LOCATION OKABENA MN+IAEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Aquic Hapludolls
TYPICAL PEDON: Okabena silty clay loam, on a slightly convex slope of about 1 percent, on a moraine, in a cultivated field. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 25 centimeters; black (10YR 2/1) silty clay loam, very dark gray (10YR 3/1) dry; moderate fine subangular blocky structure; friable; slightly acid; abrupt smooth boundary.
AB--25 to 38 centimeters; black (10YR 2/1) silty clay loam, very dark gray (10YR 3/1) dry; weak fine and very fine subangular blocky structure; friable; few dark brown (10YR 3/3) streaks on faces of peds; slightly acid; gradual wavy boundary.
Bw--38 to 56 centimeters; olive brown (2.5Y 4/3) silty clay loam; weak fine subangular blocky structure; friable; few dark yellowish brown (10YR 4/4) streaks on faces of peds; slightly acid; gradual wavy boundary.
Bkg--56 to 109 centimeters; grayish brown (2.5Y 5/2) silt loam; weak fine subangular blocky structure; friable; common white (10YR 8/1) masses of carbonates; common fine prominent yellowish brown (10YR 5/6) iron concentrations; strongly effervescent; moderately alkaline; clear wavy boundary.
BCkg1--109 to 122 centimeters; grayish brown (2.5Y 5/2) silt loam; massive; few thin seams of very fine sandy loam on faces of peds; few white (10YR 8/1) masses of carbonates; friable; common medium prominent strong brown (7.5YR 5/6) iron concentrations; strongly effervescent; slightly alkaline; gradual wavy boundary.
2BCkg2--122 to 203 centimeters; olive gray (5Y 5/2) loam; massive; friable; few white (10YR 8/1) masses of carbonates; common fine prominent yellowish brown (10YR 5/6) iron concentrations; about 6 percent gravel; slightly effervescent; slightly alkaline.
TYPE LOCATION: Major Land Resource Area (MLRA) 103-Central Iowa and Minnesota Till Prairies, Nobles County, Minnesota subset; about 2.5 miles northwest of Worthington; located about 2,100 feet south and 40 feet east of northwest corner of section 9, T. 102 N., R. 39 W.; USGS Worthington North topographic quadrangle; lat. 43 degrees 39 minutes 13 seconds N. and long. 95 degrees 31 minutes 57 seconds W., NAD 83.
RANGE IN CHARACTERISTICS:
Mollic epipedon thickness--20 to 49 centimeters
Depth to carbonates--50 to 100 centimeters
Depth to till--100 to 150 centimeters
Clay content in the particle-size control section (weighted average)--20 to 35 percent
Sand content in particle-size control section (weighted average)--2 to 15 percent
Ap or A horizon:
Hue--10YR
Value--2 or 3
Chroma--1 or 2
Texture--silty clay loam, silt loam, or loam
Clay content--27 to 35 percent
Sand content--2 to 30 percent
Rock fragment content--0 to 3 percent
Reaction--pH 5.6 to 7.3
Moist bulk density--1.20 to 1.30 g/cc
Thickness--20 to 49 centimeters
AB or BA (when present) horizon:
Hue--10YR
Value--2 or 3
Chroma--1 to 3
Texture--silty clay loam, silt loam, or loam
Clay content--27 to 35 percent
Sand content--2 to 30 percent
Rock fragment content--0 to 3 percent
Reaction--pH 5.6 to 7.3
Moist bulk density--1.20 to 1.30 g/cc
Thickness--0 to 15 centimeters
Bw horizon:
Hue--10YR or 2.5Y
Value--3 to 5
Chroma--2 to 4
Texture--silty clay loam or silt loam
Clay content--18 to 32 percent
Sand content--2 to 20 percent
Rock fragment content--0 to 3 percent
Reaction--pH 5.6 to 7.3
Moist bulk density--1.25 to 1.35 g/cc
Thickness--10 to 25 centimeters
Some pedons have are stratified silty clay loam and silt loam or have thin strata or coarser textures
Some pedons have a BC horizon that has a pH range of 5.6 to 7.8
Bkg horizon:
Hue--2.5Y or 5Y
Value--5 or 6
Chroma--1 or 2
Texture--silty clay loam or silt loam
Clay content--18 to 32 percent
Sand content--2 to 20 percent
Rock fragment content--0 to 3 percent
Reaction--pH 7.4 to 8.4
Calcium carbonate equivalent--15 to 25 percent
Moist bulk density--1.25 to 1.35 g/cc
Thickness--15 to 60 centimeters
BCkg horizon:
Hue--2.5Y or 5Y
Value--5 or 6
Chroma--1 or 2
Texture--silty clay loam or silt loam
Clay content--18 to 32 percent
Sand content--2 to 20 percent
Rock fragment content--0 to 3 percent
Reaction--pH 7.4 to 8.4
Calcium carbonate equivalent--5 to 15 percent
Moist bulk density--1.25 to 1.35 g/cc
Thickness--10 to 25 centimeters
Some pedons have are stratified silty clay loam and silt loam or have thin strata or coarser textures
2BCkg horizon:
Hue--2.5Y or 5Y
Value--5 or 6
Chroma--1 or 2
Texture--loam or clay loam
Clay content--22 to 32 percent
Sand content--30 to 45 percent
Rock fragment content--2 to 8 percent
Reaction--pH 7.4 to 8.4
Calcium carbonate equivalent--10 to 20 percent
Moist bulk density--1.35 to 1.55 g/cc
COMPETING SERIES: These are the
Amana,
Breeds,
Grantcenter,
Joy,
Joyce,
Kingston,
Klinger,
Klingmore,
Lakefield,
Larpenteur,
McCreath,
Muscatine,
Nerwoods,
Primghar, and
Ransom series.
