LOCATION SMITHLAND               IA

Established Series
Rev. BJC-JRH
09/2016

SMITHLAND SERIES

The Smithland series consists of very deep, somewhat poorly drained soils on flood plains and upland drainageways. These soils formed in alluvium. Slopes range from 0 to 5 percent. Mean annual air temperature is about 10 degrees C (50 degrees F). Mean annual precipitation is about 711 millimeters (28 inches).

TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Aquic Cumulic Hapludolls

TYPICAL PEDON: Smithland silty clay loam, on a slope of less than 1 percent, in a cultivated field, at an elevation of 331 meters (1,085 feet) above sea level. (Colors are for moist soil unless otherwise stated.)

Ap--0 to 18 centimeters (0 to 7 inches); very dark gray (10YR 3/1) silty clay loam, dark grayish brown (10YR 4/2) dry; weak fine granular structure; friable; few very fine roots; few very fine tubular pores; neutral; abrupt smooth boundary.

A1--18 to 41 centimeters (7 to 16 inches); black (10YR 2/1) silty clay loam, dark grayish brown (10YR 4/2) dry; weak fine subangular blocky structure parting to weak fine granular; friable; few fine roots; few fine tubular pores; neutral; clear smooth boundary.

A2--41 to 61 centimeters (16 to 24 inches); black (10YR 2/1) and very dark gray (10YR 3/1) silty clay loam, dark grayish brown (10YR 4/2) dry; weak fine subangular blocky structure parting to weak fine granular; friable; few fine roots; few fine tubular pores; neutral; clear smooth boundary.

A3--61 to 86 centimeters (24 to 34 inches); very dark gray (10YR 3/1) silty clay loam; weak very fine and fine subangular blocky structure; friable; few fine roots; few fine tubular pores; few fine prominent brown (7.5YR 4/4) redoximorphic concentrations; neutral; clear wavy boundary. [Combined thickness of A horizon is 61 to 91 centimeters (24 to 36 inches).]

Bg--86 to 102 centimeters (34 to 40 inches); very dark gray (10YR 3/1) silty clay loam; weak very fine and fine subangular blocky structure; friable; few fine roots; few very fine tubular pores; few fine prominent yellowish brown (10YR 5/4) redoximorphic concentrations; neutral; gradual smooth boundary. [30 to 102 centimeters (12 to 40 inches) thick]

BCg--102 to 127 centimeters (40 to 50 inches); very dark grayish brown (10YR 3/2) and dark grayish brown (10YR 4/2) silty clay loam; weak fine and medium subangular blocky structure; friable; few fine tubular pores; few fine distinct yellowish brown (10YR 5/4) and brown (7.5YR 5/4) redoximorphic concentrations; neutral; gradual smooth boundary. [0 to 30 centimeters (0 to 12 inches) thick]

Cg--127 to 152 centimeters (50 to 60 inches); dark grayish brown (10YR 4/2) silty clay loam; massive, with weak, thin alluvial stratification; friable; few very fine tubular pores; few fine distinct yellowish brown (10YR 5/4) and common brown (7.5YR 4/4) redoximorphic concentrations; neutral.

TYPE LOCATION: Monona County, Iowa; about 95 feet west and 95 feet north of the southeast corner of sec. 5, T. 84 N., R. 43 W.; USGS Mapleton SE quadrangle; lat. 42 degrees 6 minutes 39 seconds N. and long. 95 degrees 52 minutes 1 second W., NAD 27.

RANGE IN CHARACTERISTICS:
Thickness of the mollic epipedon--greater than 91 centimeters (36 inches)
Depth to carbonates--greater than 152 centimetes (60 inches)
Content of clay in the particle-size control section (weighted average)--27 to 35 percent
Content of sand in the particle-size control section (weighted average)--less than 15 percent fine sand and sand coarser than fine sand

Ap and A horizons:
Hue--10YR or is neutral
Value--2, 2.5, or 3
Chroma--0 to 2
Texture--silty clay loam
Clay content--27 to 40 percent
Sand content--1 to 15 percent
Reaction--moderately acid to neutral

Overwash phase (if it occurs):
Thickness--15 to 38 centimeters (6 to 15 inches)
Hue--10YR or is neutral
Value--2, 2.5, or 3
Chroma--0 to 2
Texture--silt loam
Clay content--15 to 27 percent
Sand content--15 to 30 percent
Reaction--moderately acid to neutral

Some pedons have an AC horizon.

