LOCATION DOUDS IAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Typic Hapludalfs
TYPICAL PEDON: Douds loam with a convex slope of 12 percent in a hayfield. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 5 inches; dark grayish brown (10YR 4/2) loam; grayish brown (10YR 5/2) dry; weak very fine and fine granular structure; friable; common very fine and fine roots; moderately acid; abrupt smooth boundary. (4 to 8 inches thick)
E--5 to 10 inches; brown (10YR 4/3) loam; grayish brown (10YR 5/2) dry; weak thin platy structure; friable; common very fine roots; common faint dark grayish brown (10YR 4/2) coatings on faces of peds and in pores; moderately acid; abrupt smooth boundary. (0 to 8 inches thick)
Bt1--10 to 14 inches; dark yellowish brown (10YR 4/4) loam; weak thin platy structure parting to weak very fine subangular blocky; friable; few fine roots; few faint dark grayish brown (10YR 4/2) clay films on faces of peds and in pores; common distinct light gray (10YR 6/1) silt coatings on horizontal faces of peds; moderately acid; abrupt smooth boundary.
Bt2--14 to 24 inches; dark yellowish brown (10YR 4/4) loam; moderate very fine and fine subangular blocky structure; friable; few fine roots; few distinct dark grayish brown (10YR 4/2) clay films on faces of peds and in pores; very strongly acid; clear smooth boundary.
Bt3--24 to 32 inches; dark yellowish brown (10YR 4/4) loam; moderate medium and coarse subangular blocky structure; friable; common distinct dark grayish brown (10YR 4/2) clay films on faces of peds and in pores; common fine and medium prominent yellowish red (5YR 5/8) redox concentrations; very strongly acid; gradual smooth boundary.
Bt4--32 to 44 inches; dark yellowish brown (10YR 4/6) loam; weak medium prismatic structure parting to weak medium and coarse subangular blocky; friable; common distinct dark grayish brown (10YR 4/2) clay films on faces of peds and in pores; few fine prominent yellowish red (5YR 5/8) and common fine and medium prominent yellowish brown (10YR 5/8) redox concentrations; many medium and coarse prominent light brownish gray (2.5Y 6/2) redox depletions; very strongly acid; gradual smooth boundary. (Combined thickness of the Bt horizons is 20 to 50 inches.)
BC--44 to 54 inches; dark yellowish brown (10YR 4/6) loam; weak medium and coarse subangular blocky structure; firm; common fine distinct yellowish brown (10YR 5/8) and few fine prominent yellowish red (5YR 4/6) redox concentrations; many fine and medium prominent light brownish gray (2.5Y 6/2) redox depletions; very strongly acid; gradual smooth boundary. (6 to 12 inches thick)
C1--54 to 70 inches; yellowish brown (10YR 5/6) clay loam; massive; friable; common fine prominent yellowish red (5YR 5/8) redox concentrations; common fine prominent light brownish gray (2.5Y 6/2) redox depletions; few fine prominent black stains; moderately acid; gradual smooth boundary.
C1--70 to 80 inches; strong brown (7.5YR 5/6) sandy loam; massive; very friable; few medium prominent pale brown (10YR 6/3) redox concentrations; few fine prominent black stains; moderately acid.
TYPE LOCATION: Van Buren County, Iowa; about 3 miles east and 3 miles north of Stockport; 100 feet west and 1360 feet south of the northeast corner of section 4, T. 70 N., R. 8 W. U.S.G.S. Lockridge West, Iowa - Iowa Topographic Quadrangle; latitude 40 degrees, 53 minutes, and 49 seconds N., longitude 91 degrees, 46 minutes, and 35 seconds W.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 36 to 72 inches. Carbonates are lacking in the solum and to a depth of several feet in the C horizon. Solum thickness and depth to stratified material decreases as gradient increases on convex slopes. Pebbles and coarser fragments are few or lacking in the upper 30 inches of the solum, but they are in strata or bands in some pedons below this depth. Douds
soils typically are moderately acid to very strongly acid in the most acid part of the solum.
