LOCATION JO                      AZ

Established Series
Rev. JMH/MJA
02/2025

JO SERIES

The Jo series consists of very shallow or shallow, well drained soils that formed in residuum derived from basalt. Jo soils are on lower positions of weathered lava fields formed from non-viscous lava flows. Slopes range from 0 to 4 percent. Mean annual precipitation is 12 inches and the mean annual temperature is about 52 degrees F.

TAXONOMIC CLASS: Fine-loamy, carbonatic, mesic Calcic Petrocalcids

TYPICAL PEDON: Jo-Cruice complex (Colors are for dry soil unless otherwise noted.)

A--0 to 3 inches (0 to 8 cm); pale brown (10YR 6/3) loam, dark brown (10YR 3/3) moist; weak medium subangular blocky; soft, loose, very sticky, very plastic; common very fine dendritic tubular pores; common very fine roots throughout; 5 percent gravel; violent effervescence; moderately alkaline, pH 8.0; clear smooth boundary

Bw--3 to 9 inches (8 to 24 cm); brown (10YR 4/3) loam, dark brown (10YR 3/3) moist; weak medium subangular blocky; slightly hard, very friable, very sticky, very plastic; common very fine dendritic tubular pores; common very fine roots throughout; 2 percent gravel; violent effervescence; moderately alkaline, pH 8.2; clear smooth boundary

Btk1--9 to 13 inches (24 to 32 cm); grayish brown (10YR 5/2) loam, brown (10YR 4/3) moist; weak medium subangular blocky; moderately hard, friable, very sticky, very plastic; common very fine dendritic tubular pores; common very fine roots throughout; common faint clay films on all faces of peds; 3 percent gravel; violent effervescence; moderately alkaline, pH 8.4; clear wavy boundary

Btk2--13 to 30 inches (32 to 75 cm); light brownish gray (10YR 6/2) gravelly sandy loam, brown (10YR 5/3) moist; structureless massive; very hard, extremely firm, moderately sticky, moderately plastic; common faint clay films on all faces of peds; 20 percent gravel; violent effervescence; strongly alkaline, pH 8.6; gradual wavy boundary

Bkm--30 to 32 inches (75 to 80 cm); cemented material; petrocalcic materials.

R--32 inches (80 cm); basalt bedrock

TYPE LOCATION: Coconino County, Arizona; located about 5.5 kilometers (3.4 miles) south of Ash Fork, Arizona; USGS Quadrangle Ash Fork; Latitude 35.173620, Longitude -112.477002, Datum WGS84

RANGE IN CHARACTERISTICS:
Soil moisture regime: aridic bordering on ustic
Mean annual soil temperature: 50 to 54 degrees F
Rock fragment content: 0 to 15 percent
Particle-size control section: from 25 centimeters to petrocalcic or 100 cm
Clay content: 18 to 35 percent

A horizon
Hue: 7.5YR or 10YR
Value: 5 or 6 (3 or 4 moist)
Chroma: 2 or 3, dry or moist
Calcium carbonate equivalent: 0 to 10 percent
Reaction: moderately alkaline

Bw or Btk horizons
Hue: 7.5YR or 10YR
Value: 4 or 5 (3 or 4 moist)
Chroma: 2 or 3, dry or moist
Texture: loam, clay loam or sandy loam
Calcium carbonate equivalent: 10 to 20 percent
Sodium Adsorption Ratio (SAR): 0 to 2
Reaction: moderately alkaline

Bkm horizon
Hue: 7.5YR or 10YR
Value: 6 or 7, dry or moist
Chroma: 2 or 3, dry or moist

COMPETING SERIES: None

GEOGRAPHIC SETTING:
Parent material: residuum derived from non-viscous basalt lava flows
Landform: weathered lava field plains
Slopes: 0 to 4 percent
Elevation: 5,200 to 7,000 feet
Mean annual air temperature: 47 to 50 degrees F
Mean annual precipitation: 10 to 14 inches
Precipitation peaks in July and August, and in winter months. May and June are much drier.
Frost-free period: 140 to 160 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cruice, Penzance, Lonti, and Taine soils. Cruice soils have an argillic horizon and are shallow to a restricted layer. Cruice soils are in upper positions on the lava field that accumulate less carbonate. Penzance soils are in alluvial areas. Lonti and Taine soils are in more viscous lava flow fields.

DRAINAGE AND PERMEABILITY: well drained, moderately rapid permeability
USE AND VEGETATION: These soils are used principally as grazing land. Native vegetation is blue grama, buffalograss, juniper, and barberry.

DISTRIBUTION AND EXTENT: Northern Arizona. MLRA 39.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.

SERIES ESTABLISHED: Coconino County, Arizona.

REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: from 0 to 9 centimeters. (A horizon)
Cambic horizon: from 3 to 33 inches. (Bw horizon).
Lithic contact: at 17 to 33 inches. (R bedrock)
Name is taken from a nearby vertical control point on land survey
Taxonomic Version: Keys to Soil Taxonomy, Thirteenth Edition, 2022
________________________________________

---

National Cooperative Soil Survey
U.S.A.