LOCATION GARWIN                  IA+MN WI

Established Series
Rev. JDH-DBO-RJB
06/2015

GARWIN SERIES

The Garwin series consists of deep, poorly drained soils formed in loess. These soils are on slightly concave heads of upland drainageways, interfluves on dissected till plains, and treads on stream terraces. Slope ranges from 0 to 2 percent. Mean annual precipitation is about 850 millimeters. Mean annual air temperature is about 9 degrees C.

TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Typic Endoaquolls

TYPICAL PEDON: Garwin silty clay loam, on a slightly concave slope of less than 1 percent, in a cultivated field, on nearly level upland. (Colors are for moist soil unless otherwise stated.)

Ap--0 to 18 centimeters; black (N 2/0) silty clay loam, very dark gray (10YR 3/1) dry; moderate fine and medium granular structure; friable; moderately acid; clear smooth boundary.

A1--18 to 30 centimeters; black (10YR 2/1) silty clay loam, very dark gray (10YR 3/1) dry; moderate fine and medium granular structure; friable; moderately acid; gradual smooth boundary.

A2--30 to 46 centimeters; very dark gray (10YR 3/1) silty clay loam, dark gray (10YR 4/1) dry; moderate fine and medium granular structure; friable; slightly acid; gradual smooth boundary. (Combined thickness of the A horizon is 35 to 60 centimeters.)

Bg1--46 to 56 centimeters; dark gray (10YR 4/1) silty clay loam; moderate fine subangular blocky structure parting to moderate medium granular; friable; very dark gray (10YR 3/1) coats on faces of peds; few fine distinct yellowish brown (10YR 5/4) redoximorphic concentrations; slightly acid; gradual smooth boundary.

Bg2--56 to 68 centimeters; dark gray (5Y 4/1) silty clay loam; moderate very fine and fine subangular blocky structure; friable; very dark gray (10YR 3/1) coats on faces of peds; few fine prominent yellowish brown (10YR 5/4) redoximorphic concentrations; slightly acid; gradual smooth boundary.

Bg3--68 to 91 centimeters; dark gray (5Y 4/1) silty clay loam; moderate very fine and fine subangular blocky structure; friable; few fine black (10YR 2/1) concretions (Mn oxides); common fine prominent yellowish brown (10YR 5/6) redoximorphic concentrations; slightly acid; gradual smooth boundary.

Bg4--91 to 107 centimeters; gray (5Y 5/1) silty clay loam; weak medium prismatic structure parting to weak fine and medium subangular blocky; friable; common fine prominent yellowish brown (10YR 5/6) redoximorphic concentrations; neutral; gradual smooth boundary. (Combined thickness of the Bg horizon is 50 to 80 centimeters.)

BCg1--107 to 122 centimeters; olive gray (5Y 5/2) silt loam; weak medium prismatic structure parting to weak fine and medium subangular blocky; few fine black concretions (Mn oxides); many fine prominent strong brown (7.5YR 5/6) redoximorphic concentrations; neutral; gradual smooth boundary.

BCg2--122 to 152 centimeters; olive gray (5Y 5/2) silt loam; weak coarse prismatic structure; friable; few fine black (10YR 2/1) concretions (Mn oxides); darker coats on edge of filled crayfish hole from 137 to 152 centimeters; many medium prominent strong brown (7.5YR 5/6) redoximorphic concentrations; neutral.

TYPE LOCATION: Major Land Resource Area (MLRA) 104-Eastern Iowa and Minnesota Till Prairies, Grundy County, Iowa subset; about 5 miles west and 3 miles south of Grundy Center; located about 1,440 feet east and 208 feet north of southwest corner of section 29, T. 87 N., R. 17 W.; USGS Grundy Center topographic quadrangle; lat. 42 degrees 18 minutes 42 seconds N. and long. 92 degrees 51 minutes 38 seconds W., NAD 83.

RANGE IN CHARACTERISTICS:
Thickness of the mollic epipedon--35 to 60 centimeters
Depth to carbonates--more than 120 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)-less than 5 percent

Ap or A horizon:
Hue--10YR to 5Y, or is neutral
Value--2 or 3
Chroma--0 to 2
Texture--silty clay loam
Clay content--27 to 35 percent
Sand content--less than 5 percent
Reaction--moderately acid to neutral

Bg horizon:
Hue--10YR to 5Y
Value--3 to 5
Chroma--1 or 2
Texture--silty clay loam
Clay content--27 to 35 percent
Sand content--less than 5 percent
Total phosphorus content--more than 500 ppm in the upper part
Reaction--slightly acid or neutral

BCg horizon:
Hue--2.5Y or 5Y
Value--4 or 5
Chroma--1 or 2
Texture--silty clay loam or silt loam
Clay content--24 to 32 percent
Sand content--less than 5 percent
Rock fragment content--0 percent
Reaction--slightly acid to slightly alkaline
Moist bulk density--1.35 to 1.45 gm/cc

Cg horizon (where present):
Hue--2.5Y or 5Y
Value--4 to 6
Chroma--1 or 2
Texture--silt loam
Clay content--20 to 26 percent
Sand content--less than 5 percent
Rock fragment content--0 percent
Reaction--slightly acid to slightly alkaline
Moist bulk density--1.35 to 1.45 gm/cc

