LOCATION CROCKETT TX+OKEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Udertic Paleustalfs
TYPICAL PEDON: Crockett fine sandy loam--cropland. (Colors are for dry soil unless otherwise stated).
Ap--0 to 8 inches; dark brown (10YR 4/3) fine sandy loam, dark brown (10YR 3/3) moist; massive; very hard, friable; few wormcasts; moderately acid; abrupt wavy boundary. (4 to 15 inches thick)
Bt1--8 to 16 inches; distinctly and coarsely mottled reddish brown (5YR 4/4) and dark brown (10YR 4/3) clay, moderate fine and medium angular blocky structure; extremely hard, very firm; few fine pores; distinct clay films and dark grayish brown stains on surfaces of peds, few fine pressure faces; vertical cracks partially filled with darker soil; few fine black iron-manganese concretions; few fine and medium prominent dark red (10R 3/6) masses of iron accumulation; moderately acid; diffuse wavy boundary.
Bt2--16 to 30 inches; olive (5Y 5/4) clay, moderate medium and coarse angular blocky structure; extremely hard, very firm; few fine pores; thin clay films on surfaces of peds, few fine pressure faces; few small slickensides; few vertical streaks of dark brown soil that is less clayey; few fine black iron-manganese concretions; common medium and coarse distinct reddish brown (5YR 4/4), and yellow (10YR 7/6) masses of iron accumulation, common medium and coarse distinct grayish brown (10YR 5/2) iron depletions; slightly acid; gradual wavy boundary.
Bt3--30 to 42 inches; pale olive (5Y 6/4) clay, olive (5Y 5/4) moist; weak coarse angular blocky structure; extremely hard, very firm; thin patchy clay films; few fine pressure faces; few small slickensides; few fine black concretions; few black streaks or stains on faces of peds; common medium distinct pale yellow (5Y 7/4) masses of iron accumulation, and common medium distinct light brownish gray (2.5Y 6/2) iron depletions; neutral; gradual wavy boundary. (combined thickness of Bt horizons is 14 t 45 inches)
BCtk--42 to 57 inches; distinctly and coarsely mottled light brownish gray (2.5Y 6/2) and pale olive (5Y 6/4) clay; weak coarse angular blocky structure; extremely hard, very firm; few thin clay films on surfaces of peds; few pressure faces and cleavage planes; few calcium carbonate concretions; few masses of calcium carbonate to 1/2-inch in diameter; few fine black iron-manganese concretions; few black streaks along pressure faces and cleavage planes; slightly alkaline; abrupt smooth boundary. (10 to 30 inches thick)
Ck1--57 to 73 inches; pale yellow (2.5Y 7/4) stratified clay loam, light yellowish brown (2.5Y 6/4) moist; massive; extremely hard and very firm in place, friable when broken; 25 percent of weakly cemented, brittle weathered shale fragments; 20 percent white calcium carbonate masses and concretions; common medium distinct dark yellowish brown (10YR 4/4) masses of iron accumulations, mainly along fractures of weathered shale; violently effervescent; moderately alkaline; diffuse smooth boundary. (0 to 30 inches thick)
Ck2--73 to 80 inches; pale yellow (2.5Y 7/4) clay loam containing about 40 percent interbedded weakly consolidated shale in layers of 1/2 to about 2 inches, shale is light olive brown (2.5Y 5/4) in lower part; massive; extremely hard, very firm in place, friable when broken; 10 percent masses of calcium carbonate in the upper part grading to none in the lower part; soil matrix is violently effervescent in spots and shale is noncalcareous; moderately alkaline.
TYPE LOCATION: Kaufman County, Texas; 250 feet east of Farm Road 986; 1.5 miles north of post office in Terrell.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 40 to 60 inches. Depth to secondary carbonates ranges from 30 to 60 inches. Some pedons do not have visible carbonates. When dry, cracks 1/2 to about 2 inches wide extend from the top of the Bt horizon to depths of 2 to 5 feet. If the A horizon is eroded or thin, the soil cracks to the surface. Pressure faces and slickensides range from few to common throughout the Bt horizon and in the BC and C horizon of some pedons. The average clay content of the control section ranges from 40 to 50 percent, and COLE ranges from 0.07 to 0.10.
The thickness of the A horizon averages less than 10 inches in 50 percent or more of the pedon but ranges up to 15 inches in subsoil troughs. It has colors with hue of 7.5YR or 10YR, value of 3 to 6, and chroma of 2 to 4. Texture is fine sandy loam, very fine sandy loam, loam, silt loam or their gravelly counterparts. Siliceous pebbles range from 0 to 35 percent by volume. Reaction ranges from moderately acid to slightly alkaline. The boundary between the A and Bt horizon is commonly wavy. It is abrupt over subsoil crests and clear in subsoil troughs with an abrupt textural between the A and Bt horizons.
