LOCATION RHOADES ND+MT SDEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Leptic Vertic Natrustolls
TYPICAL PEDON: Rhoades silt loam on a southeast facing slope of 1 percent in native grassland. (Colors are for dry soil unless otherwise stated)
E--0 to 3 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; moderate thin and medium platy structure; slightly hard, friable, slightly sticky and slightly plastic; common fine and very fine and few coarse roots; common fine and few coarse pores; slightly acid; abrupt smooth boundary. (1 to 5 inches thick)
Btn--3 to 8 inches; dark grayish brown (2.5Y 4/2) silty clay, very dark grayish brown (2.5Y 3/2) moist; strong medium columnar structure parting to strong fine and very fine angular blocky; extremely hard, very firm, very sticky and very plastic; common fine roots a faces of peds; common fine pores; light brownish gray (10YR 6/2) coatings on tops of columns; many faint clay films on faces of peds; moderately alkaline; clear wavy boundary. (4 to 20 inches thick)
Btknyz--8 to 14 inches; grayish brown (2.5Y 5/2) silty clay, very dark grayish brown (2.5Y 3/2) moist; moderate coarse prismatic structure parting to moderate fine angular blocky; very hard, very firm, very sticky and very plastic; common fine roots on faces of peds; common fine pores; common faint clay films on faces of peds; common fine flecks of gypsum and other salt crystals; few fine masses of carbonates; strong effervescence; strongly alkaline; gradual wavy boundary. (0 to 15 inches thick)
Bkyz--14 to 24 inches; grayish brown (2.5Y 5/2) silty clay, dark grayish brown (2.5Y 4/2) moist; weak coarse prismatic structure parting to moderate medium subangular blocky; very hard, very firm, very sticky and very plastic; common fine roots; common fine pores; few faint clay films on faces of peds; common fine flecks of gypsum and other salt crystals; few fine masses of carbonates; strong effervescence; strongly alkaline; gradual wavy boundary.
Bky1--24 to 40 inches; grayish brown (2.5Y 5/2) silty clay, dark grayish brown (2.5Y 4/2) moist; weak coarse prismatic structure parting to weak medium subangular blocky; very hard, very firm, very sticky and very plastic; few fine roots, common fine pores; common fine gypsum accumulations; common fine masses of carbonates; strong effervescence, strongly alkaline; gradual wavy boundary.
Bky2--40 to 46 inches; light yellowish brown (2.5Y 6/4) silty clay, light olive brown (2.5Y 5/4) moist; few fine prominent strong brown (7.5YR 5/6) redoximorphic concentrations; weak coarse subangular structure; hard, firm, very sticky and very plastic; few fine pores; few fine gypsum accumulations; common fine masses of carbonates; strong effervescence, strongly alkaline; clear wavy boundary. (Combined Bky horizons 0 to 50 inches thick)
C--46 to 60 inches; pale yellow (2.5Y 7/4) stratified silt loam and silty clay loam, light yellowish brown (2.5Y 6/4) moist; few fine prominent strong brown (7.5YR 5/6) redoximorphic concentrations; massive; hard, firm sticky and plastic; few fine masses of carbonates; violent effervescence; strongly alkaline.
TYPE LOCATION: Adams County, North Dakota; 350 feet south and 125 feet east of the northwest corner, sec. 16, T. 131 N., R. 96 W.
RANGE IN CHARACTERISTICS: Depth to soft shale, siltstone or mudstone is more than 40 inches. Some pedons have a thin A horizon. Combined A and E horizon thickness is 1 to 5 inches.
The E horizon has hue of 10YR, value of 4 to 6 and 2 to 5 moist, and chroma of 2 or 3. The A and E horizons are loam, silt loam, very fine sandy loam, fine sandy loam, silty clay loam, clay loam or silty clay. They are moderately acid to neutral.
