LOCATION RAHM IN+KYEstablished Series
The Rahm series consists of very deep, somewhat poorly drained, slowly permeable soils formed in silty alluvium on flood plains and flood-plain steps. Slopes range from 0 to 2 percent. Mean annual precipitation is about 42 inches and the mean annual temperature is about 55 degrees F.
TAXONOMIC CLASS: Fine-silty, mixed, active, nonacid, mesic Fluvaquentic Endoaquepts
TYPICAL PEDON: Rahm silt loam in a nearly level area in a cultivated field. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 8 inches; dark grayish brown (10YR 4/2) silt loam, light brownish gray (10YR 6/2) dry; moderate fine and medium granular structure; friable; dark yellowish brown (10YR 4/4) masses of iron accumulation in the matrix; neutral; abrupt smooth boundary. (6 to 10 inches thick)
Bg--8 to 24 inches; grayish brown (10YR 5/2) silt loam; weak medium and coarse subangular blocky structure; friable; common faint light brownish gray (10YR 6/2) clay depletions on faces of peds; many fine distinct yellowish brown (10YR 5/6 and 10YR 5/8) masses of iron accumulation in the matrix; neutral; clear smooth boundary. (12 to 28 inches thick)
2Btgb--24 to 45 inches; light brownish gray (10YR 6/2) silty clay loam; weak coarse prismatic structure parting to moderate medium and coarse subangular blocky; friable; few distinct light brownish gray (10YR 6/2) clay films on faces of peds; common distinct light brownish gray (10YR 6/2) clay depletions on faces of peds and in pores; many fine prominent strong brown (7.5YR 5/6) masses of iron accumulation in the matrix; moderately acid; gradual smooth boundary.
2Btb--45 to 51 inches; yellowish brown (10YR 5/6) and grayish brown (10YR 5/2) silty clay loam; moderate coarse prismatic structure parting to weak and moderate medium subangular blocky; firm; many distinct light brownish gray (10YR 6/2) clay films on faces of peds; many distinct light brownish gray (10YR 6/2) clay depletions on faces of peds; many fine very dark brown (10YR 2/2) iron and manganese concretions; strongly acid; gradual smooth boundary. (The combined thickness of the 2Btgb and 2Btb horizons is 20 to 44 inches)
2C--51 to 80 inches; brown (7.5YR 4/4) and light brownish gray (10YR 6/2) silty clay loam; massive; firm; strongly acid.
TYPE LOCATION: Spencer County, Indiana; about 1 mile west and 3 miles south of Rockport; 800 feet north and 110 feet west of the southeast corner of sec. 9, T. 8 S., R. 6 W.
RANGE IN CHARACTERISTICS: Thickness of the overwash material (Ap and Bg horizons) ranges from 20 to 36 inches. The particle-size control section ranges from 24 to 34 percent clay. Depth to the base of soil development ranges from 40 to 80 inches. The Ap and Bg horizons are neutral or slightly acid and the 2Bb, 2Bgb, and 2C horizons range from moderately acid to very strongly acid. This soil has an irregular decrease in organic carbon with depth and/or has at least 0.2 percent organic carbon at a depth of 50 inches or below.
The Ap horizon has hue of 10YR, value of 4 or 5, and chroma of 2 to 4. Texture is silt loam or silty clay loam.
The Bg horizon has hue of 10YR or 2.5Y, value of 4 or 5, and chroma of 1 to 4 with redox accumulations and depletions. Texture is silty clay loam or silt loam.
The 2Btgb, 2Btb or 2Bgb horizon has hue of 7.5YR, 10YR, or 2.5Y, value of 4 to 6, and chroma of 2 to 6. Texture is silty clay loam or silty clay.
The 2C horizon has hue of 10YR or 7.5YR, value of 4 to 6, and chroma of 2 to 6 with redox accumulations or depletions. Texture is silty clay loam or silty clay, and includes thin strata of silt loam or loam.
COMPETING SERIES: These are the Melvin, Stanhope and Wayland series. These soils do not have buried acid horizons within depths of 40 inches.
GEOGRAPHIC SETTING: Rahm soils are on slightly concave parts of flood plains and flood-plain steps along the Ohio River and its tributaries. Slopes range from 0 to 2 percent. These soils formed in neutral or slightly acid alluvium 20 to 36 inches thick and buried soils formed in older acid alluvial sediments. Mean annual precipitation is 35 to 45 inches and mean annual temperature ranges from 52 to 57 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ginat, Hatfield, Huntington, Lindside, McAdoo, Millstone, Newark, Nolin, Sciotoville, Weinbach, Wheeling and Woodmere soils. The Rahm series is in a drainage sequence with the moderately well drained Woodmere soils. The well drained Huntington, McAdoo, and Nolin soils, the moderately well drained Lindside, and somewhat poorly drained Newark soils are on nearby, lower lying flood plains. The well drained Millstone, Wheeling, moderately well drained Sciotoville, and somewhat poorly drained Hatfield and Weinbach soils are on stream terraces.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained. Permeability is slow. The potential for surafce water runoff is low. In drained areas, depth to an intermittent apparent high water table is at 0.5 to 2.0 feet from December through April in most years. This soil is subject to rare to frequent periods of flooding.
USE AND VEGETATION: The soil is mainly used to grow corn and soybeans. Some areas are in woodland. Native vegetation is mixed hardwood forest.
DISTRIBUTION AND EXTENT: Southern Indiana. The series is of small extent, and mainly in MLRA's 115 and 120.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Vanderburgh County, Indiana, 1939.
REMARKS: Diagnostic horizons and features recognized in this pedon are: 1) Ochric epipedon: the zone from 0 to 8 inches; 2) Cambic horizon: the zone from 8 to 51 inches (Bg, 2Bbg1, 2Bb2); 3) Redoximorphic features: from 0 to 80 inches (Ap, Bg, 2Bgb1, 2Bb2, 2C); 4) Buried soil: the zone from 24 to 51 inches (2Bgb1, 2Bb2).
This soil was reclassified (11/2001) from Aeric Fluvaquents to Fluvaquentic Endoaquepts based on the Eighth Edition of the "Keys to Soil Taxonomy" and the presence of a cambic horizon. The criteria for an "aeric" subgroup will be maintained as series differentia.
Additional data: Lab data available for this series: Agricultural Experiment Station, Purdue University, Station Bulletin No. 274, File No. JF7804; and S94IN123-012 at the National Soil Survey Center, Lincoln, NE.