LOCATION ROUNDUP MTInactive Series
TAXONOMIC CLASS: Fine-loamy, mixed Typic Haploborolls
TYPICAL PEDON: Roundup loam - grassland. (Colors are of dry soils unless otherwise noted.)
A1--0 to 7 inches; grayish brown (2.5Y 5/2) loam, very dark grayish brown (2.5Y 3/2) moist; very fine granular structure; soft, very friable, slightly sticky and nonplastic; clear boundary. (6 to 10 inches thick)
B2--7 to 10 inches; light yellowish brown (2.5Y 6/3) loam, light olive brown (2.5Y 5/3) moist; weak coarse prismatic structure; slightly hard, very friable, slightly sticky and slightly plastic; calcareous; gradual boundary. (3 to 5 inches thick)
C1ca--10 to 22 inches; pale yellow (5Y 7/3) loam, pale olive (5Y 6/3) moist; weak coarse prismatic structure; hard, very friable, slightly sticky and slightly plastic; strongly calcareous with common soft nodules of lime; clear boundary. (7 to 13 inches thick)
C2--22 to 28 inches; pale yellow (5Y 7/3) loam, pale olive (5Y 6/3) moist; weak to moderate platy structure; very hard, very friable, slightly sticky and slightly plastic; strongly calcareous with a few nodules and films of lime; few fragments of soft shale; gradual boundary. (2 to 6 inches thick)
R--28 to 40 inches; pale yellow (5Y 7/3),strongly calcareous,unweathered weakly consolidated siltstone; platy structure; very hard and brittle when dry but is easily crushed with fingers when moist.
TYPE LOCATION: Musselshell County, Montana, Section 27, T8N, R24E, 200 feet west and 50 feet south of N1/4 corner of section.
RANGE IN CHARACTERISTICS: The depth to the paralithic contact is 20 to 40 inches. These soils are usually moist when not frozen but some part between 7 and 20 inches will be dry for 90 cumulative days or longer in most years. All subhorizons are frozen to depths of 24 inches or more for 90 to 100 consecutive days or more in most years.
Loam is the only A or Ap texture recognized. It has a moderate to strong granular structure and has colors with values of less than 5.5 dry and 3.5 moist, chroma of 2 or 3 in hues of 2.5Y or 10YR.
The B2 and C horizons are loam with 1 to 27 percent clay. The B2 horizons have weak to moderate grades of prismatic structure and colors with chroma of 2 or 3 in hues of 2.5Y or 10YR. The Cca horizon has few to common masses or nodules of segregated lime.
The R horizon consists of calcareous siltstones or interbedded siltstones and fine grained sandstones.
COMPETING SERIES: These include the Duffy, Hogeland, Joplin, Kevin, Kremlin, Prospect, Quigley, Searing, and Shambo series in the same family; the Bitterroot series in the same subgroup; and the Barvon series in the same great group. The Duffy soils have granitic bedrock substratum and have more medium and coarse sand in the profile. The Searing series has soil colors redder than 10YR and has porcelanite bedrock between depths of 20 and 40 inches. The Hogeland, Joplin, Kevin, Kremlin, Prospect, Quigley, and Shambo series all lack paralithic contact within 40 inches. The Bitterroot and Barvon series have paralithic contact between depths of 20 and 40 inches, but the Bitterroot series has less than 18 percent clay in its control section, and the Barvon series lacks a cambic horizon.
GEOGRAPHIC SETTING: The Roundup soils are on undulating to rolling sedimentary plains. The regolith consists of strongly calcareous loam materials weathered in place from the underlying siltstones or loamy shales. The climate is cool, semiarid, continental with cold dry winters and warm moist summers. The mean annual precipitation is 12 to 16 inches. The mean annual air temperature is 42 to 45 degrees F., mean January temperature is 20 to 26 degrees F., and the mean July temperature is 65 to 70 degrees F. The frost-free period is 105 to 135 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the Andes, Barvon, Chama, Delphia, Sei, Sen, Shambo, and Vebar series. The Andes, Chama, Sei and Sen series are in deep,silty, calcareous materials; the Shambo in deep, loam, calcareous materials; and the Vebar in deep, fine sandy loam materials. The Barvon and Delphia soils have bedrock substrata within 40 inches. All these soils lack argillic horizons.
DRAINAGE AND PERMEABILITY: Well drained with medium runoff and infiltration. Permeability is moderate.
USE AND VEGETATION: The Roundup soils are used for both nonirrigated cropland and for rangeland. The important native grasses are western wheatgrass, needleandthread, prairie junegrass, and blue grama.
DISTRIBUTION AND EXTENT: The Roundup series occurs throughout eastern plains of Montana and possibly in the adjacent states. It is a moderately extensive series.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Musselshell County, Montana, 1964. Name is that of a town in this county.
REMARKS: The Roundup series was formerly classified with the Chestnut soils.
OSED scanned by SSQA. Last revised by state on 1/67.