LOCATION DALLAM             TX+NM

DALLAM SERIES

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Aridic Paleustalfs

TYPICAL PEDON: Dallam fine sandy loam--rangeland. (Colors are for dry soil unless otherwise stated.)

A--0 to 20 cm (0 to 8 inches); brown (10YR 4/3) fine sandy loam, dark brown (10YR 3/3) moist; weak fine subangular blocky and granular structure; slightly hard, friable; many fine roots; few wormcasts; neutral; clear smooth boundary. (13 to 40 cm thick)

Bt1--20 to 58 cm (8 to 23 inches); yellowish brown (10YR 5/4) sandy clay loam, dark yellowish brown (10YR 4/4) moist; weak coarse prismatic parting to weak fine subangular blocky structure; very hard, friable; many fine roots; common pores; few distinct clay films on surfaces of peds; slightly alkaline; gradual smooth boundary.

Bt2--58 to 81 cm (23 to 32 inches); yellowish brown (10YR 5/4) sandy clay loam, dark yellowish brown (10YR 4/4) moist; weak coarse prismatic parting to weak fine subangular blocky structure; very hard, friable; few fine roots; few distinct clay films on surfaces of peds; few films and filaments of calcium carbonate; slightly effervescent; moderately alkaline; clear wavy boundary. (combined thickness of the Bt horizons is 76 to 100 cm)

Btk1--81 to 145 cm (32 to 57 inches); pink (7.5YR 7/4) sandy clay loam, light brown (7.5YR 6/4), moist; weak fine subangular blocky structure; hard, friable; few distinct clay films on surfaces of peds; about 15 percent by volume calcium carbonate in the form of masses and nodules; violently effervescent; moderately alkaline; diffuse boundary. (25 to 100 cm thick)

Btk2--145 to 203 cm (57 to 80 inches); reddish yellow (7.5YR 6/6) clay loam, strong brown (7.5YR 5/6) moist; weak fine subangular blocky structure; hard, friable; few faint clay films; about 10 percent by volume calcium carbonate as masses and nodules; violently effervescent; moderately alkaline.

TYPE LOCATION: Dallam County, Texas; 823 meters (2,700 feet) west and 244 meters (800 feet) south of NE corner of sec. 13, Block 3 of the CSS Survey; (14 miles) northwest of Dalhart, Texas, along U. S. Highway 87. Latitude: 36 degrees, 12 minutes, 06 seconds N; Longitude: 102 degrees, 43 minutes, 13 seconds W; Bolin Texas USGS quad; NAD 83.

RANGE IN CHARACTERISTICS:
Soil moisture: An ustic moisture regime bordering on aridic. The soil moisture control section is dry in some or all parts for more than 180 but less than 220 days, cumulative, in normal years. July through August and December through February are the driest months. These soils are intermittently moist in September through November and March through June.
Mean annual soil temperature: 12 to 14 degrees C (54 to 59 degrees F)
Depth to argillic horizon: 13 to 40 cm (6 to 14 in)
Depth to secondary carbonates: 50 to 100 cm (16 to 36 in)
Depth to calcic horizon: 76 to more than 203 cm (30 to 80 in)
Solum thickness: more than 203 cm
Particle-size control section: 18 to 35 percent silicate clay.

A horizon:
Hue: 7.5YR or 10YR
Value: 4 or 5, 3 or 4 moist
Chroma: 2 to 4
Texture: fine sand, loamy fine sand, fine sandy loam
Effervescence: noneffervescent
Reaction: neutral or slightly alkaline
Winnowed surface layers of loamy fine sand over fine sandy loam are common

Bt horizons:
Hue: 5YR to 10YR
Value: 4 or 5, 3 or 4 moist
Chroma: 2 to 6
Texture: fine sandy loam, sandy clay loam, clay loam
Visible secondary carbonates: less than 2 percent as films and filaments
Effervescence: none to slightly effervescent
Reaction: slightly alkaline to moderately alkaline

Btk horizons:
Hue: 5YR or 7.5YR
Value: 6 to 8, 5 to 7 moist
Chroma: 2 to 6
Texture: sandy clay loam, clay loam, silty clay loam
Calcium carbonate equivalent: 5 to 65 percent
Visible secondary carbonates: 3 to 35 percent by volume as films, filaments, masses, and nodules
Effervescence: strong to violently effervescent
Reaction: moderately alkaline

