LOCATION MARFA TX

Established Series
Rev. JR/SA/NAR/RLB
10/2012

MARFA SERIES

The Marfa series consists of very deep, well drained, moderately slow permeable soils that formed in loamy and clayey alluvium derived from Tascotal tuffaceous sandstone, Perdiz igneous conglomerate, and eolian material. Marfa soils are on valley floors and stream terraces. Slope ranges from 0 to 2 percent. The mean annual precipitation is about 15 inches and the mean annual temperature is about 61 degrees F.

TAXONOMIC CLASS: Fine, mixed, superactive, thermic Pachic Argiustolls

TYPICAL PEDON: Marfa clay loam--rangeland. (Colors are for dry soil unless otherwise noted.)

A--0 to 4 inches; dark grayish brown (10YR 4/2) clay loam, very dark brown (10YR 2/2) moist; weak medium subangular blocky structure; slightly hard, friable; moderately sticky and moderately plastic; many medium and fine roots; slightly acid (pH 6.2); clear smooth boundary. (3 to 7 inches thick)

Bt1--4 to 13 inches; dark grayish brown (10YR 4/2) clay loam, very dark brown (10YR 2/2) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; hard, firm; moderately sticky and moderately plastic; many very fine and fine roots, discontinuous distinct clay films on faces of ped; neutral (pH 6.7); gradual smooth boundary.

Bt2--13 to 24 inches; dark grayish brown (10YR 4/2) clay, very dark grayish brown (10YR 3/2) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; very hard and very firm; very sticky and very plastic; common very fine and fine roots; continuous distinct clay films on faces of ped; neutral (pH 7.0); gradual smooth boundary.

Bt3--24 to 41 inches; brown (10YR 5/3) clay, dark brown (10YR 3/3) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; very hard, very firm, very sticky and very plastic; few fine and very fine roots; discontinuous distinct clay films on faces of ped; slightly alkaline (pH 7.5); gradual wavy boundary. (combined thickness of the Bt horizon is 35 to 50 inches thick))

2Btk1--41 to 55 inches; light brown (7.5YR 6/4) sandy clay loam, brown (7.5YR 5/4) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; hard, firm, sticky and plastic; few very fine and fine roots; discontinuous distinct clay films on faces of ped; slightly effervescent; few fine lime threads and fine lime masses; moderately alkaline (pH 8.0); gradual wavy boundary.

2Btk2--55 to 69 inches; light brown (7.5YR 6/3) sandy clay loam, brown (7.5YR 5/3) moist; weak medium prismatic structure parting to weak medium subangular blocky; hard, firm, sticky and plastic; discontinuous faint clay films on faces of ped; strongly effervescent; few fine lime threads and fine and medium lime masses; moderately alkaline (pH 8.3); gradual wavy boundary (combined thickness of the Btk horizons are 25 to 35 inches thick)

2Bk--69 to 80 inches; light brown (7.5YR 6/4) sandy clay loam, brown (7.5YR 5/4) moist; weak medium and coarse subangular blocky structure; hard, firm, slightly sticky and slightly plastic; common fine and medium lime masses; violently effervescent; moderately alkaline (pH 8.2) gradual wavy boundary

TYPE LOCATION: Presidio County, Texas; about 0.3 mile north of Marfa below flood control dam, or 300 feet north and 1100 feet west of ranch head quarters; Latitude: 30 degrees, 19 minutes, 09.4 seconds North; longitude: 104 degrees, 01 minutes, 46.4 seconds West. NAD83; UTM coordinates 593298 m E, 3354564 m N, Zone 13.

RANGE IN CHARACTERISTICS:

Soil Moisture - Usually dry in some or all parts for sixth tenth or more of the time that the soil temperature exceeds 41 degrees F. Some part of the epipedon is moist for more than 90 cumulative days in most years when the soil temperature exceed 41 degrees F. Aridic ustic moisture regime.

Mean annual soil temperature - 62 to 69 degrees F.

Solum thickness ranges from - 60 inches to greater than 80 inches in the majority of pedons.

