LOCATION PAHAKA             AZ
Established Series
Rev. RCH/PDC/WWJ
01/2007

PAHAKA SERIES


The Pahaka series consists of very deep, well drained soils that formed in fan alluvium. Pahaka soils are on fan terraces with slopes ranging from 0 to 5 percent. The mean annual precipitation is about 8 inches and the mean annual air temperature is about 71 degrees F.

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

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

A1--0 to 1 inch; light yellowish brown (10YR 6/4) loam, dark yellowish brown (10YR 4/4) moist; moderate medium platy structure; slightly hard, very friable, nonsticky and slightly plastic; many very fine roots; common very fine vesicular pores; 5 percent fine gravel; noneffervescent; moderately alkaline (pH 8.0); clear smooth boundary.

A2--1 to 4 inches; light yellowish brown (10YR 6/4) fine sandy loam, dark yellowish brown (10YR 4/4) moist; moderate medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine roots; common very fine vesicular pores; 5 percent fine gravel; noneffervescent; moderately alkaline (pH 8.0); clear wavy boundary. (Combined thickness of the A horizons is 2 to 6 inches)

AB--4 to 9 inches; reddish yellow (7.5YR 6/6) fine sandy loam, brown (7.5YR 4/4) moist; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine roots; common very fine irregular pores; 5 percent fine gravel, calcium carbonate coated; noneffervescent; moderately alkaline (pH 8.2); clear wavy boundary. (3 to 6 inches thick)

Bwn1--9 to 19 inches; reddish yellow (7.5YR 6/6) fine sandy loam, brown (7.5YR 4/4) moist; weak medium subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; many very fine roots; common very fine irregular pores; 14 percent gravel, calcium carbonate coated; strongly effervescent; nonsaline (ECe 1 dS/m) and slightly sodic (SAR 11); moderately alkaline (pH 8.4); gradual smooth boundary. (7 to 13 inches thick)

Bwn2--19 to 34 inches; reddish yellow (7.5YR 6/6) gravelly sandy loam, brown (7.5YR 4/4) moist; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine roots; many very fine irregular pores; 18 percent gravel, lime coated; few very fine, rounded, soft accumulations of lime; strongly effervescent; slightly saline (ECe 7 dS/m) and moderately sodic (SAR 23); moderately alkaline (pH 8.4); clear wavy boundary. (8 to 15 inches thick)

2Btknzb--34 to 46 inches; yellowish red (5YR 5/6) very gravelly sandy clay loam, yellowish red (5YR 4/6) moist; strong medium subangular blocky structure; very hard, firm, sticky and plastic; few very fine roots; many very fine tubular pores; many distinct clay films on faces of peds and bridging mineral grains; 47 percent gravel, calcium carbonate coated; many very fine, rounded and irregular, soft accumulations of calcium carbonate; strongly effervescent; moderately saline (ECe 9dS/m) and moderately sodic (SAR 27); moderately alkaline (pH 8.4); gradual wavy boundary.

2Bknzb--46 to 60 inches; pink (7.5YR 7/4) strongly cemented gravelly sandy clay loam, brown (7.5YR 5/4) moist; moderate fine subangular blocky structure; extremely hard, firm, sticky and plastic; few very fine tubular pores; 32 percent gravel, calcium carbonate coated; many fine rounded nodules; violently effervescent; moderately saline (ECe 12 dS/m) and moderately sodic (SAR 20); moderately alkaline (pH 8.4). (Combined thickness of the buried B horizon is 26 to 38 inches)

TYPE LOCATION: Maricopa County, Arizona; about 1 mile northeast of Lone Butte, on the Gila River Indian Reservation; 200 feet north and 1000 feet west of the southeast corner of section 4, T 2 S., R. 3 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. Typic aridic soil moisture regime.

The 10 to 40 inch particle size control section averages less than 18 percent clay.

Depth to buried argillic horizon - 20 to 40 inches.

Rock fragments - 5 to 55 percent in any one horizon; averages less than 35 percent in the particle-size control section.

Salinity- nonsaline to moderately saline.

Sodicity- nonsodic to moderately sodic.

Calcium carbonate - Noneffervescent to violently effervescent in the upper part; slightly to violently effervescent in the lower part.

A horizon
Hue: 7.5YR, 10YR
Value: 5 or 6 dry, 4 through 6 moist
Chroma: 3 ,4, or 6, dry or moist

Bw horizon
Hue: 7.5YR, 10YR
Value: 5, 6 or 7 dry, 4, 5, or 6 moist
Chroma: 4 or 6, dry or moist
Texture: Fine sandy loam, sandy loam, gravelly sandy loam, gravelly loam, very gravelly sandy loam (8 to 17 percent clay).
Reaction: mildly or moderately alkaline

Buried Bt horizons
Hue: 5YR, 7.5YR
Value: 4, 5, 6 or 7 dry, 3, 4, 5 or 6 moist
Chroma: 4 or 6, dry or moist
Texture: Loam, sandy clay loam, gravelly loam, gravelly sandy clay loam, gravelly clay loam, very gravelly sandy clay loam (20 to 35 percent clay). Some pedons contain sandy loam or fine sandy loam textures in addition to the finer textures.
Reaction: Mildly to strongly alkaline
Salinity: 1 to 8 dS/m
Cementation: Weakly to strongly cemented in some pedons

COMPETING SERIES: These are the Dateland and Denure series. Dateland and Denure soils do not have buried argillic horizons at moderate depths.

GEOGRAPHIC SETTING: Pahaka soils are on fan terraces. Slopes range from 0 to 5 percent. Elevations range from 1100 to 2400 feet. They formed in Holocene fan alluvium superimposed on Pleistocene relict basin floors and fan terraces. The mean annual precipitation is 7 to 10 inches occurring as summer thunderstorms and gentle winter rain. Mean annual air temperature is 69 to 75 degrees F. The frost-free period is about 240 to 325 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Denure and the Shontik soils. Shontik soils are fine-loamy. In addition are the Chuckawalla, Gunsight, Momoli and Pinamt soils that do not have buried argillic horizons at moderate depths.

DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderately rapid permeability above and moderately slow in the buried horizon.

USE AND VEGETATION: Used for livestock grazing, wildlife habitat and irrigated cropland. Vegetation is creosotebush, triangleleaf bursage and annual grasses.

DISTRIBUTION AND EXTENT: Southern Arizona. MLRA is 40. The soils of this series are not extensive.

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

SERIES ESTABLISHED: Gila River Indian Reservation, Arizona; Parts of Maricopa and Pinal Counties, 1991. Name means Eagle in the Pima Indian language.

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

Ochric epipedon - the zone from 0 to 9 inches. (A1, A2, AB horizons)

Cambic horizon - the zone from 9 to 34 inches (Bwn1, Bwn2 horizons)

Buried soil - the zone from 34 to 60 inches (2Btknzb, 2Bknzb horizons)

Classified according to Soil Taxonomy Second Edition, 1999

ADDITIONAL DATA:

NSSL Sample S84 AZ-13-6, and NSSL Sample S84 AZ-13-7.


National Cooperative Soil Survey
U.S.A.