LOCATION PULLMAN TX+NMEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, thermic Torrertic Paleustolls
TYPICAL PEDON: Pullman clay loam, on a nearly level plain, 0.3 percent slope in cultivated field at an elevation of about 3,900 feet. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 5 inches; brown (7.5YR 4/2) clay loam, dark brown (7.5YR 3/2) moist; moderate fine and medium subangular blocky structure; hard, friable; many fine and medium roots; few very fine and fine iron manganese concretions; neutral; gradual smooth boundary. (4 to 15 inches thick)
Bt1--5 to 18 inches; brown (7.5YR 4/2) clay, dark brown (7.5YR 3/2) moist; moderate medium prismatic structure parting to moderate medium angular blocky; most peds tilted 10 to 15 degrees from horizontal; very hard, very firm; common very fine and fine roots, few fine tubular pores; common distinct clay films on surfaces of peds; common pressure faces on ped surfaces; few fine iron manganese concretions; slightly alkaline; gradual smooth boundary. (6 to 20 inches thick)
Bt2--18 to 33 inches; brown (7.5YR 4/3) clay, dark brown (7.5YR 3/3) moist; moderate medium prismatic structure parting to strong medium angular blocky; most peds tilted 10 to 15 degrees from horizontal; very hard, very firm; few very fine and fine roots; few very fine and fine tubular pores; common distinct clay films on surfaces of peds; common pressure faces on ped surfaces; slightly effervescent; slightly alkaline; gradual smooth boundary. (7 to 18 inches thick)
Btk1--33 to 52 inches; brown (7.5YR 5/4) clay, brown (7.5YR 4/4) moist; moderate medium prismatic structure parting to strong medium angular blocky; most peds tilted 10 to 15 degrees from horizontal; very hard, very firm; few very fine roots; few very fine and fine tubular pores; common distinct clay films on surfaces of peds; common pressure faces on ped surfaces; few films, threads, nodules, and concretions of calcium carbonate; strongly effervescent; moderately alkaline; gradual smooth boundary. (5 to 20 inches thick)
Btk2--52 to 66 inches; strong brown (7.5YR 5/6) clay, strong brown (7.5YR 4/6) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; hard, firm; few fine and very fine tubular pores; few faint clay films on surfaces of peds; about 25 percent calcium carbonate in the form of masses, nodules, and concretions; violently effervescent; moderately alkaline; abrupt smooth boundary. (5 to 18 inches thick)
Btk3--66 to 80 inches; reddish yellow (5YR 7/6) clay loam, reddish yellow (5YR 6/6) moist; weak medium prismatic structure parting to moderate medium subangular blocky; hard, friable; few faint clay films on surfaces of peds; about 40 percent calcium carbonate in the form of masses, nodules, and concretions; violently effervescent; moderately alkaline; gradual smooth boundary.
TYPE LOCATION: Deaf Smith County, Texas; From the intersection of U.S. Highway 385 and U.S. Highway 60 in Hereford; 11.5 miles north on Highway 385; 1000 feet east in cultivated field; Latitude: 34 degrees, 58 minutes, 28.5 seconds N; Longitude: 102 degrees, 24 minutes, 02.2 seconds W; Milo Center, Texas USGS quad; NAD 27.
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 205 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: 59 to 64 degrees F.
Depth to secondary carbonates: 20 to 30 inches.
Depth to calcic horizon: 30 to 60 inches.
Thickness of the mollic epipedon: 12 to 30 inches.
Solum thickness: more than 80 inches.
Particle-size control section: 40 to 55 percent silicate clay.
A horizon:
Hue: 7.5YR or 10YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 2 or 3
Texture: clay loam, silty clay loam
Effervescence: none
Reaction: neutral to moderately alkaline
Upper Bt horizons:
Hue: 7.5YR or 10YR
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 2 or 3
Texture: clay
Effervescence: none
Reaction: slightly or moderately alkaline
Lower Bt horizons:
Hue: 5YR to 10YR
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 4 to 6
Texture: silty clay, clay
Visible calcium carbonate: less than 2 percent as films, threads, nodules and concretions.
