LOCATION PETTUS TXEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, carbonatic, hyperthermic Typic Calciustolls
TYPICAL PEDON: Pettus sandy clay loam, on northeast-facing, convex, 1 percent slope in rangeland at an elevation of 90 m (295 ft) (Colors are for dry soil unless otherwise stated.)
A--0 to 25 cm (0 to 10 in); grayish brown (10YR 5/2) sandy clay loam, very dark grayish brown (10YR 3/2) moist; weak medium prismatic structure parting to weak fine subangular blocky; slightly hard, very friable; common fine and medium roots; common fine pores; about 10 percent by volume hard caliche fragments from 2 mm to 8 cm (1/4 to 3 in) in diameter; common wormcasts; few snail shells; common fine calcium carbonate concretions; strongly effervescent; moderately alkaline; clear smooth boundary. (18 to 30 [7 to 12 in] thick)
Bk--25 to 43 cm (10 to 17 in); light brownish gray (10YR 6/2) very gravelly sandy clay loam, dark grayish brown (10YR 4/2) moist; weak medium prismatic structure parting to weak fine subangular blocky; hard, friable; common fine roots and pores; about 40 percent by volume hard caliche fragments of which 10 percent are cobbles 8 to 25 cm (3 to 10 in) across and 30 percent are pebbles 2 mm to 8 cm (1/4 to 3 in) across; common wormcasts; few snail shells; common fine and medium calcium carbonate concretions; strongly effervescent; moderately alkaline; clear wavy boundary. (13 to 51 cm [5 to 20 in] thick)
BCk1--43 to 53 cm (17 to 21 in); light gray (10YR 7/2) extremely gravelly sandy clay loam; light brownish gray (10YR 6/2) moist; weak fine subangular blocky structure; hard, friable; about 65 percent by volume hard caliche fragments of which 30 percent are cobbles 3 to 10 in across and 35 percent are pebbles 2 mm to 8 cm (1/4 to 3 in) across; about 40 percent by volume of the fine earth has coatings, masses and concretions of calcium carbonate; violently effervescent; moderately alkaline; gradual smooth boundary. (8 to 25 cm [3 to 10 in] thick)
BCk2--53 to 165 cm (21 to 65 in); white (10YR 8/1) very gravelly sandy clay loam, light gray (10YR 7/2) moist; about 60 percent by volume visible soft masses and coatings of calcium carbonate; Weak coarse subangular blocky structure; hard, friable; about 40 percent by volume hard caliche fragments 2 mm to 8 cm (1/4 to 3 in) across; about 30 percent of the fine earth has coatings, soft masses and concretions of calcium carbonate; violently effervescent; moderately alkaline.
TYPE LOCATION: Jim Wells County, Texas; from the intersection of U. S. Highway 281 and Texas Highway 359 in Alice; 3 miles west on Texas Highway 359; then 10 miles north and 2 miles northwest on County Road 236, then 70 feet southwest in rangeland. San Diego USGS quad; Latitude is 27 degrees 54 minutes 29.4 seconds; 98 degrees 9 minutes 44.4 seconds W. NAD 83.
RANGE IN CHARACTERISTICS:
Soil Moisture: An ustic soil moisture regime. The soil moisture control section is dry in some or all parts for more than 90 days in normal years. June through Augustare the driest months, while September through November is the wettest.
Mean annual soil temperature: 22 to 23.5 degrees C (72 to 74 degrees F).
Depth to highly calcareous loamy material: 51 to 76 cm (20 to 30 in)
Depth to horizon containing more than 35 percent coarse fragments: 28 to 51 cm (11 to 20 in)
Particle-size control section (weighted average)
Clay content: 22 to 35 percent
Coarse Fragments: 25 to 55 percent
A Horizon
Hue: 10YR
Value: 4 or 5
Chroma: 1 to 3
Texture: loam, sandy clay loam, gravelly loam, or gravelly sandy clay loam
Coarse fragments: 0 to 25 percent
Calcium carbonate equivalent: 30 to 55 percent
Bk Horizon
Hue: 10YR or 2.5Y
Value: 5 to 7
Chroma: 2 or 3
Texture: gravelly loam, gravelly sandy clay loam, very gravelly loam or very gravelly sandy clay loam.
