LOCATION MOTARK MOEstablished Series
TAXONOMIC CLASS: Coarse-silty, mixed, superactive, nonacid, mesic Oxyaquic Udifluvents
TYPICAL PEDON: Motark silt loam, on a nearly level flood plain, in a cultivated field, at an elevation of about 857 feet. (Colors are for moist soil unless otherwise stated)
Ap--0 to 9 inches; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; weak fine granular structure; very friable; slightly acid; abrupt smooth boundary. (6 to 10 inches thick)
C--9 to 15 inches; dark grayish brown (10YR 4/2) and brown (10YR 4/3) layers of silt loam; massive with many very thin bedding planes; very friable; few fine prominent strong brown (7.5YR 5/6) masses of iron accumulation on faces of bedding planes; neutral; gradual smooth boundary. (3 to 12 inches thick)
Cg--15 to 60 inches; dark grayish brown (10YR 4/2), grayish brown (10YR 5/2) and brown (10YR 5/3) layers of silt loam; common very thin and thin darker horizontal strata; massive with many thin to coarse bedding planes; very friable; common fine and medium prominent yellowish red (5YR 5/8) and strong brown (7.5YR 5/8) masses of iron accumulation between bedding planes and on soil matrix; common black stains between bedding planes; neutral.
TYPE LOCATION: Holt County, Missouri; about 4.5 miles west of Mound City; located about 2,600 feet south and 1,800 feet west of the northeast corner of section 32, T. 62 N., R. 39 W.; about 20 feet north of farm lane; USGS Craig topographic quadrangle; lat. 40 degrees 08 minutes 23 seconds N. and long. 95 degrees 19 minutes 14 seconds W., NAD 83.
RANGE IN CHARACTERISTICS: The Ap horizon has color value of 2 to 4 and chroma of 2 or 3. Reaction ranges from slightly acid to slightly alkaline.
The C horizon has color value of 4 or 5 and chroma of 2 or 3. Pedons that have thin strata of very dark brown (10YR 2/2), very dark grayish brown (10YR 3/2) or dark brown (10YR 3/3) are within the range of the series if they are in a sequence of stratified sediments and not surface layers of buried soils. Iron stains and masses are mostly on the faces of bedding planes and are few to common increasing in the Cg horizon. They have hue of 2.5YR to 10YR, value of 3 to 6 and chroma of 2 to 8. The C horizon is neutral or slightly alkaline. Texture of the C horizon is dominantly silt loam with less than 18 percent clay but some pedons have thin strata of silty clay loam.
COMPETING SERIES: No other series are in this family. Closely related are the Dockery, Haynie, McPaul, and Nodaway soils. Dockery soils are fine-silty and are somewhat poorly drained. Haynie and McPaul soils are calcareous and well drained. Nodaway soils are fine-silty.
GEOGRAPHIC SETTING: Motark soils are on alluvial fans and flood plains of tributary streams that flow across the slack water areas of flood plains of larger rivers and on narrow flood plains of tributary streams in uplands. Slope ranges from 0 to 2 percent. These soils formed in noncalcareous silty alluvium from soils formed in loess. The mean annual air temperature ranges from 49 to 55 degrees F. The mean annual precipitation ranges from 28 to 36 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dockery, Dupo, Luton, Napier and Wabash soils. Dockery soils are on slightly lower elevations. Dupo soils are slightly lower in elevation and are clayey in the lower part. Luton and Wabash soils are lower in elevation, have more clay throughout and are poorly or very poorly drained. Napier soils are on foot slopes and alluvial fans, have very thick dark surface layers and are well drained.
DRAINAGE AND PERMEABILITY: Moderately well drained. Surface runoff is low. Permeability is moderate. These soils are subject to rare or occasional flooding. In undisturbed areas, an apparent water table has an upper limit of 2.5 to 4.0 feet during November to June in most years.
USE AND VEGETATION: Most areas are cultivated to corn, soybeans, and small grain.
DISTRIBUTION AND EXTENT: Northwestern to Central Missouri along the Missouri River and major tributaries. The Motark soils are of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Holt County, Missouri, 1993.
REMARKS: These soils were formerly included with the McPaul series. Diagnostic horizons and features recognized in this series are: ochric epipedon - the zone from the surface of the soil to a depth of 9 inches; udic moisture regime.