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soil profile


LOCATION                 TN+KY MS

Established Series
Rev. JLN

The Lax series consists of very deep, moderately well drained soils on uplands. The soil formed in a silty mantle over gravelly alluvium and residuum of limestone. The soil has a dense fragipan in the lower subsoil. Slopes range from 2 to 20 percent.

TAXONOMIC CLASS: Fine-silty, mixed, semi-active, thermic Typic Fragiudults

TYPICAL PEDON: Lax silt loam--forested. (Colors are for moist soil unless otherwise stated.)

A--0 to 10 inches; dark yellowish brown (10YR 4/4) silt loam; weak fine granular structure; very friable; common fine roots; strongly acid; clear smooth boundary. (3 to 10 inches thick)

Bt1--10 to 20 inches; yellowish brown (10YR 5/6) silty clay loam; moderate medium subangular blocky structure; friable; few fine and medium roots; few distinct yellowish brown (10YR 5/4) clay films on faces of peds; very strongly acid; clear smooth boundary.

Bt2--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 5/4) clay films on faces of peds; few medium distinct strong brown (7.5YR 5/6) masses as iron accumulations; few medium distinct pale brown (10YR 6/3) iron depletions on ped faces and interiors; very strongly acid; clear wavy boundary. (Combined thickness of the Bt horizon ranges from 8 to 33 inches thick)

2Btx--24 to 36 inches; brownish yellow (10YR 6/6) extremely gravelly silty clay loam; weak very coarse and extremely coarse prismatic structure parting to weak fine subangular blocky; extremely firm; few very fine roots in vertical seams; common prominent yellowish brown (10YR 5/4) and pale brown (10YR 6/3) clay films on prism faces and lining vertical and horizontal seams; common fine prominent very pale brown (10YR 7/4) and light brownish gray (10YR 6/2) silt coatings on prism faces and as vertical seams; approximately 72 percent by volume fragments of gravel; brittle in 90 percent of the mass; very strongly acid; gradual smooth boundary. (6 to greater than 30 inches thick)

3Bt--36 to 60 inches; yellowish red (5YR 5/8) very gravelly silty clay; common medium prominent strong brown (7.5YR 5/6) and common fine prominent grayish brown (10YR 5/2) mottles; moderate medium subangular blocky structure; firm; common distinct yellowish red (5YR 4/6) clay films on faces of peds and coating fragments; about 40 percent by volume angular fragments of chert; very strongly acid.

TYPE LOCATION: Dickson County, Tennessee; 1.4 miles southwest of Tennessee City, 1.4 miles southwest of the intersection of US 70 and McElhiney Road, 5.1 miles northeast of the intersection of East Humphreys County Line Road and County Line Road, 0.9 mile northeast of intersection of McElhiney Road and Luffman Road, 50 feet north of McElhiney Road in woods. USGS Quad: Tennessee City; Lat: 36 degrees/ 04 minutes/ 52.29 seconds North; Long: 87 degrees/ 32 minutes/ 7.60 minutes.

RANGE IN CHARACTERISTICS: Solumn thickness is 40 to 60 inches or more. Depth to bedrock is greater than 5 feet. Depth to fragipan ranges from 18 to 36 inches. Reaction of the soil is strongly acid or very strongly acid except where lime has been added. Coarse fragments range from 0 to 15 percent in the A, Bt, and Btx horizons, and from 15 to 80 percent in the 2Btx and the 3Bt horizons.

The Ap and A horizons have hue of 10YR, value of 4 or 5, and chroma of 2 to 4. The E horizon, where present, has hue of 10YR, value of 5 or 6, and chroma of 2 to 4. Texture of the A and E horizons is silt loam.

The Bt horizon has hue of 10YR or 7.5YR, value of 4 or 5, and chroma of 4 or 6. Some pedons have redoximorphic features in shades of yellow, brown, and gray in the lower part just above the fragipan. Texture is silty clay loam or silt loam.

The Btx, where present, and 2Btx horizon have hue of 7.5YR or 10YR, value of 5 or 6, and chroma of 4 or 6. Common to many redoximorphic features are in shades of gray, yellow, brown, and red. Texture is variable. The fine-earth fraction is silt loam or silty clay loam.

The 3Bt, or 2Cx horizon if present, has hue of 7.5YR to 2.5YR, value of 4 or 5, and chroma of 4 to 8, with few to common mottles in shades of gray, yellow, brown, and red. Texture in the fine-earth fraction is silty clay loam, silty clay or clay.


There are no other series in the same family.

Series in similar families are the CaneDicksonOraPadenProvidenceSango, and Savannah series. All of these soils have less than 15 percent coarse fragments in the fragipan. Cane, Ora, and Savannah soils are fine-loamy and Providence soils are Alfisols.

GEOGRAPHIC SETTING: Lax soils are on nearly level to rolling uplands. Slopes range from 2 to 20 percent. The soils formed in a silty mantle 2 to 3 feet thick and in underlying Coastal Plain and riverine gravelly alluvium and residuum of limestone. Near the type location the mean annual air temperature is 58.2 degrees F., and the mean annual precipitation is 53.9 inches.


DicksonPadenProvidenceSangoSaffellHawthorneBodineBrandonGuthrieMountviewPickwick, and Taft series. Saffell, Bodine, Brandon, Mountview, and Pickwick soils are well drained and do not have fragipans. Hawthorne soils are somewhat excessively drained and are loamy-skeletal. Guthrie soils have dominant chroma of 2 or less between the Ap and the fragipan. Taft soils have redoximorphic depletions in the upper 10 inches of the B horizon.

DRAINAGE AND PERMEABILITY: Moderately well drained; low to medium runoff; moderate permeability above the fragipan and very slow permeability in the fragipan.

USE AND VEGETATION: About one-half of the acreage is cleared and used for growing corn, tobacco, small grains, soybeans, hay, and pasture. The remainder is in mixed hardwood forest consisting chiefly of oaks, hickories, and beech.

DISTRIBUTION AND EXTENT: Western part of Kentucky, the Highland Rim in Tennessee, northeastern Mississippi, and southeastern Missouri. The series is of moderate extent.


SERIES ESTABLISHED: Benton County, Tennessee; 1944.

REMARKS: Addition of Btx to Range in Characteristics, based upon documentation of a thin fragipan horizon formed in silty mantle above discontinuity. JCJ 9/2007

Diagnostic horizons and features in this pedon are:

Ochric epipedon - 0-10 inches

Argillic horizon - 10-60 inches

Fragipan - 24-36 inches

Lithologic Discontinuities - 24-48 inches, and 48-60 inches (2Btx and 3Bt)

National Cooperative Soil Survey