LOCATION RAFTER                  AZ

Established Series
Rev. WAS/CEM
06/2011

RAFTER SERIES

The Rafter series consists of very deep, well drained soils that formed in mixed stream and fan alluvium. Rafter soils are on stream terraces, flood plains, and alluvial fans. Slope ranges from 0 to 15 percent. The mean annual precipitation is about 18 inches and mean annual air temperature is about 60 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, thermic Cumulic Haplustolls

TYPICAL PEDON: Rafter gravelly sandy loam - rangeland. (Colors are for dry soil unless otherwise noted.) 60 to 80 percent of the surface is covered with gravel and cobble

A1--0 to 2 inches; brown (7.5YR 5/3) gravelly sandy loam, dark brown (7.5YR 3/2) moist; moderate thick and very thick platy structure; soft, very friable, nonsticky and nonplastic; common very fine roots; many very fine and fine interstitial pores; 30 percent gravel; noneffervescent; moderately acid (pH 6.0); clear smooth boundary.

A2--2 to 12 inches; brown (7.5YR 5/3) very gravelly sandy loam, dark brown (7.5YR 3/2) moist; weak very fine and fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine roots; many very fine and fine interstitial pores; 40 percent gravel; noneffervescent; moderately acid (pH 6.0); clear smooth boundary.

A3--12 to 28 inches; brown (7.5YR 5/3) extremely gravelly sandy loam, dark brown (7.5YR 3/2) moist; massive; soft, very friable, nonsticky and nonplastic; few very fine roots; many very fine and fine interstitial pores; 55 percent gravel and 20 percent cobble; noneffervescent; moderately acid (pH 6.0); abrupt smooth boundary. (Combined thickness of A horizons is 20 to 35 inches.)

C--28 to 60 inches; brown (7.5YR 5/4) extremely gravelly coarse sand, dark brown (7.5YR 3/4) moist; single grain; loose, nonsticky and nonplastic; few very fine roots; many very fine and fine interstitial pores; 70 percent gravel and 15 percent cobble; noneffervescent; neutral (pH 6.6).

TYPE LOCATION: Cochise County, Arizona; located about 1,900 feet south and 1,600 feet west of the northeast corner section 33, Township 20 S., Range 28 E.; Bruno Peak topography map; latitude 31 degrees, 44 minutes, 15 seconds North and longitude 109 degrees, 28 minutes, 58 seconds West.

RANGE IN CHARACTERISTICS:

Soil moisture - Intermittently moist in some part of the soil moisture control section during July - September and December - February. Driest during May and June. Aridic ustic soil moisture regime.

Soil Temperature: 59 to 64 degrees F.

Rock fragments: greater than 35 percent gravel and cobbles

Clay content: 3 to 18 percent in the control section

Organic matter: 1 to 3 percent

Reaction: moderately acid to slightly alkaline

A horizon
Hue: 7.5YR, 10YR
Value: 3 through 5 dry, 2 or 3 moist
Chroma: 1 through 3, dry or moist
Texture: fine sandy loam, sandy loam, loam, loamy coarse sand

C horizon
Hue: 7.5YR, 10YR
Value: 3 through 5 dry, 2 through 4 moist
Chroma: 2 through 4 dry, 1 through 4 moist
Texture: coarse sand, sand, sandy loam, loam, coarse sandy loam

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: The Rafter soils are in the Chihuahuan desert on stream terraces, flood plains, and alluvial fans at elevations of 4,200 to 6,200 feet. Slope ranges from 0 to 15 percent. These soils formed from mixed stream and fan alluvium. The mean annual precipitation is 16 to 20 inches and occurs as thunderstorms during July to September and as gentle rains during December and January. The mean annual air temperature is 57 to 62 degrees F. The frost-free period is 160 to 210 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Stanford, Ashcreek, and Hayhollow soils. These soils contain less than 35 percent rock fragments in control section.

DRAINAGE AND PERMEABILITY: well drained; slow runoff; moderately rapid to rapid permeability.

USE AND VEGETATION: Used for livestock grazing and wildlife habitat. Vegetation includes blue grama, sideoats grama, cane beardgrass, green sprangletop, plains lovegrass, Arizona cottontop, Apache plume, and shrubby buckwheat.

DISTRIBUTION AND EXTENT: Southeastern Arizona. MLRAs are 38 and 41. Rafter soils are of moderate extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona

SERIES ESTABLISHED: Cochise County, Arizona; Soil Survey of Cochise County, Arizona, Douglas-Tombstone Part; 2000.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Mollic epipedon - the zone from 0 to 28 inches (A1, A2, and A3 horizons)

Cumulic feature - irregular decrease of organic matter is inferred by color changes and stratification

Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Eleventh Edition, 2010

Revised for the correlation of AZ675, 5/2009, WWJ

Revised for the correlation of Graham County, AZ, Southwestern Part; March, 2011, WWJ

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National Cooperative Soil Survey
U.S.A.