LOCATION HOUSTON BLACK TXEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Udic Haplusterts
TYPICAL PEDON: At center of microdepression--pasture. (Colors are for dry soil unless otherwise stated.)
A1--0 to 8 inches; very dark gray (10YR 3/1) clay, black (10YR 2/1) moist; moderate fine subangular blocky and moderate medium granular structure; extremely hard, very firm, very sticky and plastic; many fine roots; common very fine pores; common medium wormcasts; few fragments of snail shells; many very fine shiny faces of peds; few fine black concretions; few fine calcium carbonate concretions; strong effervescence; moderately alkaline; clear wavy boundary. (6 to 12 inches thick)
A2--8 to 24 inches; very dark gray (10YR 3/1) clay, black (10YR 2/1) moist; moderate fine and very fine angular blocky natural fragments that form wedge like shapes peds; extremely hard, very firm, very sticky and very plastic; common fine roots; common very fine pores; shiny surfaces on many fine and very fine natural soil fragments; few fine black concretions; few fine calcium carbonate concretions; strong effervescence; moderately alkaline; gradual wavy boundary. (0 to 20 inches thick)
Bss--24 to 38 inches; dark gray (10YR 4/1) clay, very dark gray (10YR 3/1) moist; strong coarse angular blocky natural fragments that form wedge shaped peds: extremely hard, very firm, very sticky and very plastic; few fine roots; common very fine pores; many intersecting slickensides shiny surfaces on many fine, medium, and coarse ped faces; few fine black concretions; few fine calcium carbonate concretions; strong effervescence; moderately alkaline; clear wavy boundary. (0 to 20 inches thick)
Bssk1--38 to 80 inches; grayish brown (10YR 5/2) clay, dark grayish brown (10YR 4/2) moist; few medium distinct olive brown (2.5YR 4/4) and many coarse faint gray (10YR 5/1) mottles; strong coarse angular blocky natural fragments that form wedge shaped peds; extremely hard, very firm, very sticky and very plastic; few fine roots; few very fine pores; many intersecting slickensides shiny surfaces on many fine, medium, and coarse ped faces; few fine dark gray vertical streaks; few fine black concretions and soft brown masses; few fine and medium calcium carbonate concretions and soft masses; violent effervescence; moderately alkaline; gradual wavy boundary. (10 to 50 inches thick)
Bssk2--80 to 104 inches; coarsely and distinctly mottled light olive brown (2.5Y 5/4) and gray (10YR 6/1) clay; common fine faint olive brown mottles; weak medium and coarse angular blocky natural fragments that form wedge shaped peds; very firm, very sticky and very plastic; few very fine roots and pores; many prominent slickensides; few fine soft brown masses; few medium soft masses of calcium carbonate; violent effervescence; moderately alkaline.
TYPE LOCATION: Travis County, Texas; from intersection of Farm Road 973 and U. S. Highway 290 in Manor, 3.5 miles east on U. S. Highway 290, 2.4 miles northeast on Farm Road 1100, 1.0 mile northwest and 3.0 miles northeast on Manda Road, 0.5 mile southeast on Lund Road, 900 feet southwest on field road, 105 feet east in pasture.
RANGE IN CHARACTERISTICS: Thickness of the combined A and B horizons is more than 80 inches. The weighted average clay content of the particle size control section is 40 to 60 percent The soil is usually moist, but when dry it has cracks ranging from 0.5 to 4 inches wide extend from the surface to a depth of 12 inches or more Cracks remain open for 90 to 150 cumulative days in most years. Slickensides begin at depths ranging from about 16 to 24 inches below the soil surface. The soil is clayey throughout with dominant textures being clay or silty clay. Some pedons have 15 to 30 percent by volume of siliceous and other pebbles in the upper 12 inches. Dominant textures are clay or silty clay in the upper 12 inches. When dry the surface has a granular mulch about 1/2 inch thick of extremely hard discrete granules. Cycles of microdepressions and microknolls are repeated each 10 to 24 feet. In virgin areas, microknolls are 3 to 18 inches higher than microdepressions. Chromas are less than 1.5 to depths of 30 to 60 inches in the center of microdepressions and 10 to 18 inches in the center of microknolls. The extremes of amplitude or waviness of the boundary between the A and B horizons vary from about 20 to 48 inches from the center of the microknoll to the center of the microdepression.
