LOCATION CHACON TX

Established Series
Rev. WJG-CKH
11/2010

CHACON SERIES

The Chacon series consists of very deep, well drained, slowly permeable soils that formed in calcareous clays and loamy alluvium over residuum weathered from sandstone and claystone. These nearly level to gently sloping soils occur on terraces and broad smooth plains. Slopes range from 0 to 5 percent. Mean annual temperature is about 22 degrees C (72 degrees F) and mean annual precipitation is about 533 mm (21 in).

TAXONOMIC CLASS: Fine, smectitic, hyperthermic Torrertic Argiustolls

TYPICAL PEDON: Chacon clay loam, on an east facing, slightly convex, 2 percent slope in rangeland; elevation is 252 meters (829 feet). (Colors are for dry soil unless otherwise stated.)

A--0 to 38 cm (0 to 15 in); dark grayish brown (10YR 4/2) clay loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; hard, friable; many fine roots; strong effervescence; moderately alkaline; clear smooth boundary. (0 to 25 cm [10 to 18 in] thick)

Bt--38 to 81 cm (15 to 32 in); grayish brown (10YR 5/2) clay, dark grayish brown (10YR 4/2) moist; moderate fine and medium angular blocky and subangular blocky structure; very hard, firm; many fine roots; few fine pores; some surfaces of peds have shiny faces; vertical cracks 1/4 to 5/16 inch wide occur at horizontal intervals of 3 to 8 inches; strong effervescence; moderately alkaline; gradual wavy boundary. (13 to 46 cm [5 to 18 in] thick)

Btk--81 to 102 cm (32 to 40 in); grayish brown (10YR 5/2) clay, dark grayish brown (10YR 4/2) moist; moderate medium and coarse blocky structure; extremely hard, very firm; few roots in upper part but less with depth; few fine pores; shiny faces on peds presumed to be pressure planes; few vertical cracks; dark staining on few faces of peds; few pebbles to 1/2 inch diameter; few masses of calcium carbonate; strong effervescence; moderately alkaline; gradual wavy boundary. (20 to 46 cm [8 to 18 in] thick)

BCkyz1--102 to 132 cm (40 to 52 in); pale brown (10YR 6/3) clay, brown (10YR 5/3) moist; weak medium angular blocky structure; very hard, very firm; very few fine roots; few fine pores; estimated 1 or 2 percent by volume of masses of calcium carbonate up to 0.5 cm (1/4 inch) diameter; few fine masses of crystalline neutral salts; very slightly saline: violent effervescence; moderately alkaline; diffuse wavy boundary. (20 to 43 cm [8 to 17 in] thick)

BCkyz2--132 to 168 cm (52 to 66 in); very pale brown (10YR 7/4) clay, light yellowish brown (10YR 6/4) moist; weak fine and medium subangular blocky structure; very hard, very firm; contains about 5 percent of fine masses calcium carbonate; few fine crystals of gypsum; few masses of unweathered claystone; slightly saline; violent effervescence; moderately alkaline.

TYPE LOCATION: Zavala County, Texas; 8.5 miles west of La Pryor on U.S. Highway 57, then 4.5 miles north on ranch road to Turkey Creek Ranch Headquarters, then 0.8 mile east along fence line road, then 2.2 miles north along fence line road, then 0.4 mile west, then through gate and continue 0.9 mile on ranch road, then 50 feet east in rangeland. Sand Mountain, USGS topographic quadrangle; Latitude: 29 degrees, 2 minutes, 17.61 seconds N; Longitude: 99 degrees, 59 minutes, 42.71 seconds W.; NAD 83.

RANGE IN CHARACTERISTICS:

Soil Moisture: An aridic ustic moisture regime. The soil moisture control section is moist in some or all parts for less than 90 consecutive days in normal years. June to August and December to February are the driest months, while September to November and March to May are the wettest months.
Solum thickness: 102 to 203 cm (40 to 80 in) over calcareous clays stratified with weakly consolidated sandstone and shale.
Mean annual soil temperature: 21 to 23 degrees C (70 to 73 degrees F)
Mollic epipedon: 25 to 76 cm (10 to 30 in) thick.
Depth to argillic: 15 to 42 cm (6 to 17 in)
Depth to secondary carbonates: 45 to 102 (17 to 40 in)

Particle-size control section
Clay content: 35 to 50 percent
Coarse fragments: 0 to 5 percent
Vertic properties: COLE is 0.07 to 0.15 in the upper 1.25 meters. The soil cracks 0.4 to 1.0 inch wide at the surface when dry, and the cracks extend to a depth of 51 cm (20 in) or more.

