LOCATION THURBER            TX

THURBER SERIES

The Thurber series consists of very deep, moderately well drained, very slowly permeable soils that formed in slopewash from Pennsylvanian sediments. These soils are on nearly level and very gently sloping plains. Slopes ranges from 0 to 3 percent.

TAXONOMIC CLASS: Fine, smectitic, thermic Typic Haplustalfs

TYPICAL PEDON: Thurber clay loam--rangeland. (Colors are for dry soil unless otherwise stated.)

A--0 to 8 inches; dark grayish brown (10YR 4/2) clay loam, very dark grayish brown (10YR 3/2) moist; moderate medium and coarse platy structure in upper 2 inches and massive below; very hard, very firm; few fine roots; slightly alkaline; clear smooth boundary. (4 to 12 inches thick)

Bt1--8 to 20 inches; brown (10YR 4/3) clay, dark brown (10YR 3/3) moist; strong fine angular blocky structure; very hard, very firm; few fine roots; continuous clay films on surfaces of peds; slightly alkaline; clear wavy boundary. (8 to 20 inches thick)

Bt2--20 to 38 inches; brown (10YR 4/3) clay, dark brown (10YR 3/3) moist; strong fine angular blocky structure; very hard, very firm; few fine and medium roots; common clay films on surfaces of peds; few very fine masses and few fine concretions of calcium carbonate; slightly effervescent; moderately alkaline; gradual wavy boundary. (8 to 24 inches thick)

Btk--38 to 48 inches; brown (10YR 5/3) clay, brown (10YR 4/3) moist; weak medium angular blocky structure; very hard, very firm; few fine and medium roots; common clay films on surfaces of some peds; 5 percent films, threads, and masses of calcium carbonate; strongly effervescent; moderately alkaline; gradual wavy boundary. (0 to 14 inches thick)

B't1--48 to 57 inches; yellowish brown (10YR 5/4) clay loam dark yellowish brown (10YR 4/4) moist; weak fine and medium angular blocky structure; hard, firm; few fine and medium roots; common clay films on surfaces of some peds; few threads and films of calcium carbonate; strongly effervescent; moderately alkaline; gradual boundary. (0 to 15 inches thick)

B't2--57 to 71 inches; dark yellowish brown (10YR 4/4) clay loam, dark yellowish brown (10YR 3/4) moist; weak fine and medium angular blocky structure; very hard, firm; few fine roots; common clay films on surfaces of some peds; few films, threads and concretions of calcium carbonate; weakly effervescent; moderately alkaline; gradual boundary. (0 to 20 inches thick)

BC--71 to 80 inches; yellowish brown (10YR 5/8) clay loam, dark yellowish brown (10YR 4/6) moist; weak fine and medium subangular blocky structure; very hard, friable; few fine roots; few fine faint strong brown masses of iron accumulation; few concretions of calcium carbonate; noncalcareous; moderately alkaline.

TYPE LOCATION: Erath County, Texas; about 19 miles northwest of Stephenville, and about 1 mile north of the X-Ray Gas Plant; north-northwest 18.5 miles from County Courthouse on Texas Highway 108, then 100 feet west of highway in rangeland.

RANGE IN CHARACTERISTICS: The solum is more than 60 inches thick. Depth to secondary carbonates ranges from 15 to 30 inches.

The A horizon has hue of 7.5YR to 2.5Y, value of 3 to 5, chroma of 2 to 4. Texture is clay loam or silty clay loam and is both hard and massive when dry. Reaction ranges from slightly acid to slightly alkaline.

The Bt horizons have hue of 7.5YR to 2.5Y, value of 3 to 5, chroma of 2 to 4. Texture is clay loam or clay with 35 to 55 percent clay. Reaction is neutral or slightly alkaline in the upper part and slightly alkaline or moderately alkaline and calcareous in the lower part. Concretions, masses, and threads of calcium carbonate range from few to common in the lower part.

The Btk, B't, BC and in the BCk horizon, when present, are in shades of brown and gray. They are calcareous loam, sandy clay loam, clay loam, or clay. Concretions and masses of calcium carbonate ranges from few to many in the BCk horizon and none to a few in the BC and C horizons.

COMPETING SERIES: There are no other competing series. Similar soils are the Callahan, Kirkland, Paducah, Payne, and Tillman series. Callahan soils have mixed mineralogy. Kirkland and Tillman soils have epipedons that are not both massive and very hard when dry. Paducah soils have less than 35 percent clay in the control section. Payne soils have depth to secondary carbonates below 30 inches.

GEOGRAPHIC SETTING: Thurber soils are in valleys or in stream head positions. The slope is dominantly 0.5 to 2 percent, but ranges from 0 to 3 percent. Surfaces are plane to weakly concave. The soil formed in calcareous, clayey slope wash. Mean annual precipitation ranges from 26 to 32 inches, and mean annual temperature ranges from 63 to 66 degrees F. Frost free days range from 210 to 240 days, and elevation ranges from 850 to 1,750 feet. Thornthwaite annual P-E indices range from 36 to 50.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Blanket, Bonti, Bosque, Leeray, Set, and Truce series. Blanket soils have a mollic epipedon greater than 20 inches thick. Leeray soils are clayey throughout. Blanket and Leeray soils are on positions similar to Thurber soils. Bonti and Truce soils have reddish, clayey argillic horizons and are on higher positions in the landscape. Bosque soils have mollic epipedons and are below on flood plains. Set soils have a mollic epipedon and are above on escarpments and knolls.

DRAINAGE AND PERMEABILITY: Moderately well drained. Permeability is very slow. Runoff is low on slopes less than 1 percent and medium on 1 to 3 percent slopes.

USE AND VEGETATION: Used mainly for rangeland with a few areas farmed to small grain and sorghums. Native vegetation includes buffalograss, curlymesquite, vine-mesquite grass, and Texas wintergrass. Invader plants are mesquite, condalia, tasajillo, pricklypear, and ragweed.

DISTRIBUTION AND EXTENT: North Central Prairie (MLRA 80B), and West Cross Timbers (MLRA 84B) of Texas. The series is extensive.

MLRA OFFICE RESPONSIBLE: Temple, Texas

SERIES ESTABLISHED: Eastland County, Texas; 1972.

REMARKS: Thurber soils previously have been included in the Kirkland series.

Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon - 0 to 8 inches. (A horizon). Both hard and massive when dry.

Argillic horizon - 8 to 71 inches. (Bt and Btk horizons).

ADDITIONAL DATA: Lincoln Lab. Sample number 72L075, 79P908-916, 82P1535-1536, and 82P1544.