Clay content: 22 to 38 percent
Silicate clay: 20 to 34 percent
Coarse fragments: 25 to 55 percent; kind-hard caliche
Calcium carbonate equivalent: 10 to 40 percent of fine earth fraction; 40 to 55 percent of soil 2 mm to 20 mm in diameter
Identifiable secondary carbonate: amount-5 to 20 percent, size-.5 to 1 cm, kind-concretions
BCk Horizon
Hue: 10YR or 2.5Y
Value: 6 to 8
Chroma: 1 to 4
Texture: loam or sandy clay or the gravelly, very gravelly, extremely gravelly or cobbly counterparts
Coarse fragments: 15 to 80 percent; kind-strongly cemented fragments of caliche
Calcium carbonate equivalent: 40 to 70 percent in the whole soil finer than 20 mm
Identifiable secondary carbonate: amount-10 to 70 percent, size-.5 to 1 cm, kind-weakly cemented or nodular concretions, location-
COMPETING SERIES: There are no competing series in the same family. Similar soils are the Brackett (TX), Hidalgo (TX), Olmos (TX), Pernitas (TX), Quinlan (OK), Real (TX), Rehm (TX), Sarnosa (TX), Shiner (TX), Somervell (TX), and Valco (TX) series.
Brackett,
Quinlan,
Real, and
Somervell soils: mean annual soil temperatures less than 22 degrees C (72 degrees F)
Hidalgo,
Pernitas, and
Sarnosa soils: mixed mineralogy.
Olmos and
Valco soils: a petrocalcic horizons.
Rehm soils: dry in the moisture control section for longer periods; have more than 35 percent coarse fragments of chert.
Shiner soils: an ochric epipedon.
GEOGRAPHIC SETTING:
Parent material: calcareous loamy sediments that are somewhat stratified with weakly cemented sandstone and shale of the Lagarto and Goliad formations
Landscape: inland dissected coastal plains
Landform: ridges and upper backslopes on hillslopes
Slope: 0 to 8 percent
Mean annual air temperature range: 21 to 23.5 degrees C (70 to 74 degrees F)
Mean annual precipitation range: 584 to 838 mm (23 to 33 in)
Precipitation Pattern: Precipitation mostly falls during the months of May and June and again in September and October. December through March are the driest months.
Frost-free period: 275 to 300 days
Elevation: 61 to 152 m (200 to 500 ft)
Thornthwaite annual P-E indices: 25 to 40
GEOGRAPHICALLY ASSOCIATED SOILS: These include the competing Hidalgo, Olmos, and Pernitas series, and the Parrita and Randado series.
Hidalgo and
Pernitas soils: do not have gravel; on a slightly lower position on a similar landform.
Olmos soils: are shallow over a petrocalcic horizon; on a slightly higher position on a similar landform.
Parrita and
Randado soils: on slightly higher position on a similar landform; petrocalcic horizons and noncalcareous sola.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderate. Runoff is negligible on slopes less than 1 percent, very low on slopes of 1 to 3 percent, low on slopes of 3 to 5 percent, and medium on slopes of 5 to 8 percent.
USE AND VEGETATION: Used mostly for rangeland. Grass vegetation includes red grama, lovegrass tridens, witchgrass, hooded windmillgrass, and plains bristlegrass. Woody vegetation is mainly ceniza, blackbrush, and mesquite. A few small areas are cultivated in association with deeper soils. (Ecological site name: Gravelly Ridge 20-35" PZ; Ecological site number is R083AY386TX)
DISTRIBUTION AND EXTENT: Central portion of the Rio Grande Plain of Texas (MLRA 83A, 83C; LRR I). The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: San Patricio and Aransas Counties, Texas; 1974.
REMARKS: These soils were formerly included with the Zapata series. The BCk horizon is not continuously cemented throughout the pedon and is penetrated by roots. This horizon is probably a degrading petrocalcic horizon.
Diagnostic horizon and features recognized in this pedon are:
Mollic epipedon 0 to 25 cm (0 to 10 in). (A horizon)
Calcic horizon 25 to 165 cm (10 to 65 in). (Bk and BCk horizons)
Additional Comments: The official series description was updated during the correlation of Goliad County, Texas.
ADDITIONAL DATA: Engineering test data from type location on sample S72TX-125-005.
TAXONOMIC VERSION: Keys to Soil Taxonomy, Tenth Edition, 2006