LOCATION SAC IA+MN
Established Series
Rev. CSF-DJP-AAC
03/2013
SAC SERIES
The Sac series consists of very deep, moderately well drained soils formed in 50 to 100 centimeters of loess and in the underlying till. These soils occur on ridgetops and convex side slopes on the loess-mantled early Wisconsin (Tazewell) or Kansan till plain. Slope ranges from 0 to 14 percent. Mean annual air temperature is about 9 degrees C. Mean annual precipitation is about 810 millimeters.
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Oxyaquic Hapludolls
TYPICAL PEDON: Sac silty clay loam, on a convex slope of 3 percent, in a cultivated field. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 15 centimeters; black (10YR 2/1) silty clay loam, very dark gray (10YR 3/1) dry; weak fine granular structure; friable; common very fine and fine roots; common very fine and fine pores; slightly acid; clear smooth boundary.
A--15 to 31 centimeters; very dark brown (10YR 2/2) silty clay loam, very dark grayish brown (10YR 3/2) dry; weak medium granular structure; friable; common very fine and fine roots; common very fine and fine pores; moderately acid; gradual smooth boundary. (Combined thickness of the A horizon is 25 to 49 centimeters.)
AB--31 to 41 centimeters; dark brown (10YR 3/3) silty clay loam, brown (10YR 4/3) dry; weak fine subangular blocky structure parting to weak medium granular; friable; common very fine and fine roots; common very fine and fine pores; many distinct very dark grayish brown (10YR 3/2) organic coats on faces of peds; slightly acid; gradual smooth boundary. (0 to 20 centimeters thick)
Bw1--41 to 61 centimeters; brown (10YR 4/3) silty clay loam; weak fine subangular blocky structure; friable; common very fine roots; common very fine and fine pores; very few distinct very dark grayish brown (10YR 3/2) organic coats on faces of peds; slightly acid; gradual smooth boundary.
Bw2--61 to 81 centimeters; brown (10YR 4/3) silty clay loam; weak fine and medium subangular blocky structure; friable; common very fine and fine pores; common fine and medium distinct dark yellowish brown (10YR 4/6) redoximorphic concentrations; neutral; abrupt wavy boundary. (Combined thickness of the Bw horizon is 25 to 60 centimeters.)
2Bw3--81 to 97 centimeters; dark yellowish brown (10YR 4/4) silt loam; weak medium subangular blocky structure; friable; common very fine and fine pores; few faint patchy brown (10YR 4/3) coats; common fine prominent grayish brown (2.5Y 5/2) redoximorphic depletions; about 3 percent rounded cobbles; strongly effervescent; neutral; abrupt wavy boundary. (8 to 40 centimeters thick)
2Bk1--97 to 117 centimeters; yellowish brown (10YR 5/4) clay loam; weak fine prismatic structure; firm; common very fine and fine pores; common fine and medium very pale brown (10YR 8/2) carbonate masses; common fine distinct grayish brown (10YR 5/2) redoximorphic depletions; about 2 percent rounded mixed cobbles and 2 percent angular shale pebbles; strongly effervescent; moderately alkaline; clear wavy boundary.
2Bk2--117 to 140 centimeters; yellowish brown (10YR 5/6) clay loam; weak fine prismatic structure; firm; common very fine and fine pores; few prominent yellowish red (5YR 4/6) iron stains; common fine and medium very pale brown (10YR 8/2) carbonate masses; common fine distinct yellowish brown (10YR 5/8) redoximorphic concentrations; common fine prominent grayish brown (2.5Y 5/2) redoximorphic depletions; about 2 percent rounded mixed cobbles and 3 percent rounded mixed pebbles; strongly effervescent; moderately alkaline; clear wavy boundary. (Combined thickness of the Bk horizon is 30 to 100 centimeters.)
2C1--140 to 178 centimeters; yellowish brown (10YR 5/6) clay loam; massive; firm; common very fine and fine pores; few fine and medium very pale brown (10YR 8/2) carbonate masses; common fine prominent grayish brown (2.5Y 5/2) redoximorphic depletions; about 2 percent rounded mixed cobbles, 2 percent rounded mixed gravel and 3 percent angular shale fragments; strongly effervescent; moderately alkaline; gradual smooth boundary.
2C2--178 to 200 centimeters; yellowish brown (10YR 5/4) clay loam; massive; firm; common very fine and fine pores; few fine and medium very pale brown (10YR 8/2) carbonate nodules; common fine and medium prominent yellowish brown (10YR 5/8) redoximorphic concentrations; many fine and medium prominent grayish brown (2.5Y 5/2) redoximorphic depletions; about 2 percent rounded mixed cobbles and 2 percent rounded mixed pebbles; strongly effervescent; moderately alkaline
TYPE LOCATION: Major Land Resource Area (MLRA) 107A-Iowa and Minnesota Loess Hills, Clay County, Iowa subset; about 2 miles west and 2 miles south of Royal; located about 1,700 feet north and 400 feet west of the southeast corner of section 16, T. 95 N., R. 38 W., USGS Royal, topographic quadrangle; lat. 43 degrees 02 minutes 39 seconds N. and long. 95 degrees 19 minutes 46 seconds W., NAD 83.
