LOCATION KNOBLAW TX+NM+OK

Established Series
TCB-CLN
06/2020

KNOBLAW SERIES

The Knoblaw series consists of very deep, somewhat poorly drained, very slowly permeable soils that formed in clayey lacustrine sediments over loamy eolian deposits of Pleistocene age. These nearly level soils are on a playa floors. Slope range is 0 to 1 percent. Mean annual precipitation is about 483 mm (19 in) and mean annual air temperature is about 12.8 degrees C (55 degrees F).

TAXONOMIC CLASS: Fine, mixed, superactive, mesic Calcic Haplusterts

TYPICAL PEDON: Knoblaw clay--on a 0.3 percent slope in native rangeland at approximately 989 m (3,245 ft) elevation. (Colors are for dry soil unless otherwise stated.)

A--0 to 13 cm (0 to 5 in); 70 percent dark gray (10YR 4/1) and 30 percent brown (7.5YR 5/4) clay, 70 percent very dark gray (10YR 3/1) and 30 percent brown (7.5YR 4/4), moist; moderate coarse and medium angular blocky parting to weak fine granular structure; very hard, very firm; very sticky, very plastic; common fine and medium and few coarse roots; many fine moderate tubular pores; reversible trans-horizon cracks 5 cm (2 in) wide extend through the horizon; few fine irregular weakly cemented iron-manganese concretions; few fine shell fragments; noneffervescent; slightly acid, pH 6.2; clear wavy boundary. Thickness of the A or Ap horizon is 13 to 38 cm (5 to 15 in)

Bss1--13 to 30 cm (5 to 12 in); dark grayish brown (10YR 4/2) silty clay, very dark grayish brown (10YR 3/2) moist; moderate coarse prismatic parting to moderate medium wedge parting to strong medium angular blocky structure; very hard, very firm; very sticky, very plastic; few distinct slickensides; reversible trans-horizon cracks 5 cm (2 in) wide extend through the horizon; few fine spherical strongly cemented iron-manganese concretions; few fine shell fragments; noneffervescent; neutral, pH 6.8; gradual wavy boundary.

Bss2--30 to 61 cm (12 to 24 in); 70 percent dark grayish brown (10YR 4/2) silty clay, very dark grayish brown (10YR 3/2) moist, 30 percent brown (7.5YR 5/4), brown (7.5YR 4/4) moist; moderate coarse prismatic parting to moderate medium wedge parting to strong medium angular blocky structure; very hard, very firm; very sticky, very plastic; few distinct slickensides; reversible trans-horizon cracks 2.5 cm (1 in) wide extend through the horizon; noneffervescent; neutral, pH 7.2; gradual wavy boundary.

Bss3--61 to 81 cm (24 to 32 in); 90 percent brown (7.5YR 5/4) silty clay loam; 90 percent brown (7.5YR 4/4) moist, 10 percent dark grayish brown (10YR 4/2) crack fill, very dark grayish brown (10YR 3/2) moist; moderate fine and medium wedge parting to moderate medium angular blocky structure; very hard, very firm; very sticky, very plastic; few distinct slickensides; reversible trans-horizon cracks 2.5 cm (1 in) wide extend to the horizons above; noneffervescent; slightly alkaline, pH 7.7; gradual wavy boundary. Combined thickness of the Bss horizons is 33 to 104 cm (13 to 41 in)

2Btk--81 to 114 cm (32 to 45 in); strong brown (7.5YR 5/6) clay loam, strong brown (7.5YR 4/6) moist; moderate medium subangular blocky structure; hard, firm; moderately sticky, moderately plastic; few distinct carbonate coats and common distinct clay films on all faces of peds; common fine noncemented spherical and threadlike calcium carbonate masses the matrix; strongly effervescent (2 percent calcium carbonate); moderately alkaline, pH 8.0; abrupt smooth boundary. Thickness of 2Btk horizon is 18 to 56 cm (7 to 22 in)

2Bk1--114 to 175 cm (45 to 69 in); reddish yellow (7.5YR 7/6) silty clay loam, reddish yellow (7.5YR 6/6) moist; weak medium subangular blocky structure; moderately hard, friable; moderately sticky, moderately plastic; common fine spherical weakly cemented carbonate nodules and many fine noncemented carbonate masses in the matrix; violently effervescent (36 percent calcium carbonate); moderately alkaline, pH 8.0; gradual wavy boundary. Combined thickness of 2Bk horizons is 0 to 89 cm (0 to 35 in)

2Bk2--175 to 203 cm (69 to 80 in); pink (7.5YR 7/4) silty clay loam, light brown (7.5YR 6/4) moist; weak medium subangular blocky structure; moderately hard, friable; moderately sticky, moderately plastic; common fine spherical weakly cemented carbonate nodules and common fine noncemented carbonate masses in the matrix; violently effervescent (36 percent calcium carbonate); moderately alkaline, pH 7.9.

