LOCATION BUCKNELL IAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Vertic Epiaqualfs
TYPICAL PEDON: Bucknell silty clay loam, on a convex, west-facing, slope of 12 percent, in a permanent pasture. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 18 centimeters; very dark gray (10YR 3/1) and very dark grayish brown (10YR 3/2) silty clay loam, grayish brown (10YR 5/2) dry; streaks and pockets of dark grayish brown (10YR 4/2) subsoil material; weak medium subangular blocky structure parting to moderate fine platy and granular; friable; common prominent light gray (10YR 7/1) dry silt coats; slightly acid; clear smooth boundary. (15 to 23 centimeters thick)
2BE--18 to 25 centimeters; dark grayish brown (2.5Y 4/2) clay; moderate very fine and fine subangular blocky structure; firm; common prominent light gray (10YR 7/1) dry silt coats; few fine prominent yellowish brown (10YR 5/6) redoximorphic concentrations; very strongly acid; gradual smooth boundary. (0 to 15 centimeters thick)
2Btg--25 to 46 centimeters; dark gray (10YR 4/1) clay; moderate fine subangular blocky structure; firm; common distinct very dark gray (10YR 3/1) clay films; common distinct light gray (10YR 7/1) dry silt coats; common fine prominent yellowish brown (10YR 5/6) redoximorphic concentrations; very strongly acid; gradual smooth boundary.
2Bt1--46 to 69 centimeters; mottled yellowish brown (10YR 5/4), yellowish brown (10YR 5/8), and gray (10YR 5/1) clay; weak medium prismatic structure parting to moderate fine and medium subangular blocky; firm; common distinct dark gray (10YR 4/1) clay films; common prominent light gray (10YR 7/1) dry silt coats; few small pebbles; very strongly acid; gradual smooth boundary.
2Bt2--69 to 109 centimeters; mottled yellowish brown (10YR 5/6), yellowish brown (10YR 5/8), and gray (10YR 5/1) clay loam; moderate medium prismatic structure parting to moderate fine and medium subangular blocky; firm; common distinct dark gray (10YR 4/1) clay films; few small pebbles; strongly acid; gradual smooth boundary. (Combined thickness of 2Bt horizon is 50 to 100 centimeters.)
2BC--109 to 132 centimeters; mottled yellowish brown (10YR 5/6) and light gray (5Y 7/2) clay loam; weak medium prismatic structure parting to weak medium subangular blocky; firm; common distinct gray (10YR 5/1) clay films; few small pebbles; moderately acid; gradual smooth boundary. (15 to 38 centimeters thick)
2C--132 to 152 centimeters; mottled yellowish brown (10YR 5/6) and light gray (5Y 7/1) clay loam; massive; firm; few small pebbles; moderately acid.
TYPE LOCATION: Major Land Resource Area (MLRA) 109-Iowa and Missouri Heavy Till Plain, Monroe County, Iowa subset; about 1 mile north of Weller; located about 1,840 feet south and 2,240 feet east of the northwest corner of section 21, T. 73 N., R. 19 W.; USGS Weller topographic quadrangle; lat. 41 degrees 6 minutes 46 seconds N. and long. 93 degrees 3 minutes 9 seconds W., NAD 83.
RANGE IN CHARACTERISTICS:
Depth to carbonates--150 to more than 200 centimeters
Clay content in the particle-size control section (weighted average)--35 to 45 percent
Sand content in the particle-size control section (weighted average)--15 to 25 percent
Ap and A horizons:
Hue--10YR
Value--2 to 4
Chroma--1 or 2
Texture--silty clay loam, silt loam, clay loam, or loam
Clay content--25 to 35 percent
Sand content--15 to 40 percent
Reaction--strongly acid to neutral
E horizon (when present):
Hue--10YR or 2.5Y
Value--4 or 5
Chroma--2 or 3
Texture--silt loam or silty clay loam
Clay content--20 to 35 percent
Sand content--5 to 25 percent
Reaction--very strongly acid to moderately acid
In cultivated or eroded areas, the E horizon has been incorporated in the Ap horizon
2BE horizon (when present):
Hue--10YR or 2.5Y
Value--4 or 5
Chroma--2
Texture--silty clay loam, clay loam, or clay
Clay content--30 to 40 percent
Sand content--15 to 35 percent
Reaction--very strongly acid to moderately acid
2Bt horizon (upper part):
Hue--10YR or 2.5Y
Value--4 or 5
Chroma--1 or 2
Texture--clay
Clay content--35 to 50 percent (maximum clay content is usually within 25 to 46 centimeters of the surface)
Sand content--15 to 35 percent
Reaction--strongly acid or moderately acid
2Bt horizon (lower part):
Hue--10YR, 2.5Y or 5Y
Value--4 to 6
Chroma--1 to 8
Texture--clay loam
Clay content--28 to 40 percent
Sand content--20 to 40 percent
Reaction--strongly acid or moderately acid
2BC (when present) or 2C horizon:
Hue--10YR, 2.5Y or 5Y
Value--4 to 7
Chroma--1 to 8
Texture--clay loam
Clay content--28 to 35 percent
Sand content--25 to 45 percent
Reaction--moderately acid to slightly alkaline
COMPETING SERIES: These are the
Gifford,
Kilwinning,
Kniffin,
Leonard,
Mexico,
Pershing,
Rathbun,
Rinda,
Shields, and
Stateline series.
