LOCATION ORAN IA+MNEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Aquollic Hapludalfs
TYPICAL PEDON: Oran loam, on a slightly convex slope of about 2 percent, on an upland ridge top, in a cultivated field. (Colors are for moist soils unless otherwise stated.)
Ap--0 to 20 centimeters; very dark gray (10YR 3/1) loam, gray (10YR 5/1) dry; moderate very fine and fine granular structure; friable; common fine and medium roots; common fine moderate continuity dendritic tubular pores; neutral; abrupt wavy boundary. (13 to 23 centimeters thick)
E--20 to 33 centimeters; dark grayish brown (10YR 4/2) loam, gray (10YR 6/1) dry; weak very fine and fine subangular blocky structure; friable; common fine roots; common fine moderate continuity dendritic tubular pores; few faint patchy very dark grayish brown (10YR 3/2) organic coats on faces of peds; moderately acid; clear wavy boundary. (0 to 20 centimeters thick)
BE--33 to 46 centimeters; dark grayish brown (10YR 4/2) loam; weak very fine and fine subangular blocky structure; friable; common fine roots; common fine moderate continuity dendritic tubular pores; common fine distinct yellowish brown (10YR 5/4) redoximorphic concentrations; strongly acid; clear wavy boundary. (0 to 18 centimeters thick)
2Bt1--46 to 86 centimeters; brown (10YR 5/3) clay loam; weak fine subangular blocky structure; firm; common fine roots; common fine moderate continuity dendritic tubular pores; few faint discontinuous brown (10YR 4/3) clay films on faces of peds and on surfaces along pores; common fine irregular dark reddish brown (5YR 3/4) masses of iron-manganese; common fine and medium distinct yellowish brown (10YR 5/6) redoximorphic concentrations; common fine and medium faint light brownish gray (10YR 6/2) redoximorphic depletions; about 3 percent subrounded mixed rock fragments (2 to 75 millimeters in diameter); strongly acid; gradual wavy boundary.
2Bt2--86 to 114 centimeters; yellowish brown (10YR 5/4) clay loam; moderate fine and medium subangular blocky structure; firm; common fine roots; common fine moderate continuity dendritic tubular pores; few faint discontinuous brown (10YR 5/3) clay films on faces of peds and on surfaces along pores; common fine irregular dark reddish brown (5YR 3/4) masses of iron-manganese; common fine and medium distinct yellowish brown (10YR 5/6) redoximorphic concentrations; common fine and medium distinct light brownish gray (10YR 6/2) redoximorphic depletions; about 3 percent subrounded mixed rock fragments (2 to 75 millimeters in diameter); slightly acid; clear wavy boundary. (Combined thickness of the 2Bt horizon is 33 to 79 centimeters.)
2BC--114 to 203 centimeters; yellowish brown (10YR 5/6) loam; extremely coarse prismatic structure dissected by few oblique fractures; very firm; common fine irregular light gray (10YR 7/2) masses of calcium carbonate; common medium faint strong brown (7.5YR 5/6) redoximorphic concentrations; common medium prominent light brownish gray (2.5Y 6/2) redoximorphic depletions; about 5 percent rock fragments (2 to 75 millimeters in diameter); strongly effervescent; slightly alkaline.
TYPE LOCATION: Major Land Resource Area (MLRA) 104-Eastern Iowa and Minnesota Till Prairies; Winneshiek County, Iowa subset; about 5 miles west and 1 mile south of Spillville; located about 1,063 feet south and 70 feet east of the northwest corner of section 29, T. 97 N., R. 10 W.; USGS Protivin topographic quadrangle; lat. 43 degrees 11 minutes 43.8 seconds N. and long. 92 degrees 3 minutes 44.8 seconds W., NAD 83.
RANGE IN CHARACTERISTICS:
Depth to glacial till--30 to 66 centimeters
Depth to carbonates--102 to 178 centimeters
Clay content in the particle-size control section (weighted average)--18 to 30 percent
Sand content in the particle-size control section (weighted average)--35 to 50 percent
Special feature--some pedons have a stone line or thin layer, 2 to 13 centimeters thick of gravelly and sandy materials at the base of the silty or loamy sediments
A or Ap horizon:
Hue--10YR
Value--2 or 3
Chroma--1 or 2
Texture--loam or silt loam
Clay content--10 to 27 percent
Sand content--10 to 40 percent
Rock fragment content--1 to 10 percent
Reaction--strongly acid to neutral
Special features--when mixed to a depth of 18 centimeters, matrix value is 3 or less, moist, 5 or less, dry
E horizon (when present):
Hue--10YR
Value--4 or 5
Chroma--2 or 3
Texture--silt loam or loam
Clay content--5 to 20 percent
Sand content--10 to 40 percent
Rock fragment content--1 to 10 percent
Reaction--strongly acid to neutral
BE horizon (when present):
Hue--10YR or 2.5Y
Value--4 or 5
Chroma--2 or 3
Texture--loam or silt loam
Clay content--15 to 25 percent
Sand content--10 to 40 percent
Rock fragment content--1 to 10 percent
Reaction--strongly acid to neutral
Bt horizon (when present):
Hue--10YR or 2.5Y
Value--4 to 6
Chroma--3 to 6
Texture--loam or sandy clay loam
Clay content--18 to 28 percent
Sand content--40 to 60 percent
Rock fragment content--1 to 10 percent
Reaction--very strongly acid to slightly acid
Thickness--0 to 25 centimeters
2Bt horizon:
Hue--7.5YR to 2.5Y
Value--4 to 6
Chroma--2 to 8
Texture--loam, clay loam or sandy clay loam
Clay content--20 to 30 percent
Sand content--35 to 50 percent
Rock fragment content--2 to 15 percent
Reaction--very strongly acid to slightly acid
2BC horizon:
Hue--7.5YR or 10YR
Value--4 to 6
Chroma--4 to 6
Texture--loam
Clay content--18 to 27 percent, mean of 22 percent
Sand content--35 to 50 percent, mean of 44 percent
Rock fragment content--2 to 12 percent
Reaction--slightly acid to moderately alkaline
Moist bulk density--1.75 to 1.9 gm/cc
2C horizon (when present):
Hue--7.5YR or 10YR
Value--4 to 6
Chroma--4 to 6
Texture--loam
Clay content--18 to 30 percent
Sand content--30 to 55 percent
Rock fragment content--2 to 12 percent
Moist bulk density--1.75 to 1.9 gm/cc
Reaction--slightly alkaline or moderately alkaline
COMPETING SERIES: These are the
Doolyville,
Lineville,
Mosel, and
Newry series.
