LOCATION LESON                   TX

Established Series


The Leson series consists of very deep, moderately well drained, very slowly permeable soils that formed in alkaline shales and clays. These soils are on nearly level or gently sloping soils occurring on interfluves and side slopes on ridges and plains on dissected plains. Slopes range from 0 to 5 percent. Mean annual precipitation is about 1073 mm (42 in) and the mean annual air temperature is about 18.9 degrees C (66 degrees F).

TAXONOMIC CLASS: Fine, smectitic, thermic Udic Haplusterts

TYPICAL PEDON: Leson clay--cropland. Midway between microhigh and microlow. (Colors are for dry soil unless otherwise stated.)

Ap--0 to 25 cm (0 to 10 in); very dark gray (10YR 3/1) clay, black (10YR 2/1) moist; moderate fine angular blocky structure; on the surface there is a one-half inch layer that has moderate medium granular structure; extremely hard, very firm; common shiny pressure faces; few fine black concretions; moderately alkaline; gradual wavy boundary. (8 to 51 cm [3 to 20 in] thick)

Bss--25 to 76 cm (10 to 30 in); very dark gray (10YR 3/1) clay, black (10YR 2/1) moist; weak coarse angular blocky structure parting to moderate medium angular blocky; extremely hard, very firm; common intersecting slickensides and wedge-shaped peds having long axis tilted 30 to 45 degrees from the horizontal; few fine iron-manganese concretions; moderately alkaline; gradual wavy boundary. (15 to 102 cm [6 to 40 in] thick)

Bkss--76 to 152 cm (30 to 60 in); pale olive (5Y 6/3) clay, olive (5Y 5/3) moist; common medium and coarse distinct very dark gray (10YR 3/1) and many fine faint light olive brown (2.5Y 5/6) mottles; moderate fine angular blocky structure; very hard, firm; common slickensides; common fine and medium calcium carbonate concretions and few masses of calcium carbonate; lower part of layer contains few shale fragments; slightly effervescent; moderately alkaline; gradual wavy boundary. (38 to 76 cm [15 to 30 in] thick)

Ck--152 to 203 cm (60 to 80 in); olive gray (5Y 5/2) weakly consolidated shale that has clay texture; with alternating layers of light olive brown (2.5Y 5/6); evident bedding planes; extremely hard, very firm; few slickensides; contains approximately 10 percent calcium carbonate in the form of concretions and masses; few iron-manganese concretions; strongly effervescent; moderately alkaline.

TYPE LOCATION: Hopkins County, Texas; from intersection of Texas Highway 11 and 19 in Sulphur Springs, 10.8 miles west on Highway 11; 225 ft north in field. USGS Cumby topographic quadrangle; Latitude: 33 degrees, 12 minutes, 11.09 seconds N; Longitude: 95 degrees 50 minutes, 0.21 seconds W. Datum: WGS84.

Soil moisture: An ustic soil moisture regime. The soil moisture control section is dry in some or all parts for more than 90 bu less than 150 cumulative days in normal years.
Soil depth: very deep, 152 to 203 cm (60 to 80 in).
Surface features: In undisturbed areas there is gilgai microrelief. Distance between the microknoll and microdepression ranges from 1.2 to about 4.9 m (4 to about 16 ft).
Vertic features: When dry cracks 1.3 to 8 cm (1/2 to 3 in) extend from the surface to a depth of more than 30 cm (12 in).
Thickness of the mollic epipedon: 76 to 152 cm (30 to 60 in).
Depth to slickensides: 38 cm (15 in).
Depth to cambic (when present): 76 to 118 cm (30 to 47 in).
Depth to secondary calcium carbonates: 23 to 152 cm (9 to 60 in).
Depth to salt accumulations (when present): 107 cm (42 in).
Depth to gypsum accumulations (when present): 107 cm (42 in).
Depth to redox concentrations: 18 to 160 cm (7 to 63 in).
Particle-size control section (weighted average)
Clay content: 40 to 60 percent.
About 55 to 80 percent of the pedon has matrix colors of chroma 2 or more within 102 cm (40 in) of the soil surface.
The A horizon ranges from 30 to 51 cm (12 to 20 in) thick on microknolls and 76 to 152 cm (30 to 60 in) thick in microdepressions.

