LOCATION MARTINEZ AZEstablished Series
TAXONOMIC CLASS: Very-fine, kaolinitic, mesic Aridic Haplustalfs
TYPICAL PEDON: Martinez gravelly loam - grassland (Colors are for dry soil unless otherwise noted.)
A1--0 to 1 inches; brown (10YR 5/3) gravelly loam, dark yellowish brown (10YR 3/4) moist; weak thick platy structure; slightly hard, friable, slightly sticky, slightly plastic; many fine and very fine roots; common fine interstitial and tubular pores; 15 percent gravel; strongly acid (pH 5.2); abrupt smooth boundary. (1 to 3 inches thick)
A2--1 to 6 inches; brown (7.5YR 5/4) clay loam, dark brown (7.5YR 3/4) moist; weak medium subangular blocky structure; slightly hard, friable, sticky, plastic; common fine and very fine roots; common fine interstitial and tubular pores; 10 percent gravel; very strongly acid (pH 5.0); clear smooth boundary. (3 to 5 inches thick)
Bt1--6 to 10 inches; brown (7.5YR 4/4) clay, brown (7.5YR 4/4) moist; moderate fine and medium subangular blocky structure; hard, friable, sticky, plastic; many fine and very fine roots; few fine and medium interstitial and tubular pores; common thin clay films on faces of peds and in pores; 2 percent gravel; slightly acid (pH 6.2); clear smooth boundary. (3 to 10 inches thick)
Bt2--10 to 18 inches; dark yellowish brown (10YR 4/4) heavy clay, dark yellowish brown (10YR 3/4) moist; moderate medium and coarse prismatic structure; hard, friable, sticky, very plastic; common fine and very fine roots; few fine interstitial and tubular pores; many moderately thick clay films on faces of peds and in pores; common medium slickensides in lower part; neutral (pH 7.1); gradual smooth boundary. (8 to 12 inches thick)
Bt3--18 to 26 inches; yellowish brown (10YR 5/6) heavy clay, yellowish brown (10YR 5/6) moist; moderate medium and coarse subangular blocky structure; very hard, firm, sticky, very plastic; few fine and very fine roots; few fine interstitial and tubular pores; many moderately thick clay films on faces of peds and in pores; 1 percent gravel; many medium and large slickensides; slightly alkaline (pH 7.8); gradual smooth boundary. (7 to 12 inches thick)
Bt4--26 to 35 inches; yellowish brown (10YR 5/6) heavy clay, yellowish brown (10YR 5/6) moist, few fine distinct yellowish red (5YR 4/6) mottles, yellowish red (5YR 4/6) moist; moderate medium and coarse subangular blocky structure; very hard, firm, sticky, very plastic; few fine roots; few fine interstitial and tubular pores; common moderately thick clay films on faces of peds and in pores; 6 percent gravel; common pressure faces; many medium and large slickensides; moderately alkaline (pH 8.0); clear wavy boundary. (7 to 14 inches thick)
Bt5--35 to 60 inches; mottled yellowish brown (10YR 5/6), red (2.5YR 4/8) and brownish yellow (10YR 6/6) gravelly sandy clay, yellowish brown (10YR 5/6), red (2.5YR 4/8) and brownish yellow (10YR 6/6) moist; mottles are many medium and coarse and distinct; moderate medium subangular and angular blocky structure; very hard, friable, sticky, plastic; few fine roots; common very fine interstitial pores; common thin clay films on faces of peds and in pores; 18 percent gravel; slightly effervescent in spots under pebbles; moderately alkaline (pH 8.0). (6 to 12 inches thick)
TYPE LOCATION: Cochise County, Arizona; 1.3 miles SW of intersection of F.S. roads #48 and #227 and 100 feet north of road #227; approximately 1,600 feet west and 350 feet south of NE corner sec. 9, T.24S., R.l9E.
RANGE IN CHARACTERISTICS:
The solum is 35 to 60 inches or more thick
Coarse fragment content in the series control section: less than 15 percent and usually less than 5 percent
Mean annual soil temperature: 55 degrees to 59 degrees F.
Soil moisture: Aridic ustic moisture regime
CaC03 equivalent: at the site location is zero, however the soil has 1 to 2 percent CaC03 at depths of more than 35 inches in some pedons
A horizon
Hue: 10YR or 7.5YR
Value: 4 or 5 dry
Chroma: 2 through 4
Bt horizons
Hue: 10YR or 7.5YR but includes 2.5YR and 5YR below depths of 35 inches
Value: 4 or 5 dry and 3 or 4 moist
Chroma: 4 through 6
Texture: dominantly heavy clay but includes clay and heavy clay loam in the upper part and clay loam or sandy clay in the lower part
Structure: moderate fine to coarse subangular and angular blocky structure or moderate or strong, medium and coarse prismatic structure
Some pedons have a thin (1/8 to 1/4 inch thick) discontinuous light gray (10YR 7/2) layer immediately overlying the Bt1 horizons.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Martinez soils are on nearly level to gently sloping fans at elevations of 5,000 to 5,800 feet. Slopes are 0 to 3 percent. These soils formed in old alluvium from rocks such as andesite, quartzite, rhyolite, rhyolitic tuff, and sandstone. The climate is semiarid continental. Mean annual temperature is 53 degrees to 57 degrees F. The frost-free season is 140 to 200 days and annual precipitation is 15 to 20 inches of which 50 percent falls as thundershowers in July, August and September, and most of the remainder as gentle winter rains or snows in December, January and February.
GEOGRAPHICALLY ASSOCIATED SOILS: In addition to the competing Casto and White House soils, these are the Canelo, Comoro and Pima series. Canelo soils are somewhat poorly drained and very gravelly or very cobbly. Comoro and Pima soils have mollic epipedons and lack an argillic horizon.
DRAINAGE AND PERMEABILITY: Well-drained; slow runoff; very slow permeability.
USE AND VEGETATION: These soils are used as rangeland. Vegetation is blue grama, three-awn, wolftail, hairy grama, sprucetop grama, sideoats grama, purple grama, plains lovegrass, needlegrass and perennial forbs, with some manzanita and oak at the higher elevations.
DISTRIBUTION AND EXTENT: Southeastern Arizona. The series is of moderate extent. MLRA 41.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Santa Cruz County Area Arizona, 1971.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 0 to 6 inches (A horizons)
Argillic horizon - The zone from 6 to 60 inches (Bt horizons)
Classification changed from Udic subgroup to Aridic subgroup. This change was made to be consistent with the moisture regime.
Classified according to Keys to Soil Taxonomy Tenth Edition, 2006.