LOCATION OMULGA                  OH+WV

Established Series
Rev. GMG-NHM-DHK
12/2021

OMULGA SERIES


The Omulga series consists of very deep, moderately well drained soils formed in loess, colluvium, or old alluvium, and in most areas by underlying lacustrine sediments. These soils are on valley fill terraces from valley fills in abandoned preglacial drainage systems in the Allegheny Plateau. Permeability is moderate above the fragipan and slow in the fragipan. Slopes range from 0 to 15 percent. Mean annual precipitation is about 41 inches, and mean annual temperature is about 53 degrees F near the type location.

TAXONOMIC CLASS: Fine-silty, mixed, active, mesic Oxyaquic Fragiudalfs

TYPICAL PEDON: Omulga silt loam - on a 2 percent convex slope in a cultivated field. (Colors are for moist soils unless otherwise stated.)

Ap--0 to 25 cm (0 to 10 inches); brown (10YR 4/3) silt loam, very pale brown (10YR 7/3) dry; weak medium granular structure; friable; many fine roots; common distinct black (10YR 2/1) iron and manganese concretions; about 1 percent rock fragments; moderately acid; abrupt smooth boundary. (20 to 30 cm thick)

BA--25 to 38 cm (10 to 15 inches); yellowish brown (10YR 5/6) silt loam; weak coarse subangular blocky structure; friable; common fine roots; few distinct yellowish brown (10YR 5/4) clay films on faces of peds; common distinct brownish yellow (10YR 6/6) silt coatings on faces of peds; few fine prominent black (10YR 2/1) iron and manganese concretions; about 1 percent rock fragments; strongly acid; gradual wavy boundary. (0 to 15 cm thick)

Bt1--38 to 51 cm (15 to 20 inches); yellowish brown (10YR 5/6) silty clay loam; moderate medium subangular blocky structure; friable; few fine roots; few faint yellowish brown (10YR 5/6) clay films on faces of peds; common distinct light yellowish brown (10YR 6/4) silt coatings on faces of peds; few fine prominent black (10YR 2/1) iron and manganese concretions; about 1 percent rock fragments; very strongly acid; clear smooth boundary.

Bt2--51 to 61 cm (20 to 24 inches); yellowish brown (10YR 5/6) silty clay loam; moderate medium subangular blocky structure; friable; few fine roots; few faint yellowish brown (10YR 5/6) clay films on faces of peds; many distinct light yellowish brown (10YR 6/4) silt coatings on faces of peds; few fine prominent light brownish gray (10YR 6/2) iron depletions; few fine distinct yellowish brown (10YR 5/8) masses with accumulated iron oxide; about 1 percent rock fragments; very strongly acid; clear smooth boundary.

Bt3--61 to 76 cm (24 to 30 inches); yellowish brown (10YR 5/6) silty clay loam; weak coarse subangular blocky structure; firm; few fine roots; many distinct dark yellowish brown (10YR 4/4) clay films on faces of peds; many distinct pale brown (10YR 6/3) silt coatings on faces of peds; many prominent grayish brown (10YR 5/2) clay depletions on vertical faces of peds; few fine distinct yellowish brown (10YR 5/8) masses with accumulated iron oxide; about 2 percent rock fragments; very strongly acid; clear wavy boundary. (Combined thickness of the Bt horizons is 23 to 51 cm)

2Btx--76 to 109 cm (30 to 43 inches); yellowish brown (10YR 5/4) silty clay loam; moderate very coarse prismatic structure parting to weak medium subangular blocky; very firm, brittle; few fine roots; common distinct dark yellowish brown (10YR 4/4) clay films on faces of peds; many distinct grayish brown (10YR 5/2) clay depletions on vertical faces of peds; about 2 percent rock fragments; very strongly acid; clear wavy boundary. (25 to 91 cm thick)

2B't1--109 to 127 cm (43 to 50 inches); yellowish brown (10YR 5/6) silty clay loam; moderate coarse subangular blocky structure; friable; many distinct light yellowish brown (10YR 6/4) clay films on faces of peds; common prominent light brownish gray (2.5Y 6/2) clay depletions on vertical faces of peds; many coarse distinct strong brown (7.5YR 5/8) masses with accumulated iron oxide; about 2 percent rock fragments; very strongly acid; clear wavy boundary.