The A horizons have hue of 10YR to 5Y, value of 2 to 4, and chroma of 0 or 1. Soil reaction is moderately alkaline and calcareous, however, in the center of the microdepressions, the reaction ranges from slightly alkaline to moderately alkaline.
The Bss horizon has hue of 10YR, value of 2 to 4 and chroma of 0 to 1. Chroma ranges to 2 in some pedons: The lower B horizons have hue of 10YR, 2.5Y or 5Y, value of 4 to 7, and chroma of 2 to 6. The grayish brown and dark grayish brown colors occur in microdepressions and grayish brown to olive or yellow colors occur in microknolls. In some pedons chroma ranges to 8 in microknolls.
The lower B or Bk horizon has olive, brown and yellow mottles or is olive to yellow with gray mottles. Calcium carbonate content in the form of masses, threads and concretions range from few to many with total carbonate content ranging from 2 to 35 percent.
Water worn gravel of chert and quartzite are on the surface or within the A and B horizons of some pedons. Few weakly cemented iron manganese oxide concretions ranging from 1 to 5 mm in diameter occur throughout the soil.
COMPETING SERIES: These are the Bleiblerville, Branyon, Burleson, Clarita, Dimebox, Fairlie, Heiden, Leson, Luling, Ovan, Sanger, Slidell, Tamford, and Watonga soils. Bleiblerville soils are formed on Tertiary age sediments. Branyon soils are on terraces and have less amplitude of waviness. Burleson and Leson soils on terraces and are non-calcareous in the surface layer. Clarita soils have hue of 7.5YR or redder in the subsoil.. Dimebox is non-calcareous in the surface. Fairlie soils have a paralithic contact with chalk at 40 to 60 inches. Heiden, Luling, Ovan and Sanger soils have matrix chroma of 2 or more throughout and Ovan soils are on flood plains. Slidell soils contain more calcium carbonate in the control section and are underlain by marl. Tamford soils have hue of 7.5YR or redder in the subsoil. Watonga soils have sola less than 60 inches thick and are in slightly cooler climates
GEOGRAPHIC SETTING: Houston Black soils are on nearly level to sloping uplands. Slopes range from 0 to 8 percent, but are mainly 1 to 3 percent. The soil formed in calcareous clays and marls mainly of the Taylor Marl geological formation. In places, the substrata are chalks or shales. The climate is warm and subhumid. The mean annual precipitation ranges from 28 to 42 inches and the mean annual temperature ranges from 63 to 70 degrees F. Frost free days range from 220 to 250 days and elevation ranges from 400 to 1000 feet. Thornthwaite annual P-E indices range from 44 to 66.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Burleson, Branyon, Fairlie, Heiden and Ovan in the same family.and the similar Austin and Ferris soils. Burleson, Branyon and Ovan soils are on lower positions. Heiden soils are on similar landscapes with Houston Black. Austin soils are on slightly higher positions. Austin soils are underlain by chalk 20 to 40 inches dry, and prairie soils have chalk at 40 to 60 inches in depth. Ferris soils are on slightly sloping hillsides and have moist color values more than 3.5 and chroma more than 1.5 in the upper 12 inches.
DRAINAGE AND PERMEABILITY: Moderately well drained. Slow to rapid surface runoff. Water enters the soil rapidly when it is dry and cracked, and very slowly when it is moist. Permeability is very slow.
USE AND VEGETATION: Nearly all is cultivated and used for growing cotton, sorghums, and corn. Cotton root rot is prevalent on most areas and limits cotton yields and the use of some legumes in rotations. Native vegetation consists of tall and mid grass prairies of little bluestem, big bluestem, indiangrass, switchgrass, and sideoats grama, with scattered elm, mesquite, and hackberry trees.
DISTRIBUTION AND EXTENT: The Blackland Prairies and eastern part of the Grand Prairies of Texas. The series is extensive.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Brazoria County, Texas; 1902. The word "Black" was capitalized in the correlation of Kaufman County in 1947.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 38 inches
Vertic features - slickensides at a depth of 24 to 80 inches depth. High shrink-swell potential and cracks that are 1/2 to 4 inches wide at 12 inch depths during dry periods.
ADDITIONAL DATA: E. H. Templin, I. C. Mowery, and G. W. Kunze, Houston Black clay the Type Grumusol: Soil Science Society of American Proceedings, Vol. 20, No.1, January 1956. SSIR-30, S53TX-70-1, S54TX-14-90. National Soil Survey Laboratory, S77TS-027-001, S77TX-027-002, S78TX-027-003.
SIR Number. TX0093