LOCATION BLENCOE IA+MO NE SDEstablished Series
TAXONOMIC CLASS: Clayey over loamy, smectitic over mixed, superactive, mesic Aquertic Hapludolls
TYPICAL PEDON: Blencoe silty clay, on a slope of about 1/2 percent, on a flood plain in a cultivated field. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 6 inches; black (10YR 2/1) silty clay, very dark gray (10YR 3/1) dry; moderate fine subangular blocky structure; firm; many roots; few fine pores; neutral; clear smooth boundary.
A--6 to 12 inches; black (10YR 2/1) silty clay, dark gray (10YR 4/1) dry; moderate fine subangular blocky structure; firm; many roots; few fine pores; neutral; clear smooth boundary. (Combined thickness of the A horizons is 10 to 17 inches.)
BA--12 to 18 inches; very dark grayish brown (2.5Y 3/2) silty clay, grayish brown (2.5Y 5/2) dry; faces of peds very dark gray (10YR 3/1), moderate fine subangular blocky structure; firm; black (10YR 2/1) organic stains on faces of peds; few fine roots; very few fine pores; neutral; clear smooth boundary. (4 to 7 inches thick)
Bg--18 to 28 inches; dark grayish brown (2.5Y 4/2) silty clay; weak medium prismatic structure parting to weak fine subangular blocky; firm; few faces of peds have black (10YR 2/1) organic stains; many root channels; few black iron and manganese oxides; neutral; clear smooth boundary. (8 to 11 inches thick)
BCg--28 to 32 inches; dark grayish brown (2.5Y 4/2) silty clay loam; weak medium prismatic structure; friable; common root channels; few fine pores; few black iron and manganese oxides; few fine prominent strong brown (7.5YR 5/6) redoximorphic concentrations; neutral; clear smooth boundary. (0 to 5 inches thick)
2Cg--32 to 60 inches; grayish brown (2.5Y 5/2) silt loam; massive; friable; numerous roots and pores; few worm holes and worm casts; distinct calcium carbonate threads; distinct calcium carbonate concretions; few fine prominent strong brown (7.5YR 5/6) redoximorphic concentrations; strongly effervescent; moderately alkaline.
TYPE LOCATION: Fremont County, Iowa; about 5 miles north and 3 miles west of Hamburg; about 1,220 feet east and 1,840 feet south of the northwest corner of sec. 31, T. 68 N., R. 42 W., NAD 27.
RANGE IN CHARACTERISTICS:
Depth to carbonates--25 to 40 inches
Depth to cambic horizon--14 to 24 inches
Depth to redox concentrations--25 to 40 inches
Thickness of mollic epipedon--14 to 24 inches
Depth to silty alluvium--20 to 40 inches
Content of clay in the particle-size control section (weighted average)--40 to 52 percent in the upper part and 18 to 24 percent in the lower part
Content of sand in the particle-size control section (weighted average)--1 to 15 percent fine sand and sand coarser than fine sand in the upper part and 15 to 35 percent fine sand and sand coarser than fine sand in the lower part
A or Ap horizon:
Hue--10YR or neutral
Value--2 or 3
Chroma--0 to 2
Texture--silty clay or silty clay loam
Clay content--38 to 55 percent
Sand content--1 to 20 percent
Reaction--slightly acid or neutral
AB or BA horizon:
Hue--10YR or 2.5Y
Value--2 or 3
Chroma--1 or 2
Texture--silty clay or silty clay loam
Clay content--38 to 55 percent
Sand content--1 to 20 percent
Reaction--slightly acid or neutral
Bg horizon:
Hue--10YR or 2.5Y
Value--4 or 5
Chroma--2
Texture--silty clay
Clay content--43 to 50 percent
Sand content--1 to 10 percent
Calcium carbonate equivalent--0 to 32 percent
Reaction--neutral
BC or BCg horizon (if it occurs):
Hue--10YR or 2.5Y
Value--4 or 5
Chroma--2 to 4
Texture--silty clay loam or silty clay
Clay content--35 to 50 percent
Sand content--1 to 20 percent
Calcium carbonate equivalent: 0 to 20 percent
Reaction: neutral or slightly alkaline
2Cg horizon:
Hue--10YR or 2.5Y
Value--5
Chroma--2
Texture--silt loam
Clay content--18 to 24 percent
Sand content--15 to 35 percent
Calcium carbonate equivalent--5 to 30 percent
Reaction--slightly alkaline to strongly alkaline
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Parent material--20 to 40 inches of clayey alluvium and underlying silty alluvium
Landform--flood plains
Slopes--0 to 2 percent
Elevation--800 to 1,200 feet above sea level
Mean annual air temperature--47 to 54 degrees F.
Mean annual precipitation--25 to 32 inches
Frost-free period--145 to 180 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Cooper,
Keg,
Luton,
Salix, and
Woodbury soils.
Cooper--are at slightly higher elevations and have less than 35 percent clay in the upper part of the particle-size control section
Keg--are at the higher elevations, do not have saturated zones within a depth of 6 feet, and have less than 35 percent clay in the particle-size control section
Luton--are in lower landscape positions and have saturated zones within a depth of 1 foot
Salix--are at slightly higher elevations and have saturated zones within a depth of 3 to 6 feet
Woodbury--are in lower landscape positions, have saturated zones within a depth of 1 foot, and have 28 to 36 percent clay in the lower part of the particle-size control section
DRAINAGE AND PERMEABILITY:
Drainage class--somewhat poorly drained--a saturated zone occurs within a depth of 1 to 3 feet during April to June in most years and is considered apparent
Permeability--slow or moderately slow in the upper part and moderate in the lower part
Surface runoff potential--low
Flooding--rare flooding for brief or very brief periods during the months of February to November resulting from precipitation events and snowmelt
USE AND VEGETATION:
Most areas are cultivated. Principal crops are corn, soybeans, and small grain. Some areas have been drained by open ditches and land grading. The native vegetation is big bluestem, indiangrass, switchgrass, and other grasses of the tall grass prairie.
DISTRIBUTION AND EXTENT:
LRR M, MLRAs 107, 102B; flood plains of the Missouri River in Iowa, Missouri, Nebraska and South Dakota. This series is of moderate extent.
MLRA OFFICE RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Monona County, Iowa, 1951.
REMARKS:
Diagnostic horizons and features recognized in this pedon:
particle-size control section--the zone from a depth of 10 to 40 inches (A, BA, Bg, BCg, and 2Cg horizons);
series control section--the zone from the surface to a depth of 60 inches (Ap, A, BA, Bg, BCg, and 2Cg horizons);
mollic epipedon--the zone from the surface to a depth of 18 inches (Ap, A, and BA horizons);
cambic horizon--the zone from a depth of 18 to 32 inches (Bg, and BCg horizons);
udic moisture regime.
Taxonomy version: Second Edition, 1999.