The Bt horizon has a base saturation of 75 to 100 percent by sum of the cations. The dominant color, degree, and distinctness of redoximorphic features in the Bt1 horizon may be extremely variable within a distance of a few feet. It ranges from prominently mottled in shades of brown, yellow, red and olive, to a matrix of reddish brown, dark yellowish brown, or brown, with few to common redoximorphic features as described in the mottled matrix. Texture of the Bt horizon is clay loam, clay, or sandy clay. Siliceous pebbles range from 0 to 15 percent by volume. Reaction of the Bt1 horizon ranges from moderately acid to neutral.
The Bt2 and lower Bt horizons have colors in shades of brown, olive, and yellow with or without reddish redoximorphic features. The reddish features decrease with depth and range from none to a few below the Bt2 horizon. Gray iron depletions range from none to common below the Bt2 horizon. Reaction ranges from slightly acid to moderately alkaline and is typically noncalcareous.
The BCtk horizon has matrix colors in shades of brown, olive, gray, yellow or the matrix is mottled with these colors or there are redoximorphic features, strata or fragments with these colors. Texture of the BCk is clay loam, or clay with or without weathered shale fragments, pockets of loamy materials, or strata of these materials interbedded.
The Ck is in shades of brown, olive or gray. It is mainly shale or clayey siltstone stratified with soil material ranging from loam to clay. Silt and clay dominate the shale materials. Siliceous pebbles range from none to about 5 percent by volume. Reaction ranges from slightly acid to moderately alkaline but typically is slightly or moderately alkaline. Masses and concretions of calcium carbonate range from none to many.
COMPETING SERIES: These are the Axtell, Bremond, Crosstell, Kurten, Navo, Tabor, and Zulch series. Similar soils are the Normangee and Ponder series. Axtell, Kurten and Tabor soils are strongly acid in the Bt1 horizon and have base saturation of less 75 percent. Bremond soils have sola more than 60 inches thick. Crosstell and Kurten soils have hue of 7.5YR or redder in the upper part of the Bt horizon. Navo soils do not have an abrupt textural change between the A and B horizons. In addition, Axtell, Navo, and Tabor soils also have sola from 60 to greater than 80 inches. Zulch soils have sola 20 to 40 inches thick. Normangee soils do not have an abrupt textural change between the A and Bt horizons. Ponder soils do not have redoximorphic features in the upper part of the Bt horizon.
GEOGRAPHIC SETTING: Crockett soils are on broad nearly level to moderately sloping uplands. Slopes range from 0 to 10 percent, but are mostly between 1 and 5 percent. The soil formed in residuum derived from weathered alkaline marine clays, sandy clays, or shale, interbedded with sandier materials, mainly of Cretaceous age. Mean annual temperatures ranges from 64 to 70 degrees F., and mean annual precipitation ranges from 32 to 45 inches. Frost free days range from 230 to 275 days, and elevation ranges from 200 to 800 feet. Thornthwaite P- E indices ranges from 50 to 75.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the Axtell, Bonham, Burleson, Mabank, Normangee, Payne and Wilson series. Bonham soils have mollic epipedons and have sola greater than 60 inches. Burleson soils are clays throughout with slickensides. Mabank and Wilson soils are dominated by chromas or 2 or less. Axtell, Bonham, Normangee, and Payne soils are on similar landscapes with Crockett soils. Burleson, Mabank, and Wilson soils are on lower positions.
DRAINAGE AND PERMEABILITY: Moderately well drained. Permeability is very slow. Runoff is low on slopes less than 1 percent, medium on 1 to 3 percent slopes, high on 3 to 5 percent slopes, and very high on 5 to 10 percent slopes.
USE AND VEGETATION: Mainly used for growing cotton, grain sorghums, and small grain, but more than half the acreage is now in pastures. Native vegetation is prairie grasses such as bluestems, indiangrass, switchgrass, and gramas, with scattered elm, hackberry, and mesquite trees.
DISTRIBUTION AND EXTENT: Mainly in the Blackland Prairies of Texas (MLRA 86A, 86B, 87A) but minor areas are in Oklahoma. The series is extensive.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Houston County, Texas; 1905.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 8 inches, layer is hard and massive
when dry. (Ap horizon).
Pale feature - Abrupt textural change at 8 inches.
Argillic horizon - 8 to 57 inches. (Bt1, Bt2, Bt3 and BCtk
horizons)
Vertic properties - COLE is 0.07 to 0.10
Crockett and Axtell soils are close competitors. Native vegetation of Crockett was dominantly prairie grasses whereas that of Axtell was trees with an understory of grasses. Morphologically, Crockett soils are less acid and leached in the upper part of the Bt horizon than Axtell soils. At present, this difference is attributed primarily to vegetation.
ADDITIONAL DATA: LSL17760-17767, Kaufman County, Texas.
Soil Interpretation Record: TX0318