LOCATION HOUSTON AL+AR MS
The Houston series consists of moderately well drained, slowly permeable, cyclic soils that formed in alkaline clays and chalk of the Blackland Prairies. These clayey soils have very high shrink-swell potential. Slope ranges from 0 to 8 percent.
TAXONOMIC CLASS: Very-fine, smectitic, thermic Oxyaquic Hapluderts
TYPICAL PEDON: Houston clay in the center of a micro-pasture. (Colors are for moist soil unless otherwise stated.)
A11--0 to 10 inches; very dark gray (5Y 3/1) clay; moderate fine and medium granular structure; hard, firm, very plastic; common fine roots; mildly alkaline; gradual smooth boundary. (4 to 11 inches thick)
A12--10 to 25 inches; dark olive gray (5Y 3/2) clay; moderate fine angular and subangular blocky structure; hard, firm, very plastic; common fine roots; mildly alkaline; clear irregular boundary. (0 to 24 inches thick)
AC--25 to 42 inches; olive gray (5Y 4/2) clay; few fine faint mottles of very dark gray; large wedge-shaped aggregates that are bordered by intersecting slickensides; parts to successively smaller angular blocky structure; very hard, firm, very plastic, sticky; few fine black concretions; common medium and coarse calcium carbonate concretions; moderately alkaline; gradual wavy boundary. (5 to 27 inches thick)
C1--42 to 58 inches; olive (5Y 4/3) clay; few fine faint mottles of very dark gray; large wedge-shaped aggregates that are bordered by intersecting slickensides; parts to angular blocky structure; very hard, extremely firm, very firm, very plastic, sticky; few fine black concretions; common medium and coarse calcium carbonate concretions; calcareous; moderately alkaline; gradual wavy boundary. (5 to 26 inches thick)
C2--58 to 72 inches; light olive brown (2.5Y 5/6) clay; common fine distinct olive gray and few fine faint yellowish brown mottles; large wedge-shaped aggregates that are bordered by intersecting slickensides; parts to angular blocky structure; very hard, extremely firm, plastic; few medium and coarse calcium carbonate concretions; calcareous; moderately alkaline.
TYPE LOCATION: Dallas County, Alabama; 1 mile northwest of Black Belt Substation and 100 yards west of the Vaiden plots in a pasture, 1000 feet north and 1000 feet west of the SE corner of the NW 1/4 sec. 2, T. 17 N., R. 8 E.
RANGE IN CHARACTERISTICS: Depth to bedrock ranges from 4 to 9 feet. The soil is clay throughout, ranging from 60 to 80 percent with 60 to 70 percent being most common. Common or many intersecting slickensides are in the AC and C horizons. These are cyclic soils, with cycles of microknolls and microbasins repeated at linear intervals of 6 to 12 feet. The amplitude of waviness of the boundary between the A and AC horizon ranges from about 9 to 26 inches. The A horizon ranges from slightly acid through mildly alkaline. Few, common,or many calcium carbonate concretions occur in the AC and C horizons.
The A11 horizon has hue of 10YR, 2.5Y, or 5Y, value of 2 or 3, and chroma of 1 or 2, or it is (N 2/0) or (N 3/0).
The A12 horizon has hue of 10YR, 2.5Y, or 5Y, value of 2 or 3, and chroma of 2. In some pedons it has value of 4 or 5, and chroma of 2 at depths more than 30 cm from the surface.
The AC horizon has hue of 10YR, 2.5Y, or 5Y, value of 4 or 5, and chroma of 2 or 3. It is slightly acid through moderately alkaline.
The C horizon has hue of 10YR, 2.5Y, or 5Y, value of 4 or 5, and chroma 3 through 6. Many pedons have C horizons mottled with shades of brown, yellow or gray. It ranges from neutral to moderately alkaline. Chalk bedrock is commonly light gray or pale yellow in color.
COMPETING SERIES: There are no other series in this family. Closely similar soils include the
Vamont series. All of these soils except LaCerda and Redco have less than 60 percent clay in their control section. LaCerda and Redco soils have values of 4 or more within 30 cm of the surface and have mottles associated with wetness.
GEOGRAPHIC SETTING: Houston soils are on nearly level to sloping uplands with slope gradients of 0 to 8 percent. They are formed in alkaline clays and soft chalk. The climate is warm and humid.
Near the type location the average annual temperature is 67 degrees F. and the average annual precipitation is about 51 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the
Vaiden series. Binnsville and Demopolis soils have chalk within 20 inches of the surface.
Catalpa soils have irregular distribution of organic matter and less than 60 percent clay in the control section.
Sumter soils have more than 40 percent calcium carbonate equivalent and lack intersecting slickensides.
Vaiden soils are more acid and have distinct or prominent mottles within 20 inches of the surface.
DRAINAGE AND PERMEABILITY: Moderately well drained. Runoff is medium to rapid and permeability is slow.
USE AND VEGETATION: Used mainly for pasture and hay crops. Some acreage is used for soybeans.
DISTRIBUTION AND EXTENT: The Blackland Prairies of Alabama and Mississippi; possibly Arkansas, Louisiana, and Texas. The series is extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Auburn, Alabama
SERIES ESTABLISHED: Brazoria County, Texas; 1902.
REMARKS: The Houston series was formerly classified in the Grumusols great soil group.
ADDITIONAL DATA: The typical pedon is characterized in the Southern Cooperative Series N. 130, entitled @Properites of Alabama and Mississippi Black Belt Soils,@ published at Auburn University, February 1968. The pedon is Houston N. 28 - Ala., described on page 34 of that publication.
National Cooperative Soil Survey