LOCATION MACIVER MTEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Calcic Argicryolls
TYPICAL PEDON: Maciver loam, in rangeland (colors are for dry soil unless otherwise noted).
A--0 to 7 inches; very dark gray (10YR 3/1) loam, black (10YR 2/1) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine and fine and few medium roots; few very fine and fine tubular pores; 10 percent gravel; neutral (pH 7.2); gradual wavy boundary. (5 to 12 inches thick)
Bt--7 to 11 inches; yellowish brown (10YR 5/4) very gravelly clay loam, dark yellowish brown (10YR 4/4) moist; weak fine subangular blocky structure; hard, friable, moderately sticky and moderately plastic; many very fine and fine roots; few very fine and fine tubular pores; few faint clay films on faces of peds; 5 percent cobbles and 35 percent gravel; neutral (pH 7.2); clear smooth boundary. (4 to 15 inches thick)
Bk1--11 to 23 inches; pale yellow (2.5Y 7/4) very gravelly clay loam, light olive brown (2.5Y 5/4) moist; weak fine subangular blocky structure; hard, friable, slightly sticky and moderately plastic; many very fine and fine roots; few very fine and fine tubular pores; 5 percent cobbles and 35 percent gravel; many medium segregated masses of lime; violently effervescent; moderately alkaline (pH 8.2); gradual wavy boundary.
Bk2--23 to 30 inches; light yellowish brown (2.5Y 6/4) very gravely clay loam, light olive brown (2.5Y 5/4) moist; weak fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many very fine and fine roots; few very fine and fine tubular pores; 10 percent cobbles and 35 percent gravel; many medium segregated masses of lime; violent effervescent; moderately alkaline (pH 8.4); gradual wavy boundary.
Bk3--30 to 60 inches; pale brown (10YR 6/3) very gravely loam, yellowish brown (10YR 5/4) moist; weak coarse prismatic structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine roots; few very fine and fine tubular pores; 15 percent cobbles and 40 percent gravel; many medium segregated masses of lime; violently effervescent; moderately alkaline (pH 8.2). (Combined thickness of the Bk horizons is 33 to 49 inches)
TYPE LOCATION: Granite County, Montana; 1,150 feet south and 2,150 feet east of the NW corner of sec. 32, T. 5 N., R. 14 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 36 to 41 degrees F.
Moisture control section - between 4 and 12 inches.
Mollic epipedon thickness - 7 to 15 inches.
Depth to argillic horizon - 5 to 12 inches.
Depth to calcic horizon - 11 to 24 inches.
A horizon
Value: 3 or 4 dry; 2 or 3 moist
Chroma: 1 or 2; dry or moist
Clay content: 18 to 27 percent
Rock fragments: 0 to 45 percent--0 to 30 cobbles, 0 to 30 percent gravel
Reaction: pH 6.6 to 7.3 (pH 4.5 to 6.5 in impacted phase)
Bt horizon
Value: 4, 5 or 6 dry; 3, 4 or 5 moist
Chroma: 2, 3, or 4; dry or moist
Clay content: 27 to 35 percent
Rock fragments: 35 to 60 percent --0 to 10 percent cobbles, 35 to 50 percent gravel
Reaction: pH 6.6 to 7.3
Bk horizons
Hue: 2.5Y or 10YR; dry or moist
Value: 6, 7, or 8 dry; 5 or 6 moist
Chroma: 2, 3 or 4; dry or moist
Texture: loam, sandy loam, clay loam, or sandy clay loam
Clay content: 15 to 30 percent
Rock fragments: 40 to 70 percent--5 to 15 percent cobbles, 35 to 45 percent gravel
Calcium carbonate equivalent: 15 to 35 percent
Reaction: pH 7.9 to 8.4
COMPETING SERIES:
Cavemountain (NV) - has a lithic contact at depths of 40 inches or less.
Hodden (CO) - is extremely gravelly below a depth of 40 inches, has annual precipitation of 16 inches or less.
Hoodling (CO) - peak precipitation occurs during July and August.
Latigo (ID) - has 17 to 20 percent clay in the control section and has a xeric moisture regime.
Nurkey (ID) - has a xeric moisture regime.
Teeler (WY) - has hues redder than 10YR throughout.
GEOGRAPHIC SETTING:
Landform- fan remnants, alluvial fans, hills and mountains.
Elevation - 5,400 to 8,500 feet.
Slope - 1 to 60 percent.
Parent material - alluvium or colluvium derived from calcareous metamorphic and sedimentary rock sources.
Climate - long, cold winters; cool, moist springs; short, cool summers.
Mean annual precipitation - 15 to 22 inches with peak periods of precipitation occurring during the spring.
Mean annual air temperature - 34 to 39 degrees F.
Frost-free period - 30 to 70 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Levengood, Tiban, and Tibson series. Levengood, Tiban, and Tibson soils lack an argillic horizon.
DRAINAGE AND PERMEABILITY: Well drained, moderate permeability.
USE AND VEGETATION: Maciver soils are primarily used for rangeland. The potential native vegetation is mainly bluebunch wheatgrass, Idaho fescue, rough fescue, and Richardsons needlegrass. Some areas have widely spaced Douglas-fir and Rocky Mountain Juniper.
DISTRIBUTION AND EXTENT: Maciver soils are of moderate extent in southwestern Montana. MLRA 43B and 44B.
MLRA OFFICE RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Granite County, Montana, 1997.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 7 inches (A horizon);
Argillic horizon - 7 to 11 inches (Bt horizon);
Calcic horizons - 11 to 60 inches (Bk1, Bk2, and Bk3 horizons); and a
Particle-size control section - from 7 to 11 inches (Bt horizon).
Maciver soils have a cryic temperature regime and an ustic moisture regime.
ADDITIONAL DATA: Soil interpretation record MT1476.