LOCATION AGUSTIN AZ

Established Series
Rev. DB/CM/CEM
11/2014

AGUSTIN SERIES

The Agustin series consists of very deep, well drained, moderately rapidly permeable soils formed in mixed fan alluvium. These nearly level to moderately sloping soils are on fan remnants. Slopes range from 0 to 8 percent. The mean annual precipitation is about 11 inches and the mean annual air temperature is about 66 degrees F.

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, thermic Typic Haplocambids

TYPICAL PEDON: Agustin gravelly sandy loam--rangeland. (Colors are for dry soil unless otherwise noted.)

Al--0 to 1 inch; brown (7.5YR 5/4) gravelly sandy loam, brown (7.5YR 4/4) moist; weak thin platy structure; soft, very friable, nonsticky and nonplastic; many very fine and fine roots, many fine interstitial pores; 15 percent gravel; slightly alkaline (pH 7.6); clear smooth boundary.

A2--1 to 8 inches; brown (7.5YR 5/4) gravelly sandy loam, brown (7.5YR 4/4) moist; weak thin platy structure parting to weak medium granular; soft, very friable, nonsticky and nonplastic; common very fine and fine and few medium roots; common fine interstitial pores; 15 percent gravel; noneffervescent; slightly alkaline (pH 7.6); clear smooth boundary (1 to 10 inches thick).

Bkl--8 to 19 inches; brown (7.5YR 5/4) gravelly sandy loam, brown to brown (7.5YR 4/4) moist; weak fine angular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine, fine, and medium roots; common very fine and fine interstitial and tubular pores; few distinct calcium carbonate coats on rock fragments; 25 percent gravel; strongly effervescent; slightly alkaline (pH 7.8); clear smooth boundary.

Bk2--19 to 33 inches: brown (7.5YR 5/4) gravelly sandy loam, brown (7.5YR 4/4) moist; weak fine subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; common very fine and fine roots; common very fine and fine interstitial and tubular pores; common distinct calcium carbonate coats on rock fragments; 25 percent gravel; violently effervescent; moderately alkaline (pH 8.0); abrupt smooth boundary.

Bk3--33 to 42 inches; brown (7.5YR 5/4) very gravelly sandy loam, brown (7.5YR 4/4) moist; massive; hard, friable, nonsticky and nonplastic; common very fine and fine and few medium roots; few fine interstitial pores, common distinct calcium carbonate coats on rock fragments; 35 percent gravel; violently effervescent; moderately alkaline (pH 8.0); clear smooth boundary.

Bk4--42 to 60 inches; brown (7.5YR 5/4) gravelly sandy loam, brown (7.5YR 4/4) moist; moderate fine subangular blocky structure slightly hard, friable, nonsticky and nonplastic; few very fine and fine roots; common very fine and fine interstitial and tubular pores; common distinct calcium carbonate coats on rock fragments; 25 percent gravel; violently effervescent; moderately alkaline (pH 8.0).

TYPE LOCATION: Pima County, Arizona; Tohono O'odham Nation located at a latitude of 32 degrees, 04 minutes, 45 seconds N. and a longitude of 112 degrees, 02 minutes, 00 seconds W; Sec. 35, T. 15 S., R. 3 E.

RANGE IN CHARACTERISTICS:

Soil moisture - Usually dry, moist in some part for short periods during winter and early spring and intermittently moist following convection storms. The soils have a Typic Aridic soil moisture regime.

Soil temperature - 60 to 72 degrees F.

Calcium carbonate equivalent: less than 5 percent

These soils are usually calcareous, but can be noncalcareous in the upper 10 or 12 inches

Rock fragments - Gravel and cobble coarse fragments are mostly igneous and limestone, ranging from 1/8 inch to as much as 8 inches in diameter, but mostly less than 3 inches. Content of coarse fragments ranges from 5 to 35 percent in the upper 10 inches, and 15 to 35 percent in the 10 to 40-inch control section.

Clay content: ranges from 3 to 18 percent throughout the profile

A horizon
Hue: 7.5YR, 10YR
Value: 3 to 7 dry, 3 to 5 moist
Chroma: 2 to 6, dry or moist
Reaction: slightly alkaline or moderately alkaline.

Bk, Bw and C horizons (where present)
Hue: 5YR, 7.5YR, 10YR
Value: 4 to 7 dry, 3 to 5 moist
Chroma: 3 or 4 dry, 2 to 4 moist
Texture: sandy loam, loam, coarse sandy loam, fine sandy loam, includes minor strata ranging in texture from sandy clay loam to loamy coarse sand.

COMPETING SERIES: These are Filaree (AZ), Hayhook (AZ), Lostman (AZ), Nasagold (CA), Pajarito (NM), Pyxo (CA), and Sahuarita (AZ) series. Filaree and Hayhook soils are noneffervescent to a depth of 20 inches or more. Pajarito soils have less than 15 percent coarse fragments in the PSCS. Pyko soils are moderately deep to weathered bedrock. Sahuarita soils have buried argillic horizons. All of these soils are moist in some part of the soil moisture control section for less than 20 days cumulative between July and September.

GEOGRAPHIC SETTING: Agustin soils are on fan remnants. Slopes are dominantly about 5 percent but range from 0 to 8 percent. The regolith consists of calcareous, moderately coarse-textured mixed fan alluvium. Mean annual precipitation ranges from 10 to 12 inches, and mean annual air temperature ranges from 58 to 69 degrees F. Frost-free period ranges from 190 to 280 days, and elevation ranges from 1,760 to 3,800 feet.

GEOGRAPHICALLY ASSOCIATED SOILS: These include the competing Pajarito, Sahuarita, and Hayhook soils and the Vado series. Vado soils contain more than 35 percent rock fragments.

DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderately rapid. Runoff is negligible on slopes less than 3 percent, very low on 3 to 5 percent slopes, and low on 5 to 8 percent slopes.

USE AND VEGETATION: Used for livestock grazing. Vegetation consists of creosotebush, triangle bursage, mesquite, Rothrock grama, and annual forbs and grasses.

DISTRIBUTION AND EXTENT: Southern Arizona. MLRA is 40 and 41. The series is of moderate extent.

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

SERIES ESTABLISHED: East Valencia Area, New Mexico; 1970.

REMARKS: The type pedon was moved to the Tohono O'odham Nation, Arizona, Parts of Maricopa, Pima, and Pinal Counties soil survey area on 10/2001 to better represent the series concept.

Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon - 0 to 8 inches (A1 and A2 horizons)

Cambic horizon - 8 to 33 inches (Bk1 and Bk2 horizons)

Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Twelfth Edition, 2014.

Revised for the correlation of AZ661, 11/08, PDC

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

Revised for the correlation of White Sands Missile Range, New Mexico; October, 2014, NMS

National Cooperative Soil Survey
U.S.A.