LOCATION FALBA TXEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Aquic Paleustalfs
TYPICAL PEDON: Falba fine sandy loam--pasture. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 5 inches; brown (10YR 5/3) fine sandy loam, pale brown (10YR 6/3) dry; few fine distinct yellowish brown mottles; weak platy structure; hard, very friable; common fine roots; very strongly acid; abrupt smooth boundary. (3 to 8 inches thick)
E--5 to 7 inches; grayish brown (10YR 5/2) fine sandy loam, light brownish gray (10YR 6/2) dry; common fine distinct yellowish brown mottles; massive; hard, very friable; few fine roots; amplitude of the contact between the E and the Bt horizon is about 5 inches across a horizontal distance of two feet; very strongly acid; abrupt wavy boundary. (0 to 6 inches thick)
Bt1--7 to 17 inches; dark grayish brown (10YR 4/2) clay, grayish brown (10YR 5/2) dry; common fine and medium distinct yellowish brown (10YR 5/6) mottles; few fine prominent strong brown and yellowish red mottles; weak coarse prismatic structure parting to moderate medium and fine angular blocky; extremely hard, very firm; few fine roots, some of which are concentrated between prisms; few shiny pressure faces on the peds; very strongly acid; gradual wavy boundary. (6 to 15 inches thick)
Bt2--17 to 24 inches; dark grayish brown (10YR 4/2) on the outside of the peds and grayish brown (2.5Y 5/2) on the inside of the peds; clay; light brownish gray (10YR 6/2) dry; few medium distinct strong brown (7.5YR 5/6) mottles associated with strongly cemented black nodules; weak coarse prismatic structure parting to moderate medium and coarse blocky; extremely hard, very firm; few fine roots between prisms; few very fine sand pockets about 1 cm in diameter between some peds; few shiny pressure faces; very strongly acid; clear wavy boundary. (6 to 17 inches thick)
BCt--24 to 33 inches; about 65 percent light brownish gray (2.5Y 6/2) sandy clay loam, light gray (2.5Y 7/2), dry; few medium prominent strong brown (7.5YR 5/6) mottles; weak coarse and medium angular blocky structure; very hard, very firm; dark grayish brown (10YR 4/2) thick continuous clay films between the blocks; few fine roots; few lenses of loam that may be partially weathered tuffaceous fine sandstone; 35 percent soft tuffaceous sandstone fragments from 1 to 10 cm across the long axis; few strongly cemented iron concretions up to about 1.5 cm in diameter; few soft white masses; very strongly acid; abrupt wavy boundary. (0 to 10 inches thick)
Cr--33 to 55 inches; very pale brown (10YR 7/3) tuffaceous fine sandstone with angular fractures white (10YR 8/1) dry; weakly cemented; few fine roots along fractures in dark thin clay flows; few medium strongly cemented black concretions and few soft red and yellow masses; slightly alkaline.
TYPE LOCATION: Walker County, Texas; from the intersection of Texas Highway 30 and Interstate 45 in Huntsville, 7.7 miles west on Texas Highway 30, north on Farm Road 2550 4.5 miles to the intersection of Farm Road 2550 and Farm Road 1696, 1.3 miles west on Farm Road 1696, 1.4 miles south on Roberts Road and 1056 feet west in pasture. (Longitude: 95 degrees, 43 minutes, 30 seconds North; Latitude: 42 degrees, 31 minutes, 16 seconds West.)
RANGE IN CHARACTERISTICS: Solum thickness ranges from 20 to 40 inches and corresponds to the depth to tuffaceous sandstone, siltstone, or tuffaceous clays. The COLE may exceed 0.09 in the Btg horizons, but the potential linear extensibility of the soil is less than 6 cm. Siliceous pebbles range from none to few throughout the pedon.
The A horizon averages less than 10 inches thick in more than 50 percent of the pedons, but it is as much as 15 inches thick over subsoil troughs. The A horizon has hue of 2.5Y or 10YR with value of 4 to 7, and chroma of 1 to 3. The E horizon, where present, is one or two units of value higher then the A horizon. Mottles in the A horizons range from none to common. The texture of the A and E horizons are fine sandy loam, sandy loam, or loamy fine sand. The A and E horizons are strongly acid or very strongly acid. The boundary between the A or E horizon and Bt horizon is abrupt and ranges from smooth to wavy.
