LOCATION LOUGHBORO MO
Established Series
Rev. BLB-RLT
12/2021
LOUGHBORO SERIES
The Loughboro series consists of very deep, poorly drained, slowly permeable soils on broad upland ridges or divides. They formed in loess overlying water worked loamy and clayey sediments from granite bedrock. Slopes range from 0 to 3 percent. Mean annual temperature is 56 degrees F, and mean annual precipitation is 42 inches.
TAXONOMIC CLASS: Fine, smectitic, mesic Aeric Glossaqualfs
TYPICAL PEDON: Loughboro silt loam - on a 1 percent slope in idle grass cover with a few scattered oak and hickory trees at 1,170 feet elevation. (Colors are for most conditions unless otherwise stated.)
A--0 to 2 inches; brown (10YR 5/3) silt loam; pale brown (10YR 6/3) dry; weak fine granular structure; very friable; many fine and medium roots; strongly acid; abrupt smooth boundary. (1 to 4 inches thick)
E1--2 to 10 inches; yellowish brown (10YR 5/4) silt loam; weak thick platy structure; very friable; many fine and medium roots; few fine faint brown (10YR 4/3) iron depletions; very strongly acid; clear smooth boundary.
E2--10 to 15 inches; yellowish brown (10YR 5/6) silt loam; weak thick platy structure parting to weak medium subangular blocky; very friable; many fine roots; few fine faint brown (10YR 4/3) iron depletions; common fine discontinuous light brownish gray (10YR 6/2) clay depletions on faces of peds and along old root channels; very strongly acid; clear wavy boundary. (Combined thickness of the E horizon is 10 to 20 inches thick)
B/E--15 to 22 inches; grayish brown (10YR 5/2) silty clay loam (Bt); moderate fine and medium subangular blocky structure; firm; common faint clay films on surfaces of peds; light brownish gray(10YR 6/2) silt loam (E) tonguing into the Bt and coating vertical faces of peds and filling old root channels and cracks; very friable; common fine prominent yellowish red (5YR 4/6) and common medium distinct brown (10YR 5/3) masses of iron accumulation; common fine roots; very strongly acid; abrupt wavy boundary. (5 to 12 inches thick)
Btg1--22 to 32 inches; grayish brown (10YR 5/2) silty clay; weak coarse subangular blocky structure; very firm; common fine roots; few pressure faces (slickensides); common distinct clay films on faces of peds; gray (10YR 5/1) iron depletions; common fine prominent yellowish red (5YR 4/6) masses of iron accumulation; very strongly acid; gradual wavy boundary.
Btg2--32 to 39 inches; grayish brown (10YR 5/2) silty clay loam; weak coarse prismatic structure; very firm; few fine roots; common faint clay films on faces of peds; few clay flows in channels and on vertical faces; common fine prominent strong brown (7.5YR 5/6), yellowish red (5YR 4/6) and brown (7.5YR 4/4) masses of iron accumulation; 5 percent gravel (20 mm to 2 mm in diameter); very strongly acid; gradual irregular boundary. (Combined thickness of the Bt horizon is 9 to 31 inches thick.)
2Cg1--39 to 59 inches; light brownish gray (10YR 6/2) silt loam; weak very coarse prismatic structure; firm; few fine roots; common medium distinct brown (10YR 5/3) masses of iron accumulation; few fine faint grayish brown (10YR 5/2) iron depletions; 5 percent gravel (20 mm to 2 mm in diameter); very strongly acid; diffuse wavy boundary.
2Cg2--59 to 67 inches; light brownish gray (10YR 6/2) silt loam; massive; very firm; common medium prominent brown (7.5YR 4/4) and common fine prominent yellowish red (5YR 4/6) masses of iron accumulation; 5 percent gravel (20 mm to 2 mm in diameter); strongly acid.
