LOCATION SCHRAP                  AZ

Established Series
Rev. SDC/MLR
04/2011

SCHRAP SERIES

The Schrap series consists of very shallow and shallow, well drained soils formed in alluvium from shale, schist and sandstone. Schrap soils are on hills, mountains and pediments and have slopes of 5 to 60 percent. Mean annual precipitation is about 14 inches and the mean annual air temperature is 62 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, nonacid, thermic, shallow Ustic Torriorthents

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

A--0 to 2 inches; light reddish brown (5YR 6/4) very channery loam, reddish brown (5YR 4/4) moist; weak thin platy structure; soft, very friable, nonsticky and nonplastic; common very fine roots; common fine interstitial pores; slightly acid (pH 6.5); clear smooth boundary. (1 to 4 inches thick)

C--2 to 11 inches; yellowish red (5YR 5/6) very channery loam, yellowish red (5YR 4/6) moist; massive; soft, very friable, slightly sticky and slightly plastic; common very fine, fine and medium roots; common very fine and fine interstitial pores; neutral (pH 6.8); abrupt wavy boundary. (0 to 11 inches thick)

2Cr--11 to 60 inches; variegated fractured schist; common very fine and fine roots and few fine calcium carbonate coatings in fractures.

TYPE LOCATION: Pima County, Arizona; 675 feet west and 100 feet north of the southeast corner of section 11, T. 21 S., R. 8 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.

Depth to bedrock - 4 to 12 inches. Some pedons have a lithic contact at depths of 20 to 40 inches

Soil temperature - 60 to 70 degrees F.

Rock fragments - 35 to 85 percent channers and flagstones

Organic matter content - less than 1 percent

Clay content - averages more than 18 percent in the particle-size control section

Reaction - slightly acid to slightly alkaline

A horizon
Hue: 5YR, 7.5YR, 10YR
Value: 4 to 6 dry, 2 to 4 moist
Chroma: 2 to 4, dry or moist

C horizon
Hue: 5YR, 7.5YR, 10YR
Value: 3 to 6 dry, 3 or 6 moist
Chroma: 3 to 6, dry or moist
Texture: loam, clay loam, sandy clay loam

COMPETING SERIES: This is the Romero (AZ) series. Romero soils average less than 18 percent clay in the control section.

GEOGRAPHIC SETTING: Schrap soils are on hills, mountains and pediments. Slopes range from 5 to 65 percent but are dominantly 10 to 25 percent. They formed in alluvium from shale, schist and sandstone. Elevations range from 3,200 to 5,720 feet. Mean annual precipitation is 12 to 16 inches occurring as summer thunderstorms and winter rain. Mean annual air temperature is 58 to 68 degrees F. The frost-free period is about 170 to 240 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Caralampi, Graham, and White House soils. Caralampi and White House soils are very deep. Graham soils have argillic horizons.

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

USE AND VEGETATION: Used for livestock grazing. Vegetation is oak, three awn, black and sideoats grama, sprucetop and slender grama, wooly bunchgrass, little bluestem, mesquite, calliandra, ocotillo, mimosa, catclaw, barrel, and other cacti.

DISTRIBUTION AND EXTENT: Southern Arizona. This soil occurs in LRR-D, MLRA 41. The Schrap soil is extensive.

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 2 inches (A horizon)

Paralithic contact - the boundary at 11 inches (2Cr horizon)

Entisol feature - the absence of diagnostic subsurface horizons

Type location moved in 1990 because original site was 3 inches deep and did not meet the Soil Taxonomy thickness requirement of 4 inches to be considered soil.

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

Revised for the correlation of AZ661, 2/2009, WWJ

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

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National Cooperative Soil Survey
U.S.A.