LOCATION MAHAN LAEstablished Series
TAXONOMIC CLASS: Fine, kaolinitic, thermic Typic Hapludults
TYPICAL PEDON: Mahan fine sandy loam, on a convex 3 percent slope, in clear cut area.
(Colors are for moist soil unless otherwise stated)
Ap--0 to 5 inches; yellowish red (5YR 4/6) fine sandy loam, weak fine subangular blocky structure; friable; many medium and fine roots; common coarse roots; about 12 percent by volume ironstone gravel; strongly acid; clear smooth boundary. (3 to 8 inches thick)
Btl--5 to 21 inches; red (2.5YR 5/6) sandy clay; moderate coarse subangular blocky structure; friable; common medium and fine roots; common fine tubular pores; about 2 percent by volume ironstone gravel; many thin continuous clay films on surfaces of peds; strongly acid; clear wavy boundary.
Bt2--21 to 35 inches; red (2.5YR 5/8) sandy clay loam; common medium faint yellowish red (5YR 4/6) mottles; moderate medium subangular blocky structure; friable; few medium and common fine roots; common medium and fine tubular pores; about 3 percent by volume ironstone gravel; common thin discontinuous clay films on surfaces of peds; strongly acid; clear smooth boundary.
Bt3--35 to 50 inches; red (2.5YR 4/6) sandy clay loam; weak medium subangular blocky structure; friable; few fine roots; common thick discontinuous clay films on surfaces of peds; about 7 percent by volume ironstone gravel; few fragments of ironstone that are 3 to 10 inches across the long axis; many white (lOYR 8/1) platy clay bodies up to 1 inch in diameter oriented along relict bedding planes; strongly acid; clear smooth boundary. (Combined thickness of Bt horizons is 20 to 50 inches)
BC--50 to 59 inches; red (2.5YR 5/6) sandy clay loam; many coarse distinct yellowish red (5YR 5/8) mottles; weak medium blocky structure; friable; few slightly brittle peds; few fine roots; about 9 percent by volume ironstone gravel; few fragments of ironstone are 3 to 10 inches across the long axis; few thin discontinuous clay films on surfaces of peds; common fine white bodies of clay; common fine pockets of strong brown (7.5YR 5/6) sandy loam; strongly acid; clear smooth boundary. (0 to 15 inches thick)
C--59 to 82 inches; stratified yellowish red (5YR 5/8) sandy clay loam and yellowish brown (lOYR 5/8) sandy loam; massive; friable; common prominent white (lOYR 8/1) clay bodies, maximum thickness of alternating layers is 6 inches; very strongly acid.
TYPE LOCATION: Claiborne Parish, Louisiana; about 7.25 miles west northwest of Athens; 875 feet north and 2,620 feet east of the southwest corner of sec. 1, T. 19 N., R. 8 W.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 40 to more than 60 inches. Gravel-sized ironstone fragments make up from 1 to 40 percent of the volume of the A horizon and from 0 to 15 percent of the Bt, BC, and C horizons. A few coarse fragments of ironstone 3 to 20 inches across are in the A, Bt, and BC horizons of most pedons. The particle size control section is 35 to 60 percent clay.
The A horizon has hue of 10YR, 7.5YR, or 5YR, value of 3 to 5, and chroma of 2 to 6. It is sandy loam, fine sandy loam, or their gravelly counterparts. Reaction is strongly acid or moderately acid, except where limed.
The E horizon, where present, has hue of 7.5YR or 5YR, value of 4 or 5, and chroma of 4 to 6. It is loamy fine sand, sandy loam, or fine sandy loam. Reaction is strongly acid or moderately acid.
The Bt horizon has hue of 5YR, 2.5YR, or 10R, value of 4 or 5, and chroma of 6 or 8. It is clay, sandy clay loam, sandy clay, clay loam, or loam. Silt content of the Bt horizon is less than 30 percent. Mottles in shades of brown and gray may be in lower parts of the Bt horizon in some pedons. Reaction ranges from very strongly acid to moderately acid.
The BC horizon has hue of 5YR, 2.5YR, or lOR, value of 4 or 5, and chroma of 6 or 8. Mottles in shades of brown and gray range from none to common. Texture is sandy loam, fine sandy loam, clay loam, sandy clay loam, or sandy clay. Reaction ranges from very strongly acid to moderately acid.
The C horizon typically is stratified sandy clay loam, sandy loam, or clay loam. The loamy materials are reddish or brownish. Small pockets and horizontal seams of whitish clay (kaolin) range from none to many. Thin to thick layers of weakly cemented sandstone are in some pedons. Reaction ranges from very strongly acid to moderately acid.
COMPETING SERIES: Soils in the same family are Appling, Aragon, Cecil, Chestatee, Georgeville, Herndon, Hulett, Kolmoki, Madison, Mayodan, Nankin, Pacolet, Spotsylvania, and Wedower. Similar competing series include Alto, Bub, Cuthbert, Kirvin, Luverne, Meth, Nacogdoches, Redsprings, Sacul, Sweatman, and Trawick. The Appling, Cecil, Chestatee, Georgeville, Herndon, Hulett, Madison, Mayodan, Palolet, Spotsylvania, and Wedowee soils formed in acid residuum on the Piedmont uplands and are underlain by residium, saprolite, or crystalline rock. The Alto, Bub, Meth, Nacogdoches, Redsprings, and Trawick soils have a base saturation of more than 35 percent within 50 inches below the top of the argillic horizon. The Aragon soils have chert fragments throughout. The Cuthbert, Kirvin, Luverne, Sacul, and Sweatman soils have mixed mineralogy and do not have a high content of siderite. The Kolomoki soils are on stream terraces and formed in fluvial sediments that contain an appreciable amount of silt. The Nankin soils are less red than the Mahan soils, and they do not contain fragments of ironstone.
GEOGRAPHIC SETTING: Mahan soils are on gently sloping to moderately sloping uplands. Slopes range from l to 15 percent. The soil formed in iron-rich, clayey, marine sediments that are moderately high in siderite. The typifying pedon is forming in sediments of the Cockfield or Cook Mountain Formation, Claiborne Group, and Eocene Series. The annual temperature is 65 degrees F., and the average rainfall is 50 inches near the type location. The summer moisture deficit is about 4 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Sacul soils and the Betis, Bowie, Briley, Ruston, and Woodtell soils. The Betis and Briley soils are in similar positions, have thick sandy epipedons, and loamy particle size control sections. The Bowie and Ruston soils are in similar positions and are fine-loamy. The Woodtell soils are on lower side slopes and have a base saturation that is greater then 35 percent at a depth of 50 inches below the top of the argillic horizon.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderate and runoff is medium to rapid.
USE AND VEGETATION: Most areas are in woodland. Forest vegetation includes loblolly and shortleaf pines, hickory, southern red oak, sweetgum, and other hardwood trees.
DISTRIBUTION AND EXTENT: Louisiana and possibly east Texas. The series is of small extent.
MLRA OFFICE RESPONSIBLE: Little Rock, Arkansas
SERIES ESTABLISHED: Claiborne Parish, Louisiana; 1986.
REMARKS: The Mahan soils were formerly included with the Kirvin series. The series name was taken from that of a small community in Claiborne Parish, Louisiana.
ADDITIONAL DATA: Laboratory data for the typifying pedon were obtained from the Louisiana Agricultural Experiment Station, sample S83LA027-5(1-8).