LOCATION RACOMBES TXEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, active, hyperthermic Pachic Argiustolls
TYPICAL PEDON: Racombes sandy clay loam--irrigated cropland.
(Colors are for dry soil unless otherwise stated.)
Ap--0 to 6 inches; very dark gray (10YR 3/1) sandy clay loam, black (10YR 2/1) moist; moderate fine granular structure; slightly hard, friable; many fine pores; mildly alkaline; clear smooth boundary. (5 to 9 inches thick)
A1--6 to 13 inches; very dark gray (10YR 3/1) sandy clay
loam, black (10YR 2/1) moist; moderate fine subangular blocky structure; slightly hard, friable; many fine pores; mildly
alkaline; clear smooth boundary. (5 to 18 inches thick)
Bt1--13 to 25 inches; dark grayish brown (10YR 4/2) sandy
clay loam, very dark grayish brown (10YR 3/2) moist; moderate
medium blocky structure; hard, friable; many fine pores; clay
films on surfaces of peds; mildly alkaline; clear smooth boundary. (8 to 24 inches thick)
Bt2--25 to 37 inches; brown (10YR 5/3) sandy clay loam, dark brown (10YR 4/3) moist; weak medium prismatic structure parting to moderate medium blocky; very hard, firm; common pores; patchy clay films on surfaces of peds; mildly alkaline; clear smooth boundary. (10 to 17 inches thick)
Bw--37 to 49 inches; brown (7.5YR 5/4) sandy clay loam, dark brown (7.5YR 4/4) moist; few faint strong brown (10YR 5/6)
mottles; weak subangular blocky structure; hard, friable;
calcareous; moderately alkaline; gradual smooth boundary. (12 to
24 inches thick)
Ck1--49 to 65 inches; light brown (7.5YR 6/4) sandy clay
loam, brown (7.5YR 5/4) moist; few faint strong brown (10YR 5/6) mottles; structureless; hard, friable; common soft bodies and concretions of calcium carbonate; calcareous; moderately alkaline; gradual smooth boundary. (12 to 16 inches thick)
Ck2--65 to 72 inches; light brown (7.5YR 6/4) sandy clay
loam, brown (7.5YR 5/4) moist; structureless; common soft bodies
and concretions of calcium carbonate; calcareous; moderately alkaline.
TYPE LOCATION: Hidalgo County, Texas; about 3.5 miles east of the intersection of Farm Road 107 and Farm Road 491 at La Villa,
Texas, then 0.6 mile north on county road to field road, then 0.4 mile east on field road and 75 feet south of road in field.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 40 to 60 inches. The mollic epipedon ranges from 20 to 44 inches thick. Depth to secondary carbonates ranges from 24 to 50 inches. Electrical conductivity is 1 to 4 mmhos/cm in most pedons, but
ranges from 4 to 16 mmhos/cm in saline pedons.
The A horizon is very dark gray (10YR 3/1), very dark grayish
brown (10YR 3/2), dark grayish brown (10YR 4/2), or dark gray
(10YR 4/1). It is loam or sandy clay loam with clay content
ranging from 16 to about 28 percent. It is neutral or mildly alkaline.
Weighted average clay content of the Bt horizon ranges from 26 to
34 percent. Texture is sandy clay loam or clay loam. Clay films
are thin and patchy to nearly continuous on both horizontal and vertical surfaces of peds. Structure is weak to moderate fine or medium blocky. Weak to moderate medium or coarse prisms occur in some pedons.
The Bt1 horizon is very dark grayish brown (10YR 3/2), dark
grayish brown (10YR 4/2), very dark gray (10YR 3/1), dark gray
(10YR 4/1), grayish brown (10YR 5/2), dark brown (10YR 4/3, 3/3),
or brown (10YR 5/3). It ranges from neutral to moderately
alkaline.
The Bt2 horizon is dark grayish brown (10YR 4/2), brown (10YR 5/3; 7.5YR 5/2, 5/4), grayish brown (10YR 5/2), pale brown (10YR 6/3),
or yellowish brown (10YR 5/4). It is mildly alkaline or
moderately alkaline.
The Bw is grayish brown (10YR 5/2), brown (10YR 5/3; 7.5YR 5/4), light brownish gray (10YR 6/2), light brown (7.5YR 6/4), or pale brown (10YR 6/3). In some pedons this horizon contains secondary calcium carbonate and is designated as a Bk horizon.
The C horizon is light brown (7.5YR 6/4), pink (7.5YR 7/4),
reddish yellow (7.5YR 6/6, 7/6), very pale brown (10YR 7/3, 7/4, 8/4), or pale brown (10YR 6/3). It is sandy clay loam or clay
loam. Weakly cemented concretions and soft bodies of calcium carbonate range from about 3 to 15 percent by volume.
COMPETING SERIES: These include
Altus,
Bippus,
Bosque,
Christine,
Clareville,
Cuero,
Czar,
Medley,
Ramadero,
Rio,
Sinton,
Smithville, and
Tordia series. Altus, Bippus, Bosque, Medley, and Smithville soils have mean annual soil temperatures less than 72 degrees F. Clareville, Rio, and Tordia soils have more than 35 percent clay in their control sections. Christine soils have < 4 mmhos/cm conductivity in the Bt horizons. Cuero soils are moist
in the moisture control section for longer periods of time. Czar soils have from 18 to 26 percent clay in the B2t horizon.
Ramadero and Sinton soils lack Bt horizons.
GEOGRAPHIC SETTING: Racombes soils are on nearly level deltaic or coastal terraces with plane to concave surfaces having gradients
less than 1 percent. The soil formed in alkaline sediments 8 to
10 feet thick. The climate is subtropical with a mean annual precipitation of 23 to about 30 inches. The mean annual
temperature is 70 to 74 degrees F., and the Thornthwaite annual
P-E index is 22 to about 40.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the competing
Rio series, and
Hidalgo,
Lyford,
Raymondville, and
Willacy series
which occur in the adjacent uplands. Hidalgo, Lyford,
Raymondville, and Willacy soils have a mollic epipedon less than
20 inches thick; in addition, Raymondville soils have more than 35 percent clay in their control sections.
DRAINAGE AND PERMEABILITY: Moderately well drained; slow to
medium runoff; moderate permeability. In irrigated areas a water table may occur at depths of 3 to 8 feet during the spring and
fall. After cyclonic storms or periods of extremely heavy
rainfall the soils may pond or flood for short periods.
USE AND VEGETATION: Used mostly for irrigated cropland. Main
crops are cotton, grain sorghum, citrus, and winter vegetables. Native grasses consist of fourflower trichloris, plains
bristlegrass, Arizona cottontop, windmillgrass, whorled dropseed,
and threeawn. Woody vegetation is mesquite trees and other thorny brush.
DISTRIBUTION AND EXTENT: Eastern portion of the Rio Grande Plain
of Texas, and probably in Mexico. The series is of moderate
extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Cameron County, Texas; 1974.
REMARKS: These soils were formerly included with the Ramadero series.