2B't2--127 to 157 (50 to 62 inches); yellowish brown (10YR 5/6) silty clay; moderate coarse angular blocky structure; firm; common distinct light yellowish brown (10YR 6/4) and common prominent yellowish red (5YR 4/6) clay films on faces of peds; many prominent light brownish gray (2.5Y 6/2) clay depletions on vertical faces of peds; about 1 percent rock fragments; very strongly acid; gradual wavy boundary.

2B't3--157 to 201 cm (62 to 79 inches); yellowish brown (10YR 5/6) clay; weak medium subangular blocky structure; firm; common distinct light yellowish brown (10YR 6/4) and common prominent yellowish red (5YR 4/6) clay films on faces of peds; many prominent light brownish gray (2.5Y 6/2) clay depletions on vertical faces of peds; very strongly acid; gradual wavy boundary. (Combined thickness of the 2B't horizons is 0 to 102 cm)

2C--201 to 216 cm (79 to 85 inches); brown (7.5YR 5/2) clay; massive; very firm; gray (5Y 6/1) very thin horizontal bands in the matrix; very strongly acid.

TYPE LOCATION: Scioto County, Ohio; about 3.5 miles (5.6 Km) north of Muletown in Madison Township, about 1,930 feet (588 m.) west and 890 feet (271 m.) south of the northeast corner, sec. 17, T. 4 N., R. 20 W.; Stockdale Quadrangle; lat. 38 degrees 55 minutes 03.8 seconds N., and long. 82 degrees 52 minutes 26.3 seconds W., NAD 83; UTM Zone 17,1894680 easting and 334210 northing, NAD 83.
RANGE IN CHARACTERISTICS: Thickness of the solum ranges from 115 to 230 cm. Depth to the fragipan ranges from 45 to 90 cm. Volume of rock fragments, generally water-worn gravel, ranges up to 5 percent above the fragipan, up to 10 percent in the Btx, or B't horizons, where present, and up to 15 percent in the 2Btx, 2B't, 2BC, and 2C horizons.

The Ap horizon has hue of 10YR, value of 4 or 5 moist and 6 or 7 dry, and chroma of 2 or 3. Some pedons have an A horizon, 2 to 10 cm (1 to 4 inches) thick, that has value of 2 or 3 and chroma of 1 or 2, and an E horizon, 8 to 20 cm thick, that has value of 5 or 6 and chroma of 3 or 4. The A and E horizons are very strongly acid to moderately acid, but range to neutral where limed.

The Bt horizon has hue of 10YR or 7.5YR, value of 4 or 5, and chroma of 3 to 8. It is silt loam or silty clay loam. It is strongly acid to extremely acid. Some pedons have a Btx horizon that has hue of 10YR or 7.5YR, value of 4 to 6, and chroma of 3 to 6. It is silt loam or silty clay loam. It is strongly acid to extremely acid. In some cases, B't or BC horizons occur and have colors and textures similar to the Btx horizon. These horizons are very strongly acid to moderately acid. Btx horizons extending below a depth of 40 inches may range to clay loam.


The 2Btx horizon has hue of 7.5 YR, 10YR, or 2.5Y, value of 4 to 6, and chroma of 3 to 6. It is silt loam or silty clay loam. It is strongly acid to extremely acid. It is silt loam, silty clay loam, clay loam or loam.

The 2B't, 2BC, and 2C horizons have hue of 7.5YR, 10YR, or 2.5Y; value of 4 to 6; and chroma of 2 to 6. The 2B't horizon is typically silt loam, silty clay loam, clay loam, silty clay or clay. The 2BC and 2C horizons are often stratified and range from sandy loam to clay. They commonly are very strongly acid to moderately acid but range to neutral in thick layers of silty clay and clay.