The A horizon has 10YR hue, value of 3 and chroma of 1 or 2. Cultivated areas have an Ap horizon of 10YR hue, value of 4 or 5, and chroma of 2 or 3. It is loam, silt loam, or clay loam.
The E horizon has 10YR hue, value of 4 or 5, and chroma of 2 or 3. The E horizon is loam or silt loam containing noticeable sand. Eroded or cultivated areas have all or part of the E horizon mixed with the Ap horizon.
Some pedons have a BE horizon.
The Bt horizon has hue of 10YR or 7.5YR, value of 4 or 5, and chroma of 4 to 8. Redox concentrations of 7.5YR or 5YR hue are usually below a depth of 24 inches, and redox depletions of 10YR or 2.5Y hue are below a depth of 30 inches in some pedons. The Bt horizon is loam, clay loam, sandy loam, or sandy clay loam. Strata of loam, sandy loam, or loamy sand are common in the BC and C horizons. The upper 20 inches of the argillic horizon averages between 26 and 32 percent clay. Above a depth of 36 inches the sandy layers are typically less than 6 inches thick.
COMPETING SERIES: These are the Caprell, Lindley, McHenry, Norden, Pecatonica, Westville, and Whalan series of the same family and the Caleb, Galland, and Mystic series. All of the soils except Caleb, Galland, and Mystic soils lack stratification in the lower part of the solum and are not formed in leached alluvium of pre-Sangamon age. Caprell, McHenry, and Westville soils formed in loess or silty material over glacial till. Lindley soils formed in glacial till. Norden soils formed in loamy residuum over sandstone bedrock. Pecatonica soils formed in loess or silty material over a glacial till derived palesol. Whalan soils formed in glacial till and a thin layer of residuum over limestone bedrock. Caleb and Mystic soils have thicker and/or darker A1 horizons. Galland and Mystic soils average more than 35 percent clay in the series control section, and are somewhat wetter.
GEOGRAPHIC SETTING: Douds soils are on convex ridgetops and side slopes of high stream terraces that border valleys of major streams and their tributaries. Slope gradients range from 9 to 40 percent. Douds soils formed in mixed alluvium of pre-Sangamon age that ranges from 10 to 30 feet in thickness. Mean annual air temperature ranges from 47 to 56 degrees F, and mean annual precipitation ranges from about 30 to 35 inches. The annual frost free period ranges from about 155 to 180 days. Elevation ranges from about 600 to 1200 feet above mean sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Caleb, Galland, Lindley, and Mystic soils and the Chequest, Clinton, and Weller soils. The Caleb soils are on similar landscape positions. The Galland and Mystic soils are on higher stream terraces, and the Lindley soils are on adjacent upland slopes. The Chequest soils are on nearby flood plains. They are poorly drained. The Clinton and Weller soils are also on somewhat higher positions of nearby loess mantled stream terraces. They contain less sand throughout and lack stratification in the lower part of the solum.
DRAINAGE AND PERMEABILITY: Moderately well drained. Surface runoff is medium to rapid. Permeability is variable but generally moderate in the upper part of the solum and moderate to moderately rapid in the lower part. The depth to an intermittent apparent water table is 4 to 5 feet sometime from November through July in most years.
USE AND VEGETATION: Commonly used for growing cultivated crops, but some is used for pasture. Corn, soybeans, small grains, and hay are grown on the less sloping areas. Many steeper areas are left in pasture. Native vegetation was oak-hickory forest.
DISTRIBUTION AND EXTENT: Southern and southeastern Iowa and possibly states adjoining these areas. The series is of moderate extent and is in MLRA 108 and 109.
MLRA OFFICE RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Van Buren County, Iowa, 1960. The site location was moved approximately 14 miles in 1991 because access was denied on the old site.
REMARKS: Diagnostic horizons and features recognized in this pedon are: ochric epipedon - the zone from the surface of the soil to a depth of 10 inches (Ap and E horizons); argillic horizon - the zone from approximately 10 to 44 inches (Bt1, Bt2, Bt3,and Bt4 horizons); udic moisture regime.
Water table depth has been updated by agreement by the MLRA 108 steering committee on water table depths and drainage class, 4/98