Bg horizon:
Hue--10YR
Value--2 to 4
Chroma--1 or 2
Texture--silty clay loam
Clay content--30 to 35 percent
Sand content--1 to 15 percent
Reaction--moderately acid to neutral

BCg horizon:
Hue--10YR or 2.5Y
Value--3 or 4
Chroma--1 or 2
Texture--silty clay loam
Clay content--30 to 35 percent
Sand content--1 to 15 percent
Reaction--moderately acid to neutral

Cg horizon:
Hue--10YR or 2.5Y
Value--3 or 4
Chroma--1 or 2
Texture--silty clay loam, silt loam, or clay loam
Clay content--25 to 35 percent
Sand content--1 to 25 percent
Reaction--slightly acid or neutral

COMPETING SERIES: These are the Ely, Lawson, and Littleton series.
Ely--have a mollic epipedon less than 91 centimeters (36 inches) in thickness
Lawson--have a mollic epipedon less than 91 centimeters (36 inches) in thickness
Littleton--have a mollic epipedon less than 91 centimeters (36 inches) in thickness

GEOGRAPHIC SETTING:
Parent material--alluvium
Landform--flood plains and upland drainageways
Slopes--0 to 5 percent
Elevation--213 to 366 meters (700 to 1,200 feet) above sea level
Mean annual air temperature--8 to 13 degrees C (46 to 55 degrees F)
Mean annual precipitation--508 to 914 millimeters (20 to 36 inches)
Frost-free period--140 to 160 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ackmore, Colo, Kennebec, Nodaway, and Zook soils.
Ackmore--are in landform positions similar to those of the Smithland soils, have an ochric epipedon 13 to 25 centimeters (5 to 10 inches thick), and have buried horizons
Colo--are in similar landscape positions as Smithland soils and have a saturated zone within a depth of 0.3 meters (1 foot) during March to June in most years
Kennebec--are in the slightly higher elevations and have a saturated zone between depths of 0.91 to 1.83 meters (3 to 6 feet) during April to June in most years
Nodaway--are in the slightly higher elevations, have an ochric epipedon 15 to 25 centimeters (6 to 10 inches) thick, and have a saturated zone between depths of 0.91 to 1.83 meters (3 to 6 feet) during April to June in most years
Zook--are in the lower elevations, have a clay content of 35 to 44 percent in the particle-size control section, and have a saturated zone within a depth of 0.3 meters (1 foot) during March to June in most years

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--somewhat poorly drained--a saturated zone occurs between depths of 0.3 to 0.91 meters (1 to 3 feet) during March to June in most years and is considered apparent
Saturated hydraulic conductivity: 1.00 to 10.00 micrometers per second
Flooding--rare to occasional flooding with very brief or brief duration during the months of February to November from precipitation events and snowmelt

USE AND VEGETATION:
Most areas are cultivated. The principal crops are corn, soybeans, small grains and hay. A few areas are in permanent pasture with widely spaced willow and cottonwood trees. The native vegetation is big bluestem, indiangrass, switchgrass, and other grasses of the tall grass prairie.

DISTRIBUTION AND EXTENT:
LRR M, MLRAs 102B and 107; western Iowa and possibly eastern Nebraska and northwestern Missouri. This series is of moderate extent.

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

SERIES ESTABLISHED: Monona County, Iowa, 1995.

REMARKS:
Particle-size control section--the zone from a depth of 25 to 100 centimeters (A1, A2, A3, and Bg horizons);
series control section--the zone from the surface to a depth of 150 centimeters (Ap, A1, A2, A3, Bg, BCg, and Cg horizons).

Diagnostic horizons and features recognized in this pedon:
mollic epipedon--the zone from the surface to a depth of 127 centimeters (50 inches) (Ap, A1, A2, A3, Bg, and BCg horizons);
cambic horizon--the zone from a depth of 86 to 127 centimeters (34 to 50 inches) (Bg and BCg horizons);
udic moisture regime.

Few to common, high chroma redoximorphic concentrations are at depths below 61 centimeters (24 inches).

Cation-exchange class is inferred from lab data for similar soils in the surrounding area.

Taxonomy version--Keys to Soil Taxonomy, twelfth edition, 2014.

These soils have been placed in the Colo series in previous surveys.

ADDITIONAL DATA:
Laboratory data--Iowa State University Experiment Station, Ames Iowa, File No. 56335-56342 and pedon number 00-IA193-012A
Laboratory data--Kellogg Soil Survey Laboratory, Lincoln, Nebraska pedon S1998IA047001

---

National Cooperative Soil Survey
U.S.A.