LOCATION CROOM              MD

CROOM SERIES

TAXONOMIC CLASS: Loamy-skeletal, mixed, semiactive, mesic Typic Hapludults

TYPICAL PEDON: Croom gravelly sandy loam - wooded (colors are for moist soils)

Oi--2 to 0 inches; hardwood leaf litter, mostly oak.

A--0 to 2 inches; very dark grayish brown (10YR 3/2) gravelly sandy loam; weak fine granular structure; friable; many roots; strongly acid; clear smooth boundary. (0 to 5 inches thick)

E--2 to 7 inches; grayish brown (2.5Y 5/2) gravelly sandy loam; weak fine granular structure; friable; many roots; strongly acid; clear smooth boundary. (0 to 5 inches thick)

EB--7 to 12 inches; pale yellow (2.5Y 7/4) gravelly sandy loam; weak fine granular structure; very friable; common roots; strongly acid; abrupt smooth boundary. (5 to 10 inches thick).

Bt1--12 to 28 inches; yellowish brown (10YR 5/6) very gravelly silt loam; massive, extremely hard, very firm, sticky, plastic; few roots in upper part thinning to none below 16 inches; distinct, dark yellowish brown (10YR 4/4) and prominent, strong brown (7.5YR 5/8) clay films on pebbles; strongly acid; clear wavy boundary.

Bt2--28 to 48 inches; variegated yellowish brown (10YR 5/4), strong brown (7.5YR 5/8) and yellowish red (5YR 5/8) very gravelly loamy sand; massive; very hard, very firm, slightly sticky, slightly plastic; some pebbles coated with strong brown (7.5YR 5/8) clay; 80 percent round pebbles; strongly acid; diffuse smooth boundary. (Combined thickness of the Bt is 36 to 92 inches)

C--48 to 120 inches; stratified yellowish brown (10YR 5/4) and light brownish gray (10YR 6/2) gravelly sand; single grain; loose; very strongly acid.

TYPE LOCATION: Prince Georges County, Maryland, one-half mile south of Cheltenham.

RANGE IN CHARACTERISTICS: The thickness of the solum ranges from 40 to 120 inches. Rock fragment content by volume ranges from 35 to 70 percent in the A horizon, 50 to 70 percent in the upper Bt horizon, and from 15 to 90 percent in the lower part of the Bt and in the C horizon. Soil reaction ranges from very strongly acid to moderately acid in unlimed areas.

The A horizon has hue of 10YR or 2.5Y, value of 3 to 4 and chroma of 1 to 4. Texture of fine earth fraction is loam, sandy loam or loamy sand.

The E horizon has hue of 10YR or 2.5Y, value of 4 to 7 and chroma of 2 to 4. Fine earth texture is sandy loam, loam or loamy sand.

The Bt horizon has hue of 10YR to 5YR, value of 4 to 6 and chroma of 4 to 8. Fine earth texture is sandy loam, loamy sand, sandy clay loam, loam or clay loam. It is hard or very hard, and firm or very firm.

The BC horizon, where present, has hue of 10YR to 5YR, value of 4 to 6, and chroma of 2 to 8. Fine earth texture is sandy loam, loamy sand, sand, loam, sandy clay loam, or clay loam. It may be stratified.

The C horizon has hue of 10YR to 5YR, value of 4 to 6 and chroma of 2 to 6. Fine earth texture is sand, loamy sand or sandy loam. It is stratified.

COMPETING SERIES: These are the Blackthorn, Elliber, Gainesboro, Hartleton, Irondale, Lew, Mertz, Pattenburg, Trevlac, and Weverton soils. Blackthorn soils have a cambic horizon, are 40 or more inches to the upper boundary of the Bt horizon, and formed in colluvium over residuum. Elliber soils weathered from cherty limestone and do not have very hard, very firm B horizons. Gainesboro and Trevlac soils have sedimentary bedrock at less than 40 inches. Hartleton soils have sola thinner than 40 inches and bedrock at 40 to 65 inches. Irondale soils are in residuum from igneous rocks, are 20 to 40 inches to bedrock, and have dominantly cobbly textures. Lew soils have friable B horizons and fragments of greenstone. Mertz soils have angular rock fragments of chert and sandstone. Pattenburg soils have sola less than 40 inches thick and friable B horizons. Weverton soils are in slope creep materials over residuum and are confined to the Blue Ridge Anticlinorium.

GEOGRAPHIC SETTING: Croom soils are on dissected uplands of the northern Atlantic Coastal Plain. They are on dissected convex slopes, hillsides, and hilltops. Slopes range from 0 to 40 percent. They formed in gravelly, sandy and clayey fluvial deposits and deltaic deposits. The mean annual temperature is 50 to 58 degrees F., and mean annual precipitation is 38 to 44 inches.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Aura, Chillum, Sassafras and Beltsville soils. All these soils have less than 35 percent gravel in the particle size control section.

DRAINAGE AND PERMEABILITY: Well drained. Surface runoff is medium. Permeability is moderately slow to moderate. The available moisture capacity is low.

USE AND VEGETATION: A small part of the acreage is used for cropland. Tobacco and some truck crops are grown. A large part of the acreage is cutover and second-growth forest consisting of oaks, Virginia pine, yellow poplar, dogwood, and sweetgum.

DISTRIBUTION AND EXTENT: Maryland and New Jersey. The series has small extent.

MLRA OFFICE RESPONSIBLE: Morgantown, West Virginia

SERIES ESTABLISHED: Prince Georges County, Maryland, 1941.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon -- The zone from the surface to 2 inches (A horizon).
Albic horizon -- The zone from 2 to 7 inches (E horizon).
Argillic horizon -- The zone from 12 to 48 inches (Bt1 and Bt2 horizons).
Typic Udult feature -- No part of the moisture control section is dry for as long as 90 consecutive days and the base saturation is less than 35 percent at a depth of 1.25m beneath the top of the argillic horizon.
Loamy-skeletal feature -- The zone from 12 to 32 inches has between 18 and 35 percent clay and more than 35 percent rock fragments.

TABULAR SERIES DATA:

SOI-5  Soil Name   Slope  Airtemp FrFr/Seas Precip  Elevation
MD0049 CROOM       0- 60   47- 59  160-220  30- 46    20- 370 

SOI-5  FloodL FloodH Watertable Kind   Months  Bedrock Hardness
MD0049 NONE          6.0-6.0              -     60-60        

SOI-5  Depth  Texture                3-Inch  No-10  Clay%   -CEC-
MD0049  0-12  GR-SL GR-L              0-  0  50- 75 10-23    -   
MD0049  0-12  GRV-SL                  0-  0  30- 55 10-23    -   
MD0049 12-28  GRV-SCL GRV-SL GRV-L    0-  0  30- 55 10-35    -   
MD0049 28-48  GRV-LS GRV-SL GRV-SCL   0-  0  30- 55  5-30    -   
MD0049 48-99  GRV-S GRV-SL GRV-LS     0-  0  30- 55  5-20    -   

SOI-5  Depth    -pH-     O.M.  Salin  Permeab   Shnk-Swll
MD0049  0-12  4.5- 6.0  1.-3.   -     0.6- 2.0  LOW      
MD0049  0-12  4.5- 6.0  1.-3.   -     0.2- 2.0  LOW      
MD0049 12-28  4.5- 6.0    -     -     0.2- 2.0  LOW      
MD0049 28-48  4.5- 6.0    -     -     0.6-  20  LOW      
MD0049 48-99  4.5- 6.0    -     -     0.6-  20  LOW