Effervescence: none to slight
Reaction: slightly or moderately alkaline
Btk horizons:
Hue: 5YR or 7.5YR
Value: 5 to 7 dry, 4 to 6 moist
Chroma: 4 to 6
Texture: clay loam, silty clay loam, silty clay, clay
Visible calcium carbonate: 20 to 60 percent by volume as films, threads, masses, nodules, and concretions.
Effervescence: violent
Reaction: moderately alkaline
COMPETING SERIES:
Pantex is the only competing series. Similar soils include the
Darrouzett,
Lofton,
Olton,
Sherm, and
Zella series.
Pantex series are on similar landscape positions and have a calcic horizon within 60 to 80 inches of the soil surface
Darrouzett, Sherm, and Zella series are on similar landscape positions and have an average annual soil temperature of less than 59 degrees F.
Lofton series are on slightly lower landscape positions and do not have a hue of 7.5YR or redder in the matrix.
Olton series are on similar landscape positions and have
COLE of less than 0.06.
GEOGRAPHIC SETTING:
Parent material: loamy and clayey eolian sediments in the Blackwater Draw Formation of Pleistocene age.
Landform: slightly convex, nearly level to very gently sloping plains
Slopes: range from 0 to 3 percent.
Mean annual air temperature: 57 to 62 degrees F.
Mean annual precipitation: 17 to 21 inches.
Frost-free period: 180 to 220 days.
Elevation: 3,000 to 4,600 feet.
Thornthwaite annual P-E Index Values: 30 to 34.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing
Pantex and similar
Lofton and
Olton soils as well as the
Estacado,
Lazbuddie,
McLean,
Pep, and
Randall soils.
Olton and Pantex soils are on similar landscape positions.
Lofton soils are on slightly lower landscape positions.
Estacado and Pep soils occupy similar but more sloping positions near draws or playas and are calcareous to the surface.
Lazbuddie soils occur on playa terraces and have an ochric epipedon.
McLean and Randall soils are on lower landscape positions and have smectitic
mineralogy.
DRAINAGE AND PERMEABILITY: Well drained. Slow permeability. Surface runoff is medium on 0 to 1 percent slopes and high on 1 to 3 percent slopes.
USE AND VEGETATION: Mainly cultivated to irrigated and dryland cotton, corn, grain sorghum, and winter wheat. Climax vegetation in rangeland includes blue grama and buffalograss, with lesser amounts of vine-mesquite, western wheatgrass, galleta or tobosa, silver bluestem, wild alfalfa, and prairieclover. This soil has been correlated to the Deep Hardland (077CY022TX) range site in MLRA-77C.
DISTRIBUTION AND EXTENT: Southern High Plains of Texas and eastern New Mexico (MLRA-77C in LRR H). The series is extensive.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Potter County, Texas; 1929.
REMARKS: This is a benchmark soil.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: 0 to 18 inches. (Ap, Bt1 horizons)
Argillic horizon: 5 to 80 inches. (Bt, Btk horizons)
Calcic horizon: 52 to 80 inches. (Btk horizons)
Vertic properties: Deep, wide cracks more than 20 inches deep and wedge-shaped aggregates. COLE more than 0.06.
ADDITIONAL DATA: NSSL data available on mechanical analysis and mineralogy - Sample nos.: S99TX-117-001 (Deaf Smith County, Texas); S97TX-153-001 (Floyd County, Texas); S80TX-375-001, S80TX-375-002, S80TX-375-003 (Potter County, Texas); S95TX-381-001, S95TX-381-002, S95TX-381-003, S91TX-381-001, S79TX-381-003, S79TX-381-005 (Randall County, Texas); S94TX-437-001, S94TX-437-002, S94TX-437-003 (Swisher County, Texas). Texas Agricultural Experiment Station Bulletin 1372, "Pullman Soils: Distribution, importance, variability, and management", 1991, P.W. Unger and F.B. Pringle.
TAXONOMIC VERSION: Keys to Soil Taxonomy, Ninth Edition, 2003.