LOCATION BLAKE              IA+IL MO NE SD

BLAKE SERIES

The Blake series consists of very deep, somewhat poorly drained soils on flood plains. These soils formed in recently deposited calcareous, silty alluvium. Permeability is moderate in the upper part and moderate or moderately rapid in the lower part. Slopes range from 0 to 2 percent. Mean annual air temperature is about 11 degrees C (about 51 degrees F). Mean annual precipitation is about 710 millimeters (about 28 inches).

TAXONOMIC CLASS: Fine-silty, mixed, superactive, calcareous, mesic Aquic Udifluvents

TYPICAL PEDON: Blake silty clay loam, on a nearly level, southwest-facing slope in a cultivated field, at an elevation of 307 meters (1,007 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) and very dark grayish brown (10YR 3/2) silty clay loam, very dark gray (10YR 3/1) crushed, grayish brown (10YR 5/2) dry; weak very fine subangular blocky structure; friable; few fine pores; few dark stains around root channels; slightly effervescent; slightly alkaline; clear smooth boundary. [15 to 25 centimeters (6 to 10 inches) thick]

Cg1--18 to 61 centimeters (7 to 24 inches); dark grayish brown (10YR 4/2) and dark gray (10YR 4/1) silty clay loam, olive brown (2.5Y 4/4) kneaded, light brownish gray (10YR 6/2) dry; massive with weak thin alluvial stratification; few fine dark accumulations (oxides); few fine distinct dark yellowish brown (10YR 4/4) masses of iron; few fine distinct grayish brown (2.5Y 5/2) redoximorphic depletions; slightly effervescent; slightly alkaline; clear smooth boundary. [30 to 127 centimeters (12 to 50 inches) thick]

Cg2--61 to 152 centimeters (24 to 60 inches); grayish brown (2.5Y 5/2) silt loam; massive with weak thin alluvial stratification; very friable; common very fine pores; some streaks of pale brown (10YR 6/3) calcium carbonate concentrations; few fine distinct dark gray (10YR 4/1) redoximorphic depletions; strongly effervescent; slightly alkaline.

TYPE LOCATION: MLRA 107B (Iowa and Missouri Deep Loess Hills), Harrison County Iowa subset; about 6 miles west of Missouri Valley; about 1,950 feet east and 140 feet south of the northwest corner of sec. 16, T. 78 N., R. 45 W.; USGS Modale quadrangle; lat. 41 degrees 33 minutes 35 seconds N. and long. 96 degrees 1 minute 35 seconds W., NAD 83

RANGE IN CHARACTERISTICS:
Depth to carbonates--0 to 25 centimeters (0 to 10 inches)
Content of clay in the particle-size control section (weighted average)--22 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 or A horizon:
Hue--10YR or 2.5Y
Value--3 or 4
Chroma--1 or 2
Texture--silty clay loam, silt loam, or loam
Clay content--18 to 38 percent
Sand content--1 to 40 percent fine sand and sand coarser than fine sand
Reaction--neutral to moderately alkaline

Cg1 horizon:
Hue--10YR or 2.5Y
Value--3 or 4
Chroma--1 to 4
Texture--silt loam or silty clay loam but individual strata range in texture from very fine sandy loam to silty clay
Clay content--22 to 35 percent
Sand content--less than 15 percent fine sand and sand coarser than fine sand
Reaction--slightly alkaline or moderately alkaline
Some pedons have strata that do not have redoximorphic features

Cg2 horizon:
Hue--10YR or 2.5Y
Value--2 to 5
Chroma--1 to 3
Texture--silt loam or silty clay loam
Clay content--10 to 30 percent
Sand content--less than 15 percent fine sand and sand coarser than fine sand
Reaction--slightly alkaline or moderately alkaline

Some pedons have strata between depths of 102 to 152 centimeters (40 to 60 inches) of loamy very fine sand, loam, very fine sandy loam or silty clay up to 30 centimeters (12 inches) thick
Some pedons have very thin darkened layers
Some pedons have a sandy substratum below a depth of 152 centimeters (60 inches)

COMPETING SERIES: This is the Lossing series.
Losing--have a sand content of 15 to 50 percent in the lower two thirds of the series control section

GEOGRAPHIC SETTING:
Parent material--recently deposited calcareous, silty alluvium
Landform--flood plains
Slopes--0 to 2 percent
Elevation--200 to 500 meters (about 700 to 1,650 feet) above sea level
Mean annual air temperature--8 to 13 degrees C (47 to 56 degrees F)
Mean annual precipitation--510 to 910 centimeters (20 to 36 inches)
Frost-free period--135 to 165 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Albaton, Grable, Haynie and Onawa soils.
Albaton--are in the slightly lower landscape positions and have a saturated zone within a depth of 30 centimeters (1 foot) during April to June in most years
Grable--are in landscape positions similar to those of the Blake soils, do not have a saturated zone within a depth of 183 centimeters (6 feet) during April to June in most years and have a sand content of 65 to 95 percent in the lower two thirds of the particle-size control section
Haynie--are at the higher elevations, do not have a saturated zone within a depth of 183 centimeters (6 feet) during April to June in most years and have a sand content of less than 15 percent in the particle-size control section
Onawa--are in landscape positions similar to those of the Blake soils and have a clay content of 10 to 18 percent in the lower two thirds of the particle-size control section

DRAINAGE AND PERMEABILITY:
Drainage--a saturated zone occurs within depths of 30 to 90 centimeters (1 to 3 feet) during April to June in most years, is considered apparent and the depth to saturation has been influenced by the down-cutting of nearby streams
Permeability--moderate in the upper part and moderate or moderately rapid in the lower part
Surface runoff potential--low
Flooding--rare, occasional, or frequent flooding for brief periods during the months of February to November resulting from precipitation events and snowmelt and flooding from streambank overflow is limited where dams and levees protect areas

USE AND VEGETATION:
Most areas are cultivated. The principal crops are corn, oats, and soybeans. Some areas are leveled and irrigated. The native vegetation is big bluestem, indiangrass, switchgrass, and other grasses of the tall grass prairie.

DISTRIBUTION AND EXTENT:
Major Land Resource Areas (MLRAs):
63B - Southern Rolling Pierre Shale Plains
102C - Loess Uplands)
107B - Iowa and Missouri Deep Loess Hills
115B - Central Mississippi Valley Wooded Slopes, Southern Part
115C - Central Mississippi Valley Wooded Slopes, Northern Part
Flood plains of the Missouri and Mississippi Rivers.
This series is of moderate extent.

MLRA OFFICE RESPONSIBLE: St. Paul, Minnesota

SERIES ESTABLISHED: Woodbury County, Iowa, 1971.

REMARKS:
Particle-size control section--the zone from a depth of 25 to 100 centimeters (about 10 to 40 inches - Cg1 and Cg2 horizons);
Series control section--the zone from the surface to a depth of 150 centimeters (about 60 inches - Ap, Cg1 and Cg2 horizons).

Diagnostic horizons and features recognized in this pedon:
Diagnostic Surface Horizon: ochric epipedon--the zone from the surface to a depth of 18 centimeters (7 inches - Ap horizon)
Soil Moisture Regime: udic.
Cation-exchange class is inferred from lab data for similar soils in the surrounding area.
Taxonomy version--Second Edition, 1999.

Blake soils were correlated as Onawa silty clay loam in previous soil surveys.

ADDITIONAL DATA:
Laboratory data--Iowa State University, Ames, Iowa.