LOCATION STOHMAN                 TX+NM

Established Series
SSS-TAC-TCB
09/2023

STOHMAN SERIES

The Stohman series consists of soils that are very shallow or shallow, well drained, and moderately permeable above a very slowly permeable petrocalcic horizon. These soils formed in a thin mantle of calcareous, loamy eolian deposits from the Blackwater Draw Formation of Pleistocene age over indurated caliche of Pliocene age. These soils are on nearly level and very gently sloping plains. Slope ranges from 0 to 3 percent. Mean annual precipitation is about 483 mm (19 in), and the mean annual air temperature is about 16 degrees C (61 degrees F).

TAXONOMIC CLASS: Loamy, mixed, superactive, thermic, shallow Petrocalcic Calciustepts

TYPICAL PEDON:Stohman fine sandy loam, in rangeland at an elevation of about 1,082 m (3,550 ft). (Colors are for dry soil unless otherwise stated.)

A--0 to 10 cm (0 to 4 in); brown (7.5YR 5/4) fine sandy loam, brown (7.5YR 4/3) moist; weak fine granular structure; soft, very friable; slightly sticky, slightly plastic; many very fine, fine, and medium roots; 10 percent fine distinct spherical strongly cemented carbonate nodules and 4 percent medium nonflat subrounded indurated calcrete fragments; strongly effervescent; moderately alkaline; clear wavy boundary. (Thickness is 4 to 20 cm [2 to 8 in].)

Bw--10 to 20 cm (4 to 8 in); brown (10YR 5/3) sandy clay loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; slightly hard, firm; moderately sticky, moderately plastic; common very fine and medium roots; 2 percent fine distinct spherical strongly cemented calcium carbonate nodules and 4 percent medium nonflat subrounded indurated calcrete fragments; strongly effervescent; moderately alkaline; clear wavy boundary. (Thickness is 4 to 20 cm [2 to 8 in].)

Bk--20 to 38 cm (8 to 15 in); pale brown (10YR 6/3) loam, brown (10YR 5/3) moist; moderate medium subangular blocky structure; slightly hard, friable; moderately sticky, moderately plastic; common very fine and many fine roots; 20 percent carbonate, finely disseminated, 5 percent medium distinct irregular calcium carbonate masses, 10 percent fine distinct spherical strongly cemented calcium carbonate nodules and 3 percent medium nonflat subrounded indurated calcrete fragments; violently effervescent; moderately alkaline; clear wavy boundary. (Thickness is 4 to 20 cm, [2 to 8 in].)

Bkkm1--38 to 71 cm (15 to 28 in); white (10YR 9.5/1) indurated platy calcrete containing a few fractures; laminar in the upper part; thin to thick, concentrically-banded pisolitic structure below the laminar layer; massive; common very fine, fine, and medium roots along fractures between calcrete plates; violently effervescent; moderately alkaline; gradual wavy boundary.

Bkkm2--71 to 102 cm (28 to 40 in); 85 percent pale pinkish white (7.5YR 9/2) and 15 percent pink (5YR 7/3) indurated platy calcrete containing a few fractures; laminar in the upper part; thin to thick, concentrically-banded pisolitic structure below the laminar layer, 85 percent pale pinkish white (7.5YR 9/2) and 15 percent pink (7.5YR 7/3) moist; massive; violently effervescent; moderately alkaline; gradual wavy boundary. (Combined thickness of the Bkkm horizons is 13 to 102 cm, [5 to 40 in].)

2BCkk--102 to 203 cm (40 to 80 in); white (10YR 8/1) and light gray (10YR 7/2) extremely cobbly sandy loam, white (10YR 8/1) and light brownish gray (10YR 6/2) moist; massive; very weakly to moderately cemented; common very fine and fine roots; 40 percent gravel-sized and 45 percent cobble-sized calcrete fragments; violently effervescent; moderately alkaline; gradual wavy boundary.

