LOCATION YARBAM             AZ

YARBAM SERIES

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, thermic Aridic Lithic Haplustolls

TYPICAL PEDON: Yarbam very cobbly loam - rangeland. (Colors are for dry soil unless otherwise noted.) 35 to 70 percent of the surface is covered with gravel, cobble, and/or stones

A--0 to 2 inches; very dark brown (10YR 2/2) very cobbly loam, black (10YR 2/1) moist; weak thin platy structure; soft, very friable, nonsticky and nonplastic; few very fine and fine roots; few fine irregular pores; common distinct organic coatings on rock fragments; 5 percent stones, 15 percent cobble and 20 percent gravel; violently effervescent, 27 percent calcium carbonate equivalent; slightly alkaline (pH 7.4); clear smooth boundary. (1 to 5 inches thick)

C--2 to 9 inches; very dark grayish brown (10YR 3/2) very gravelly loam, black (10YR 2/1) moist; massive; soft, very friable, nonsticky and nonplastic; many very fine and fine roots; few fine irregular and tubular pores; common distinct organic coatings on rock fragments; 40 percent gravel; violently effervescent, 31 percent calcium carbonate equivalent; slightly alkaline (pH 7.6); abrupt wavy boundary. (7 to 15 inches thick)

R--9 inches; limestone.

TYPE LOCATION: Cochise County, Arizona; located at a latitude of 31 degrees, 27 minutes, 20 seconds North and longitude of 110 degrees, 16 minutes, 10 seconds West; about 700 feet north and 2,200 feet east from the southwest corner of Section 1, T. 23 S., R. 20 E.

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: 35 to 70 percent gravel, cobble and/or
stones

Reaction: slightly alkaline to moderately alkaline

Clay content: 5 to 18 percent

Organic matter: 1 to 3 percent

Calcium carbonate equivalent: 20 to 40 percent

Depth to unweathered bedrock: 6 to 20 inches

A horizon
Hue: 7.5YR, 10YR
Value: 2 through 5 dry, 2 through 4 moist
Chroma: 1 through 3, dry or moist
Texture: loam, fine sandy loam, sandy loam

C horizon
Hue: 7.5YR, 10YR
Value: 2 through 7 dry, 2 through 4 moist
Chroma: 1 through 3, dry or moist
Texture: loam, fine sandy loam, sandy loam, loamy sand

COMPETING SERIES: These are the Brewster (TX), Budlamp (AZ), Canquya (AZ) and Siphoncan (AZ) series. Brewster soils contain 18 to 35 percent clay in the control section. Budlamp soils are noneffervescent and have a pH that is moderately acid to neutral. Canquya and Siphoncan are inactive.

GEOGRAPHIC SETTING: Yarbam soils are on pediments, hill and mountain side slopes and shoulders at elevations of 4,600 to 6,800 feet. Slopes range from 6 to 65 percent. These soils formed in slope alluvium, colluvium and residuum from calcareous sedimentary rocks that include limestone, marble and calcareous sandstone. The mean annual precipitation is 16 to 23 inches and occurs as thunderstorms during July to September and as gentle rains during December to February. 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 Oversight, Gardencan, Lanque, Budlamp and Woodcutter soils. Oversight, Gardencan and Lanque soils are very deep. Budlamp and Woodcutter soils do not contain calcium carbonate.

DRAINAGE AND PERMEABILITY: Well drained; very rapid runoff;
moderately rapid permeability.

USE AND VEGETATION: Used for livestock grazing and wildlife habitat. Vegetation includes tanglehead, sideoats grama, bullgrass, southwestern stipa, Schott's agave, sotol, black grama, bullgrass, and silktassel.

DISTRIBUTION AND EXTENT: Southern Arizona. Yarbam soils are of moderate extent. MLRA is 41.

MLRA OFFICE RESPONSIBLE: Phoenix, Arizona

SERIES ESTABLISHED: Cochise County, Arizona; Soil survey of Coronado National Memorial; 1996.

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

Mollic epipedon - The zone from 0 to 9 inches (A, C horizons)

Lithic contact - The boundary at 9 inches (R horizon)

Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Tenth Edition, 2006.

Reclassified Aridic Lithic subgroup 2007.