LOCATION MONTEROSA NM+AZ+TXEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, thermic, shallow Ustic Petrocalcids
TYPICAL PEDON: Monterosa very gravelly sandy loam - rangeland. (Colors are for dry soil unless otherwise noted). The soil surface is about 95 percent covered with a desert pavement of rhyolite gravel, mainly less than 1 inch in diameter with a few up to 2 inches in diameter. A very few gravel have thin, discontinuous carbonate coatings. Some of the gravel is partially to completely coated with black desert varnish.
Ak--0 to 2 inches; dominantly pinkish gray (7.5YR 6/2) very gravelly sandy loam, brown (7.5YR 4/2) moist with smaller amount light brown (7.5YR 6/4); weak thin platy structure; soft; few coarse roots; some thin (less than 1mm) reddish brown layers between plates in upper part; gravel tops are usually carbonate-free, and some are stained reddish brown; gravel bottoms have thin, discontinuous carbonate coatings; effervescent; moderately alkaline; abrupt smooth boundary. (1 to 3 inches thick)
Bk1--2 to 7 inches; brown (7.5YR 5/4) very gravelly sandy clay loam, brown (7.5YR 4/4) moist; weak fine crumb and weak medium and fine subangular blocky structure; slightly hard; common fine and very fine roots; carbonate coatings on gravel, thickest on undersides; coatings are thicker in the lower part of the horizon; some gravel tops in the upper part of the horizon are carbonate-free and a few are stained reddish brown; a few carbonate filaments; effervescent; moderately alkaline; clear smooth boundary. (4 to 10 inches thick)
Bk2--7 to 12 inches; brown (7.5YR 5/4) very gravelly sandy clay loam, brown (7.5YR 4/4) moist; a soft mass of weak fine crumbs; common fine roots; common extremely hard carbonate-cemented fragments mainly 1/2 to 2 inches in diameter which are lighter than very pale brown (10YR 8/2); effervescent; moderately alkaline; abrupt smooth boundary. (2 to 7 inches thick)
Bkm1--12 to 14 inches; very pale brown (10YR 8/2) carbonate-cemented material, very pale brown (10YR 8/2) moist, small amounts are slightly darker and redder massive; extremely hard; upper 1/8 to 1/2 inch is laminar; gravel beneath laminar horizon separated by carbonate; moderately alkaline; clear wavy boundary. (1 to 6 inches thick)
Bkm2--14 to 22 inches; pink (7.5YR 8/4) light brown (7.5YR 6/4) moist; carbonate-cemented material; massive; very and extremely hard; many gravel separated by carbonate; effervescent; moderately alkaline; clear wavy boundary. (4 to 20 inches thick)
2Bk1--22 to 35 inches; lighter than very pale brown (10YR 8/3) clay loam, very pale brown (10YR 8/3) moist, with smaller amount pink (7.5YR 7/4); weak medium subangular blocky structure; hard and very hard; a few gravel coated with carbonate; effervescent; moderately alkaline; clear smooth boundary. (0 to 15 inches thick)
2Bk2--35 to 52 inches; pink (7.5YR 8/4) very gravelly sandy clay loam, light brown (7.5YR 6/4); massive; weak fine and very fine crumb structure; soft and loose; gravel largely discrete but a few are weakly cemented; thin, continuous carbonate coatings on gravel and sand grains; effervescent; moderately alkaline.
TYPE LOCATION: Dona Ana County, New Mexico; in the NE1/4 SE1/4 of section 19, R.3 E., T.23 S.; about 200 feet west of section line, about 0.2 mile south of the 1/4 corner between sections 19 and 20.
RANGE IN CHARACTERISTICS:
Soil moisture: Intermittently moist in some part of the soil moisture control section during December through April and July through September. Driest during May and June. Ustic aridic soil moisture regime.
Soil temperature - 60 to 68 degrees F.
Depth to the petrocalcic horizon - 7 to 20 inches
Particle size control section:
Clay content: averages 18 to 27 percent clay
A horizon
Hue: 7.5YR, 10YR
Value: 5 through 7 dry, 3 through 5 moist
Chroma: 2 through 4, dry or moist
Bk horizon
Hue: 7.5YR, 10YR
Value: 5 through 7 dry, 3 through 5 moist
Chroma: 2 through 4, dry or moist
Texture: sandy loam, sandy clay loam
Bkm horizon continuously cemented except for scattered cracks and pipes of non-indurated material.
When value in the A and B horizons is as dark as 5 dry and 3 moist, the horizons are too thin or contain too little organic carbon for a mollic epipedon.
COMPETING SERIES: These are the Kimrose (AZ), and Pedregosa (AZ) series. Kimrose soils have very thick hardpans that extend to 60 inches or more and have mean annual precipitation of 12 to 16 inches. Pedregosa soils contain 5 to 18 percent clay in the particle size control section.
GEOGRAPHIC SETTING: These soils are on remnants of alluvial fans and fan-piedmonts of late or mid-Pleistocene age. Elevations range from 4,300 to 5,600 feet. Ridges are common. Longitudinal slopes along ridge crests range from about 3 to 10 percent. Slopes of ridge sides range from 3 to 25 percent. The soils formed in very gravelly sediments derived from such rocks as rhyolite and andesite. The mean annual temperature ranges from 58 degrees F. to 66 degrees F. Mean annual precipitation ranges from about 8 to 13 inches with a marked summer maximum.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Boracho, Caralampi, Nolam, Pinaleno, Santo Tomas, and Terino soils and the competing Delnorte soils. Boracho soils have mollic epipedons. Caralampi and Pinaleno soils have argillic horizons and lack petrocalcic horizons. Nolam soils have argillic horizons and calcic horizons. Santo Tomas soils have mollic epipedons and lack petrocalcic horizons. Terino soils have argillic horizons.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderate
permeability.
USE AND VEGETATION: Used for livestock grazing and wildlife habitat. Vegetation is mainly creosotebush and ratany with a few Yucca baccata and prickly pear. In places, there are scattered clumps of fluffgrass and threeawn.
DISTRIBUTION AND EXTENT: Southern New Mexico, Arizona and Texas. It is of moderate
extent. MLRAs 40, 41 & 42.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Desert Soil Geomorphology Project, Dona Ana County, New Mexico; 1971.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 0 to 2 inches (A horizon)
Petrocalcic horizon - The zone from 12 to 22 inches (Bkm1, Bkm2 horizons)
Classified according to Soil Taxonomy Second Edition, 1999.
This series represents an identified soil within the Desert Soil-Geomorphology Project, Las Cruces, New Mexico. The project was a study of soils and geomorphology in an arid and semi-arid environment. The series is extensively referenced in many documents, publications and thesis. Revision outside the project area is discouraged in order to preserve the historical concept for research.