In pedons that have a 2B horizon at a depth of less than 24 inches, a 3B or 3C horizon commonly is identified at the contact with underlying stratified materials.

COMPETING SERIES: These are the Apalona, Ava, Bedford, Boston, Cincinnati, Fountainville, Grantsburg, Hildebrecht, Hosmer, Lawrenceville, Nicholson, Otwell, Otwood, Solsberry, Weisburg, and Zanesville series. A similar soil is the Monongahela series. Apalona soils have primarily channers that are non-water-worked sandstone and siltstone below the lithologic discontinuity. Ava soils have bisequal soil development. Bedford soils have redder hue and higher clay content in the lower control section. Boston soils typically have limestone bedrock at 50 to 70 inches. Cincinnati soils have mixed coarse fragments from glacial till in the lower part of the solum. Fountainville, Nicholson, Otwood and Weisburg soils formed partly in residuum from bedrock and do not have stratification in the lower part. In addition, Weisburg soils have some coarse fragments of mixed lithology from glacial till. Grantsburg and Hosmer soils formed in loess, do not have stratification in the lower part of the solum, and do not contain coarse fragments. Hildebrecht soils have fragments of chert in the lower part of the solum. Lawrenceville soils have a more mottled fragipan and do not have silty coatings in the upper part of the fragipan. Otwell soils have stratified materials at depths of less than 40 inches and typically are less acid in the B and C horizons. Sollsberry and Zanesville soils contain sandstone channers in the lower solum. Monongahela soils contain more sand in the control section and have a lower base saturation at 30 inches below the top of the fragipan.

GEOGRAPHIC SETTING: Omulga soils are in valley fills in an abandoned preglacial drainage system of the Allegheny Plateau. Slope gradients are 0 to 15 percent. The soils formed in loess, colluvium or old alluvium and in most areas by underlying lacustrine sediments. The loess mantle ranges up to 24 inches in thickness. Mean annual precipitation ranges from about 38 to 43 inches, and mean annual temperature ranges from about 52 to 56 degrees F.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Allegheny, Doles, Gallia, Tygart, Vincent and Wyatt soils. Allegheny, Gallia, Vincent and Wyatt soils are on similar landscape positions. Allegheny and Gallia soils are fine-loamy and Wyatt and Vincent soils are fine. Doles soils are somewhat poorly drained and are on nearly level areas. Tygart soils are nearly level, somewhat poorly drained, and have more clay.

DRAINAGE AND PERMEABILITY: Moderately well drained. The potential for surface runoff is low to high. Permeability is moderate above the fragipan and slow in the fragipan. Water is perched above the fragipan during late winter and spring months.

USE AND VEGETATION: Most areas of this soil are cultivated. Primary crops are corn, soybeans, wheat and hay. Some areas are pastured or wooded. Native vegetation is mixed, deciduous hardwood forest.

DISTRIBUTION AND EXTENT: Southern Ohio and Northwestern West Virginia. The series is of large extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia

SERIES ESTABLISHED: Jackson County, Ohio, 1981.

REMARKS: Series revision in 2009 is based on extensive field studies in Ohio of soils mapped as Captina, Otwell and Omulga. The study resulted in recorrelation of map units in 16 counties.

Diagnostic horizons and features recognized in this pedon are:
ochric epipedon - 0 to 38 cm (Ap and BA horizons);
argillic horizon - 38 to 201 cm (Bt1 through 2B't3 horizons);
fragipan 76 to 109 cm (2Btx horizon);
redoximorphic features 51 to 201 cm;
lithologic discontinuity at a depth of 76 inches (top of 2Btx horizon).

ADDITIONAL DATA: Characterization data from the Ohio State University on SC-10, the typical pedon, is available. Other data from the same source includes AT-6, BT-8, JK-4, JK-13, JK23, MN-15, PK-4, PK-5, PK-6, and PK-7.

Revised: 01/2001-AR, DRM; 07/2007-GMG, NHM, DHK; 11/2009-DHK


National Cooperative Soil Survey
U.S.A.