LOCATION COMUS                   MD+DE PA VA

Established Series
Rev. KK- MJ


The Comus series consists of very deep, well drained soils on floodplains. They formed in alluvium high in mica. Saturated hydraulic conductivity is moderately high to high. Slopes range from 0 to 8 percent. Mean annual temperature is about 50 degrees F. and the mean annual precipitation is about 40 inches.

TAXONOMIC CLASS: Coarse-loamy, mixed, active, mesic Fluventic Dystrudepts

TYPICAL PEDON: Comus silt loam - on a 1 percent slope in a cultivated field. (Colors are for moist soil unless otherwise stated)

Ap-- 0 to 12 inches; brown (10YR 4/3) silt loam; weak fine and medium granular structure; friable, slightly sticky; slightly plastic; many fine and medium roots; moderately acid (limed); clear smooth boundary. (8 to 12 inches thick)

Bw1-- 12 to 18 inches; dark yellowish brown (10YR 4/4) silt loam; weak medium and coarse granular and fine subangular blocky structure; friable, slightly sticky and slightly plastic; common fine roots; very few fine smooth pores; moderately acid; gradual smooth boundary

Bw2-- 18 to 30 inches; brown (7.5YR 4/4) silt loam; weak coarse granular and fine subangular blocky structure; friable, slightly sticky and slightly plastic; few fine roots; many mica flakes; moderately acid; abrupt smooth boundary. (Combined B horizon thickness is 18-28 inches)

2C--30 to 60 inches, strong brown (7.5YR 5/6) gravelly sandy loam; massive, single grain; very friable; non sticky and non plastic; very few fine roots; stratification is evident; 20 percent rounded gravel; 5 percent rounded cobbles; many mica flakes; strongly acid.

TYPE LOCATION: Cecil County, Maryland; on floodplain of Elk Creek, opposite Elkton Water Works.

RANGE IN CHARACTERISTICS: The thickness of the solum ranges from 24 to 40 inches. The depth to bedrock is more than 6 feet. Water worn rock fragments range from 0 to 15 percent in the solum and 0 to 40 percent in the 2C horizon including up to 10 percent cobbles but the weighted average for the particle-size control section is less than 35 percent. The soil ranges from very strongly acid to moderately acid throughout, unless limed.

The A or Ap horizon has hue of 7.5YR or 10YR, value of 3 through 5, and chroma of 1 through 4, with the lowest value and chroma confined to A1 horizons. The A horizon is silt loam, loam, sandy loam, or fine sandy loam.

The Bw horizon has hue of 7.5YR or 10YR, value or 4 or 5, and chroma of 4 through 6 except some pedons have subhorizons with hue of 5YR. The B horizon is loam, silt loam, sandy loam, or fine sandy loam with average clay content of 10 to 18 percent.

The C or 2C horizon has hue of 7.5YR or 10YR, value of 4 through 6, and chroma of 2 through 6. Faint low-chroma mottling is at depths greater than 40 inches in some pedons. The 2C horizon ranges from gravelly loamy sand to silty clay loam, with loamy sand or loamy fine sand restricted to depths greater than 40 inches and silty clay loam restricted to thin layers. It is stratified.

COMPETING SERIES: The Linden and Pope series are in the same family. The Linden and Pope soils do not contain mica and in addition, the Linden soils have B horizons with dominant hues of 5YR or redder. Pope soils developed in sediments derived from sandstons and shales.

GEOGRAPHIC SETTING: Comus soils are on floodplains in the northern Atlantic Coastal Plain and the mesic Southern Piedmont. Slopes range from 0 to 8 percent. Comus soils formed in recent alluvium containing moderate to large amounts of mica. The climate is temperate and humid. The mean annual temperature ranges from 45 to 55 degrees F., and mean annual precipitation is about 40 inches.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Chester, Codorus, Delanco, Elioak, Elsinboro, Gaila, Glenelg, Hatboro, Kinkora, and Manor soils. All of these soils except Manor contain more than 18 percent clay in the particle size control section. Manor soils are micaceous. In addition, Codorus and Delanco soils are moderately well drained. Hatboro and Kinkora are poorly drained. Chester, Elioak, Gaila, Glenelg, and Manor soils are on uplands. Codorus and Hatboro soils are on floodplains. Delanco, Elsinboro, and Kinkora soils are on terraces.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained. Surface runoff is slow. Saturated hydraulic conductivity is moderately high to high.

USE AND VEGETATION: The majority of the areas of Comus soils are used as pasture or are cultivated. Corn and soybeans are the principle crops. Native vegetation is Northern red oak, yellow poplar, red maple and black walnut.

DISTRIBUTION AND EXTENT: Pennsylvania, Maryland, Delaware, and Virginia. The series is of moderate extent.


SERIES ESTABLISHED: Howard County, Maryland, 1965.

REMARKS: The Comus soils were formerly included with the Congaree series in mapping. The 2/99 revision updates classification to the 8th Edition of Keys to Soil Taxonomy. This soil is placed in the active CEC activity family based on comparison with other soils.

Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from the surface of the soil to a depth
of approximately 12 inches (Ap horizon).
Cambic horizon - the zone from approximately 12 to 30 inches (Bw1, Bw2 horizons).
Fluventic udepts feature - evidence of stratification within a depth of 1.25m of the surface or to a lithic or paralithic contact.

Additional Data:

SOI-5 Soil Name Slope Airtemp FrFr/Seas Precip Elevation&
MD0050 COMUS 0- 5 - - - -

SOI-5 FloodL FloodH Watertable Kind Months Bedrock Hardness&
MD0050 RARE COMMON 6.0-6.0 - 60-60

SOI-5 Depth Texture 3-Inch No-10 Clay% -CEC-
MD0050 0-30 SIL L FSL 0- 5 80-100 5-18 -
MD0050 30-60 SR GR-SL SICL 0- 20 45-100 5-34 -

SOI-5 Depth -pH- O.M. Salin Saturated hydraulic conductivity
MD0050 0-30 4.5- 6.0 1.-3. 0- 0 0.6- 2.0 LOW
MD0050 30-60 4.5- 6.0 - 0- 0 0.6- 6.0 LOW

Prior revision 11/2002 CER-MK

10/2007 and 2/2008 revisions update description and competing series.

National Cooperative Soil Survey