TYPE LOCATION: Hansford County, Texas; from the intersection of State Highway 207 and Farm Road 520 south of Spearman, 3.5 miles west on Farm Road 520; 1000 ft (305 m) south into playa basin

USGS topographic quadrangle: Morse SE Texas
Latitude: 36 degrees, 7 minutes, 19 seconds N
Longitude: 101 degrees, 18 minutes, 37 seconds W
Datum: WGS84

Decimal Degrees
Latitude: 36.1219368
Longitude: -101.3101883

UTM Northing: 3999945
UTM Easting: 292092
UTM Zone 14S

RANGE IN CHARACTERISTICS:
Soil moisture: An ustic moisture regime bordering on udic. The soil moisture control section cracks and is dry in some or all parts more than 90 but less than 150 cumulative days in normal years. July through August and November through March are the driest months. Soil is intermittently moist from September through October and April through June. These soils receive runoff from surrounding uplands and the soil moisture control section is moist for longer periods of time than is normal for the climate.
Solum thickness: More than 203 cm (80 in)
Depth to redoximorphic features: 0 to 50 cm (0 to 20 in)
Depth to slickensides: 13 to 38 cm (5 to 15 in)
Depth to secondary carbonates: 48 to 127 cm (19 to 50 in)
Depth to calcic horizon: 102 to 150 cm (40 to 60 in)
Depth of episaturation: 0 to 107 cm (0 to 42 in) intermittently from April through October
Vertic features: 0 to 122 cm (0 to 48 in); when dry, seasonal cracks 0.5 to 5 cm (0.2 to 2 in) wide extend through one or more horizons to a depth of 100 cm (39 in) or more. Also, a layer greater than 15 cm (6 in) thick with wedge-shaped peds and/or slickensides. Gilgai micro-relief is commonly observed in undisturbed areas. Linear Extensibility averages from 7 to 12 cm in the upper 100 cm (40 in).

Particle-size control section (weighted average):
Total clay content: 40 to 55 percent
Silicate clay content: 40 to 55 percent
Clay-sized carbonate content: 0 to 1 percent
Sand Content: 5 to 25 percent
Rock Fragments: none

A and Ap horizons:
Hue: 7.5YR or 10YR
Value: 3 to 5 dry, 2 to 4 moist
Chroma: 1 to 4 moist or dry
Texture: clay loam, silty clay, or clay
Total clay content: 35 to 60 percent
Silicate clay content: 35 to 60 percent
Sand content: 3 to 25 percent
Rock fragments: noneEffervescence: none
Reaction (pH): slightly acid or neutral (6.1-7.3)

Bss and Bssg horizons:
Hue: 7.5YR or 10YR
Value: 3 to 6 dry, 2 to 5 moist
Chroma: 1 to 4 moist or dry
Texture: silty clay or clay
Total clay content: 40 to 60 percent
Silicate clay content: 40 to 60 percent
Sand content: 3 to 25 percent
Rock fragments: none
Redoximorphic features: None to few, fine to medium; faint to distinct, masses of manganese and oxidized iron, nodules of iron-manganese, surface coats of manganese
Calcium carbonate equivalent: 0 to 1 percent
Effervescence: none to slight
Reaction (pH): neutral to slightly alkaline (6.6-7.8)

2Btk horizons (where present):
Hue: 5YR to 10YR
Value: 4 to 8 dry, 3 to 6 moist
Chroma: 2 to 6 moist or dry
Texture: clay loam, silty clay loam, silty clay, or clay
Total clay content: 30 to 42 percent
Silicate clay content: 25 to 42 percent
Clay-sized carbonate: 0 to 5 percent
Sand content: 3 to 30 percent
Rock fragments: none
Identifiable calcium carbonate: 2 to 30 percent; fine to very coarse; finely disseminated carbonate, films, masses, concretions, and nodules
Calcium carbonate equivalent: 2 to 25 percent
Effervescence: slight to violent
Reaction (pH): slightly or moderately alkaline (7.4-8.4)