The Bt and BCt horizons have hue of 2.5Y or 10YR, value of 4 to 7 and chroma of 1 or 2. Mottles range from none to common, fine to medium, and from yellowish brown to yellowish red. The Bt horizons are clay, sandy clay loam, or clay loam, with the clay content ranging from 35 to 50 percent. White masses of barite are present in some pedons. Some pedons have a few soft masses of calcium carbonate in the lower 6 inches. Reaction is very strongly acid or strongly acid in the upper part and very strongly acid to neutral in the lower part.
Many pedons have a transitional Bt/Cr horizon. Some pedons contain fragments of sandstone or concretions of carbonate up to about 25 percent by volume.
The Cr or Crt layer ranges from clayey tuff, tuffaceous clay, volcanic ash, fine grained sandstone to siltstone. It ranges from olive to grayish or brownish in color. In some pedons these materials are considered a lithologic discontinuity due to changes in sand to silt ratios. Soft masses and concretions of calcium carbonate range from none to few. Reaction ranges from slightly alkaline to strongly acid.
COMPETING SERIES: These are the Arol, Cadell, Chazos, Gredge, Hassee, Niotaze, and Singleton series Similar soils are the Burlewash, Lufkin, Flemington, and Shalba series. Arol soils have value of less than 4 in the upper Bt horizon. Cadell, Chazos, Gredge, Hassee, Flemington, and Lufkin soils have sola thicker than 40 inches. Burlewash soils are well drained and have higher chroma colors in the Bt horizons. Shalba soils have sola less than 20 inches thick. Niotaze soils have chroma of 2 or more in the Bt horizon and are in cooler climates. Singleton soils have less than 60 percent of the matrix occupied by low chroma colors.
GEOGRAPHIC SETTING: Falba soils are on nearly level to sloping erosional uplands. Slopes range from 0 to 8 percent and surfaces are plane to convex. The soils formed in interbedded clays, tuffs, ash beds, sandstones, and pyroclastics as typified by the Catahoula Formation. Mean annual precipitation ranges from 35 to 45 inches and mean annual temperature ranges from 67 to 70 degrees F. Frost free days range from 240 to 280 days and elevation ranges from 200 to 550 feet. Thornthwaite annual P-E indices range from 52 to 72. The average summer moisture deficit ranges from 6 to 8 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Arol, Burlewash, Greenvine, Lufkin, Shalba and Singleton series and the Elmina series. Arol, Lufkin, Shalba and Singleton soils are on similar landscape positions. Burlewash and Greenvine soils are on nearby sloping, convex areas. Greenvine soils have vertic properties and lack an argillic horizon. Elmina soils are on similar positions, but have sandy surface layers 20 to 40 inches thick.
DRAINAGE AND PERMEABILITY: Moderately well drained. Permeability is very slow. Runoff is low on 0 to 1 percent slopes, medium on 1 to 3 percent slopes, high for 3 to 5 percent slopes and very high on 5 to 8 percent slopes.
USE AND VEGETATION: Mainly pastureland and rangeland. Large acreages were once planted to cotton, but are now unimproved pastures. Improved pastures are coastal bermudagrass. Native vegetation is a post oak savannah. Major grasses being little bluestem, indiangrass, switchgrass, big bluestem and sideoats grama. A few shortleaf pine have encroached this soil in the extreme eastern part of the area of occurrence.
DISTRIBUTION AND EXTENT: Southeastern and south-central Texas, mainly between the Trinity and Colorado Rivers. The series is of extensive.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Walker County, Texas; 1975.
REMARKS: Falba soils were formerly included in Lufkin series.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 7 inches. (A and E horizons)
Albic horizon - 5 to 7 inches. (E horizon)
Argillic horizon - 7 to 33 inches. (Bt and BCt horizons)
Aquic feature - Grayish brown soil color with mottles from 7 to 24 inches.
Paralithic contact - at 33 inches.
ADDITIONAL DATA: National Soil Survey Laboratory: 70TX-236- 2(71L009-71L014).