TYPE LOCATION: St. Francois County, Missouri; about 3 miles southwest of Doe Run on Highway W at intersection with Highway V. Approximately 1,495 feet north and 2,490 feet east of the southwest corner, sec. 25, T. 35 N., R. 4 E; Iron Mountain Lake, lat. 37 degrees 42 minutes 32 seconds N. and long. 90 degrees 32 minutes 36 seconds W..
RANGE IN CHARACTERISTICS: Solum thickness typically is about 40 inches and ranges from 28 to 65 inches. Depth to hard rock is greater than 60 inches. The particle-size control section averages between 36 and 48 percent clay.
The A horizon has hue of 10YR, value of 3 to 5 and chroma of 2 or 3. An Ap horizon has 10YR hue, value of 4 or 5 and chroma of 2 to 5. Texture is silt loam. Reaction is extremely acid to strongly acid, except it is higher where limed.
The E horizon has hue of 10YR, value of 4 or 6 and chroma of 3 to 6. Texture is silt loam. It is extremely acid to strongly acid, but higher where limed.
The Bt part of the B/E horizon has 7.5YR or 10YR hue, value of 4 to 6 and chroma of 2 to 4. It is silt loam, silty clay loam or silty clay. It is extremely acid to strongly acid. The E part has 7.5YR or 10YR hue, value of 5 to 7 and chroma of 2.
The Btg horizon has hue of 7.5YR, 10YR, or 2.5Y; value of 5 or 6; and chroma of 2. It typically is silty clay or silty clay loam and rarely clay or clay loam. Content of coarse fragments by volume larger than 3 inches in diameter ranges from 0 to 5 percent and content of fragment 3 inches to 2 mm in diameter ranges from 0 to 5 percent. It is extremely acid to strongly acid.
The Cg horizon has 7.5YR, 10YR or 2.5Y hues; value of 5 or 6; and chroma of 1 to 6. It is silt loam, loam, and silty clay loam. Coarse fragments by volume larger than 3 inches range from 0 to 5 percent. Coarse fragments by volume 3 inches to 2 mm in diameter range from 0 to 10 percent. It is extremely acid to strongly acid.
COMPETING SERIES: The Loughboro series is the only member of this family.
GEOGRAPHIC SETTING: These soils are on nearly level to gentle slope on broad upland ridges, divides or small plateaus. They are adjacent to higher lying hills or mountains of igneous origin. They formed in loess overlying water worked loamy sediments from granite bedrock. Slopes range from 0 to 3 percent. Mean annual precipitation ranges from 40 to 45 inches and the mean annual temperature ranges from 52 to 57 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Delassus,
Irondale,
Knobtop and
Syenite series. They are well or moderately well drained soils with brown Bt horizons that occur on steeper slopes. In addition, the Delassus soils have fragipans. Irondale and Knobtop soils are 20 to 40 inches to rhyolite and Syenite soils are 20 to 40 inches to granite rock.
DRAINAGE AND PERMEABILITY: Poorly drained. Runoff is slow. Additional runoff is received from adjacent higher areas. Permeability is slow in the subsoil and moderately slow in the substratum.
USE AND VEGETATION: Most areas have been cleared and cultivated but are now used for pasture and hay or have reverted to young hardwood growth consisting of wild plum, hawthorn, persimmon, black locust and native grasses. A small acreage is cropped to corn. The remaining areas are in native forest of mixed hardwoods of mainly oak and hickory.
DISTRIBUTION AND EXTENT: In the St. Francois Mountains of the Ozarks region (MLRA 116C) of southeast Missouri. The series is of small extent.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: INDIANAPOLIS, INDIANA
SERIES ESTABLISHED: St. Francois, Missouri, 1979.
REMARKS: Diagnostic horizons and features recognized in this series are: ochric epipedon - the zone from the surface of the soil to a depth of about 15 inches (A, E, and E2 horizons);
argillic horizon - the zone from approximately 15 inches to 39 inches (B/E, Btg1, and Btg2 horizons).
National Cooperative Soil Survey
U.S.A.