A, or Ap horizons:
Hue: 10YR to 5Y and N
Value: 2 to 4
Chroma: 0 or 1
Some pedons contain a few mottles in colors and shades of brown and olive in the lower part. Texture: clay or silty clay
Reaction: slightly acid to moderately alkaline.

Bss or Bkss horizons:
Hue: 10YR to 5Y
Value: 2 to 5
Chroma: 0 to 4.
There are few to many mottles in colors and shades of gray, brown, and yellow.
It is calcareous or noncalcareous and typically contains few to common calcium carbonate concretions and soft masses.
Texture: clay or silty clay
Reaction: neutral to moderately alkaline.

Ck, Cdk, BCkss, or Ckssyz horizon:
Hue: 10YR to 5Y
Value: 4 to 6
Chroma: 2 to 6
It is stratified clay and weakly consolidated shale; bedding planes are evident in most pedons.
Few to common concretions and soft masses of calcium carbonate are in most pedons.
Gypsum crystals range from none to common.
Reaction: mildly or moderately alkaline.

COMPETING SERIES: These are the Bleiberville, Branyon, Burleson, Clarita, Deport, Dimebox, Ellis, Fairlie, Heiden, Houston Black, Lazare, Luling, Ovan, Sanger, Slidell, Sparenberg, and Watonga series.
Bleiberville, Branyon, Fairlie, Heiden, Houston Black, Ovan, Sanger, and Slidell soils: are calcareous in the surface layer.
Burleson soils: have matrix chromas of 1 or less throughout the upper 102 cm (40 in).
Clarita and Tamford soils: have hue of 7.5YR or redder in the subsoil.
Dimebox soils: have ironstone pebbbles and contin calcium sulfate in all parts of the pedon.
Fairlie soils: are underlain by chalk at 102 to 152 cm (40 to 60 in) depth.
Lazare soils: are moist for shorter periods in the soil moisture control section and are in enclosed depressions.
Luling soils: have chroma of 1.5 or more in the surface layers.
Sparenberg soils: occur in a zone of lesser annual precipitation
Watonga soils: have sola less than 152 cm (60 in) thick, and are in slighly cooler climates.

Parent material: alkaline shales and clays
Landscape: nearly level to gently sloping uplands
Slope: 0 to 5 percent, but mainly are 1 to 3 percent
Mean annual precipitation: 864 to 1,118 mm (34 to 44 in)
Mean annual air temperature: 17.1 to 21.1 degrees C (63 to 70 degrees F)
Frost-free period: 230 to 260 days
Elevation: 99 to 241.3 m (324 to 791 ft)
Thornthwaite P-E Index: 44 to 72

GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Branyon, Burleson, Houston Black and Heiden in the same family and similar Ferris and Wilson series.
Branyon, Burleson and Wilson soils: are in similar or slightly lower positions.
Heiden and Ferris soils: have an A horizons with chroma 1 of 2.
Wilson soils: have loamy surface layers and firm textured Bt horizons.
Ferris, Heiden, and Houston Black soils: are on higher areas.

DRAINAGE AND PERMEABILITY: Moderately well drained. Runoff is medium; Permeability is very slow. Water enters the soil rapidly when it is dry and cracked, and very slowly when it is moist.

USE AND VEGETATION: Mainly cultivated and used for crops such as cotton, grain sorghums, and corn. Native grasses are mainly bluestem, indiangrass, and gramas. Improved pastures are planted to bermudagrass and lovegrass. Scattered trees include bois d'arc, hackberry, elm, post oak, and locust.

DISTRIBUTION AND EXTENT: The Blackland Prairies of Texas. (MLRA(s) 86A, and possibly in 85 and 133B. The series is extensive.


SERIES ESTABLISHED: Hopkins County, Texas; 1973.

REMARKS: The soil was formerly included in the Burleson or Hunt series.

Diagnostic horizons and features recognized in this pedon are:

Mollic epipedon: 0 to 76 cm (0 to 30 in)(Ap and Bss horizons)
cambic horizon: 76 to 152 cm (30 to 60 in)(Bkss horizon)
Vertic features: High shrink-swell potential and cracks that are 1.3 to 8 cm (1/2 to 3 in) wide at a depth of 30 cm (12 in) or more during dry periods.
Slickensides: At a depth of 25 to 152 cm (10 to 60 in)
Depth to secondary calcium carbonates: 76 to 203 cm (30 to 80 in)
Depth to redox concentrations: 152 to 203 cm (60 to 80 in)


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

National Cooperative Soil Survey