LOCATION WEBSTER IA+MNEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Typic Endoaquolls
TYPICAL PEDON: Webster silty clay loam on a concave slope of about 1 percent gradient in a cultivated field. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 8 inches; black (N 2/0) silty clay loam, very dark gray (10YR 3/1) dry; weak fine subangular blocky structure; friable; neutral; clear smooth boundary.
A--8 to 16 inches; black (N 2/0) silty clay loam, very dark gray (10YR 3/1) dry; few fine faint very dark grayish brown (2.5Y 3/2) redox depletions; weak medium subangular blocky structure; friable; about 3 percent gravel; few worm casts; neutral; clear smooth boundary. (Combined thickness of the A horizons is 14 to 24 inches.)
BAg--16 to 21 inches; dark gray (5Y 4/1) clay loam; few fine distinct dark grayish brown (2.5Y 4/2) redox depletions; weak fine subangular blocky structure; friable; continuous very dark gray (5Y 3/1) coatings on faces of peds; many roots; many pores; neutral; gradual smooth boundary. (0 to 6 inches thick)
Bg1--21 to 26 inches; olive gray (5Y 5/2) clay loam; common fine faint dark gray (5Y 4/1) redox depletions; weak fine subangular blocky structure; friable; discontinuous very dark gray (10YR 3/1) coatings on faces of peds; many roots; many fine pores and worm holes; few fine dark concretions (iron and manganese oxides); neutral; clear smooth boundary.
Bg2--26 to 32 inches; light olive gray (5Y 6/2) clay loam; weak fine subangular blocky structure; friable; discontinuous dark gray (5Y 4/1) coatings on faces of peds; few roots; many fine and medium pores; few dark concretions (iron and manganese oxides); few very dark gray (10YR 3/1) organic coatings along root channels and cleavage planes; neutral; gradual smooth boundary. (Combined thickness of the Bg horizons is 7 to 26 inches.)
BCg--32 to 40 inches; light olive gray (5Y 6/2) loam; few fine prominent yellowish brown (10YR 5/4 and 5/8) redox concentrations; weak fine subangular blocky structure; friable; few roots; few white masses and streaks of calcium carbonate in the lower part; slightly alkaline; clear smooth boundary. (0 to 9 inches thick)
Cg--40 to 60 inches; light olive gray (5Y 6/2) loam; common medium prominent yellowish brown (10YR 5/4 and 5/8) redox concentrations; massive; friable; about 3 percent gravel; strongly effervescent; slightly alkaline.
TYPE LOCATION: Hamilton County, Iowa; about 1 mile south of Webster City; 700 feet west and 1,480 feet north of the southeast corner of sec. 12, T. 88 N., R. 26 W.; USGS Webster City, Iowa quadrangle, latitude 42 degrees 26 minutes 45 seconds N., longitude 93 degrees 49 minutes 06 seconds W.
RANGE IN CHARACTERISTICS: Solum thickness generally ranges from 24 to 42 inches, but it is as much as 50 inches in some pedons. The depth to free carbonates has about the same range as solum thickness, although in some pedons the BCg horizon lacks free carbonates. The mollic epipedon ranges from 14 to 24 inches in thickness. Rock fragments make up 1 to 10 percent, by volume, of those horizons formed in glacial till.
The Ap and A horizons have hue of 10YR, 2.5Y or is neutral, value of 2 or 3, and chroma of 0 or 1. They are clay loam, loam, or silty clay loam with 15 to 20 percent sand.
The Bg and BCg horizons have hue of 5Y or 2.5Y, value of 4 or 5, and chroma of 1 or 2. Redox concentrations or oxide concretions of high and low chroma are typically present. They are typically clay loam or loam, with silty clay loam with a moderate sand content in the range. Clay content typically averages from 25 to 35 percent and sand content between about 18 and 45 percent. Clay films and a slight clay increase occur in some pedons but do not meet the criteria for an argillic.
