percent

C horizon (when present)
Value: 4 to 7 dry, 4 to 6 moist
Chroma: 2 to 4, dry or moist
Rock fragments by volume: 5 to 15 cobbles; 30 to 40 gravel, averaging 35 to 55 percent
Calcium carbonate equivalent: 9 to 12 percent

COMPETING SERIES: These are the Altar (AZ) and Ohtwo (TX) series. Altar soils are neutral profiles and contain less than 3 percent calcium carbonates in the particle size control section.
Ohtwo soils are underlain by basalt bedrock at 60 inches and contain 20 to 35 percent clay in the particle size control section.

GEOGRAPHIC SETTING: Pilabo soils are on dipslopes of hogbacks, escarpments, hills, and cuestas and have slopes ranging from 15 to 35 percent. They formed in colluvium and alluvium derived from tuffs. Elevations range from 5,000 to 6,250 feet. Average annual precipitation ranges from 8 to 14 inches, mean annual air temperature ranges from 57 to 64 degrees F., and the average frost-free period is 180 to 240 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Caliza, Laborcita, Lemitar, Nickel, Nolam, and Puertecito soils. Caliza, Laborcita and Nickel soils have calcic horizons. Lemitar soils have a lithic contact at depth of less than 20 inches. Nolam and Puertecito soils have an argillic horizon.

DRAINAGE AND PERMEABILITY: Well drained; rapid runoff; moderate permeability.

USE AND VEGETATION: The major use of this soil is livestock grazing. Native vegetation is black grama, sideoats grama, galleta, Mormon-tea, and creosotebush.

DISTRIBUTION AND EXTENT: Southcentral New Mexico. Pilabo soils are of moderate extent. MLRA 42.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona

SERIES ESTABLISHED: Socorro County, New Mexico, 1984.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon - the zone from the surface of the soil to a depth of about 3 inches (A horizon).

Cambic horizon - the zone from 3 to 17 inches (Bw1, Bw2 horizons).

Classification was changed from loamy-skeletal, mixed, thermic Aridic Haplustolls to loamy-skeletal, mixed, thermic, Ustic Haplocambids. Pedons that meet the color, depth, and organic carbon content of a mollic epipedon are not moist 3 months or more of the year (cumulative) during the growing season.

The soil moisture regime should be reevaluated. Typic aridic soil moisture regime or Ustic aridic soil moisture regime? 8 to 10 inches of precipitation will not meet current paradigm established for MLRA 42 for soils in Ustic aridic moisture regime. This contradicts the current soil moisture and temperature regime paradigm utilized in MLRA 42. The 8 to 10 inches of annual precipitation is in a Typic aridic moisture regime.

Classified according to Soil Taxonomy Second Edition, 1999; Keys to Soil Taxonomy, Twelfth Edition, 2014.

Revised for the correlation of White Sands Missile Range, New Mexico; October, 2014, NMS

National Cooperative Soil Survey
U.S.A.