RANGE IN CHARACTERISTICS:
Thickness of the mollic epipedon--25 to 50 centimeters
Depth to carbonates--50 to 100 centimeters
Depth to till--50 to 100 centimeters
Clay content of the particle-size control section (weighted average)--27 to 35 percent
Sand content of the particle-size control section (weighted average)--8 to 15 percent
Some pedons have a coarse textured layer at the contact of the loess and till that ranges from 7 to 20 centimeters in thickness
Ap and A horizon:
Hue--10YR
Value--2 or 3
Chroma--1 or 2
Texture--silty clay loam
Clay content--27 to 37 percent
Sand content--less than 10 percent
Rock fragment content--0 percent
Reaction--moderately acid to neutral
AB or BA horizon (when present):
Hue--10YR
Value--2 or 3
Chroma--2 or 3
Texture--silty clay loam
Clay content--27 to 37 percent
Sand content--less than 10 percent
Rock fragment content--0 percent
Reaction--slightly acid or neutral
Bw horizon:
Hue--10YR or 2.5Y
Value--4 or 5
Chroma--3 or 4
Texture--silty clay loam or silt loam in the lower part
Clay content--25 to 35
Sand content--less than 10 percent
Rock fragment content--0 percent
Reaction--slightly acid or neutral
2Bw horizon:
Hue--10YR
Value--4 or 5
Chroma--3 or 4
Texture--silt loam, loam or clay loam
Clay content--22 to 30 percent
Sand content--20 to 40 percent
Rock fragment content--1 to 10 percent
Calcium carbonate equivalent--1 to 30 percent
Reaction--slightly acid to slightly alkaline
2Bk horizon:
Hue--10YR
Value--4 or 5
Chroma--3 or 4
Texture--loam or clay loam
Clay content--22 to 30 percent
Sand content--20 to 40 percent
Rock fragment content--1 to 10 percent
Calcium carbonate equivalent--15 to 30 percent
Reaction--slightly alkaline or moderately alkaline
Moist bulk density--1.4 to 1.7 g/cc
2BC or 2C horizon:
Hue--10YR
Value--4 or 5
Chroma--3 to 6
Texture--loam or clay loam
Clay content--18 to 32 percent
Sand content--20 to 45 percent
Rock fragment content--1 to 10 percent
Calcium carbonate equivalent--1 to 30 percent
Reaction--slightly alkaline or moderately alkaline
Moist bulk density--1.4 to 1.7 g/cc
COMPETING SERIES: This is the
Crooksford series.
Crooksford--have a moist bulk density of 1.30 to 1.55 g/cc in the lower third of the series control section
GEOGRAPHIC SETTING:
Parent material--50 to 100 centimeters of loess and in the underlying till
Landform--ridge tops and convex side slopes on the loess-mantled early Wisconsin (Tazewell) or Kansan till plain
Slope--0 to 14 percent
Elevation--185 to 610 meters above sea level
Mean annual air temperature--6 to 13 degrees C
Mean annual precipitation--585 to 1,040 millimeters
Frost-free days--150 to 220 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Afton,
Annieville,
Galva,
Marcus and
Primghar soils.
Afton--are on lower landscape positions in swales and toeslopes and are frequently saturated at 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
Annieville--are on landscape positions similar to those of the Sac soils and have a sand content that average less than 5 percent in the upper two thirds of the series control section
Galva--are on landscape positions similar to those of the Sac soils and have a sand content that averages less than 10 percent throughout the series control section
Marcus--are on slightly lower landscape positions and are frequently saturated at 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
Primghar--are on lower landscape positions and have a frequently saturated zone between depths of 0.3 and 1 meter during the wettest periods of years when precipitation is within one standard deviation of the 30 year mean of annual precipitation
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--moderately well drained--a frequently saturated zone occurs between depths of 0.75 meter and 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 may be perched for transitory periods
Saturated hydraulic conductivity--1.0 to 10 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 sections--Western lake section and Dissected till plains
MLRAs--Loess uplands (102C), Iowa and Minnesota Loess Hills (107A), and Iowa and Missouri Deep Loess Hills (107B)
LRR M; northwest Iowa and southwest Minnesota
Extent--large
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Clay County, Iowa, 1970.
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 horizons and features recognized in this pedon include:
mollic epipedon--the zone from 0 to 41 centimeters (Ap, A, and AB horizons);
cambic horizon--the zone from 41 to 140 centimeters (Bw1, Bw2, 2Bw3, 2Bk1, 2Bk2 horizons);
udic moisture regime.
Oxyaquic subgroup based on saturation above a depth of 1 meter and is supported by the presence of redoximorphic features.
Further investigation is needed to determine the structural class of the lower C or BC horizons. This till typically exhibits fractures and structural planes to depths of 2 meters or more.
This soil was previously considered as well drained. Field evidence of saturation and redoximorphic patterns support the current concept of moderately well drained.
Cation-exchange activity class is supported by lab data from the NSSL.
Taxonomy version--Keys to Soil Taxonomy, eleventh edition, 2010.
ADDITIONAL DATA:
Laboratory data--Soil Survey Investigations Report No. 3, Soil Survey Data and Descriptions for Some Soils of Iowa, Soil Conservation Service, U. S. Department of Agriculture in cooperation with Iowa Agriculture and Home Economics Experiment Station.
Further lab characterization data can be found from the Kellogg Soil Survey Laboratory, Lincoln Nebraska: 59IA041005, 59IA041006, 84IA035001, 84IA035003, 84IA1410011, 84IA1410012, 84IA1410021, 84IA1410022, 84IA1410023, 85IA0350021, 85IA0350022, 85IA0350023, 85IA0350031, 85IA0350032, 85IA0350033, 85IA1410031, 85IA1410033, 85IA1410041, 85IA1410042, 86IA0350041, 86IA0350042, 86IA1410032, 87IA035001, 87IA035002, 87IA035003, 87IA141001, 87IA141002, 87IA141003, 87IA1410051, 87IA1410052, 95IA041005; Iowa State University: 1969IA021001, 1972IA141001,1982IA035001.
National Cooperative Soil Survey
U.S.A.