LOCATION CONCHO NM

Established Series
Rev. JBC/SSP/LWH/SAZ/WWJ
12/2022

CONCHO SERIES

The Concho series consists of very deep, well drained, slowly permeable soils that formed in alluvium, fan alluvium and stream alluvium derived from sandstone and shale. Concho soils are on valley floors and drainageways. Slopes range from 0 to 3 percent. Mean annual precipitation is about 14 inches, and mean annual temperature is about 50 degrees F.

TAXONOMIC CLASS: Fine, mixed, superactive, mesic Aridic Argiustolls

TYPICAL PEDON: Concho clay loam--in reseeded rangeland on a 1 percent slope at an elevation of 6,925 feet. (Colors are for dry soils unless otherwise noted.)

Ap1--0 to 1 inches; brown (10YR 5/3), clay loam, very dark grayish brown (10YR 3/2) moist; strong thin platy structure parting to moderate fine granular; soft, very friable, sticky and plastic; many very fine and fine roots; many fine irregular and few fine vesicular pores; neutral; clear smooth boundary. (The combined thickness of A horizons is 1 to 5 inches)

Ap2--1 to 5 inches; brown (10YR 5/3) clay, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; hard, firm, sticky and very plastic; many very fine and fine roots; many fine irregular pores; many prominent clay films coating faces of peds; neutral; clear smooth boundary.

Btss1--5 to 18 inches; yellowish brown (10YR 5/4) clay, dark brown (10YR 3/3) moist; moderate coarse prismatic structure parting to strong medium subangular blocky; very hard, very firm, sticky and very plastic; common very fine and fine roots; common fine irregular pores; many prominent clay films coating faces of peds; few slickensides; slightly effervescent; slightly alkaline; gradual wavy boundary. (The combined thickness of Bt horizons is 4 to 37 inches)

Btss2--18 to 32 inches; brown (10YR 5/3) clay, brown (10YR 4/3) moist; weak very coarse subangular blocky structure; extremely hard, extremely firm; sticky and very plastic; few very fine and fine roots; common fine irregular pores; many prominent clay films coating faces of peds; many slickensides; very slightly effervescent; moderately alkaline; gradual irregular boundary.

Btkss--32 to 51 inches; brown (10YR 5/3) clay, brown (10YR 4/3) moist; weak fine and medium subangular blocky structure; extremely hard, extremely firm; sticky and very plastic; few very fine and fine roots; common fine irregular pores; many prominent clay films coating faces of peds; many slickensides; common fine irregular soft masses of calcium carbonate; slightly effervescent; slightly alkaline; clear irregular boundary. (The combined thickness of Btk horizons is 22 to 51 inches)

Btkz--51 to 65 inches; brown (10YR 4/3) clay; dark brown (10YR 3/3) moist; weak fine and medium subangular blocky structure; extremely hard, extremely firm; sticky and very plastic; few very fine and fine roots; common fine irregular pores; common prominent clay films coating faces of peds; common fine clusters of salt crystals; few fine irregular soft masses of calcium carbonate; slightly effervescent; slightly alkaline.

TYPE LOCATION: McKinley County, New Mexico; about 2.8 miles north of Pescado Reservoir on the Zuni Indian Reservation; 108 degrees 33 minutes 9 seconds west longitude, 35 degrees 8 minutes 54 seconds north latitude.

RANGE IN CHARACTERISTICS:

Soil Moisture: Continuously moist, in most years, in some part of the soil moisture control section November through April and intermittently moist July through October. The period of maximum precipitation is July through October. The soil is driest during May and June. Aridic ustic moisture regime.

Soil Temperature: 48 to 55 degrees F

Particle-size control section: 35 to 55 percent clay

Slickensides: (when present) occur from 5 to 50 inches

Cracks: 3 to 7 mm wide at 20 inches below the surface.

Salt accumulations: (when present) occur below 45 inches. Electrical Conductivity ranges from 0 to 4 mmhos/cm.

Depth to calcium carbonate: 10 to 30 inches

A horizon:
Hue: 10YR or 2.5Y
Chroma: 2 or 3 moist
Rock fragments: 0 to 5 percent sandstone pebbles
Reaction: neutral or slightly alkaline

Bt horizons:
Hue: 7.5YR, 10YR or 2.5Y
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 3 or 4 dry, 2 to 4 moist
Texture: clay or clay loam
Reaction: neutral or slightly alkaline

Btk or Bk horizons:
Hue: 10YR or 2.5Y
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 3 or 4 dry, 2 or 3 moist
Texture: clay loam or clay
Reaction: slightly or moderately alkaline
Calcium carbonate equivalent: less than 5 percent

COMPETING SERIES: These are the Abrazo (NM), Cantina (NM), Carnero (NM), Celsosprings (NM), Charette (NM), Cueva (NM), Remunda (NM), and Philmont (NM) series. The Abrazo, Carnero and Cueva soils are moderately deep to a lithic or paralithic contact. The Celosprings and Quivera soils have 15 to 35 percent rock fragments in the Bt horizons. The Charette soils have calcium carbonates below 30 inches and have basalt pebbles and cobbles in the substratum. Cantina, Charette, Remunda and Philmont soils are not continuously moist in some part of the soil moisture control section November through April.

GEOGRAPHIC SETTING: The Concho soils formed in Holocene alluvium, fan alluvium and stream alluvium derived from sandstone and shale and are on valley floors and drainageways. Slopes are 0 to 3 percent. Elevations range from 6600 to 7000 feet. The mean annual temperature is 46 to 53 degrees F., and the mean annual precipitation is 13 to 16 inches. The frost free period is 100 to 135 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hosta soils on fan terraces; the Bryway and Galzuni soils on footslopes of hills; the Knifehill soils on stream terraces; and the Toldohn and Vessilla soils on escarpments of mesas and cuestas. The Hosta and Galzuni soils lack mollic epipedons. Bryway soils are moderately deep to shale. Knifehill soils have mollic epipedons thicker than 20 inches. The Toldohn and Vessilla soils are very shallow and shallow to shale and sandstone.

DRAINAGE AND PERMEABILITY: Well drained, medium to high runoff, and slow permeability.

USE AND VEGETATION: This series is used for rangeland. The present vegetation is big sagebrush, rabbitbrush, blue grama, western wheatgrass and bottlebrush squirreltail.

DISTRIBUTION AND EXTENT: This series occurs in New Mexico and Arizona. MLRA 35, LRR-D. This series is of small extent.

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

SERIES ESTABLISHED: McKinley County, Zuni Mountain Area, New Mexico, 1964.

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

Mollic epipedon: The zone from 0 to 18 inches. (Ap1, Ap2 and Btss1 horizons)

Argillic horizon: The zone from 5 to 65 inches. (Btss1, Btss2, Btkss and Btkz horizons)

The type location was moved in 1992 to better reflect the concept of the Aridic Argiustolls classification.

Classified according to Soil Taxonomy Second Edition, 1999.

National Cooperative Soil Survey
U.S.A.