LOCATION FORREST AZ+NM

Established Series
Rev. AAD/JEJ/PDC/CEM/WWJ
04/2011

FORREST SERIES

The Forrest series consists of very deep, well drained soils that formed in fan alluvium. Forrest soils are on basin floors, fan terraces, and fan piedmonts and have slopes of 0 to 15 percent. The mean annual precipitation is about 14 inches and the mean annual air temperature is about 64 degrees F.

TAXONOMIC CLASS: Fine, mixed, superactive, thermic Ustic Calciargids

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

A1--0 to 2 inches; brown (7.5YR 5/4) loam, brown (7.5YR 4/4) moist; weak thin platy structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine roots; many very fine and fine vesicular pores; few fine gravel; noneffervescent; slightly acid (pH 6.5); abrupt smooth boundary. (1 to 3 inches thick)

A2--2 to 4 inches; brown (7.5YR 5/4) loam, brown (7.5YR 4/4) moist; massive; slightly hard, friable, moderately sticky and moderately plastic; common very fine and fine roots; few fine tubular pores; few fine gravel; noneffervescent; slightly acid (pH 6.5); clear smooth boundary. (1 to 3 inches thick)

Bt1--4 to 11 inches; reddish brown (5YR 4/3) clay loam, dark reddish brown (5YR 3/4) moist; moderate medium and coarse subangular blocky structure; very hard, friable, moderately sticky and moderately plastic; common very fine and fine roots; few very fine tubular pores; common small pressure faces; noneffervescent; neutral (pH 7.0); gradual smooth boundary. (5 to 9 inches thick)

Bt2--11 to 16 inches; reddish brown (5YR 4/4) clay, dark reddish brown (5YR 3/4) moist; moderate medium and coarse subangular and angular blocky structure; very hard, friable, moderately sticky and moderately plastic; common very fine and fine roots; few very fine tubular pores; common small pressure faces; noneffervescent; slightly alkaline (pH 7.5); clear smooth boundary. (4 to 8 inches thick)

Bt3--16 to 20 inches; reddish brown (5YR 4/4) clay, dark reddish brown (5YR 3/4) moist; moderate medium subangular blocky structure; very hard, friable, moderately sticky and moderately plastic; common very fine and fine roots; few very fine tubular pores; common small pressure faces; 3 percent gravel; noneffervescent; slightly alkaline (pH 7.5); clear wavy boundary. (3 to 8 inches thick)

Bt4--20 to 29 inches; red (2.5YR 4/6) clay, dark red (2.5YR 3/6) moist; strong medium prismatic structure; very hard, firm, moderately sticky and moderately plastic; common very fine and fine roots; many large pressure faces; 3 percent gravel; strongly effervescent; moderately alkaline (pH 8.0); abrupt wavy boundary. (6 to 15 inches thick)

2Bkl--29 to 35 inches; reddish yellow (5YR 6/6) loam, yellowish red (5YR 5/6) moist; massive; hard, friable, moderately sticky and moderately plastic; common very fine and fine roots; common fine tubular pores; many medium and coarse nodules and irregular soft calcium carbonate masses; violently effervescent, 33 percent calcium carbonate equivalent; moderately alkaline (pH 8.0); gradual wavy boundary. (10 to 20 inches thick)

2Bk2--35 to 50 inches; light brown (7.5YR 6/4) loam, light brown (7.5YR 6/4) moist; massive; hard, friable, slightly sticky and moderately plastic; few very fine and fine roots; few fine tubular pores; many medium and coarse nodules and irregular soft calcium carbonate masses; violently effervescent, 30 percent calcium carbonate equivalent; moderately alkaline (pH 8.0); gradual wavy boundary. (10 to 20 inches thick)

2Bk3--50 to 60 inches; light brown (7.5YR 6/4) loam, strong brown (7.5YR 5/6) moist; massive; hard, friable, slightly sticky and slightly plastic; few very fine and fine roots; few fine tubular pores; 3 percent gravel; common medium and coarse nodules and irregular soft calcium carbonate masses; violently effervescent, 18 percent calcium carbonate equivalent; moderately alkaline (pH 8.2).

TYPE LOCATION: Cochise County Arizona; approximately 1 mile northwest of Sunsites, Arizona; 1,200 feet north and 1,200 feet west of the southeast corner of Section 13, T. 17 S., R. 24 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. Ustic aridic soil moisture regime.

Soil Temperature: 59 to 70 degrees F.

Rock Fragments: Averages less than 35 percent in the control section; can range to 50 percent in any one subhorizon

Depth to calcic horizon: 20 to 40 inches. Calcium carbonate equivalent averages 15 to 40 percent

Organic matter: Averages 1 percent or more in the surface

A horizon
Hue: 5YR, 7.5YR, 10YR
Value: 3 through 6 dry, 2 through 5 moist
Chroma: 2 through 6, dry, 1 to 6 moist
Reaction: moderately acid to moderately alkaline

Bt horizon
Hue: 2.5YR, 5YR, 7.5YR
Value: 3 through 8 dry, 2 through 6 moist
Chroma: 2 through 6, dry or moist
Texture: Clay loam, clay, sandy clay; but can range to include sandy clay loam
Reaction: Slightly acid to moderately alkaline

Bk or C horizon
Hue: 5YR, 7.5YR
Value: 5 through 8 dry, 4 through 7 moist
Chroma: 2 through 6, dry or moist
Texture: Loam, fine sandy loam, sandy loam; but can range to include sandy clay loam or coarser textures

Some pedons have Btk horizons

Some pedons contain trace amounts of gypsum throughout.

COMPETING SERIES: These are the Bernardino (AZ), Penthouse (AZ) and Stellar (NM) series. Bernardino soils have a calcic horizon above 20 inches. Penthouse soils have textures finer than moderately fine in the series control section. Stellar soils have a much lower mean annual rainfall component and are dry in the soil moisture control section for longer periods.

GEOGRAPHIC SETTING: Forrest soils are on basin floors, fan terraces, and fan piedmonts and have slopes of 0 to 15 percent. Elevations range from 3,500 to 5,200 feet. These soils formed in fan alluvium from mixed sources. The mean annual precipitation ranges from 12 to 16 inches. The mean annual air temperature is 57 to 68 degrees F. The frost-free period is 160 to 250 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Bernardino and White House soils. In addition is the Caralampi soil. Caralampi soils average more than 35 percent rock fragments in the control section.

DRAINAGE AND PERMEABILITY: Well drained; slow or medium runoff; slow permeability.

USE AND VEGETATION: Forrest soils are used for livestock grazing and wildlife habitat. The present vegetation is sideoats grama, black grama, cane beardgrass, plains lovegrass, blue grama, hairy grama, sand dropseed, vine mesquite, curly mesquite, false mesquite, Mormon-tea, mimosa, yucca, ocotillo, cacti and agave.

DISTRIBUTION AND EXTENT: Southeastern Arizona and Southwestern New Mexico. This series is of moderate extent. MLRA is 41.

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

SERIES ESTABLISHED: Cochise County (Sulphur Springs Valley), Arizona, 1948.

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

Ochric epipedon - the zone from 0 to 4 inches (A1, A2 horizons)

Argillic horizon - the zone from 4 to 29 inches (Bt1, Bt2, Bt3, Bt4 horizons) Clay films were not recognized in fine textured soils when this pedon was described in 1969.

Calcic horizon - the zone from 29 to 60 inches (2Bk1, 2Bk2, 2Bk3 horizons)

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

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

National Cooperative Soil Survey
U.S.A.