Established Series


The Pitzer series consists of soils that are very shallow or shallow to a petrocalcic horizon. They are well drained and moderately permeable soils that formed in calcareous, loamy, gravelly materials. These soils are on gently sloping to strongly sloping uplands. Slopes range from 1 to 12 percent.

TAXONOMIC CLASS: Loamy, mixed, superactive, thermic, shallow Petrocalcic Calciustolls

TYPICAL PEDON: Pitzer gravelly loam--rangeland. (Colors are for dry soil unless otherwise stated.)

A--0 to 6 inches; dark grayish brown (10YR 4/2) gravelly loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; slightly hard, friable; about 20 percent caliche pebbles; common siliceous pebbles; strongly effervescent; moderately alkaline; abrupt smooth boundary. (4 to 14 inches thick)

Bkm1--6 to 11 inches; pinkish white (7.5YR 8/2) indurated caliche, fractured plates 5 to 24 inches across and 1 to 4 inches thick; hardness about 3 on Moh's scale; common siliceous pebbles embedded in matrix; gradual smooth boundary. (2 to 12 inches thick)

Bkm2--11 to 20 inches; pinkish white (7.5YR 8/2) indurated massive caliche; hardness about 2 on Moh's scale; common siliceous pebbles embedded in matrix; gradual wavy boundary. (0 to 20 inches thick)

BCk--20 to 76 inches; reddish yellow (5YR 6/6) very gravelly sandy loam, yellowish red (5YR 5/6) moist; 50 percent siliceous and limestone pebbles in a weakly cemented porous mass; pebbles coated with secondary calcium carbonate; violently effervescent; moderately alkaline; clear smooth boundary. (30 to 80 inches thick)

2Cd--76 to 80 inches red (2.5YR 5/6) soft weathered shale that has clay texture, red (2.5YR 5/6) moist; a few splotches and strata of greenish gray; violently effervescent; moderately alkaline.

TYPE LOCATION: Taylor County, Texas; 3.2 miles south of the intersection of Farm Road 707 and Interstate 20 in Tye, Texas, on Farm Road 707, then 0.9 mile west on paved county road and 225 feet south near gravel pit.

RANGE IN CHARACTERISTICS: Solum thickness is 4 to 20 inches. Depth to layers containing more than 35 percent coarse fragments of siliceous and limestone pebbles ranges from 10 to 36 inches.

The A horizon has hue of 5YR to 10YR, value of 4 or 5, and chroma of 2 or 3. Texture is loam, clay loam, gravelly loam, or gravelly clay loam; coarse fragments of caliche and siliceous pebbles comprise 5 to 30 percent.

The Bkm horizon is platy or nodular in the upper portion, is massive in the lower portion, and is 4 to 24 inches thick. Hardness on Moh's scale is 2 to 3.5.

The BCk horizon has 35 to 80 percent by volume of siliceous and limestone pebbles that are coated with secondary calcium carbonate. Texture of the fine earth fraction is loam, sandy loam, or sandy clay loam. This horizon is weakly consolidated or weakly cemented and in some pedons contains strata with varying percentages of coarse fragments.

Depth to a 2Cd horizon of weathered shale or a 2R horizon of limestone, when either are present, is 40 to more than 80 inches.

COMPETING SERIES: These include the Carbine (AZ), Espy (TX), Kimbrough, and Queeny (TX) series. Similar soils include the Cho, Kavett, and Mereta series. Carbine soils do not have shale or limestone below the petrocalcic horizon. Espy soils have a cambic horizon separating the mollic epipedon from the petrocalcic horizon. Kimbrough soils have an aridic moisture regime, and in addition, do not have gravelly substrata containing siliceous pebbles. Queeny soils are moist for longer periods in the moisture control section. Cho soils do not have layers, within a 40-inch depth, with more than 35 percent coarse fragments of siliceous and limestone pebbles. Kavett, and Mereta soils are clayey, and in addition, do not have gravelly substrata containing siliceous pebbles.

GEOGRAPHIC SETTING: Low hills or knobs in uplands that are presumed to be ancient alluvial terraces (Uvalde Formation) deposited over Permian clayey shale and limestone. Slopes range from 1 to 12 percent. Mean annual precipitation ranges from 20 to 28 inches. Mean annual soil temperature ranges from 60 degrees to 67 degrees F. Frost free days range from 210 to 230 days, and elevation ranges from 1,250 to 2,250 feet. The Thornthwaite P-E indices range from 30 to 40.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Nuvalde, Owens, Tillman, Vernon, and Weymouth series. These soils do not have petrocalcic horizons.

DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderate in the soil material above the slowly permeable petrocalcic horizon. Runoff is medium on 1 to 5 percent slopes, high on 5 to 12 percent slopes.

USE AND VEGETATION: Mostly rangeland or used in mining as a source of gravel. Native vegetation is buffalograsss, sideoats grama, black grama, and catclaw. Stunted mesquite and redberry juniper are on some areas.

DISTRIBUTION AND EXTENT: Rolling Limestone Prairie and the Rolling Plains of Texas. The series is moderately extensive.


SERIES ESTABLISHED: Taylor County, Texas; 1971.

REMARKS: These soils formerly were included in the Kimbrough and Cho series.

Diagnostic horizons and features recognized in this pedon are:

Mollic epipedon - 0 to 6 inches. (A horizon)

Petrocalcic horizon - the Bkm horizons from 6 to 20 inches.

Underlying material - contains more than 35 percent siliceous and limestone fragments.

National Cooperative Soil Survey