LOCATION PEP TX+NM

Established Series
Rev. JKA-RM-TCB
09/2022

PEP SERIES

The Pep series consists of very deep, well drained, moderately permeable soils that formed in calcareous, loamy eolian sediments in the Blackwater Draw Formation of Pleistocene age. These soils are on nearly level to gently sloping plains and side slopes above playas and along draws. Slope ranges from 0 to 5 percent. Mean annual precipitation is 483 mm (19 in), and mean annual temperature is 16 Degrees C (61 degrees F).

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, thermic Aridic Calciustolls

TYPICAL PEDON: Pep clay loam, on a very gently sloping plain, 1 percent slope in cultivated land at an elevation of about 1,238 m (4,060 feet). (Colors are for dry soil unless otherwise noted.)

A--0 to 25 cm (0 to 10 in); reddish brown (5YR 4/3) clay loam, dark reddish brown (5YR 3/3) moist; moderate fine and medium subangular blocky structure; slightly hard, friable; common fine roots, many very fine pores; strongly effervescent; moderately alkaline; gradual smooth boundary. (13 to 36 thick)

Bw--25 to 41 cm (10 to 16 in); yellowish red (5YR 5/6) clay loam, yellowish red (5YR 4/6) moist; moderate fine and medium subangular blocky structure; hard, friable; common fine roots; common very fine pores; less than 2 percent visible calcium carbonate by volume as films, filaments, and finely disseminated carbonates; strongly effervescent; moderately alkaline; gradual smooth boundary. (13 to 43 cm thick)

Bk--41 to 81 cm (16 to 32 in); reddish yellow (5YR 6/6) clay loam, yellowish red (5YR 5/6) moist; moderate medium subangular blocky structure; slightly hard, friable; few fine roots; few very fine pores; about 20 percent calcium carbonate by volume as filaments and finely disseminated carbonates; violently effervescent; moderately alkaline; gradual irregular boundary. (0 to 48 cm thick)

Bkk--81 to 203 cm (32 to 80 in); reddish yellow (5YR 7/6) clay loam, reddish yellow (5YR 6/6) moist; moderate medium subangular blocky structure; slightly hard, friable; common very fine and fine irregular pores; about 55 percent calcium carbonate by volume as masses, nodules, and finely disseminated carbonates; violently effervescent; moderately alkaline.

TYPE LOCATION: Deaf Smith County, Texas; from the intersection of U.S. Highway
385 and Farm Road 1058 in Hereford, 19.0 miles north on U.S. Highway 385 to Farm
Road 2587, 6.0 miles west on Farm Road 2587, 4.5 miles north and 0.4 mile east on unpaved county roads, 200 ft. south in cultivated field; Longitude: 35 degrees, 09 minutes, 56.4 seconds, N; Latitude: 102 degrees, 28 minutes, 39 seconds, W; Vega South, 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: 15 to 18 degrees C (59 to 64 degrees F).
Thickness of the mollic epipedon: 20 to 50 cm (8 to 20 in).
Depth to secondary calcium carbonate: 25 to 50 cm (10 to 20 in).
Depth to calcic horizon: 46 to 100 cm (18 to 40 in).
Solum thickness: more than 203 cm (80 in).
Particle-size control section: 18 to 35 percent silicate clay

A horizon:
Hue: 7.5YR or 10YR
Value: 4 or 5, 2 or 3 moist
Chroma: 2 to 4
Texture: loam, very fine sandy loam, clay loam
Effervescence: slight to violent
Reaction: slightly alkaline or moderately alkaline

Bw horizons (where present):
Hue: 5YR or 7.5YR
Value: 4 to 7, 3 to 6 moist
Chroma: 3 to 6
Texture: loam, clay loam, sandy clay loam
Visible calcium carbonate: l to 2 percent finely disseminated and as filaments, films, and very fine and fine nodules
Effervescence: strong to violent
Reaction: slightly alkaline or moderately alkaline

Bk horizon:
Hue: 5YR or 7.5YR
Value: 6 to 7, 5 to 6 moist
Chroma: 3 to 8
Texture: loam, clay loam, sandy clay loam
Visible calcium carbonate: 5 to 50 percent by volume as filaments, films, masses, nodules, and finely disseminated carbonates.
Calcium carbonate by weight: 3 to 40 percent
Effervescence: strong or violent
Reaction: moderately alkaline