A horizon

Hue: 10YR
Value: 3 to 5
Chroma: 1 or 2
Texture: sandy clay loam, clay loam, loam, or clay
Clay content: 22 to 42
Base saturation: 100 percent
Calcium carbonate equivalent: 5 to 15 percent
EC (dS/m): 0 to 4
Gypsum: 0 to 1 percent
SAR: 0 to 2
Effervescence: slightly to strongly
Reaction: slightly or moderately alkaline

Bt or Btk horizon

Hue: 10YR or 2.5Y
Value: 4 to 6
Chroma: 1 to 4
Texture: sandy clay, clay loam, or clay
Clay content: 35 to 50
Base saturation: 100 percent
Calcium carbonate equivalent: 5 to 20 percent
Identifiable secondary carbonate: 2 to 20 percent, fine and medium, films, threads, masses, throughout
EC (dS/m): 0 to 4
Gypsum: 0 to 1 percent
SAR: 0 to 2
Effervescence: slightly to strongly
Reaction: slightly or moderately alkaline

BCkyz horizon

Hue: 10YR or 2.5Y
Value: 5 to 7
Chroma: 2 or 4
Texture: sandy clay, clay loam, or clay
Clay content: 35 to 50
Base saturation: 100 percent
Calcium carbonate equivalent: 9 to 20 percent
Identifiable secondary carbonate: 2 to 20 percent, fine and medium, films, threads, masses, throughout
Salt concentrations: 2 to 20 percent, fine and medium, films, threads, masses, throughout
EC (dS/m): 4 to 8
Gypsum: 1 to 3 percent
SAR: 2 to 13
Effervescence: slightly to strongly
Reaction: moderately alkaline

Cd horizon (where present)
Soft interbedded mudstone, shale, and sandstone

COMPETING SERIES: There are no competing series in the same family. Similar soils are the Clareville (TX), Coy (TX), Culp (TX), Elmendorf (TX), Laparita (TX), and Lofton (TX) series.
Clareville soils: have mollic epipedons over 51 cm (20 in) thick and have a COLE less than 0.07
Coy, Elmendorf and Laparita soils: have mollic epipedons over 50 cm (20 in) thick and are moist in the moisture control section for longer periods.
Culp and Lofton soils: have average soil temperatures less than 22 degrees C (72 degrees F).

GEOGRAPHIC SETTING:
Parent material: calcareous loamy and clayey alluvium over residuum weathered from sandstone and shale of Eocene age
Landform: terraces and broad smooth plains
Slope: 0 to 5 percent
Mean annual air temperature: 21 to 23 degrees C (70 to 73 degrees F)
Mean annual precipitation: 508 to 635 mm (20 to 25 in)
Frost-free period: 275 to 290 days
Elevation: 76 to 274 m (250 to 900 ft)
Thornthwaite annual P-E indices: 20 to 31

GEOGRAPHICALLY ASSOCIATED SOILS: These include the Catarina (TX), Cotulla (TX), Dant (TX), Maverick (TX), Montell (TX), Pryor (TX), Tonio (TX), and Uvalde (TX) series.
Catarina, Cotulla, and Maverick soils: are more saline and have higher exchangeable sodium contents, have ochric epipedons and are on slightly higher positions
Dant soils: have densic material from 102 to 150 cm (40 to 60 in) and occur on similar or slightly higher surfaces
Uvalde soils: have a calcic horizon within 102 cm (40 in) and occur on similar or slightly higher surfaces
Pryor and Tonio soils: have ochric epipedons and occur on similar or slightly higher surfaces

DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; slow permeability.

USE AND VEGETATION: Mostly rangeland. Small areas are cultivated to such crops as small grain, grain sorghum, and introduced grasses. A few areas are irrigated for producing cotton, corn, grain sorghum, small grain, truck crops, and introduced grasses. The original plant community was open grassland dominated by mid-grasses with occasional mesquite trees and woody shrubs. Bundleflower, bush sunflower and orange zexmania are important forbs. In early stages of retrogression, such plants are pink pappusgrass and plains bristlegrass increase but decrease with further deterioration. Other plants which increase or invade are hooded windmillgrass, Hall's panicum, tobosa grass, curley mesquitegrass, threeawns, red grama, mesquite, whitebrush, blackbrush, condalias, wolfberry, spiny hackberry, guyacan, guajillo, twisted acacia, Texas persimmon, and prickly pear cactus.

DISTRIBUTION AND EXTENT: Western Rio Grande Plain, Texas; LRR I; MLRA 83B. The series is of moderate extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas

SERIES ESTABLISHED: Zavala County, Texas; 1982. The name is from a small creek in Zavala County.

REMARKS: These soils were formerly included in the Dant series.

Diagnostic horizons and features recognized in this pedon are:

Mollic epipedon: 0 to 38 cm (0 to 15 in)

Argillic horizon: 38 to 102 cm (15 to 40 in)

Torrertic feature: clay content is greater than 35 percent; Cole is greater than 0.07, and cracks that remain open more than 6 months.

ADDITIONAL DATA: Local lab data was performed for 2 pedons from McMullen County.

TAXONOMIC VERSION: Keys to Soil Taxonomy, Eleventh Edition, 2010

National Cooperative Soil Survey
U.S.A.