LOCATION LEDRU NMEstablished Series
TAXONOMIC CLASS: Clayey, mixed, superactive, thermic Lithic Haplargids
TYPICAL PEDON: Ledru gravelly clay loam - native rangeland (Colors are for dry soil unless otherwise noted.)
A--0 to 4 inches; brown (10YR 5/3) gravelly clay loam, dark brown (10YR 3/3) moist; weak fine crumb structure; soft, very friable, sticky, plastic; many fine and very fine roots; common fine interstitial pores; slightly alkaline; clear smooth boundary. (2 to 5 inches thick)
Bt1--4 to 13 inches; brown (7.5YR 5/2) silty clay, dark brown (7.5YR 3/2) moist; weak medium prismatic structure parting to moderate medium subangular blocky; very hard, very friable, sticky, plastic; many fine and very fine roots; few fine tubular and interstitial pores; many moderately thick, clay films on surfaces of peds and in pores; slightly alkaline; clear smooth boundary. (4 to 8 inches thick)
Btk2--13 to 17 inches; brown (7.5YR 5/2) silty clay; brown (7.5YR 4/2) moist; moderate medium subangular blocky structure; very hard, very friable, sticky, plastic; few fine and very fine roots; few fine tubular pores; moderately thick continuous clay film on surfaces of peds and in pores; strongly calcareous; slightly alkaline; abrupt boundary. (4 to 7 inches thick)
R--17 inches; Indurated conglomerate; extremely hard. (Many feet thick)
TYPE LOCATION: Luna County, New Mexico; ditch bank south side of road; 990 feet south, 660 feet east of NW corner SW1/4 sec. 11, T.20S., R.8W.
RANGE IN CHARACTERISTICS:
Soil moisture - Typic aridic moisture regime based on 10 inches of precipitation.
Depth to conglomerate - less than 20 inches.
Surface rock fragments ranges from - 20 to 80 percent.
Particle size control section -
Rock fragments: (1 to 2 inches in diameter) occur in the profile and range from 5 to 15 percent
A horizon
Hue: 10YR or 7YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 2 or 3
Other features: A horizon and upper B horizon range from noncalcareous to slightly calcareous grading to strongly calcareous in the lower B horizon with few to common small lime masses
B horizon
Hue: 7.5YR or 10YR
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 2 or 3
Texture: silty clay or clay
Clay content: range from 35 to 60 percent.
R horizon
Upper part has thin lime coatings.
COMPETING SERIES: This is the Luxor (NM) series. Luxor soils have Cr horizons of highly weathered rhyolite bedrock and small angular hard rhyolite gravel.
GEOGRAPHIC SETTING: Ledru soils are on low rolling hills of typically 10 to 25 percent slope but range from 3 to 30 percent slopes. The topography is commonly hilly and the slopes short and irregular. The area is dissected by numerous arroyos which are usually well covered with grass with little active erosion. These soils formed in moderately fine and fine textured material derived from mixed igneous rock, mainly from rhyolite and basalt. At the type location the mean annual temperature is about 60 degrees F. The mean annual rainfall is about 10 inches most of which falls during the summer.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Lehmans, Brenda, Nickel, and Stellar soils. Brenda, Nickel, and Stellar soils lack lithic contacts within a depth of 40 inches. Also, Nickel soils lack argillic horizons and average more than 35 percent rock fragments in the control section.
DRAINAGE AND PERMEABILITY: Well drained; rapid runoff; very slow permeability.
USE AND VEGETATION: Used as rangeland. The dominant vegetation is tobosa, black grama, sideoats, and blue grama.
DISTRIBUTION AND EXTENT: Southern New Mexico. The series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Luna County, New Mexico, 1973.
REMARKS:
Diagnostic horizon and features recognized in this pedon are:
Ochric epipedon the zone from 0 to 4 inches (A horizon) Even though the A and Bt horizons have mollic colors, this soil is not moist for long enough period to meet the minimum moisture requirement for a mollic epipedon.
Argillic horizon - the zone from 4 to 17 inches (Bt1 and Btk2 horizons)
Particle size control section the zone from 4 to 17 inches Bt1 and Btk2 horizons)
This soil receives about 10 inches of annual precipitation which is characteristic of the Typic aridic moisture regime. This soil is not moist long enough to meet the minimum moisture requirement for a mollic epipedon. Classification changed from Argiustolls to Haplargids in 2006.