Bkk horizon:
Hue: 5YR or 7.5YR
Value: 6 to 8, 5 to 7 moist
Chroma: 1 to 4
Texture: loam, clay loam, sandy clay loam
Visible calcium carbonate: 50 to 70 percent by volume as masses, nodules, and finely disseminated carbonates.
Calcium carbonate by weight: 40 to 60 percent
Effervescence: violent
Reaction: moderately or strongly alkaline

COMPETING SERIES: These are the Mansic (OK), Murray (TX), Portales (NM), and the
Snyder (TX) series. Similar soils include the Estacado, Mansker, Plemons, and
Zita series.
Mansic series: has less than 10 percent whitish concretions or other masses of segregated calcium carbonate in the Bk horizon and is 25 to 51 cm (10 to 20 in) deep to the zone of lime segregation.
Murray series: occurs on piedmont slopes and fan terraces.
Portales series: has a calcic horizon at 13 to 38 cm (5 to 15 in) depth and does not have colors 7.5YR or redder.
Estacado, Mansker, and Plemons series: have an argillic horizon.
Snyder series: depth to a calcic horizon is less than 50 cm (20 in).
Zita series: is not calcareous above the calcic horizon and does not have colors redder than 7.5YR.

GEOGRAPHIC SETTING:
Parent material: calcareous, loamy eolian deposits from the Blackwater Draw
Formation of Pleistocene age.
Landform: nearly level to gently sloping plains and playa slopes.
Slopes: 0 to 5 percent.
Mean annual air temperature: 14 to 17 degrees C (57 to 62 degrees F).
Mean annual precipitation: 406 to 533 mm (16 to 21 in).
Frost-free period: 185 to 220 days.
Elevation: 823 to 1,615 m (2,700 to 5,300 feet).
Thornthwaite annual P-E Index Values: 25 to 36.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Portales series, the similar Estacado and Zita soils and Acuff, Olton, Pantex, and Pullman series.
Portales, Estacado and Zita soils: are on similar or slightly lower landscape positions.
Acuff soils: are on similar landscape positions and have an argillic horizon.
Olton, Pantex, and Pullman soils: are on similar landscape positions, have an argillic horizon, and average more than 35 percent clay in the particle-size control section.

DRAINAGE AND PERMEABILITY: Well drained. Moderate permeability. Surface runoff is negligible on 0 to 1 percent slopes and low on 1 to 5 percent slopes.

USE AND VEGETATION: Widely used for dryland and irrigated crop production.
Principal crops grown are cotton, grain sorghum, and wheat. Climax native vegetation is mainly mid and short grasses and includes blue grama, sideoats grama, and buffalograss, with lesser amounts of vine-mesquite, western wheatgrass, galleta or tobosa, silver bluestem, wild alfalfa, and prairie clover with a light to moderate overstory of mesquite. This soil has been correlated to the Limey Upland (R077CY028TX) range site in MLRA-77.

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

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

SERIES ESTABLISHED: Series proposed Deaf Smith County, Texas; 1991, Established
Deaf Smith County, Texas; 1999.

REMARKS: This soil was formerly included with the Portales and Zita series.
Diagnostic horizons and features recognized in this pedon are:

Mollic epipedon: 0 to 25 cm (0 to 10 in). (A horizon)
Cambic horizon: 25 to 41 cm (10 to 16 in). (Bw horizon)
Secondary calcium carbonate: 41 to 81 cm (16 to 32 in). (Bk horizon)
Calcic horizon: 81 to 203 cm (32 to 80 in). (Bkk horizon)
Plugged (kk) horizon: 81 to 203 cm (32 to 80 in). (Bkk horizon)
Note: the kk feature is defined as pedogenic carbonate accumulation that is characterized by laterally continuous carbonates that have engulfed rock, sand, silt, and clay particles; plugged the macro porosity of the soil horizon with 50 percent or more calcium carbonate; and obliterated the original soil structure.

ADDITIONAL DATA: Lubbock SS Lab - S2021TX0451067 (Briscoe County, Texas).

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

National Cooperative Soil Survey
U.S.A.