Amana--do not have carbonates within a depth of 150 centimeters
Breeds--have a paralithic contact with shale within a depth of 150 centimeters
Grantcenter--do not have rock fragments in the series control section
Joy--do not have carbonates within a depth of 100 centimeters
Joyce--have a sand content of more than 70 percent in the lower third of the series control section
Kingston--do not have rock fragments in the series control section
Klinger--do not have carbonates within a depth of 100 centimeters
Klingmore--do not have carbonates within a depth of 100 centimeters
Lakefield--have carbonates within a depth of 25 centimeters
Larpenteur--have carbonates within a depth of 25 centimeters
McCreath--have a moist bulk density of 1.6 to 1.8 g/cc in the lower third of the series control section
Muscatine--do not have carbonates within a depth of 100 centimeters
Nerwoods--have a moist bulk density of 1.7 to 1.9 g/cc in the lower third of the series control section
Primghar--do not have rock fragments in the series control section
Ransom--have a sand content of more than 30 percent within a depth of 100 centimeters and have moist bulk density of 1.45 to 1.65 g/cc in the lower third of the series control section
GEOGRAPHIC SETTING:
Parent material--100 to 150 centimeters of silty lacustrine sediments or loess and in the underlying till
Landform--nearly level to convex slopes on lake plains or moraines
Slope--0 to 12 percent
Elevation--300 to 400 meters above sea level
Mean annual air temperature--6 to 10 degrees C
Mean annual precipitation--585 to 890 millimeters
Frost-free period--155 to 200 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Canisteo,
Clarion,
Nicollet, and
Webster soils.
Canisteo--are on lower landscape positions on nearly level slopes and have carbonates within a depth of 50 centimeters
Clarion--are on higher landscape positions on back slopes and have a sand content that averages 30 to 50 percent in the particle-size control section
Nicollet--are on landscape positions similar to those of the Okabena soils and have a sand content that averages 20 to 35 percent in the particle-size control section
Webster--are on lower landscape positions on nearly level slopes and have a sand content that averages 18 to 45 percent in the particle-size control section
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--somewhat poorly drained--a frequently saturated zone occurs between 0.45 and 0.75 meter during the wettest periods of years when precipitation is within one standard deviation of 30 year mean of annual precipitation
Saturated hydraulic conductivity1.00 to 10.00 micrometers per second
USE AND VEGETATION:
Most areas are cultivated. The principal crops are corn and soybeans. The native vegetation is big bluestem, little bluestem, switchgrass, and other grasses of the tall grass prairie.
DISTRIBUTION AND EXTENT:
Physiographic Division--Interior Plains
Physiographic Province--Central Lowland
Physiographic Section--Western lake section
MLRA--Central Iowa and Minnesota Till Prairies (103)
LRR--M; south-central and southwestern Minnesota, north-central and northwestern Iowa
Extent--moderate
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota; MLRA SSO 10-5 (Albert Lea, Minnesota).
SERIES ESTABLISHED: Nobles County, Minnesota, 2004.
REMARKS:
Particle-size control section--the zone from a depth of 25 to 100 centimeters; series control section--the zone from the surface to a depth of 150 centimeters.
Diagnostic horizon and features recognized in this pedon are:
mollic epipedon--the zone from the surface of the soil to a depth of 38 centimeters (Ap and AB horizons);
cambic horizon--the zone from a depth of 38 to 56 centimeters (Bw horizon); calcic horizon--the zone from a depth of 109 to 122 centimeters (Bkg horizon);.
udic moisture regime.
Cation-exchange activity class is inferred from lab data from similar soils in the surrounding area.
Taxonomy version--Keys to Soil Taxonomy, tenth edition, 2006.