LOCATION POTRATZ IDEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Xeric Haplocalcids
TYPICAL PEDON: Potratz silt loam, range. (Colors are for dry soil unless otherwise noted.)
A1--0 to 3 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; weak thin and very thin platy structure parting to weak fine and very fine granular; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and fine and few coarse roots; many very fine vesicular and interstitial pores; neutral (pH 6.8); clear wavy boundary. (0 to 4 inches thick)
B1--3 to 5 inches; pale brown (10YR 6/3) silt loam, dark brown (10YR 4/3) moist; weak fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine, and few medium roots; common very fine pores; few thin clay films on faces of peds and in pores; very few bleached or uncoated silt and sand grains; neutral (pH 7.1); clear wavy boundary. (2 to 5 inches thick)
B2--5 to 10 inches; pale brown (10YR 6/3) heavy silt loam, dark brown (10YR 4/3) moist; weak prismatic structure parting to weak medium and fine subangular blocky; hard, friable, sticky and plastic; common very fine and fine, and few medium roots; many very fine tubular pores; few thin clay films on faces of peds and in pores; few uncoated silt and sand grains along vertical cracks; neutral (pH 7.2); abrupt smooth boundary. (3 to 11 inches thick)
IIC1ca--10 to 15 inches; very pale brown (10YR 7/3) loam, brown (10YR 5/3) moist; weak medium subangular blocky structure; slightly hard, very friable; common very fine to medium roots; many very fine tubular pores; about 20 to 25 percent nodules or insect (cicada) krotovinas of soil material, hard, firm, about 0.5 to 0.7 inch in diameter, and 0.7 to 1 inch long; strongly calcareous; few carbonate coatings and spots; moderately alkaline (pH 8.3); clear wavy boundary. (2 to 12 inches thick)
IIC2ca--15 to 24 inches; light gray (10YR 7/2) loam, brown 910YR 5/3) moist; massive; hard, firm; few very fine and fine roots; in places some roots matted above the cemented crusts and around the harder nodules; few very fine tubular pores; about 20 percent nodules; in places one or more, very thin (less than 1 mm), horizontal, wavy, discontinuous, weakly silica-lime cemented lenses or crusts; strongly calcareous and many soft spots and veins of carbonates; moderately alkaline (pH 8.4); abrupt irregular boundary. (0 to 20 inches thick)
IIR--24 inches; basalt; lime-coated on upper surface and in pores and fractures in upper 1 to 2 feet. Continuous to undetermined depth.
TYPE LOCATION: Canyon County, Idaho; about 4 miles north of Melba; 2 percent slopes at 2,825 feet elevation; 475 feet west and 785 feet south of the NE corner of the SE1/4 section 11, T.1N., R.2W.
RANGE IN CHARACTERISTICS: The mean annual soil temperature ranges from 47 degrees to 54 degrees F., and the mean summer temperature at a depth of 20 inches from 65 degrees to 72 degrees F. The soils are usually dry, but are moist for 60 to 80 consecutive days in late winter and spring. Depth to bedrock is 20 to 40 inches. Depth to the Cca horizon is 8 to 20 inches. Few fine basalt pebbles are distributed throughout the profile; and some areas are cobbly or stony. The section between depth of 10 inches and the bedrock averages 18 to 27 percent clay, more than 15 percent coarser than very fine sand, and less than 35 percent rock fragments. The hue is chiefly 10YR, but ranges 2.5Y.
The A and B horizons range from neutral to moderately alkaline. The Ap horizon, or the upper 7 inches when mixed, has chroma of 2 or 3 and value of 5 through 7 dry and 3 through 5 moist. The organic matter of the upper 15 inches averages more than 0.9 percent. The B horizon is silt loam, or loam. It has weak prismatic to weak or moderate subangular blocky structure. Clay films range from none to few or common and are thin.
COMPETING SERIES: These are the Agency, Ferdelford (t), Legler (t), North Powder, Pocan, and Redmond series in the same family and the McCain and Vickery series. Agency soils lack calcic horizons. Ferdelford soils have weathered tuff at depths of less than 20 inches. Legler soils have sola thicker than 40 inches. McCain soils have argillic horizons. North Powder soils have a paralithic contact at depths of 20 to 40 inches. Pocan soils are 40 to 60 inches deep over granitic bedrock. Redmond soils have 20 to 60 percent ash in the control section. Vickery soils have a duripan and lack bedrock.
GEOGRAPHIC SETTING: Potratz soils are on level basalt plains at elevations of 2,000 to 4,500 feet. Slopes range from 0 to 30 percent. The soils formed in a thin covering of loess over residuum (or possibly colluvium) weathered from basalt. The climate is dry summers. Frost-free period is 120 to 160 days. Mean annual precipitation is 8 to 11 inches, including 0.5 to 2 feet of snow.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing McCain soils and the Power and Scism soils. Power soils have argillic horizons. Scism soils are deeper than 40 inches and have a duripan.
DRAINAGE AND PERMEABILITY: Well drained; slow to very rapid runoff; moderate permeability.
USE AND VEGETATION: Some irrigated for hay, pasture, small grains, corn, potatoes, and sugar beets; most of the rest is used for rangeland. Vegetation is mainly big sagebrush, winterfat, Sandberg bluegrass, bluebunch wheatgrass, beardless wheatgrass, Thurber needlegrass, cheatgrass, Russian thistle, and wild mustard.
DISTRIBUTION AND EXTENT: Southwestern Idaho and adjoining regions. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Canyon County, Idaho, 1973.