LOCATION KORCHEA ND+MT SD WY
Established Series
Rev. DDO-CJH
01/2023
KORCHEA SERIES
The Korchea series consists of very deep, well drained, moderately permeable soils that formed in stratified alluvium. These soils are on flood plains and low stream terraces and have slope ranging from 0 to 6 percent. Mean annual air temperature is 42 degrees F, and mean annual precipitation is 15 inches.
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, calcareous, frigid Mollic Ustifluvents
TYPICAL PEDON: Korchea loam - on a plane level slope of less than 1 percent under native grass. (Colors are for dry soil unless otherwise stated. Where described the soil was moist throughout.)
A--0 to 6 inches; grayish brown (10YR 5/2) stratified loam, very dark grayish brown (10YR 3/2) moist; weak coarse and medium subangular blocky structure parting to moderate fine granular; hard, very friable, slightly sticky and slightly plastic; many fine roots; many fine pores; slight effervescence; moderately alkaline; clear smooth boundary. (5 to 15 inches thick)
C1--6 to 15 inches; grayish brown (10YR 5/2) stratified loam, very dark grayish brown (10YR 3/2) moist; weak coarse prismatic structure parting to moderate medium subangular blocky; hard, friable, slightly sticky and slightly plastic; common fine roots; many fine pores; slight effervescence; moderately alkaline; abrupt smooth boundary.
C2--15 to 18 inches; grayish brown (2.5Y 5/2) stratified fine sandy loam, dark grayish brown (2.5Y 4/2) moist; massive; slightly hard, very friable, slightly sticky, and slightly plastic; common fine roots; many fine pores; slight effervescence; moderately alkaline; abrupt smooth boundary.
C3--18 to 36 inches; grayish brown (2.5Y 5/2) stratified loam, silt loam and very fine sandy loam, dark grayish brown (2.5Y 4/2) moist; massive; hard, friable, slightly sticky, and slightly plastic; common fine roots in upper part, few fine roots in lower part; very few fine masses of carbonates; strong effervescence; moderately alkaline; gradual smooth boundary.
C4--36 to 60 inches; grayish brown (2.5Y 5/2) stratified fine sandy loam and loam, dark grayish brown (2.5Y 4/2) moist; massive; slightly hard and hard, friable, slightly sticky and slightly plastic; few fine roots; slight effervescence; moderately alkaline.
TYPE LOCATION: Bowman County, North Dakota; about 15 miles south and 1 mile east of Bowman; 790 feet south and 110 feet west of the northeast corner, sec. 36, T. 129 N., R. 102 W.
RANGE IN CHARACTERISTICS: The 10- to 40-inch control section averages between 18 and 35 percent clay and between 15 to 40 percent fine sand and coarser. The soil typically contains carbonates to the surface, but the upper few inches of some pedons do not effervesce. Some pedons contain one or more thin dark colored strata. The decrease in organic carbon is irregular with depth.
The A horizon has hue of 10YR or 2.5Y, value of 3 to 5 and 2 or 3 moist, and chroma of 2 or 3. It is loam, silt loam, very fine sandy loam, fine sandy loam, sandy loam, silty clay loam or clay loam. It is neutral to moderately alkaline.
The C horizon typically has hue of 2.5Y or 10YR, but 5Y is in the range, value of 4 to 7 and 3 to 6 moist, and chroma of 2 to 4. It is loam, silt loam, silty clay loam, clay loam, fine sandy loam, sandy loam or very fine sandy loam. It is slightly alkaline to strongly alkaline. Layers of coarser or finer textures are in some pedons at depths of 40 to 60 inches.
COMPETING SERIES: There are no other series in the same family.
GEOGRAPHIC SETTING: Korchea soils are on flood plains and low terraces. Slope gradients commonly are less than 2 percent, but range from 0 to 6 percent. The soils formed in stratified loamy alluvium. Mean annual air temperature ranges from 38 to 45 degrees F, and mean annual precipitation from 12 to 19 inches. Precipitation range up to 20 inches in the foothills of the mountains. Most of the precipitation comes in the spring and summer.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Farland,
Frazer,
Havrelon,
Lohler,
Manning,
Parshall,
Wyola,
Shambo,
Stady,
Straw,
Tally and
Velva series. All but Havrelon and Lohler soils have mollic epipedons. In addition, Lohler soils are fine textured. Farland, Manning, Parshall, Wyola, Stady and Tally soils are on higher lying terraces. Frazer, Havrelon and Lohler soils are on flood plains. Shambo soils are on higher lying terraces. Straw and Velva soils are on similar low terraces.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is negligible to medium depending on slope. Permeability is moderate. The soils are rarely to commonly flooded. Flooding is most common in the spring with rapid snow melt.
USE AND VEGETATION: Soils are cropped to small grains, hay, and corn. Some are irrigated. They are also used for range and pasture. Native vegetation was needleandthread, green needlegrass, western wheatgrass, a variety of forbs and a few shrubs.
DISTRIBUTION AND EXTENT: In stream valleys in western North Dakota, eastern Montana, and northwestern South Dakota. The series is of large extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Salina, Kansas
SERIES ESTABLISHED: Bowman County, North Dakota, 1969.
REMARKS: Diagnostic horizons and features recognized in this pedon are: irregular decrease in organic carbon with depth (stratifications in A and C horizons); dark colored A horizon (color value less than 4 moist and less than 6 dry).
National Cooperative Soil Survey
U.S.A.