LOCATION BRINKMAN WIEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Mollic Paleudalfs
TYPICAL PEDON: Brinkman silt loam on a convex 2 percent slope in cropland at an elevation of about 1345 feet. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 9 inches; very dark grayish brown (10YR 3/2) silt loam with about 5 percent mixing of dark yellowish brown (10YR 4/4), grayish brown (10YR 5/2) dry; moderate medium granular structure; friable; common fine and very fine roots; neutral; abrupt wavy boundary. (7 to 9 inches thick)
Bt1--9 to 18 inches; dark yellowish brown (10YR 4/4) silt loam; moderate medium subangular blocky structure; friable; common fine and very fine roots; many prominent dark brown (7.5YR 3/2) clay films on faces of peds; neutral; clear wavy boundary.
Bt2--18 to 35 inches; dark yellowish brown (10YR 4/4) silt loam; moderate medium subangular blocky structure; friable; few fine and very fine roots; many faint brown (10YR 4/3) clay films on faces of peds; slightly acid; clear wavy boundary.
Bt3--35 to 47 inches; dark yellowish brown (10YR 4/4) silt loam; moderate medium subangular blocky structure; friable; few fine and very fine roots; few fine prominent yellowish brown (10YR 5/6) masses of iron accumulation; many faint brown (10YR 4/3) clay films on faces of peds; slightly acid; gradual wavy boundary.
Bt4--47 to 59 inches; dark yellowish brown (10YR 4/4) silt loam; moderate coarse subangular blocky structure; friable; few fine and very fine roots; common fine prominent yellowish brown (10YR 5/6) masses of iron accumulation and few fine prominent pale brown (10YR 6/3) masses of iron depletion; many faint brown (10YR 4/3) clay films on faces of peds; slightly acid; gradual wavy boundary.
Bt5--59 to 71 inches; yellowish brown (10YR 5/4) silt loam; weak coarse subangular blocky structure; friable; many medium prominent strong brown (7.5YR 5/6) masses of iron accumulation and many fine prominent grayish brown (10YR 5/2) masses of iron depletion; many faint dark yellowish brown (10YR 4/4) clay films on faces of peds; about 2 percent chert channers by volume; slightly acid; clear wavy boundary. (Combined thickness of the Bt horizons ranges from 41 to 73 inches.)
2Bt6--71 to 80 inches; strong brown (7.5YR 4/6) clay; moderate medium prismatic structure; firm; common medium prominent strong brown (7.5YR 5/6) masses of iron accumulation and few fine prominent grayish brown (10YR 5/2) masses of iron depletion; many faint brown (7.5YR 4/4) clay films on faces of peds; about 13 percent chert channers by volume; slightly acid.
TYPE LOCATION: LaCrosse, Wisconsin; about 1/2 mile west of Middle Ridge; 1510 feet west and 1890 feet north of the southeast corner of sec. 3, T. 15 N., R. 5 W.
RANGE IN CHARACTERISTICS: Thickness of the loess deposits and depth to the clayey pedisediment ranges from 45 to 80 inches but generally is from 60 to 80 inches. A lithic contact with dolostone bedrock is between a depth of 80 and 120 inches or more. Thickness of the A horizon, depth to layer of maximum clay content, thickness of the Bt horizon, and depth to dolostone bedrock decrease with increasing gradient on convex slopes. Clay content of the particle-size control section averages from 20 to 25 percent. Total sand content is less than 12 percent in the loess and content of fine sand or coarser is 5 percent or less. Rock fragments are absent in the loess mantle, except in the horizon directly above the clayey pedisediment, which may have up to 5 percent chert fragments. Dolostone and chert fragments are in the pedisediment. Total volume of rock fragments ranges from 5 to 35 percent in the clayey pedisediment. Volume of channers ranges from 5 to 35 percent and volume of flagstones ranges from 0 to 15 percent.
The Ap horizon has hue of 10YR, value of 2 or 3, and chroma of 1 or 2. It is silt loam. Reaction ranges from strongly acid to slightly acid but ranges to neutral, where the soil is limed.
The Bt horizon has hue of 10YR, value of 3 to 5, and chroma of 3 or 4. It is silt loam or silty clay loam. Reaction ranges from strongly acid to slightly acid but ranges to neutral in the upper part, where the soil is limed. Clay content ranges from 18 to 29 percent.
The 2Bt horizon has hue of 2.5YR, 5YR, or 7.5YR, value of 3 to 6, and chroma of 3 to 8. It is clay loam, silty clay loam, clay, silty clay, or the channery and flaggy analogues. Clay content is 35 to 75 percent. Reaction ranges from very strongly acid to slightly acid.
COMPETING SERIES: This is the Valton series. Valton soils have a loess mantle that is 15 to 40 inches thick.
GEOGRAPHIC SETTING: Brinkman soils are on hills in bedrock controlled uplands. Slopes range from 2 to 12 percent. Brinkman soils formed in loess and in a layer of clayey pedisediment. Frost free period ranges from about 135 to 160 days. Elevation ranges from 1200 to 1360 feet. Mean annual precipitation ranges from about 28 to 33 inches. Mean annual air temperature ranges from about 47 degrees to 51 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: Near the Type Location these include the well drained Mt. Carroll and Valton soils. Mt. Carroll soils have loess deposits greater than 80 inches. Valton soils have loess deposits 15 to 40 inches thick over the clayey pedisediment.
DRAINAGE AND PERMEABILITY: Moderately well drained. Permeability is moderate in the loess and very slow to slow in the clayey pedisediment. Brinkman soils have a perched seasonal high water table at a depth of 3.5 to 6 feet for 1 month or more per year at some time during the period of October to June in 6 or more out of 10 years.
USE AND VEGETATION: These soils are used for cropland. Common crops are corn, small grains, and hay.
DISTRIBUTION AND EXTENT: Brinkman soils will be found throughout the "Driftless Area" where the thicker clayey rountree is covered by loess deposits 45 to 80 inches thick. As of 1998 they have been mapped only in LaCrosse County, Wisconsin.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota.
SERIES ESTABLISHED: LaCrosse County, Wisconsin, 2001. The name of the series is from a ridge in southern LaCrosse County.
REMARKS: The clayey pedisediment is of uncertain origin. Currently it is thought to be a depositional feature and is locally referred to as the "Rountree Formation". In the past it was thought to be clayey residuum from dolostone.
Diagnostic horizons and features recognized in this pedon are: ochric epipedon - zone from the surface to a depth of approximately 9 inches (A horizon); argillic horizon - zone from approximately 9 to 80 inches (Bt1, Bt2, Bt3, Bt4, Bt5, and 2Bt6 horizons); udic moisture regime.