TYPE LOCATION:Yoakum County, Texas; from the intersection of U.S. HWY 380 and U.S. HWY 82 in Plains, 7.5 miles west on U.S. HWY 380 7.5 miles to intersection with Yoakum County Road 195; 0.9 miles south on Yoakum County Road 195 to intersection with an oil well road; 0.2 miles west on oil well road; west 1250 ft in rangeland; Latitude: 33 degrees, 13 minutes, 37.8 seconds N; Longitude: 102 degrees, 56 minutes, 48.4 seconds W; Plains NW, 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. December through February are the driest months. These soils are intermittently moist in September through November and March through July.
Mean annual soil temperature: 15 to 18 degrees C (59 to 64 degrees F).
Depth to petrocalcic horizon: 10 to 50 cm (4 to 20 in).
Solum thickness: more than 203 cm (80 in.).
Particle-size control section (weighted average): 15 to 30 percent silicate clay
Coarse fragments: 2 to 15 percent
CEC/clay ratio: more than 0.60

A horizon:
Hue: 7.5YR or 10YR
Value: 3 to 5, 2 or 3 moist
Chroma: 2 or 3
Texture: loamy fine sand, fine sandy loam, very fine sandy loam or loam
Coarse fragments: 2 to 15 percent of calcrete fragments
Calcium carbonate equivalent: 0 to 30 percent
Effervescence: strong or violent
Reaction: slightly alkaline or moderately alkaline
Visible calcium carbonate: 5 to 20 percent in the form of finely disseminated masses, or nodules

Bw horizon:
Hue: 7.5YR or 10YR
Value: 3 to 5, 2 to 4 moist
Chroma: 2 to 4
Texture: fine sandy loam, loam or sandy clay loam
Coarse fragments: 2 to 15 percent of calcrete fragments
Calcium carbonate equivalent: 0 to 2 percent
Effervescence: strong or violent
Reaction: slightly alkaline or moderately alkaline
Visible calcium carbonate: 1 or 2 percent in the form of finely disseminated masses, or nodules

Bk horizon:
Hue: 7.5YR or 10YR
Value: 5 to 7, 4 to 6 moist
Chroma: 2 to 4
Texture: fine sandy loam, loam or sandy clay loam
Coarse fragments: 2 to 15 percent of calcrete fragments
Calcium carbonate equivalent: 3 to 40 percent
Effervescence: strong or violent
Reaction: slightly alkaline or moderately alkaline
Visible calcium carbonate: 2 or 40 percent in the form of finely disseminated masses, or nodules

Bkkm horizon
Hue: 7.5YR or 10YR
Value: 7 or 8, 7 moist
Chroma: 1 to 3
This horizon ranges from indurated, fractured, with a thin to thick laminar zone in the upper part to continuously indurated with thin to thick, concentrically-banded pisolitic structure below the laminar layer.

2BCkk horizon
Hue: 7.5YR or 10YR
Value: 7 or 8, 6 or 7 moist
Chroma: 1 to 4
Texture: extremely gravelly sandy loam, extremely gravelly loam, extremely cobbly sandy loam
Coarse fragments: more than 60 percent calcrete fragments with interstitial soil materials
Calcium carbonate by weight: more than 40 percent
Effervescence: violent
Reaction: moderately alkaline

COMPETING SERIES:There are no competing series in the same family. Similar soils are theBlakeney,Carbine,Conger,Espy,Eunice,Kimberson,Kimbrough,Laverne,Pitzer,PotterQueeny, and Slaughterseries.
Blakeney,CongerandEunicesoils: are dry in the soil moisture control section for longer periods.

Carbine,EspyandKimbroughsoils: are dry in the soil moisture control section for longer periods and have darker color values in the surface horizons.
Kimbersonsoils: have darker color values in the surface horizons.
Ozona,PitzerandQueenysoils: are moist in the soil moisture control section for longer periods and have darker color values in the surface horizons.
Lavernesoils: have a loamy-skeletal particle-size control section and have parent materials derived from the OgallalaFormationof Miocene-Pliocene age.
Pottersoils: are dry in the soil moisture control section for longer periods and do not have an indurated petrocalcic horizon.
Slaughter soils: have a clayey particle-size class and an argillic horizon.

