LOCATION ARNO TX+NMEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, thermic Halic Haplotorrerts
TYPICAL PEDON: Arno clay--abandoned cropland. (Colors are for dry soil unless otherwise stated.)
Apz--0 to 8 inches; brown (7.5YR 4/2) clay, dark brown (7.5YR 3/2) moist; moderate medium angular blocky structure parting to fine angular and subangular blocky; extremely hard, extremely firm, very sticky and very plastic; many fine and medium roots; few fine pores; many very fine masses of salts; cracks 0.25 to 0.5 inch wide; very slightly saline; strongly effervescent; moderately alkaline; clear smooth boundary. (6 to 14 inches thick)
Byz--8 to 18 inches; brown (7.5YR 4/2) silty clay, dark brown (7.5YR 3/2) moist; moderate medium subangular blocky structure parting to medium and fine angular and subangular blocky; extremely hard, extremely firm; very sticky, very plastic; common fine and medium roots; few very fine pores; common fine and medium masses and threads of calcium sulfate and other salts; few very fine gypsum crystals; common distinct slickensides, cracks 0.25 inch wide; slightly saline; strongly effervescent; moderately alkaline; gradual smooth boundary. (6 to 12 inches thick)
Bssyz1--18 to 41 inches; reddish brown (5YR 4/4) clay, dark reddish brown (5YR 3/4) moist; weak coarse prismatic structure parting to medium angular blocky; extremely hard, extremely firm, very sticky and very plastic; cracks about 0.5 cm wide extend to lower boundary; many distinct slickensides; few very fine pores; many fine and medium threads and elongated masses of calcium sulfate and other salts on surfaces of bedding planes and slickensides; few very fine gypsum crystals; few very fine calcium carbonate concretions; partially decayed plants on some of the bedding planes; few fine and medium roots; strongly saline; strongly effervescent; moderately alkaline; gradual smooth boundary. (20 to 48 inches thick)
Bssyz2--41 to 80 inches; reddish brown (5YR 5/4) silt loam, reddish brown (5YR 4/4) moist; weak coarse prismatic structure parting to weak medium and coarse angular blocky; very hard, very firm, very sticky and plastic; few fine and medium masses and threads of calcium sulfate and other salts; common fine calcium carbonate concretions; few very fine gypsum crystals; strongly saline; strongly effervescent; moderately alkaline;.
TYPE LOCATION: From the junction of Farm Road 516 and Farm Road 873 in Barstow; 2.5 miles northwest on Farm Road 873; 1.4 miles southwest on County Road; 100 feet northwest in abandoned cropland. (Latitude: 31N, 27, 50; Longitude: 103W, 26, 51).
RANGE IN CHARACTERISTICS:
Soil moisture: Intermittently moist in some part of the soil moisture control section during July-September and December-April. Driest during May and June. Ustic aridic soil moisture regime.
Soil temperature: 59 to 72 degrees F.
Thickness of the soil over any contrasting textural horizon is more than 80 inches in more than half of all pedons
Cracks- When dry, have cracks 1 to 2-1/2 cm wide at a depth of 20 inches or more. Cracks remain closed for less than 60 consecutive days in 6 out of 10 years.
Particle size control section -
Silicate clay content in the 10 to 40 inch control section ranges from 35 to 60 percent.
Some pedons have strata of very fine sandy loam or silt loam between 40 and 80 inches.
Electrical conductivity - greater than 15 dS/m in some layer above 40 inches that are at least 6 inches thick.
A horizon
Hue: 2.5YR, 5YR, or 7.5YR
Value: 4 to 6
Chroma: 2 to 4.
Texture: silty clay loam, clay, or silty clay
Electrical conductivity: ranges from 2 to 16 dS/m.
B horizons
Hue: 2.5YR to 5Y with some part being 5YR or 2.5YR.
Texture: silty clay loam, silty clay or clay. Discontinuous layers or lenses up to 1 inch thick clay loam or fine sandy loam
Electrical conductivity: ranges from 8 to 32 dS/m
Sodium adsorption ratio: ranges from 15 to 50 percent
Salinity: moderately to strongly affected by salinity.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: These soils occupy recent flood plains of the Pecos River and its tributaries. Surfaces are mostly plane to convex, and slopes are less than about 1 percent. The soil formed in calcareous and saline clayey alluvium. Mean annual precipitation ranges from 9 to 16 inches (9 to 16 inches precipitation zone is this typic aridic, ustic aridic or possibly the aridic ustic moisture regime) and mean annual temperatures range from 60 to 69 degrees F. Frost free days range from 220 to 240 days and elevations ranges from 2,150 to 3,000 feet. Thornthwaite P-E indices are less than 25.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Gila, Harkey, Patrole, and Pecos series. Patrole soils do not have vertic properties, have a contrasting particle-size control section and are on lower positions near streams. Dalby and Verhalen soils have slickensides and are on similar or slightly lower positions. Gila and Harkey soils average less than 18 percent clay in the 10 to 40 inch particle size control section, and are on slightly lower positions nearer streams. Pecos soils are on similar positions.
DRAINAGE AND PERMEABILITY: Moderately well drained. Permeability is very slow. Runoff is low. Water enters the soil rapidly when the soil is dry and cracked, but very slow when the soil is moist.
USE AND VEGETATION: Mostly native rangeland. Principal vegetation includes a sparse cover of alkali sacaton grass, pickleweed, some fourwing saltbush, and scrubby mesquite and salt cedar trees.
DISTRIBUTION AND EXTENT: Southwestern Texas (MLRA 42) and Southeastern New Mexico. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Reeves County, Texas; 1922.
REMARKS: Classification was changed from fine, mixed (calcareous) thermic Vertic Torrifluvents to fine montmorillonitic, thermic Halic Haplotorrerts in 1993, based on reevaluation of the type location pedon and application of the Keys to Soil Taxonomy. Based on NSSL sample No. S93TX-475-001, mineralogy classification is changed from montmorillonitic to mixed mineralogy.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 8 inches. (Ap horizon)
Cambic horizon - 8 to 80 inches. (B horizons)
Halic feature - The soil has electrical conductivity greater than 15 dS/m in some horizons 6 inches thick or more within 40 inches of the surface.
ADDITIONAL DATA: National Soil Survey Laboratory data from the type location, S93TX-475-001, Pedon 93P 416, Samples 93P 3097-3100. SOIL INTERPRETATION RECORD NUMBER: TX0108