LOCATION DECOTY                  TX

Established Series
Rev. JLR/LEL/RLB
10/2012

DECOTY SERIES

The Decoty series consists of shallow and very shallow, well drained soils with moderately permeable surface layers over very slowly permeable ignimbrite bedrock. These undulating to hilly soils are on erosional surfaces on questas and hills. They formed in loamy residuum weathered from Mitchell Mesa ignimbrite. Slope gradients range from 1 to 30 percent.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, thermic Lithic Ustic Haplocalcids

TYPICAL PEDON: Decoty very channery fine sandy loam. (Colors are for dry soils unless otherwise noted.)

A--0 to 5 inches, brown (7.5YR 5/3) very gravelly fine sandy loam, dark brown (7.5YR 3/3) moist; weak medium granular structure; slightly hard, friable; slightly sticky and slightly plastic; many fine and medium roots; common fine tubular pores; 45 percent ignimbrite gravel with thin coatings of carbonate; strongly effervescent; moderately alkaline (pH 7.9); abrupt smooth boundary. (2 to 6 inches thick)

Bk--5 to 14 inches, pinkish gray (7.5YR 7/2) extremely cobbly fine sandy loam, brown (7.5YR 5/3) moist; weak fine and medium subangular blocky structure; slightly hard, friable; slightly sticky and slightly plastic; common fine and medium roots; common fine and medium tubular pores; 50 percent ignimbrite cobbles, 20 percent ignimbrite gravel; rock fragments have thin continuous coatings and pendants of carbonate; strongly effervescent; moderately alkaline (pH 7.9); abrupt wavy boundary. (5 to 14 inches thick)

R--14 inches, gray (5YR 5/1) indurated ignimbrite bedrock; fractures are more than 4 inches apart; thin to medium continuous carbonate coats on the upper surface of rock fragments and in seams

TYPE LOCATION: Presidio County, Texas; from the junction of U.S. Highways 90 and 67 in Marfa; 7.3 miles southwest on Highway 67 to Ranch Road 169; 24.6 miles southeast on Ranch Road 169 to end of pavement (Casa Piedra county road); 3.2 miles south on Casa Piedra county road to Puerto Portillo county road; 4.4 miles east on Puerto Portillo county road to ranch road; 1.8 miles south and east on ranch road; 100 feet west in rangeland. Puerto Portillo, USGS topographic quadrangle; Latitude: 29 degrees 49 minutes 18 seconds North; Longitude: 103 degrees 54 minutes 58 seconds West, NAD 83. UTM coordinates 604728 m E, 3299518 m N, Zone 13

RANGE IN CHARACTERISTICS:

Soil Moisture: Ustic aridic soil moisture regime. Intermittently moist in some part of the soil moisture control section during July-September

Mean annual soil temperature- 60 to 69 degrees

Depth to lithic contact- 7 to 20 inches

Particle size control section-Clay content: 8 to 18 percent

Rock fragments: 35 to 80 percent ignimbrite rock fragments

Calcium carbonate equivalent: 15 to 30 percent

A horizon
Hue: 7.5YR or 10YR
Value: 4 to 7 dry, 3 to 6 moist
Chroma: 2 to 4 dry or moist
Texture: sandy loam, fine sandy loam, loam
Reaction: slightly alkaline or moderately alkaline
Other features: Rock fragments cover 60 to 95 percent of the surface

Bk horizon
Hue: 7.5YR or 10YR,
Value: 4 to 7 dry, 3 to 6 moist
Chroma: 2 to 4 dry or moist
Texture: sandy loam, fine sandy loam, loam
Reaction: slightly alkaline or moderately alkaline

COMPETING SERIES: This is the Allamore (TX) series. Allamore soils contain Precambrian metamorphic sandstone and siltstone rock fragments. Allamore soil particle size control section is dominated by 5YR hues.

GEOGRAPHIC SETTING: The Decoty soils are on undulating to hilly convex erosional surfaces in questas and hills. Slopes range from 1 to 30 percent. These soils formed in loamy residuum weathered from Mitchell Mesa ignimbrite. Mean annual precipitation ranges from 10 to 15 inches, with most occurring from July through September. Mean annual temperature ranges from 60 to 68 degrees F. Frost-free days range from 200 to 250 days. Elevation ranges from 3500 to 5000 feet.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Boludo (TX) and Sauceda (T) soils. Boludo soils have a petrocalcic horizon above a lthic contact. Sauceda soils do not have a calcic horizon.

DRAINAGE AND PERMEABILITY: Well drained. Runoff is medium on slopes of 1 to 3 percent, high on slopes of 3 to 5 percent, and very high on slopes greater than 5 percent. Permeability is moderate in the surface and very slow in the ignimbrite bedrock.

USE AND VEGETATION: This soil is used for rangeland. Woody plants in the overstory include ocotillo, lechuguilla, sotol, mariola, creosote bush, algerita, skeletonleaf goldeneye, javelinabush, and lotebush. Dominant grasses are black grama, chino grama, threeawns, Arizona cottontop, and bush muhly.

DISTRIBUTION AND EXTENT: West Texas. MRLA 42. The soil is of minor extent.

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

SERIES ESTABLISHED: Presidio County, Texas, 2012.

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

Ochric epipedon - The zone from the soil surface to 5 inches (A horizon)

Calcic horizon - The zone from 5 to 14 inches (Bk horizon)

Lithic contact - The boundary at 14 inches (R horizon)

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

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National Cooperative Soil Survey
U.S.A.