LOCATION MONAHANS TX

Established Series
Rev. ACT
07/2012

MONAHANS SERIES

The Monahans series consists of very deep, well drained, moderately permeable soils formed in ancient alluvium containing significant amounts of gypsum and calcium carbonate. These soils are on nearly level to gently sloping upland plains and fan skirts on fan piedmonts. Slopes range from 0 to 5 percent.

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, thermic Typic Calcigypsids

TYPICAL PEDON: Monahans fine sandy loam--irrigated cropland (colors are for dry soil unless otherwise stated).

Ap--0 to 8 inches; pale brown (10YR 6/3) fine sandy loam, brown (10YR 4/3) moist; weak fine subangular blocky and weak fine granular structure; slightly hard, very friable, slightly sticky, and slightly plastic; many fine roots; common tubular pores; many fine and medium insect casts and burrows; few fine concretions and masses of calcium carbonate; strongly effervescent; moderately alkaline; abrupt smooth boundary (4 to 12 inches thick).

Bk--8 to 28 inches; light brown (7.5YR 6/4) fine sandy loam, brown (7.5YR 4/4) moist; moderate fine subangular blocky structure; slightly hard, friable, sticky, and slightly plastic; few fine roots; common fine tubular pores; few insect casts and burrows; common fine masses of calcium carbonate; few fine gypsum crystals; few igneous gravel; violently effervescent; slightly alkaline; gradual wavy boundary (10 to 24 inches thick).

Bky1--28 to 48 inches; pink (7.5YR 8/4) sandy clay loam, light brown (7.5YR 6/4) moist; weak fine and medium subangular blocky structure; slightly hard, friable, sticky, and plastic; 15 percent gypsum crystals and calcium carbonate in the form of fine masses and weakly cemented concretions; violently effervescent; slightly alkaline; diffuse wavy boundary (6 to 30 inches thick).

Bky2--48 to 60 inches; pink (7.5YR 7/4) sandy clay loam, brown (7.5YR 5/4) moist; weak fine and medium subangular blocky structure; slightly hard, friable, sticky; 10 percent masses of calcium carbonate and gypsum crystals; strongly effervescent; slightly alkaline.

TYPE LOCATION: Ward County, Texas; In Barstow, from the intersection of U.S. Highway 80 and Farm Road 516, 5.3 miles northwest on Farm Road 516 to gravel road, 0.45 mile west on gravel road to a field road, 0.15 northwest, 100 feet east (Latitude: 31N, 30, 43; Longitude: 103W, 27, 44).

RANGE IN CHARACTERISTICS:

Soil moisture: Typic aridic moisture regime

Solum thickness: 60 to more than 80 inches

Texture of the 10- to 40-inch particle size control section: fine sandy loam, loam, or sandy clay loam.

Silicate clay content: 6 to 18 percent

Carbonate clay: 0 to 10 percent

Depth to gypsic horizon: 16 to 36 inches

Calcium carbonate plus gypsum: averages less than 40 percent by weight

Reaction: slightly alkaline or moderately alkaline

A horizon
Hue: 7.5YR, 10YR
Value: 4 to 7, dry or moist
Chroma: 2 to 4, dry or moist
Texture: fine sandy loam, loam, very fine sandy loam, fine sand

Bk or Bw horizons
Hue: 5YR, 7.5YR, 10YR
Value: 4 to 7, dry or moist
Chroma: 3 to 6, dry or moist
Texture: loam, fine sandy loam, sandy clay loam, very fine sandy loam
Igneous gravel: 0 to 10 percent by volume

Bky horizon
Hue: 5YR, 7.5YR, 10YR
Value: 6 to 8, dry or moist
Chroma: 2 to 6, dry or moist
Calcium carbonate: 10 to 20 percent visible calcium carbonate in the form of fine, weakly cemented concretions and masses
Gypsum: 5 to 15 percent of visible gypsum crystals
Calcium carbonate equivalent: 15 to 40 percent in the upper part and 5 to 15 percent in the lower part
Gypsum content: 15 to 30 percent. Gypsum content does not decrease with depth of soil

COMPETING SERIES: These are the Alamogordo (NM), Borderline (AZ), Hobcan (AZ), Monzingo (AZ), and Ugyp (AZ) series. Hobcan soils have gypsic horizons closer to the surface (8 to 16 inches). Monzingo soils contain Cd horizons. Alamogordo, Borderline, and Ugyp soils' depth to gypsic horizon is less than 10 inches.

GEOGRAPHIC SETTING: Monahans soils are on nearly level to gently sloping upland plains and fan skirts on fan piedmonts. Most slopes are less than 2 percent but range up to about 5 percent. The regolith consists of calcareous and gypsiferous old alluvium and basin deposits from limestone and igneous mountains. Mean annual temperature ranges from 62 to 68 degrees F., and mean annual precipitation ranges from about 7 to 12 inches. Frost free days range from 200 to 240 days, and elevation ranges from 2,000 to 4,000 feet. Thornthwaite P-E indices are less than 25.

GEOGRAPHICALLY ASSOCIATED SOILS: These include the Hoban, Hodgins, Holloman, Pajarito, Reeves, and Upton series. Hoban soils are on similar or slightly lower positions, have fine-silty control sections and do not contain significant amounts of gypsum. Hodgins soils are on slightly lower positions and have more than 18 percent clay in the control section. Holloman soils are on similar positions and are shallow to gypsiferous sediments. Pajarito soils are on similar positions and do not have gypsic horizons. Reeves soils are on similar positions. Upton soils are at slightly higher elevations and have petrocalcic horizons within 20 inches.

DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderate. Runoff is negligible on slopes less than 1 percent, very low on 1 to 3 percent slopes, and low on 3 to 5 percent slopes.

USE AND VEGETATION: Primarily used for livestock grazing, which is of low productive capacity. Some areas are used for irrigated cropland. Rangeland vegetation is desert shrubs, such as creosote bush, four-wing salt bush, small mesquite trees, tarbush, and sparse grasses such as bush muhly, plains bristlegrass, black grama, sand dropseed, mesa dropseed, perennial threeawns, hooded windmill, and fluffgrass. Irrigated crops are mainly cotton, grain sorghums, and alfalfa.

DISTRIBUTION AND EXTENT: These soils are in the Trans-Pecos area of Texas (MLRA 42). The series is of moderate extent.

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

SERIES ESTABLISHED: Ward County, Texas; 1969.

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

Ochric epipedon: the zone from 0 to 8 inches (Ap horizon)

Calcic horizon: the zone from 8 to 48 inches (Bk and Bky1 horizons)

Gypsic horizon: the zone from 28 to 60 inches (Bky1 and Bky2 horizons)

Classified according to Keys to Soil Taxonomy, Tenth Edition, 2006.

Classification change from Calcic Gypsiorthids to Typic Calcigypsids based on application of the 6th edition of SOIL TAXONOMY.

Classification was changed in 1994 based on NSSL data (S90TX-475-001) from the type location in Ward County, Texas. The data indicates the soils have a silicate clay content less than 18 percent, and a calcic horizon above and within the gypsic horizon.

Soil Interpretation Record Number: TX0135

Updated competing series section 3/13/08, CEM.

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

Revised for the correlation of Hudspeth County, Texas (Main Part) and Culberson County, Texas (Main Part); July, 2012, NMS

National Cooperative Soil Survey
U.S.A.