LOCATION PEDREGOSA AZ

Established Series
Rev. WAS/CEM
10/2013

PEDREGOSA SERIES

The Pedregosa series consists of very shallow and shallow to a hardpan, well drained soils that formed in mixed calcareous fan alluvium. Pedregosa soils are on fan remnant. Slope ranges from 3 to 20 percent. The mean annual precipitation is about 14 inches (356 mm) and the mean annual air temperature is about 63 degrees F (17 degrees C).

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, thermic, shallow Calcic Petrocalcids

TYPICAL PEDON: Pedregosa very gravelly fine sandy loam - rangeland (colors are for dry soil unless otherwise noted). 40 to 50 percent of the surface is covered with gravel and cobbles.

A--0 to 1 inch (0 to 3 cm); brown (7.5YR 4/3) very gravelly fine sandy loam, dark brown (7.5YR 3/3) moist; weak granular structure; loose, nonsticky and nonplastic; common very fine and fine roots; few fine irregular pores; 52 percent gravel; violently effervescent, 6.5 percent calcium carbonate equivalent; moderately alkaline (pH 8.2); clear smooth boundary (1 to 3 inches thick).

Bk--1 to 7 inches (3 to 18 cm); brown (7.5YR 4/3) very gravelly fine sandy loam, dark brown (7.5YR 3/3) moist; weak fine subangular blocky structure; soft, very friable, moderately sticky and moderately plastic; common very fine and fine and few medium roots; common fine irregular and tubular pores; many distinct calcium carbonate coatings on rock fragments; 40 percent gravel; violently effervescent, 9 percent calcium carbonate equivalent; moderately alkaline (pH 8.4); abrupt smooth boundary (5 to 15 inches thick).

Bkkm--7 to 13 inches (18 to 33 cm); fractured hardpan; extremely hard, strongly cemented by calcium carbonate; violently effervescent; abrupt wavy boundary (5 to 20 inches thick).

2Ck--13 to 60 inches (33 to 152 cm); 70 percent white (7.5YR 8/1) and 30 percent brown (7.5YR 5/4) very gravelly sandy loam, 70 percent pinkish gray (7.5YR 7/2) and 30 percent strong brown (7.5YR 4/6) moist; massive; hard, firm, moderately sticky and moderately plastic; few very fine and fine roots; stratified laminar capping throughout; many distinct calcium carbonate coatings on rock fragments; common fine irregular hard calcium carbonate masses; 54 percent gravel; violently effervescent, 35 percent calcium carbonate equivalent; moderately alkaline (pH 8.0).

TYPE LOCATION: Cochise County, Arizona; located about 2,200 feet west and 1,450 feet south from the northwest corner of section 20, Township 20 S., Range. 23 E.; Tombstone topography map; latitude 31 degrees, 41 minutes, 55 seconds North and longitude 110 degrees, 00 minutes, 57 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. Ustic Aridic soil moisture regime.

Soil temperature: 59 to 69 degrees F (15 to 20.6 degrees C).

Surface rock fragments: 0 to 35 percent
Rock fragments: 35 to 60 percent gravel and cobbles

Reaction: slightly alkaline to strongly alkaline

Clay content: 5 to 18 percent in the control section

Organic matter: 1 to 2 percent

Calcium carbonate equivalent: 5 to 25 percent

Depth to petrocalcic horizon: 5 to 25 inches (13 to 64 cm)

A horizon
Hue: 7.5YR, 10YR
Value: 3 to 6 dry, 2 to 4 moist
Chroma: 2 or 3 dry, 2 to 4 moist
Texture: loam, fine sandy loam, sandy loam

Bk horizon
Hue: 7.5YR, 10YR
Value: 3 to 6 dry, 2 to 6 moist
Chroma: 2 to 4 dry or moist
Texture: loam, fine sandy loam, sandy loam, silt loam

2Ck horizon
Hue: 7.5YR, 10YR
Value: 4 to 8 dry, 4 to 7 moist
Chroma: 1 to 6 dry, 2 to 6 moist
Texture: sandy loam, loamy sand, loam
Calcium carbonate content: 15 to 40 percent

COMPETING SERIES: These are the Delnorte (TX), Kimrose (AZ), Missile (NM), Winkel (UT), and Yurm (NV) series. Kimrose soils have 18 to 35 percent clay in the particle-size control section. Missile soils have greater than 60 percent rock fragments in the control section. Delnorte, Winkel, and Yurm soils are in the Typic Ardic soil moisture regime. Winkel soils have bedrock at 20 to 40 inches.

GEOGRAPHIC SETTING: The Pedregosa soils are in the Chihuahuan desert on fan remnants at elevations of 3,000 to 5,000 feet (915 to 1524 meters). Slope ranges from 3 to 65 percent. These soils formed from mixed calcareous fan alluvium. The mean annual precipitation is 12 to 16 inches (305 to 406 mm) and occurs as thunderstorms during July to September and as gentle rains during December and January. The mean annual air temperature is 57 to 67 degrees F (14 to 19.4 degrees C). The frost-free period is 180 to 230 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Tombstone, Elgin, Stronghold, Mabray, Forrest, and Bonita soils. Tombstone, Elgin, Stronghold, Forrest, and Bonita soils are all very deep. Mabray soil is very shallow and shallow to bedrock.

DRAINAGE AND PERMEABILITY: Well drained; medium to high runoff; moderately rapid permeability.

USE AND VEGETATION: Used for livestock grazing and wildlife habitat. Vegetation includes sideoats grama, cane beardgrass, hairy grama, fluff grass, black grama, and yucca.

DISTRIBUTION AND EXTENT: Southeastern Arizona. LRR-D, MLRA is 41. Pedregosa soils are of minor 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:

Ochric epipedon - the zone from 0 to 1 inch (0 to 3 cm) (A horizon)

Calcic horizon - the zone from 0 to 7 inches (0 to 18 cm) (A and Bk horizons)

Petrocalcic horizon - the zone from 7 to 13 inches (18 to 33 cm) (Bkm horizon)

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

Updated competing series section 3/17/2008, CEM

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

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

Revised for the correlation of Black Hills-Sedona, AZ, August 2012, CEM
Revised for the correlation the SDJR - MLRA 38 - Tombstone-Eloma-Pedregosa complex, 5 to 65 percent slopes project, September 2013, LJG2

National Cooperative Soil Survey
U.S.A.