2Bk and 2Bkk horizons (where present):
Hue: 5YR to 10YR
Value: 6 to 8 dry, 5 to 7 moist
Chroma: 3 to 6 moist or dry
Texture: loam, clay loam, silt loam, or silty clay loam
Total clay content: 20 to 40 percent
Silicate clay content: 15 to 25 percent
Clay-sized carbonate: 5 to 30 percent
Sand content: 4 to 35 percent
Rock fragments: 0 to 14 percent; fine or medium gravel, strongly or very strongly cemented concretions and nodules of calcium carbonate
Identifiable calcium carbonate: 10 to 60 percent; fine to very coarse; finely disseminated carbonate, films, masses, concretions, and nodules
Calcium carbonate equivalent: 15 to 55 percent
Effervescence: strong or violent
Reaction (pH): moderately alkaline (7.9-8.4)

COMPETING SERIES: There are no competing series. Similar soils include the Hansford, Lautz, and Ness series.
Hansford series: have aquic moisture conditions and do not have a calcic horizon.
Lautz series: have a higher clay percentage in the particle-size control section and do not have a calcic horizon.
Ness series: have smectitic mineralogy and do not have a calcic horizon.

GEOGRAPHIC SETTING:
Parent material: clayey lacustrine sediments over loamy eolian deposits of Pleistocene age.
Landscape: high plains
Landform: playas
Slope: 0 to 1 percent
Mean annual precipitation: 432 to 584 mm (17 to 23 inches)
Thornthwaite annual P-E Index Values: 25 to 36
Mean annual air temperature: 11.7 to 13.9 degrees C (53 to 57 degrees F)
Frost-free period: 170 to 195 days
Elevation: 731.5 to 1249.7 m (2,400 to 4,100 ft)
GEOGRAPHICALLY ASSOCIATED SOILS: These are the similar Hansford and Lautz soils and the Balko, Canina, Dalhart, Dumas, Forgan, Gruver, Hugoton, Oslo, Perryton, Sherm, Sunray, Twichell, and Waka soils.
Hansford and Lautz soils: occur on similar landscape positions.
Balko, Canina, Dalhart, Dumas, Forgan, Gruver, Hugoton, Oslo, Perryton, Sherm, Sunray, and Twichell soils: occur on higher landscape positions and have an argillic horizon.
Waka soils: occur in drainageways, have a fine-silty particle size class, and are periodically flooded.

DRAINAGE AND PERMEABILITY:
Drainage: somewhat poorly drained
Permeability: very slow
Runoff: ponded
Ponding: frequency-occasional; depth-5 to 30 cm (2 to 12 in); duration-brief to long

USE AND VEGETATION:
Major uses: livestock grazing and wildlife habitat. A few small areas used for crop production.
Native vegetation: Western wheatgrass, buffalograss, blue grama, vine mesquite, Texas blueweed, kochia, western ragweed, cocklebur, sunflower, and mares-tail. Bur ragweed, sedges, spike rushes, bushy knotweed, frog-fruit, and saltmarsh aster may occur in wetter areas. Native range vegetation varies according to amount of water available.
Crops: wheat, corn, and grain sorghum
Ecological sites assigned to phases and components of this series are listed below. Current ecological site assignments are in Web Soil Survey. Components of this series include the following ecological sites: Playa (R077AY005TX)
DISTRIBUTION AND EXTENT:
General Area: Oklahoma and Texas Panhandles
Land Resource Region: H - Central Great Plains Winter Wheat and Range Region
Major Land Resource Area 77A - Southern High Plains, Northern Part
Extent: minor

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Temple, Texas

SERIES ESTABLISHED: Hansford County, Texas 2006.

REMARKS: These soils were formerly included in the Randall and Ness series.

Diagnostic horizons and features recognized in this pedon:
Slickensides: 13 to 81 cm (5 to 32 in) (Bss1, Bss2, and Bss3 horizons)
Vertic features: cracks that open and close each year and remain open for less than 150 cumulative days during most years.
Secondary carbonates: 81 to 203 cm (32 to 80 in) (2Btk, 2Bk1 and 2Bk2 horizons)
Calcic horizon: 114 to 203 cm (45 to 80 in) (2Bk, and 2Bk2 horizons)
Lithologic Discontinuity: 81 to 203 cm (32 to 80 in) (2Btk, 2Bk1 and 2Bk2 horizons)
Redoximorphic features: 0 to 30 cm (0 to 12 in) (A and Bss1 horizons)

ADDITIONAL DATA: KSSL data available: S1999TX195001 (TL-Hansford County, Texas)

TAXONOMIC VERSION: Keys to Soil Taxonomy, Twelfth Edition, 2014.

National Cooperative Soil Survey
U.S.A.