LOCATION LUD IDEstablished Series
TAXONOMIC CLASS: Clayey, smectitic, mesic, shallow Xeric Argidurids
TYPICAL PEDON: Lud silt loam--on a 3 percent slope under rangeland vegetation at 5,340 feet elevation. When described on June 10, 1982, the soil was slightly moist throughout. (Colors are for dry soil unless otherwise stated.)
A--0 to 2 inches; pale brown (10YR 6/3) silt loam, dark brown (10YR 3/3) moist; moderate medium platy structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine roots; many very fine tubular pores; 5 percent gravel and 5 percent cobbles; neutral (pH 6.6); clear smooth boundary. (2 to 4 inches thick)
Bt1--2 to 8 inches; pale brown (10YR 6/3) silty clay loam, brown (10YR 4/3) moist; weak fine angular blocky structure; hard, firm, sticky and plastic; common very fine and fine roots; many very fine tubular pores; few faint clay films on faces of peds and in pores; neutral (pH 7.2); clear smooth boundary. (3 to 6 inches thick)
Bt2--8 to 11 inches; pale brown (10YR 6/3) silty clay loam, brown (10YR 4/3) moist; strong medium angular blocky structure; hard, firm, sticky and plastic; common very fine roots; common very fine tubular pores; many distinct clay films on faces of peds and in pores; strongly effervescent (4 percent calcium carbonate); mildly alkaline (pH 7.6); clear smooth boundary. (3 to 10 inches thick)
Bkq--11 to 16 inches; very pale brown (10YR 7/3) gravelly loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; very hard, very firm, slightly sticky and slightly plastic; few very fine roots; few very fine tubular pores; 20 percent gravel; violently effervescent (32 percent calcium carbonate); mildly alkaline (pH 7.8); abrupt smooth boundary. (2 to 7 inches thick)
Bkqm--16 to 26 inches; white (10YR 8/1) fractured duripan, very pale brown (10YR 7/3) moist; massive; indurated; extremely hard, extremely firm; many 1/8 inch to 1 inch thick lime-silica cemented lenses; few very fine roots in fractures of the duripan; fractures are 1/4 inch wide and 9 inches apart; violently effervescent; moderately alkaline (pH 8.4); abrupt wavy boundary. (3 to 20 inches thick)
2R--26 inches; dark gray (10YR 4/1) fractured basalt, black (10YR 2/1) moist; lime coated; violently effervescent.
TYPE LOCATION: Twin Falls County, Idaho; about 13 miles west of Rogerson, Idaho, in the northeast 1/4, northeast 1/4, northwest 1/4, section 17, T. 14 S., R. 14 E.
RANGE IN CHARACTERISTICS:
Depth to the duripan - 10 to 20 inches
Depth to bedrock - 21 to 40 inches
Average clay content in the control section - 35 to 45 percent Average annual soil temperature - 47 to 49 degrees F.
A horizon
Value - 5 or 6 dry, 3 or 4 moist
Chroma - 2 or 3 dry or moist
Bt horizon
Value - 6 or 7 dry, 4 or 5 moist
Chroma - 3 or 4 dry or moist
Subangular blocky or angular blocky structure
Textures - SICL, SIC, CB-SICL, CB-SIC
Gravel - 0 to 10 percent
Cobbles - 0 to 10 percent
Reaction - neutral or mildly alkaline
Bkqm horizon
Thickness of laminar caps - 1/8 to 1 1/2 inches
Structure - massive or platy
Cementation below laminar caps - weak through very strong
Width of fractures - 1/8 to 1/2 inches
Distance between fractures - 8 to 20 inches
Thickness of duripan - 3 to 20 inches
Thickness of subsequent laminations - 1/8 to 1 inch
COMPETING SERIES: These are the Buffaran (T), Indian Creek, Midraw (T), and Norfork (T) series. Buffaran and Indian Creek soils are greater than 60 inches deep to bedrock. Midraw soils have gravelly clay loam or gravelly clay textures in the Bt horizon. Norfork soils have 20 to 30 percent coarse fragments in the control section.
GEOGRAPHIC SETTING: Lud soils are on terraces. The slope ranges from 2 to 10 percent. The soils formed in alluvium from mixed sources. Elevations are 4,500 to 5,300 feet. The average annual precipitation ranges from 9 to 11 inches. The average annual temperature is 45 to 47 degrees F. The frost free season is 100 to 120 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Arness, Chuska, and Owsel soils. Arness and Chuska soils occur on lower terraces, and are loamy. Owsel soils occur on terrace sideslopes, and are very deep.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; slow permeability.
USE AND VEGETATION: Lud soils are used for rangeland. Native vegetation is Wyoming big sagebrush, bluebunch wheatgrass, and Sandberg bluegrass.
DISTRIBUTION AND EXTENT: Lud soils are of moderate extent in south central Idaho.
MLRA OFFICE RESPONSIBLE: Reno, Nevada
SERIES ESTABLISHED: Twin Falls County, Idaho, 1992.
REMARKS: Clay percent by hydrometer: 0-2 inches-22 percent; 2-8 inches-37 percent; 8-11 inches-35 percent; 11-16 inches-30 percent.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 0 to 2 inches (A horizon)
Argillic horizon - the zone from 2 to 11 inches (Bt1 and Bt2 horizons)
Calcic horizon - the zone from 11 to 26 inches (Bkq and Bkqm horizons)
Duripan - the zone from 16 to 26 inches (Bkqm horizon)
Lithic contact - 26 inches