LOCATION BROADAX WA+IDEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Calcic Argixerolls
TYPICAL PEDON: Broadax silt loam - cultivated. (Colors are for dry soil unless otherwise stated.)
Apl--0 to 4 inches; dark grayish brown (10YR 4/2) silt loam, very dark brown (10YR 2/2) moist; weak very fine granular structure; soft, very friable, slightly sticky and slightly plastic; few roots; many very fine pores; slightly acid (pH 6.2); clear smooth boundary. (3 to 5 inches thick)
Ap2--4 to 8 inches; dark grayish brown (10YR 4/2) silt loam, very dark brown (10YR 2/2) moist; weak medium subangular blocky structure; soft, very friable, moderately sticky and slightly plastic; few roots; many fine pores; slightly acid (pH 6.2); clear smooth boundary. (0 to 6 inches thick)
A--8 to 16 inches; yellowish brown (10YR 5/4) silt loam, dark brown (10YR 3/3) moist; weak coarse subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; few roots; few very fine pores; neutral (pH 6.8); gradual smooth boundary. (6 to 9 inches thick)
Bt--16 to 31 inches; yellowish brown (10YR 5/4) heavy silt loam, dark yellowish brown (10YR 3/4) moist; moderate coarse prismatic structure parting to moderate fine subangular blocky; hard, firm, moderately sticky and moderately plastic; few roots; few very fine pores; faint patchy clay films on faces of peds; slightly alkaline (pH 7.4); clear wavy boundary. (8 to 24 inches thick)
Btk--31 to 35 inches; yellowish brown (10YR 5/4) silt loam, brown (10YR 4/3) moist; moderate medium prismatic structure parting to moderate fine subangular blocky; hard, firm, moderately sticky and slightly plastic; few roots; few fine pores; faint patchy clay films on faces of peds; strongly effervescent; thin carbonate accumulations along faces of peds; moderately alkaline (pH 8.2); clear wavy boundary. (2 to 5 inches thick)
Bk1--35 to 44 inches; pale brown (10YR 6/3) silt loam, brown (10YR 4/3) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few roots; many fine pores; soft powdery carbonate accumulations along cracks and seams; violently effervescent; strongly alkaline (pH 8.6); clear smooth boundary. (7 to 12 inches thick)
Bk2--44 to 60 inches; brown (10YR 5/3) silt loam, brown (10YR 4/3) moist; massive, soft, very friable, slightly sticky, nonplastic; few roots; many fine and common very fine pores; soft powdery carbonate accumulations along cracks and in seams; violently effervescent; strongly alkaline (pH 8.6).
TYPE LOCATION: Lincoln County, Washington; 1,600 feet west and 2,220 feet south of the northeast corner of section 18, T. 24 N., R. 38 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 47 to 53 degrees F. These soils are usually moist, but are dry in all parts between depths of 4 and 12 inches for 75 to 105 consecutive days in 7 out of 10 years. The argillic horizon contains 18 to 35 percent clay and less than 15 percent sand coarser than very fine sand. Depth to the base of the argillic horizon is more than 30 inches. The mollic epipedon is 10 to 20 inches thick. Depth to bedrock or duripan is 40 to over 60 inches. Depth to secondary carbonates is 25 to 44 inches.
The A horizon has value of 4 or 5 dry, value of 2 or 3 moist, and chroma of 1 to 3 moist, 2 to 4 dry. Reaction is moderately acid to slightly alkaline. This horizon has moderate or weak granular, platy, or blocky structure. Some pedons have an AB horizon.
The Bt horizon has value of 4 to 7 dry, value of 2 to 4 moist and chroma of 2 to 4 moist or dry. Texture is heavy silt loam or silty clay loam. Reaction is slightly alkaline or moderately alkaline. The lower part has secondary carbonates in pores, root channels or within the matrix within a depth of 44 inches. It has distinct to faint continuous clay films, dominantly on vertical faces of peds; and has strong or moderate prismatic or blocky structure.
The Bk horizon has value of 5 to 7 dry, value of 3 to 5 moist and chroma of 3 or 4 moist or dry. Texture is silt loam, loam, or sandy loam. Reaction is slightly alkaline to strongly alkaline. Some pedons have up to 10 percent medium sand composed of quartz and feldspar and up to 10 percent coarse fragments.
A Btkb horizon is present in some pedons.
COMPETING SERIES: These are the McKay, Morrow, Nephi, Parleys, and Wannacott, series. McKay soils have a lithologic discontinuity within 40 inches to material with 20 to 50 percent coarse fragments. Morrow soils have a lithic contact at a depth of 20 to 40 inches. Nephi soils have hue of 7.5YR or 5YR in the Bt horizon. Parleys soils have a calcic horizon and a Bt horizon which is neutral or slightly acid. Wannacott soils are gravelly below the argillic horizon above 40 inches.
GEOGRAPHIC SETTING: Broadax soils are on hills and plateaus at elevations of 1,500 to 3,500 feet. Slopes are 0 to 40 percent. The soils formed in old loess mixed with recent loess in the upper part. Summers are hot and dry and winters are cool and moist. The mean annual precipitation is dominantly 15 to 18 inches: the low precipitation phase ranges to 12 to 15 inches; some areas in Idaho range to 20 inches. The average July temperature is 69 degrees F. and the average January temperature is 27 degrees F. The mean annual temperature is 48 to 50 degrees F. The frost-free season is 105 to 170 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Anders, Bagdad, Benge, Calouse, Dragoon, and Reardan soils. Anders and Benge soils lack an argillic horizon and are less than 18 percent clay in the control section. Bagdad soils are coarse-silty. Calouse soils lack an argillic horizon. Dragoon soils are underlain by a paralithic contact with granite at a depth of 20 to 40 inches. Reardan soils are in a fine family. Anders soils are on plateaus and channel scablands. Benge and Calouse soils are on hills. Benge soils are on terraces. Dragoon and Reardan soils are on mountain side slopes.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; moderate or moderately slow permeability.
USE AND VEGETATION: These soils are used mostly for cropland but other minor uses include livestock grazing and timber production. Dryland small grains are common crops. Native vegetation is Idaho fescue, bluebunch wheatgrass, balsamroot, and scattered big sagebrush on the low precipitation phase and ponderosa pine with an understory of Idaho fescue, bluebunch wheatgrass, common snowberry and rose on the high precipitation phase.
DISTRIBUTION AND EXTENT: Eastern Washington and northern Idaho. MLRA 8. The series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Lincoln County, Washington, 1978.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon the zone from 0 to 16 inches
Argillic horizon the zone from 16 to 35 inches
Carbonate accumulation the zone from 31 to 60 inches
Particle-size control section the zone from 16 to 35 inches