LOCATION GRULLA TXEstablished Series
TAXONOMIC CLASS: Fine, mixed, active, calcareous, hyperthermic Vertic Fluvaquents
TYPICAL PEDON: Grulla clay--cropland.
(Colors are for dry soil unless otherwise stated.)
Ap--0 to 7 inches; grayish brown (10YR 5/2) clay, dark
grayish brown (10YR 4/2) moist; weak angular blocky structure; the upper 1/2 inch is one unit of value higher and consists of recent waterlain sediments of clay texture; extremely hard, very firm;
few earthworm casts; few roots; calcareous; moderately alkaline; clear smooth boundary. (5 to 8 inches thick)
C1--7 to 30 inches; light brownish gray (2.5Y 6/2) clay,
grayish brown (2.5Y 5/2) moist; many coarse faint mottles of dark grayish brown (10YR 4/2) moist and many coarse distinct mottles of reddish brown (5YR 4/4) moist, on the outside of some of the clay fragments; the reddish mottles which decrease in number and size
with depth, do not penetrate the fragments; the fragments are of variable size but are mainly about 2 inches across the axis; the interfaces are dull and not shiny; distinct horizontal cleavage planes; very hard, very firm, sticky and plastic; very few pores
in the clay fragments; contains few remnants of leaves on the interfaces; calcareous; moderately alkaline; abrupt smooth
boundary. (10 to 36 inches thick)
Ab--30 to 36 inches; grayish brown (2.5Y 5/2) clay, dark
grayish brown (2.5Y 4/2) moist; few fine yellowish brown mottles; weak angular blocky structure; same consistence as horizon above; calcareous; moderatley alkaline; clear smooth boundary. (0 to 10 inches thick)
C2--36 to 62 inches; light brownish gray (10YR 6/2) clay, grayish brown (10YR 5/2) moist; many distinct fine mottles of yellowish brown along interfaces of fragments; massive; fine
bedding planes are evident; same consistence as horizons above; calcareous; moderately alkaline.
TYPE LOCATION: Cameron County, Texas; 8.0 miles south 10 degrees west of La Feria; in a cultivated field 100 feet west of International Boundary and Water Commission Levee which point is
0.7 miles south and 0.6 mile east via levee with its junction with county road. Junction with county road is 1.6 miles south of U.
S. Highway 281.
RANGE IN CHARACTERISTICS: These soils, when dry, have cracks 1 to
10 cm wide that reach to a depth of at least 50 cm from the
surface. Soil salinity ranges from none to moderately affected.
The Ap or surface layer is grayish brown (10YR 5/2; 2.5Y 5/2),
light brownish gray (10YR 6/2; 2.5Y 6/2), or pale brown (10YR
6/3). In pedons with moist values less than 3.5 the layer is less than 25 cm thick. Most pedons contain recent sediments, and the surface layer is clay loam, silty clay, or clay.
The C horizon is light brownish gray (10YR 6/2; 2.5Y 6/2), or
light gray (10YR 7/2) with few to common yellowish and brownish mottles. The 10 to 40 inch control section is clay or silty clay with clay content ranging from 45 to 60 percent. Bedding planes
are few to common. Loamy strata 1 to 2 inches thick occur at
depths below 40 inches in some pedons.
COMPETING SERIES: There are no competing series in the same
family. Series in similar families include the
Aransas, Flamingo,
Harlingen, Hialeah,
Ijam, and
Matamoros series. Aransas soils
have color values of the A horizons less than 3.5 when moist. Harlingen soils have intersecting slickensides. Ijam soils have
mean annual soil temperatures less than 72 degrees F. Flamingo
and Hialeah soils have carbonatic mineralogy. Matamoros soils
lack mottles or matrix colors that are due to wetness.
GEOGRAPHIC SETTING: Grulla soils occupy slightly depressed to
nearly level areas in active flood plains that overflow about
twice in 5 years and in old partially filled resacas in inactive stream channels along major streams. These soils formed in clayey alluvial sediments several feet thick. The climate is
subtropical. Annual precipitation ranges from about 17 to 30
inches, mean annual air temperature is 71 degrees to 74 degrees
F., and the Thornthwaite annual P-E index is about 22 to 34.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the competing
Matamoros series and the
Camargo and
Rio Grande series which occur
in the same active flood plains. Camargo and Rio Grande soils
have a 10 to 40 inch control section with less than 35 percent
clay.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; very slow
runoff or ponded; very slow permeability. Unless artifically drained, water remains on the surface for several weeks after
large rains. The soils are usually saturated at some season along during the year, usually during the fall or winter months.
USE AND VEGETATION: Mostly for irrigated cropland, some
nonirrigated cropland and range. Crops are cotton, grain sorghum, and vegetables. Native vegetation consists of mesquite, huisache, retama, sienna bush, sedges, buffalograss, and trichloris grass.
DISTRIBUTION AND EXTENT: Occurs in the southern part of the Rio Grande Plain of Texas along the Rio Grande and major tributaries. The series is of moderate extent consisting of an estimated 25,000 acres.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Cameron County, Texas; 1970.
REMARKS: These soils have been included in the Harlingen series
and considered in the Alluvial and Grumusol great soil group.