Thickness of mollic epipedon - 0 to 41 inches

Particle size control section - Clay content: 35 to 55 percent

Depth to secondary calcium carbonate: ranges from 40 to 60 inches.

Coarse fragments in the solum: less than 5 percent.

Gypsum - 0 to 5 percent

A horizon
Hue: 7.5YR or 10YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 1, 2, or 3 dry, or moist
Reaction: slightly acid to neutral.

Bt horizons
Hue: 7.5YR or 10YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 2 or 3 dry or moist
Clay content: 35 to 55 percent.
Texture: clay or clay loam
Reaction: neutral to slightly alkaline

2Btk horizons
Hue: 7.5YR or 10YR
Value: 5, 6, or 7 dry or moist
Chroma: 3 or 4 dry or moist
Texture: clay loam or sandy clay loam.
Coarse fragments: less than 5 percent
Calcium carbonate equivalent: 5 to 10 percent.
Reaction: slightly alkaline to moderately alkaline

Bk horizons
Hue: 7.5YR or 10YR
Value: 6 or 7 dry, 4 or 5 moist
Chroma: 3 or 4 dry or moist
Texture: clay loam, sandy clay loam, or loam.
Clay content: 18 to 35 percent
Rock fragments: 5 to 10 percent
Calcium carbonates equivalent: 5 to 15 percent
Reaction: slightly alkaline to moderately alkaline

COMPETING SERIES: These are the Abilene (TX), Blanket (TX), McLain (OK), and Roark (OK)(T)series.

Abilene, Blanket, Roark, and Mclain soils are moist in the soil moisture control section for longer periods and the precipitation ranges from 20 to 40 inches.

Abilene soils contain 15 to 40 percent calcium carbonates.

Blanket soils have secondary carbonates above 40 inches.

GEOGRAPHIC SETTING: The Marfa soils are nearly level to gently sloping soils on valley floors and low stream terraces. Slopes are 0 to 2 percent. These soils developed in loamy and clayey alluvium derived from Tascotal tuffaceous sandstone, Perdiz igneous conglomerate, and eolian material. Mean annual precipitation ranges from 14 to 20 inches, occurring mainly during May through October. Run off from adjacent mountains, noncalcareous felsic parent material, and a relatively stable landscape contribute to the development of an argillic horizon. Mean annual temperature ranges from 59 to 67 degrees F. Frost free days range from 180 to 240 days and elevation ranges from 4,000 to 6,695 feet.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Musquiz, Murray, Phantom, Fort Russell (T), and Eppenauer series. Musquiz and Murray soils have mollic epipedons that are less than 20 inches deep. In addition Murray soils contain less than 35 percent clay in the particle size control section. Phantom soils have mollic epipedon less than 20 inches deep and do not have an argillic horizon. Fort Russell soils are coarse-loamy and shallow to a paralithic contact. Eppenauer soils are fine loamy and moderately deep to a paralithic contact.

DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderately slow. Runoff is low. This soil receives additional run on moisture from higher adjacent areas.

USE AND VEGETATION: The major use is livestock grazing. Vegetation is of the mixed prairie type consisting of blue grama, cane bluestem, sideoats grama, perennial threeawn, plains bristlegrass, and buffalo grass.

DISTRIBUTION AND EXTENT: West Texas. MLRA 42. The series is of moderate extent.

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

SERIES ESTABLISHED: Presidio County, Texas, 2012. The soil was named after the city of Marfa, Texas.

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

Particle size control section - the zone from 4 to 24 inches - (Bt1 and Bt2 horizons)

Mollic epipedon - the zone from 0 to 41 inches (A, Bt1, Bt2 and Bt3 horizons)

Argillic horizon - the zone from 4 to 69 inches deep. (Bt1, Bt2, Bt3, 2Btk1, and 2Btk2 horizons)

Ustic features - this soil has an Ustic moisture regime that borders on the Aridic moisture regime.

Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Eleventh Edition, 2010

Revised for the correlation of Presidio County, Texas ; Oct, 2012, WWJ

ADDITIONAL DATA: Larry Ratliff Masters Thesis Texas Tech. Univ. 1968.

National Cooperative Soil Survey
U.S.A.