LOCATION WEEKS IDEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Haplic Haploxerollic Durixerolls
TYPICAL PEDON: Weeks loam, nonirrigated cropland. (Colors are for dry soil unless otherwise noted.)
Ap--0 to 7 inches; grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; moderate very fine granular structure; soft, very friable, slightly sticky and slightly plastic; common fine, few medium roots; many fine interstitial pores; neutral (pH 7.0); clear smooth boundary. (5 to 10 inches thick)
A12--7 to 10 inches; grayish brown (10YR 5/2) fine sandy loam, dark grayish brown (10YR 4/2) moist; weak very fine granular structure; soft, friable, slightly sticky and slightly plastic; common fine, few medium roots; many fine and very fine, few medium tubular pores; neutral (pH 7.2); clear smooth boundary. (2 to 6inches thick)
B2--10 to 14 inches; brown (10YR 5/3) light clay loam, dark brown (10YR 4/3) moist; weak medium prismatic structure that parts to moderate medium and fine subangular blocky structure; hard, friable, sticky and plastic; common fine roots; many fine and medium tubular pores; slightly glazing on vertical and horizontal surfaces; mildly alkaline (pH 7.6); gradual smooth boundary. (3 to 10 inches thick)
B3--14 to 21 inches; pale brown (10YR 6/3) loam, dark brown (10YR 4/3) moist; moderate medium and fine angular blocky structure; hard, friable, slightly sticky and slightly plastic; few fine roots; common fine, few medium tubular pores; moderately alkaline (pH 8.0); clear smooth boundary. (4 to 14 inches thick)
C1casi--21 to 24 inches; light gray (10YR 7/2) light loam, brown (10YR 5/3) moist; weak medium platy structure that parts to weak medium angular blocky structure; very hard, firm; few fine roots in cracks; common fine, few medium tubular pores; thin very weakly cemented plates with pale brown root mats; strongly calcareous; moderately alkaline (pH 8.2); abrupt smooth boundary. (4 to 5 inches thick)
C2casi--24 to 26 inches; white (10YR 8/2) light loam, grayish brown (10YR 5/2) moist; weak medium platy structure; extremely hard, very firm; common fine tubular pores; 0.25 inch thick weakly cemented and brittle plates; strongly calcareous; moderately alkaline (pH 8.4); clear smooth boundary. (1 to 2 inches thick)
C3ca--26 to 36 inches; white (10YR 8/2) light loam, brown (10YR 5/3) moist; weak medium angular blocky structure; very hard, friable; common fine tubular pores; strongly calcareous, common fine lime veins; moderately alkaline (pH 8.4); gradual smooth boundary. (9 to 12 inches thick)
C4--36 to 60 inches; brown (10YR 5/3) moist light loam, massive; slightly hard, friable; few fine tubular pores; moderately calcareous; moderately alkaline (pH 8.4).
TYPE LOCATION: Cassia County, Idaho; about 5 miles south and 7.5 miles east of Burley, Idaho; 300 feet east and 50 feet north of the southwest corner of section 15, T.11S., R.24E.
RANGE IN CHARACTERISTICS: Depth to the duripan ranges from 20 to 40 inches. Coarse fragments range from none to about 5 percent, by volume, pebbles or cobbles on the surface and in the profile. The mean annual soil temperature ranges from 49 to 53 degrees F. The mollic epipedon ranges from 7 to 12 inches thick.
The A horizon has value of 5 or 6 dry, 3 or 4 moist, and chroma of 2 or 3. It is loam or fine sandy loam.
The B horizon has glazed coatings on peds with value of 4 or 5 dry, and chroma of 3 or 4. It is loam, clay loam, or silty clay loam. This horizon has weak prismatic or moderate subangular blocky or moderate angular blocky structure.
The Ccasi horizon has 20 to 50 percent of the upper boundary of the plates coated with silica cementation. The Cca horizon has 15 to 20 percent calcium carbonate and is extremely hard or very hard. The C horizon is stratified sandy loam, fine sandy loam, and loam.
COMPETING SERIES: This is the McMeen series which has a fine loamy particle size class.
GEOGRAPHIC SETTING: Weeks soils are on alluvial fans and have slopes of 0 to 7 percent. They formed in alluvium from mixed sources including sandstone, quartzite, mica schist, and with admixture of loess. Elevations are 4,200 to 5,500 feet. The climate is semiarid. The mean annual precipitation is 11 to 13 inches. The mean annual temperature is 47 to 51 degrees F. The frost free season is about 100 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Buko, Disautel, and Mackey soils. Buko soils have an ochric epipedon. Disautel soils lack cemented C horizons. Mackey soils have bedrock within 20 inches of the surface.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; moderate permeability.
USE AND VEGETATION: Used mainly for dryland grain production; some areas used for range and small areas are irrigated. Vegetation is mainly big sagebrush and bunchgrasses.
DISTRIBUTION AND EXTENT: South central Idaho. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Cassia County, Idaho, 1975.