The Cg horizon has hue of 2.5Y or 5Y, value of 4 through 6 and chroma of 1 or 2. The texture of the moderately coarse substratum phase is loam, fine sandy loam or sandy loam. It has 12 to 22 percent clay with a total sand content more than 40 percent. The texture of the moderately fine substratum phase is loam or clay loam. The clay content is 20 to 30 percent with total sand content of less than 45 percent. Thin strata of silty or sandy material are in the lower part of the soil in some pedons. Where the soils contain such strata, loam till is generally at depths of 3 to 6 feet.
COMPETING SERIES: These are the Clyde, Colwood, Faxon, free, Kossuth, Letri, Reddick, Selma, Tripoli, and Wolcott series in the same family and the Biscay, Canisteo, and Drummer series. Clyde soils are commonly leached to greater depths, contain more yellowish brown and strong brown mottles in the lower part of the sola, contain more glacial boulders, and generally are more stratified in the subsoil and substrata. Colwood soils commonly have less clay in the 10- to 40-inch control section, and they are more stratified. Faxon soils have lithic contacts at depths of less than 40 inches. Free soils have more than 15 percent rock fragments at depths of 20 to 40 inches and less than 20 percent clay in the upper 20 inches of the argillic horizon. Kossuth soils average more clay in the upper part of the solum and have a distinct break in parent materials. Letri soils typically have thinner sola and are shallower to free carbonates and have firm consistence at depths of less than 40 inches. Reddick soils have finer textures in the lower part of the B horizon. Selma soils typically have thicker sola and coarse textured C horizons beginning at depths between 40 and 60 inches. Tripoli soils have higher chroma in the B horizon, firm consistence at depths of less than 40 inches, and a stone line at the top of loam till at depths of 18 to 30 inches. Wolcott soils have firm glacial till C horizons and are very poorly drained. Biscay soils have sand and gravel within depths of 40 inches. Canisteo soils are calcareous throughout. Drummer soils are fine-silty.
GEOGRAPHIC SETTING: Webster soils are on relatively undissected till plains of Wisconsin age. Slopes are nearly plane to slightly concave and range in gradient from 0 to 3 percent. Webster soils formed in loamy glacial till of mixed mineralogy and from local alluvium from such till. Mean annual air temperature is about 45 to 49 degrees F, and mean annual precipitation is about 28 to 32 inches. Frost free days range from 120 to 180. Elevation above sea level ranges from 700 to 1400 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Canisteo soils and the Clarion, Glencoe, Harps, Nicollet, Okoboji, and Wacousta soils. Canisteo soils are on similar landscape positions. Clarion and Nicollet soils are the most common associates and form a drainage sequence with Webster soils. Clarion and Nicollet soils lack gleyed B horizons and are on slightly higher elevations. Glencoe soils have mollic epipedons over 24 inches thick. Harps soils are highly calcareous and are on rims of depressions. Okoboji soils have thicker A horizons and typically contain less sand in the sola. Wacousta soils have thinner A horizons and clear or abrupt boundary to the B horizon. Okoboji, Glencoe and Wacousta soils are in depressions.
DRAINAGE AND PERMEABILITY: Webster soils are poorly drained, and most areas are artificially drained with tile and open ditches. Runoff is slow. Permeability is moderate. The seasonal high water table is a depths of 0 to 1 foot from November to July in most years where undrained.
USE AND VEGETATION: Largely cultivated and cropped intensively to corn and soybeans. Small grain and hay are other major crops. Native vegetation is predominantly wet-site tall prairie grasses.
DISTRIBUTION AND EXTENT: North-central and central Iowa and south-central Minnesota. Extensive in MLRA-103.
MLRA OFFICE RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Clay County, Iowa, 1916.
REMARKS: Diagnostic horizons and features recognized in this pedon are: Mollic epipedon - the zone from the surface of the soil to a depth of 16 inches (Ap and A horizon); Cambic horizon - the zone from a depth of 16 to 40 inches (BAg, Bg1, Bg2 and BCg horizons); aquic moisture regime based on low chroma colors below the mollic epipedon.
The concepts of moderately coarse and moderately fine substratum phases were established by the mlra-103 steering committee. The Des Moines Lobe till gets sandier and contains less clay as one progresses south along the path of the Des Moines advance.
Competing series not updated as of this edit.