The Btn horizons have hue of 10YR or 2.5Y, value of 3 to 5 and 2 to 4 moist, and chroma of 2 or 3. They are silty clay loam, clay loam, clay or silty clay and have less than 15 percent fine sand and coarser sand and average between 35 and 50 percent clay. They are neutral to strongly alkaline. They have coarse or medium columnar structure. The columns separate to blocks in some pedons. They are firm or very firm. Clay films and organic stains are on faces of columns.
The Bky horizon has hue of 10YR, 2.5Y, or 5Y, value of 4 to 7 and 3 to 5 moist, and chroma of 2 to 4. It commonly is clay loam, loam, silty clay loam, silty clay or clay. It is moderately alkaline or strongly alkaline. It has few to common gypsum crystals. Some pedons have a By, Bk, BC or BCy horizon.
The C horizon has hue of 10YR, 2.5Y or 5Y, value of 4 to 7 and 3 to 6 moist, and chroma of 1 to 4. It is silt loam, loam, clay loam, silty clay loam, silty clay or clay. Coarser textures are allowed below 40 inches. It is stratified in some pedons. It is moderately alkaline or strongly alkaline. Some pedons have a Cy or Cz horizon. Some pedons do not have a C horizon.
The Cr horizon, when present, typically is massive soft shale, siltstone or mudstone. Some pedons have a Cr horizon at depths of 40 to more than 60 inches.
COMPETING SERIES: These are the Adger, Dogtooth, Exline, Ferney, Mekinock, Miranda and Scairt series as previously classified. Adger soils have an ustic moisture regime that borders on aridic. Dogtooth, Mekinock and Scairt soils have shale bedrock at depths of 20 to 40 inches. Exline soils have chroma of 1 in the A horizon and formed in lacustrine sediments. Ferney soils have redoximorphic features, have more than 15 percent fine sand and coarser in the particle-size control section, a udic moisture regime and formed in till. Miranda soils formed in till and have 1 to 10 percent rock fragments throughout.
GEOGRAPHIC SETTING: Rhoades soils are on level to steep concave swales on uplands and terraces. Slope gradients commonly are 1 to 9 percent but range from 0 to 25 percent. The soils formed in stratified loamy and clayey materials derived from soft shale, siltstone or mudstone. Mean annual air temperature ranges from 39 to 45 degrees F, and mean annual precipitation from 13 to 18 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Arnegard, Belfield, Daglum, Grail, Lawther, Morton, Regent and Vebar soils. Arnegard, Belfield, Grail and Lawther soils occur in nearby swales. Arnegard, Grail and Lawther soils do not have natric horizons. Belfield soils do not have visible salts or gypsum within a depth of 16 inches. Daglum soils occur on similar positions as Rhoades soils. Daglum soils do not have visible gypsum within depths of 16 inches. Morton, Regent and Vebar soils are on slightly higher position than Rhoades soils on terraces and uplands. These soils do not have do not have natric horizons.
DRAINAGE AND PERMEABILITY: Moderately well and well drained. Runoff is medium to very high depending on slope. Permeability is very slow. A seasonal high water table is at a depth of 3.5 to 5.0 feet at some time during the period of April through June in the moderately well drained phase. It is at a depth of 4 to more than 6 feet for the same period in the well drained phase.
USE AND VEGETATION: Mostly in grassland used for range and pasture. Native vegetation is short- and mid-prairie grasses such as western wheatgrass, blue grama, sedges and also some legumes, prickly pear and clubmoss. Some areas are cultivated mostly to small grains.
DISTRIBUTION AND EXTENT: Southwestern North Dakota, northwestern South Dakota, and eastern Montana. The soil is extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: McKenzie County, North Dakota, 1932.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of 14 inches after mixing the upper 7 inches (E, Btn and Btknyz horizons); natric horizon - the zone from 3 to 14 inches (Btn and Btknyz horizons).
The series includes some soils formerly placed in the Moline and Wade series. Soils formerly included in the Rhoades series but now separated are in the Absher, Beckton, Belfield and Daglum series.
ADDITIONAL DATA: Type location lab sample number S61ND-45-6. Other lab samples S54SD-53-1, S54SD-53-2 and S61ND-45-8.