COMPETING SERIES: These are the Chalmers, Chetomba, Dolbee, Drummer, Dunham, Elpaso, Elvira, Gillett Grove, Hartsburg, Madelia, Marcus, Mascoutah, Maxcreek, Maxfield, Maxmore, Ossian, Patton, Pella, Rushmore, Sable, and Wacousta series.
Chalmers--have a clay content of 12 to 18 percent and have matrix hues of 10YR in the lower third of the series control section
Chetomba--have carbonates within a depth of 100 centimeters
Dolbee--formed in alluvium and typically averages more than 10 percent sand in the lower third of the series control section
Drummer--have a sand content that averages more than 15 percent in the lower third of the series control section
Dunham--have a rock fragment content of more than 15 percent in the lower third of the series control section
Elpaso--have a sand content that averages more than 10 percent in the lower third of the series control section
Elvira--have a sand content that averages more than 50 percent in the lower third of the series control section
Gillett Grove--have a sand content of 25 to 45 percent in the lower third of the series control section
Hartsburg--have carbonates within a depth of 90 centimeters
Madelia--have carbonates within a depth of 100 centimeters
Marcus--have carbonates within a depth of 120 centimeters
Mascoutah--have a mean annual soil temperature of more than 13 degrees C
Maxcreek--have a sand content of more than 15 percent in the lower third of the series control section
Maxfield--have a sand content of 25 to 50 percent in the lower third of the series control section
Maxmore--have a sand content of 30 to 70 percent in the lower third of the series control section
Ossian--have a clay content that averages 18 to 27 percent in the particle-size control section
Patton--have a sand content of 7 to 25 percent in the lower third of the series control section
Pella--have carbonates within a depth of 100 centimeters
Rushmore--have carbonates within a depth of 90 centimeters
Sable--have a total phosphorus content of less than 400 ppm in the upper part of the cambic horizon
Wacousta--have carbonates within a depth of 50 centimeters

GEOGRAPHIC SETTING:
Parent material--loess
Landform--slightly concave heads of upland drainageways, summits of interfluves on dissected till plains, and on treads of stream terraces
Slope--0 to 2 percent
Elevation--155 to 460 meters above sea level
Mean annual air temperature--6 to 11 degrees C
Mean annual precipitation--735 to 965 millimeters
Frost-free period--145 to 205 days

GEOGRAPHICALLY ASSOCIATED SOILS: Garwin soils are associated and in a hydrosequence with the Muscatine and Tama soils.
Muscatine--are at slightly higher landscape positions on summits of interfluves and have a frequently saturated zone between depths of 0.3 to 1.1 meters during the wettest portions of years when precipitation is within one standard deviation of the 30 year mean of annual precipitation
Tama--are at higher and lower landscape positions on convex ridges and side slopes and do not have a frequently saturated zone within a depth of 1.8 meters in years when precipitation is within one standard deviation of the 30 year mean of annual precipitation

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--poorly drained--these soils are frequently saturated between the soil surface and a depth of 0.3 meter during the wettest portions of years when precipitation is within one standard deviation of the 30 year mean of annual precipitation
Saturated hydraulic conductivity--1.0 to 10.0 micrometers per second

USE AND VEGETATION:
Most areas are cultivated. The principal crops are corn, soybeans, small grains, and legume hay. The native vegetation is big bluestem, little bluestem, switchgrass, and other grasses of the tall grass prairie. See Additional Data section for native vegetative cover in Iowa and Minnesota.

DISTRIBUTION AND EXTENT:
Physiographic Division--Interior Plains
Physiographic Province--Central Lowland
Physiographic sections--Dissected till plains and Wisconsin driftless section
MLRAs--Eastern Iowa and Minnesota Till Prairies (104), Northern Mississippi Valley Loess Hills (105), and Illinois and Iowa Deep Loess and Drift (108)
LRR M; eastern Iowa, southeastern Minnesota, and southwestern Wisconsin
Extent--moderate

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana

SERIES ESTABLISHED: Tama County, Iowa, 1944.

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 the surface to a depth of 46 centimeters (Ap, A1, and A2 horizons);
cambic horizon--the zone from a depth of 46 to 107 centimeters (Bg1, Bg2, Bg3, and Bg4 horizons);
aquic 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.

Complete stratigraphic and chemical data are available in T. E. Fenton's thesis, Iowa State University, Ames, Iowa.

The differences between Sable and Garwin series need further study.

ADDITIONAL DATA: In Iowa and Minnesota, the native vegetative cover is a herbaceous wetland community commonly inhabited with Bluejoint Grasses, Fowl Bluegrasses, Green Muhlies, Fox Sedges, Field Sedges, Dudleys Rushes, Torreys Rushes, Swamp Milkweeds, False Sneezeweeds, False Asters, New England Asters, White Panicled Asters, and Wild Mints. Source: Iowa State Office, Natural Resources Conservation Service, Des Moines, IA.

---

National Cooperative Soil Survey
U.S.A.