Doolyville--are in areas that have a mean annual air temperature of 10 to 13 degrees C, a mean annual precipitation range of 1,740 to 2,160 millimeters, and are on slopes of 30 to 50 percent
Lineville--have a clay content of 35 to 45 percent in the lower third of the series control section
Mosel--have carbonates within a depth 102 centimeters and do not have rock fragments in the lower third of the series control section
Newry--have a moist bulk density range of 1.5 to 1.75 gm/cc in the lower third of the series control section
GEOGRAPHIC SETTING:
Parent material--30 to 66 centimeters of silty or loamy sediments and the underlying loamy glacial till
Landform--interfluves and long side slopes on dissected till plains on the Iowan Erosion Surface
Slope--0 to 9 percent
Elevation--300 to 400 meters above sea level
Mean annual air temperature--7 to 10 degrees C
Mean annual precipitation--735 to 940 millimeters
Frost-free period--160 to 195 days
GEOGRAPHICALLY ASSOCIATED SOILS: Members of the typical catena include
Bassett,
Kasson,
Racine, and
Skyberg soils.
Bassett--are on higher elevations on side slopes and do not have a frequently saturated zone within a depth of 1.8 meters in normal years
Kasson--are at slightly higher elevations on side slopes and have a frequently saturated zone at a depth of 0.75 meter in normal years
Racine--are on higher elevations on shoulders and narrow summits and do not have a frequently saturated zone within a depth of 1.8 meters in normal years
Skyberg--are at lower elevations in flat to concave drainageways and are frequently saturated at the soil surface in normal years
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--somewhat poorly drained--a frequently saturated zone occurs at a depth of 0.3 meter during April to June in normal years and both perched and apparent saturation can occur on this soil based on the season and intensity of rainfall during a given period of time
Saturated hydraulic conductivity--1.00 to 10.00 micrometers per second (moderately high) in the silty or loamy sediments and 0.01 to 1.00 micrometers per second (low or moderately low) in the glacial till
Surface runoff potential--negligible to low
USE AND VEGETATION:
Most areas are cultivated. The principal crops are corn, small grains, soybeans, and hay. The native vegetation is big bluestem, little bluestem, switchgrass, other grasses of the tall grass prairie and mixed deciduous trees.
DISTRIBUTION AND EXTENT:
Physiographic Division--Interior Plains
Physiographic Province--Central Lowland
Physiographic section--Dissected till plains
MLRA--Eastern Iowa and Minnesota Till Prairies (104)
LRR M; northeast Iowa and southeast Minnesota
Extent--moderate
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Bremer County, Iowa, 1965
REMARKS:
Particle-size control section--the zone from a depth of 46 to 96 centimeters (2Bt1 and 2Bt2 horizons);
series control section--the zone from the surface to a depth of 150 centimeters (Ap, E, BE, 2Bt1, 2Bt2, and 2BC horizons).
Diagnostic horizons and features recognized in this pedon:
ochric epipedon--the zone from the surface to a depth of 33 centimeters (Ap and E horizons);
albic horizon--the zone from a depth of 20 to 33 centimeters (E horizon);
argillic horizon--the zone from a depth of 46 to 114 centimeters (2Bt1 and 2Bt2 horizons);
udic moisture regime.
Some pedons have vertical seams or wedges of sand or loamy sand about 5 to 30 centimeters wide and about 0.9 to 1.2 meters deep extending downward from the stone line into the glacial till.
Cation-exchange activity class is inferred from lab data from similar soils in the surrounding area.
Aquollic subgroup based on matrix value of 2 in the zone from the surface to a depth of 20 centimeters (Ap horizon) and redoximorphic depletions in the zone from a depth of 46 to 86 centimeters (2Bt1 horizon).
Taxonomy version--Keys to Soil Taxonomy, tenth edition, 2006.
The change to bulk density of 1.75 to 1.90 gm/cc and low to moderately low saturated hydraulic conductivity was based on field and lab data and supported by the MLRA 104 steering committee.
Not all pedons have the increase in clay content necessary for an argillic horizon however, this is waived due to the change in parent materials.