LOCATION UNISON VA+NC
Established Series
Rev. RLG;NAM;MHC;MKC
01/2023
UNISON SERIES
Soils of the Unison series are very deep and well drained. They are on mountain footslopes, alluvial fans, or stream terraces. Permeability of the soil is moderate. Slopes range from 0 to 45 percent. Mean annual temperature is about 55 degrees F. Mean annual precipitation is about 40 inches.
TAXONOMIC CLASS: Fine, mixed, semiactive, mesic Typic Hapludults
TYPIFYING PEDON: Unison loam - pasture (Colors are for moist soil.)
Ap--0 to 9 inches; brown (7.5YR 4/4) loam; moderate fine granular structure; very friable; many fine roots; 5 percent angular quartz gravel; moderately acid; clear smooth boundary. (0 to 12 inches thick)
BA--9 to 12 inches; reddish brown (5YR 4/4) clay loam; weak fine and very fine subangular blocky structure; friable; many fine roots; few thin clay films on faces of peds; 5 percent angular quartz gravel; moderately acid; clear smooth boundary.
Bt1--12 to 33 inches; yellowish red (5YR 4/6) clay; moderate fine subangular blocky structure; firm, sticky, plastic; common fine roots; thin patchy clay films on faces of peds; 5 percent greenstone and granodiorite gravel and cobbles; moderately acid; clear smooth boundary.
Bt2--33 to 50 inches; strong brown (7.5YR 5/6) clay; weak fine subangular blocky structure; firm, sticky, plastic; common fine roots; few thin clay films on faces of peds; 10 percent greenstone and granodiorite gravel and cobbles; moderately acid; gradual wavy boundary. (Combined thickness of Bt horizons ranges from 15 inches to 50 inches.)
C--50 to 72 inches; strong brown (7.5YR 5/6) cobbly clay loam; massive; friable, sticky; 25 percent greenstone and granodiorite gravel and cobbles; moderately acid.
TYPE LOCATION: Madison County, Virginia; 1.5 miles north of Graves Mill, 100 yards south of house.
RANGE IN CHARACTERISTICS: Thickness of solum ranges from 30 to 60 inches or more. Depth to hard bedrock is greater than 6 feet. Content of rock fragments range from 0 to 50 percent in the A, Ap, E, BA, and BE horizons, 0 to 35 percent in the Bt horizon and 0 to 75 percent in the BC and C horizons. These consist of subangular, rounded or angular gravel or cobbles of crystalline rocks. The soil is very strongly acid through moderately acid throughout unless limed.
The A horizon, where present, has hue of 7.5YR or 10YR, value of 3 or 5 and chroma of 3 through 6. A horizons with value of 3 are 6 inches or less thick. It is fine sandy loam, loam, or silt loam.
The Ap horizon, where present, has hue of 7.5YR or 10YR, value of 3 or 5 and chroma of 3 through 6 with hue of 5YR in some eroded areas. Ap horizons with value of 3 are 6 iches or less thick. It is fine sandy loam, loam, or silt loam.
The E horizon, where present, has hue of 7.5YR or 10YR, value of 4 or 5 and chroma of 3 through 6. It is fine sandy loam, loam, or silt loam.
The BE or BA horizon, where present, has hue of 7.5YR or 10YR, value of 4 or 5, and chroma of 3 through 6. Textures include silty clay loam, clay loam, and heavy silt loam.
The Bt horizon has hue of 5YR through 10YR, value of 4 or 5, and chroma of 3 through 8. This horizon is clay, silty clay, clay loam, or silty clay loam.
The BC horizon, where present, has hue of 2.5YR through 7.5YR, value of 3 through 8, chroma of 3 through 6. It is loam, clay loam, silty clay loam, silty clay or clay.
The C or 2C horizon has hue of 2.5YR through 7.5YR, value of 4 through 8, and chroma of 3 through 6. It is loam, silt loam, clay loam, silty clay loam, sislty clay, or clay. Some pedons have unconforming sandy, gravelly, and cobbly substrata.
COMPETING SERIES: These are the
Agnos,
Boden,
Braddock,
Buckhall,
Buffstat,
Christian,
Clifton,
Fairfax,
Gassville,
Groseclose,
Howell,
Littlejoe,
Lodi,
Monmouth,
Muse,
Nantahala,
Pervina,
Quantico,
Sequoia,
Timberville,
Trappist, and
Warminster series in the same family. Agnos, Boden, and Gassville soils have bedrock at 40 to 60 inches. Braddock soils have red Bt horizons. Buckhall, Buffstat, Christian, Clifton, Groseclose, Littlejoe, Lodi, Muse, Nantahala, Pervina, Quantico, Sequoia, Timberville, Trappist, and Warminister soils have rock fragments related to material other than acid or basic crystalline rocks. Fairfax soils have a discontinuity of alluvium over residuum. Howell and Monmouth soils have hue of 2.5Y or 5Y in the lower Bt.
GEOGRAPHIC SETTING: Unison soils are on footslopes, alluvial fans, or stream terraces. Slopes are commonly 2 to 15 percent, but the range includes 0 to 45 percent. Unison soils formed in colluvium and alluvium 3 to 6 feet thick derived from a mixture of basic rocks or basic and acidic crystalline rocks. Annual temperature ranges from 52 degrees F to 57 degrees F, and annual precipitation ranges from 35 to 45 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing
Braddock soils and the
Drayke,
Meadowville,
Myersville,
Porters,
Thurmont and
Trego soils all on adjacent uplands. Drayke soils are redder throughout. Meadowville, Myersville, Porters, and Thurmont soils have less clay in the subsoil. Trego soils have a fragipan.
DRAINAGE AND PERMEABILITY: Well drained, medium or rapid runoff; moderate permeability.
USE AND VEGETATION: About one-half of the acreage is used for growing cultivated crops, pasture and orchards. Crops include corn, small grains, hay, fruit and vegetables. Woodland vegetation consists of mixed hardwoods, dominated by oaks, maple, poplar, hemlock and pine.
DISTRIBUTION AND EXTENT: Piedmont Plateau and footslopes of the Blue Ridge Mountains in Virginia, and possibly in Maryland and North Carolina. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia
SERIES ESTABLISHED: Loudoun County, Virginia, 1956.
REMARKS: The 2/99 revision updates classification to the 8th Edition of Keys to Soil Taxonomy. This soil is placed in the semiactive CEC activity class based on comparison with similar soils such as Braddock.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon-zone from 0 to 9 inches (Ap horizon)
Argillic horizon-zone from 12 to 50 inches (Bt horizons)
SIR = VA0057, VA0133 (GRAVELLY), VA0067 (STONY)
MLRA = 130, 147, 148
REVISED = 1/92-MHC; 2/99-MKC
National Cooperative Soil Survey
U.S.A.