GEOGRAPHIC SETTING:
Parent material: a thin mantle of calcareous, loamy eolian deposits from the Blackwater Draw Formation of Pleistocene age over indurated caliche of Pliocene age.
Landform: nearly level and very gently sloping plains, typically adjacent to escarpments, and summit positions on knolls and interfluves.
Slope: 0 to 3 percent.
Elevation: 792 to 1,463 m (2,600 to 4,800 ft).
Mean annual air temperature: 14 to 17 degrees C (57 to 63 degrees F).
Mean annual precipitation: 432 to 533 mm (17 to 21 in.).
Frost-free period: 185 to 220 days
Thornthwaite annual P-E Index: 25 to 36

GEOGRAPHICALLY ASSOCIATED SOILS:These are theArvana,Bippus,Friona,Kimberson,Midessa,Potter,Sharvana,Slaughter,StegallandZitasoils.
Arvanasoils: occur on similar to slightly higher landscape positions and have an argillic horizon and have a petrocalcic horizon at a depth of 51 to 102 cm (20 to 40 in.) below the soil surface.
Bippussoils: occur on lower landscape positions and do not have a petrocalcic horizon.
FrionaandStegallsoils: occur on similar to slightly higher landscape positions, have an argillic horizon, darker color values in the surface horizons and have a petrocalcic horizon at a depth of 51 to 102 cm (20 to 40 in.) below the soil surface.
Kimbersonsoils: are on similar landscape positions.
MidessaandZitasoils: occur on similar or slightly lower landscape positions and do not have a petrocalcic horizon.
Pottersoils: are on slightly lower landscape positions.
Sharvanasoils: are on similar landscape positions and have both an argillic and a petrocalcic horizon at a depth of 25 to 51 cm (10 to 20 in.) below the soil surface.
Slaughter soils: occur on similar or slightly lower landscape positions and have darker color values in the surface horizons.

DRAINAGE AND PERMEABILITY:Well drained and very slow permeability. Runoff is high on slopes less than 1 percent and very high on 1 to 3 percent slopes.

USE AND VEGETATION:These soils are used nearly exclusively for livestock grazing. Climax vegetation includes sideoats grama, little bluestem, buffalograss, hairy grama, slim tridens, purple and wright threeawns,
bushsunflower, gray goldaster, daleas, gayfeather, plains blackfoot, sundrops,
catclaw, ephedra, hackberry, and javelinabrush. This soil has been correlated to the Very Shallow (R077CY037TX) ecological site in MLRA-77C.

DISTRIBUTION AND EXTENT:Southern High Plains, Southern Part (MLRA 77C in LRR H) of western Texas and eastern New Mexico. The series is extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE:Temple, Texas

SERIES ESTABLISHED:MLRA-77 Soil Survey Update; Roosevelt County, New Mexico, 2016

REMARKS:These soils were formerly included in the Kimberson series.

Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon: 0 to 10 cm (0 to 4 in). (A horizon)
Cambic horizon: 10 to 20 cm (4 to 8 in). (Bw horizon)
Calcic horizon: 20 to 38 cm (8 to 15 in) and 102 to 203 cm (40 to 80 in.). (Bk and 2BCkk horizons)
Petrocalcic horizons: 38 to 102 cm (15 to 40 in). (Bkkm1 and Bkkm2 horizons)
Lithologic discontinuity: 102 to 203 cm (40 to 80 in). (2BCkk horizon)

ADDITIONAL DATA:NSSL data available from type location; S12TX501001.

Taxonomic Version: Keys to Soil Taxonomy, Twelfth Edition, 2014.

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National Cooperative Soil Survey
U.S.A.