LOCATION LESON TXEstablished Series
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 10 inches; 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. (3 to 20 inches thick)
Bss--10 to 30 inches; 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. (6 to 40 inches thick)
Bkss--30 to 60 inches; 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. (15 to 30 inches thick)
Ck--60 to 80 inches; 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 feet north in field.
RANGE IN CHARACTERISTICS: Solum thickness range from 60 to 80 inches. The weighted average clay content of the particle size control section ranges from 40 to 60 percent. When dry cracks 1/2 to 3 inches extend from the surface to a depth of more than 12 inches. In undisturbed areas there is gilgai microrelief. Distance between the microknoll and microdepression ranges from 4 to about 16 feet. There are few to many slickensides below a depth of about 15 inches. About 55 to 80 percent of the pedon has matrix colors of chroma 2 or more within 40 inches of the soil surface. Carbonates are below the A horizon and ranges from 9 to 60 inches.
The A horizons have hue of 10YR to 5Y and N, value of 2 to 4, and chroma of 0 or 1. Some pedons contain a few mottles in colors and shades of brown and olive in the lower part. The A horizon ranges from 12 to 20 inches thick on microknolls and 30 to 60 inches thick in microdepressions. It is clay or silty clay and is slightly acid to moderately alkaline.
The Bss horizons have hue of 10YR to 5Y, value of 2 and chroma of 0 to 1 in the upper part and value of 3 to 5, and chroma of 2 to 4 in the lower part. There are few to many mottles in colors and shades of gray, brown, and yellow. It is calcareous or noncalcareous clay or silty clay and typically contains few to common calcium carbonate concretions and soft masses. The Bkss horizon is neutral to moderately alkaline.
The Ck horizon has hue of 10YR to 5Y, value of 4 to 6 and chroma of 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. The Ck horizon is mildly or moderately alkaline.
COMPETING SERIES: These are the Bleiberville, Branyon, Burleson, Clarita, Dimebox, Fairlie, Heiden, Houston Black, Luling, Ovan, Sanger, Slidell, Tamford and Watonga series. Bleiberville, Branyon, Fairlie, Heiden, Houston Black, Ovan, Sanger, and Slidell are calcareous in the surface layer. Burleson soils have matrix chrmas of 1 or less throughout the upper 40 inches. Clarita and Tamford soils have hue of 7.rYR 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 40 to 60 inches depth. Luling soils have chroma of 1.5 or more in the surfae layers. Watonga soils have sola less than 60 inches thick, and are in slighly cooler climates.
GEOGRAPHIC SETTING: Leson soils are on nearly level to gently sloping uplands. Slope gradients range from 0 to 5 percent, but mainly are 1 to 3 percent. The soil formed in alkaline shales and clays. The climate is warm and subhumid. The mean annual precipitation ranges from 34 to 44 inches and mean annual average temperature ranges from 63 to 70 degrees F. Frost free days range from 230 to 260 days and elevation ranges from 350 to 750 feet. Thornthwaite annual P-E indices are 44 to 72.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Branyon, Burleson, Houston Black and Heiden in the same family.also the Ferris and Wilson series. Heiden and Ferris soils have A horizons with chroma 1 of 2. Wilson soils have loamy surface layers and firm textured Bt horizons. Ferris, Heiden, and Houston Black are on higher areas. Branyon, Burleson and Wilson are in similar or slightly lower positions.
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. The series is extensive.
MLRA OFFICE RESPONSIBLE: Temple, Texas
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 30 inches
cambic horizon - 30 to 60 inches.
Vertic features - Slickensides at a depth of 10 to 60 inches. High shrink-swell potential and cracks that are 1/2 to 3 inches wide at a depth of 12 inches or more during dry periods.
SIR Number. TX0074