Established Series


The Matagorda series consists of deep, somewhat poorly drained, very slowly permeable soils formed in loamy and clayey marine sediments. These soils are on nearly level to gently sloping coastal terraces. Slopes range from 0 to 2 percent.

TAXONOMIC CLASS: Fine, mixed, active, hyperthermic Typic Natraqualfs

TYPICAL PEDON: Matagorda very fine sandy loam - rangeland.
(Colors are for moist soil unless otherwise stated.)

A--0 to 5 inches; dark grayish brown (10YR 4/2) very fine sandy loam, light brownish gray (10YR 6/2) dry; massive; hard, friable; few fine roots; few fine pores; neutral; abrupt wavy boundary. (2 to 6 inches thick)

E--5 to 14 inches; light brownish gray (10YR 6/2) very fine sandy loam, light gray (10YR 7/2) dry; massive; hard, friable; few fine roots; few fine pores; abrupt wavy boundary. (1 to 10 inches thick)

Btg1--14 to 22 inches; yellowish brown (10YR 5/4) clay loam, light yellowish brown (10YR 6/4) dry, ped exteriors are black (10YR 2/1), very dark gray (10YR 3/1) and dark gray (10YR 4/1); moderate coarse columnar structure parting to moderate medium angular blocky; 1/4 inch cap of grayish brown (10YR 5/2) loam on columns; very hard, firm; roots are flattened slong faces of peds; common clay films; mildly alkaline; gradual wavy boundary. (6 to 14 inches thick)

Btg2--22 to 31 inches; olive yellow (2.5YR 6/6) clay, yellow (2.5YR 7/6) dry; few faint light olive brown mottles; moderate coarse angular blocky structure; very hard, firm; few fine roots; peds have gray (10YR 5/1) coatings; common clay films; few fine black concretions; moderately alkaline; gradual smooth boundary. (8 to 25 inches thick)

BC--31 to 47 inches; light yellowish brown (2.5YR 6/4) sandy clay loam, pale yellow (2.5YR 7/4) dry; few fine distinct reddish yellow (7.5YR 6/6) mottles; weak coarse blocky structure; very hard, firm; few fine roots; few clay films; common fine black concretions; few thin vertical streaks of light gray fine sand; moderately alkaline; gradual wavy boundary. (10 to 20 inches thick)

C--47 to 76 inches; light gray (2.5Y 7/2) sandy clay loam, white (2.5Y 8/2) dry; few fine and medium prominent reddish yellow (7.5YR 6/6) mottles; massive; very hard, firm, few thin vertical streaks of fine sand; moderately alkaline.

TYPE LOCATION: Calhoun County, Texas; in rangeland about 13 miles southeast of Port Lavaca near Indianola; 7.3 miles southeast of intersection of State Highways 238 and 316; 1.3 miles southeast on paved road toward Indianola; 0.75 mile south on road to cemetery; 0.67 mile west on ranch road; 100 feet north of road.

RANGE IN CHARACTERISTICS: Solum thickness ranges from 35 to 60 inches.

The A horizon is dark grayish brown (10YR 4/2), grayish brown (10YR 5/2), light brownish gray (10YR 6/2), gray (10YR 7/2), or light brownish gray (10YR 6/2). The E horizon is gray (10YR 5/1), light gray (10YR 6/1, 7/1, 7/2), or light brownish gray (10YR 6/2). The A and E horizons are very fine sandy loam or fine sandy loam. Within pedons, thickness of the epipedon ranges from 3 to 19 inches within horizontal distances of 3 feet; ranges of average thickness over any pedon are those given in the pedon description. It is slightly acid or neutral.

Interiors of the peds of the Btg horizon are yellowish brown (10YR 5/4, 5/6), light yellowish brown (10YR 6/4; 2.5Y 6/4), brownish yellow (10YR 6/6), olive yellow (2.5Y 6/6), light olive brown (2.5Y 5/4, 5/6), strong brown (7.5YR 5/6), brown (10YR 5/3; 7.5YR 5/2, 5/4), grayish brown (10YR 5/2; 2.5Y 5/2), or light brownish gray (10YR 6/2; 2.5Y 6/2). Fine and medium mottles are in shades of gray, brown, yellow, and red. Ped Exteriors of the Btg1 horizon are black (10YR 2/1), very dark gray (10YR 3/1), and dark gray (10YR 4/1). Ped exteriors of the Btg2 horizon are dark gray (10YR 4/1), gray (10YR 5/1), or light gray (10YR 6/1). The Btg horizon is sandy clay, clay, or clay loam. Clay content ranges from 35 to 50 percent in the upper 20 inches of the Bt horizon. The Bt horizon ranges from slightly acid through moderately alkaline; exchangeable sodium ranges from 15 to 30 percent. Salinity ranges from free to moderately affected. The BC horizon has the same color range as the Btg, except peds are not coated. It is sandy clay loam, clay loam, sandy clay, or clay.

The C horizon is light gray (10YR 7/1, 7/2; 2.5Y 7/2), light brownish gray (10YR 6/2; 2.5Y 6/2), pinkish gray (7.5YR 6/2), light brown (7.5YR 6/4), strong brown (7.5YR 5/6), pale brown (10YR 6/3), light yellowish brown (10YR 6/4; 2.5Y 6/4), brownish yellow (10YR 6/6), or olive yellow (2.5Y 6/6). It is clay, sandy clay, clay loam, or sandy clay loam. Calcium carbonate concretions are in the C horizon of some pedons.

COMPETING SERIES: These include the Jarron series and the similar Lindsey, Livia, Verdun, and Willamar series. Jarron soils have higher salinity and a different native plant community. In addition, Jarron soils are ponded for longer periods. Lindsey, and Verdun soils have mean annual soil temperatures of less than 72 degrees F. Livia soils have montmorillonitic mineralogy and a higher silt content. Willamar soils have less than 35 percent clay in the Bt horizon.

GEOGRAPHIC SETTING: Matagorda soils are in level to gently undulating landscapes within 10 feet of sea level near the gulf coast. Slopes are dominantly less than 1 percent, but range up to 2 percent. The soil formed in clayey and loamy sediments. The average annual precipitation is 30 to 40 inches and average annual temperature is 70 to 73 degrees F. The annual Thornthwaite P-E index ranges from 40 to 64.

GEOGRAPHICALLY ASSOCIATED SOILS: These include the Livia soils of the competing series as well as the Rahal and Veston series. Rahal soils have sandy epipedons thicker than 20 inches and lack natric horizons. Veston soils lack argillic horizons.

DRAINAGE AND PERMEABILITY: Somewhat poorly drained; runoff is slow; permeability is very slow. Storm tides cover the soils with sea water. The soil is saturated within 24 inches of the surface during the cool season.

USE AND VEGETATION: Used for rangeland and for growning rice. Native vegetation includes gulf cordgrass, seashore saltgrass, knotroot bristlegrass, marshhay cordgrass, low panicums and bushy sea-oxeye. A few small mesquite trees are in places.

DISTRIBUTION AND EXTENT: Central part of the gulf coast of Texas. The series is of moderate extent.


SERIES ESTABLISHED: Calhoun County, Texas; 1972.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon - 0 to 14 inches.

Albic horizon - 5 to 14 inches.

Natric horizon - 14 to 31 inches.

ADDITIONAL DATA: Soil Survey Laboratory, Lincoln, Nebraska. Lab. Nos. 70L147-70L152 and 70L153-70L158.

National Cooperative Soil Survey
U. S. A.