Gifford--have a sand content that averages less than 15 percent in the particle-size control section
Kilwinning-have a sand content that averages less than 10 percent in the particle-size control section
Kniffin--have a sand content that averages 1 to 4 percent in the particle-size control section
Leonard--have a sand content of less than 15 percent in the upper third of the series control section
Mexico--have a sand content of less than 15 percent in the upper two thirds of the series control section
Pershing--have a sand content that averages less than 5 percent in the particle-size control section
Rathbun-- have a sand content that averages less than 5 percent in the particle-size control section
Rinda--have a frequently saturated zone from the surface to a depth of 0.3 meter during the wettest periods of years when precipitation is within one standard deviation of the 30 year mean of annual precipitation, see remarks
Shields--have carbonates within a depth of 107 centimeters
Stateline--have a frequently saturated zone from the surface to a depth of 0.3 meter during the wettest periods of years when precipitation is within one standard deviation of the 30 year mean of annual precipitation
GEOGRAPHIC SETTING:
Parent material--partially truncated, exhumed paleosol that developed in till (Kansan age)
Landform--convex shoulder slopes and side slopes on dissected till plains
Slope--5 to 40 percent
Elevation--155 to 460 meters above sea level
Mean annual air temperature--8 to 12 degrees C
Mean annual precipitation--840 to 1,040 millimeters
Frost-free period--170 to 210 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Gara,
Pershing, and
Rinda soils.
Gara--are on lower landscape positions on side slopes and nose slopes and have a clay content that averages 30 to 35 percent in the particle-size control section
Rinda--are on higher landscape positions on secondary interfluves or on shoulder slopes or side slopes and have a frequently saturated zone from the surface to a depth of 0.3 meter during the wettest periods of years when precipitation is within one standard deviation of the 30 year mean of annual precipitation
Pershing--are on higher landscape positions on convex side slopes and ridgetops and have a sand content that averages less than 5 percent in the particle-size control section
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--somewhat poorly drained--a frequently saturated zone occurs between depths of 0.3 to 1.0 meter during the wettest periods of years when precipitation is within one standard deviation of the 30 year mean of annual precipitation, this saturation is considered perched
Saturated hydraulic conductivity--1.0 to 10.0 micrometers per second in the upper material and 0.1 to 1.0 micrometers per second in the underlying material
USE AND VEGETATION:
Most areas are cultivated. The principal crops are corn, oats, and soybeans. Steeper slopes typically are pastured, wooded or both wooded and pastured. The native vegetation is mixed prairie grasses and deciduous trees.
DISTRIBUTION AND EXTENT:
Physiographic Division--Interior Plains
Physiographic Province--Central Lowlands
Physiographic section--Dissected till plains
MLRAs--Illinois and Iowa Deep Loess Hills (108) and Iowa and Missouri Heavy Till Plain (109)
LRR M; southern Iowa
Extent--small
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Monroe County, Iowa, 1982.
REMARKS:
Particle-size control section--the zone from a depth of 25 to 75 centimeters;
series control section--the zone from the surface to a depth of 150 centimeters.
Diagnostic horizons and features recognized in this pedon include:
ochric epipedon--the zone from the surface to a depth of 18 centimeters (Ap horizon);
argillic horizon--the zone from 25 centimeters to a depth of 109 centimeters (Bt1, Bt2, and Bt3 horizons);
aquic moisture regime.
Differentiation between the Bucknell and Rinda soils needs further study.
Taxonomy version--Keys to Soil Taxonomy, tenth edition, 2006.