COMPETING SERIES: These are the Perico, Predawn, and Rickmore series. Similar soils include Cobb, Dalhart, and Menard series.
Perico series: have effervescent horizons throughout.
Predawn series: have an abrupt clay increase of 15 percent or more in the upper argillic horizon.
Rickmore series: have chroma less than 5 in the upper 150 cm of argillic horizon; in addition have more than 35 percent silicate clay in the lower argillic horizon.
Cobb and Menard series: have annual soil temperatures more than 15 degrees C. Dalhart series: have a clay decrease of 20 percent from the maximum within 150 cm of the mineral soil surface.

GEOGRAPHIC SETTING:
Parent Material: loamy eolian sediments of Pleistocene age.
Landform: eolian plain or an interdune on sandhills.
Slopes: dominantly 1 to 3 percent, but range from 0 to 5 percent
Elevation: 920 to 1,478 meters (2,000 to 4,000 ft)
Mean annual air temperature: 11 to 13 degrees C (46 to 61 degrees F)
Mean annual precipitation: 356 to 483 mm (16 to 22 in)
Frost-free period: 150 to 200 days
Thornthwaite annual P-E Index Values: 25 to 36.

GEOGRAPHICALLY ASSOCIATED SOILS: These include the similar Dalhart, Perico, and Rickmore series and the Dumas, Gruver, Optima, Oslo, Sherm, Sunray, Texline, and Vingo series.
Dalhart, Perico, and Rickmore soils: are on similar landscape positions.
Dumas, Gruver, Oslo, Sherm, Sunray, and Texline soils: are on slightly lower landscape positions and have a mollic epipedon.
Optima soils: are on slightly higher landscape positions and do not have an argillic horizon.
Vingo soils: are on slightly higher landscape positions and have a coarse-loamy particle size control section.

DRAINAGE AND PERMEABILITY: Well drained and moderately permeable. Surface runoff is negligible on 0 to 1 percent slopes, very low on 1 to 3 percent slopes, and low on 3 to 5 percent slopes.

USE AND VEGETATION: Mainly used for crop production but also used for livestock grazing. Principal crops grown are wheat and grain sorghum. The plant community for fine sandy loams is short and mid grasses with a lesser tall grass component, mid grasses tend to dominate this site. The main plant species are sideoats grama, blue grama, and little bluestem, with minor amounts of Indiangrass, vine mesquite, sand dropseed, buffalograss, gauras, catclaw sensitive briar, prairie clover, and sagewort. Woody plants include catclaw acacia and yucca. The plant community for fine sands and loamy fine sands is tall and mid grasses with tall grasses tending to dominate. The major plant species include little bluestem, sand bluestem, sand lovegrass, sand paspalum, and sideoats grama with minor amounts of silver bluestem, sand dropseed, hooded windmillgrass, fall witchgrass, hairy grama, and perennial threeawn. Woody plants comprise 10 to 20 percent of the plant community and include sand shinoak, sand sagebrush, and skunkbush. This soil has been correlated to the Sandy Loam (R-077BY020TX) and Sandy (R-077BY658TX) ecological site in MLRA-77B.

DISTRIBUTION AND EXTENT: Southern High Plains, Northwestern Part (MLRA 77B in LRR H) of Texas and New Mexico north of the Canadian River. The series is moderately extensive.

MLRA OFFICE RESPONSIBLE: Temple, Texas

SERIES ESTABLISHED: Dallam County, Texas; 1970.

REMARKS: Series revised MLRA-77 Update Soil Survey; Hansford County, Texas; 2006.
Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon: 0 to 20 cm (A horizon)
Argillic horizon: 20 to 203 cm (Bt1, Bt2, Btk1, and Btk2 horizons)
Calcic horizon: 81 to 145 cm (Btk1 horizon)

ADDITIONAL DATA: NSSL Laboratory Data available: S73TX-111-001, S95TX-111-001, S95TX-111-002, S95TX-111-003 (Dallam County, TX); S73TX-205-001, S73TX-205-002 (Hartley County, TX)

TAXONOMIC VERSION: Soil Taxonomy, Tenth Edition, 2006.