LOCATION VENZUNI NMEstablished Series
TAXONOMIC CLASS: Very-fine, smectitic, mesic Aridic Haplusterts
TYPICAL PEDON: Venzuni silty clay--in rangeland on a southwest facing convex slope of 3 percent at an elevation of 6,830 feet. (Colors are for dry soils unless otherwise noted.)
A--0 to 2 inches; reddish brown (2.5YR 4/4) silty clay, dark reddish brown (2.5YR 3/4) moist; moderate thin platy structure parting to moderate fine granular; soft, very friable, sticky and plastic; many very fine and fine roots; few fine irregular pores; strongly effervescent; slightly alkaline; abrupt smooth boundary. (2 to 3 inches thick)
BC--2 to 12 inches; reddish brown (2.5YR 4/4) silty clay, dark reddish brown (2.5YR 3/4) moist; massive; very hard, very firm, very sticky and very plastic; common very fine and fine roots; common fine irregular pores; common pressure faces; strongly effervescent; moderately alkaline; clear smooth boundary. (0 to 10 inches thick)
Bss1--12 to 19 inches; dark reddish brown (2.5YR 3/4) clay, dark reddish brown (5YR 3/3) moist; massive; very hard, very firm, very sticky and very plastic; few very fine and fine roots; common fine irregular pores; many pressure faces and few slickensides; strongly effervescent; moderately alkaline; clear smooth boundary.
Bss2--19 to 46 inches; reddish brown (2.5YR 4/4) clay, dark reddish brown (2.5YR 3/4) moist; massive; very hard, very firm, very sticky and very plastic; few very fine and fine roots; few fine irregular pores; many pressure faces and common slickensides; strongly effervescent; moderately alkaline; gradual smooth boundary. (The combined thickness of the Bss horizons is 22 to 43 inches.)
2Bss3--46 to 65 inches; dark yellowish brown (10YR 4/4) clay, dark yellowish brown (10YR 3/4) moist; massive; extremely hard, extremely firm; very sticky and very plastic; few very fine roots; few very fine irregular pores; common pressure faces and few slickensides; strongly effervescent; slightly alkaline. ( 0 to 19 inches thick.)
TYPE LOCATION: McKinley County, New Mexico; Burned Timber Quadrangle; about 1.7 miles southeast of the Upper Nutria Village on the Zuni Reservation; 700 feet north and 1,200 feet east of the southwest corner of sec. 20, T. 12 N., R. 16 W.; 108 degrees 33 minutes 6 seconds west longitude, and 35 degrees 14 minutes 58 seconds north latitude.
RANGE IN CHARACTERISTICS:
Soil Moisture: The SMCS is usually moist, in all parts, for less than 90 cumulative days from April through October. It is usually dry, in some part, for more than 120 days cumulative days during the same period. It is continuously moist in some part November through April, but not moist all parts for 45 consecutive days from January through April. 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 56 degrees F
Particle-size control section: 60 to 80 percent clay
Vertic properties: slight gilgai on surface, self-mulching surface, 0.5 inch wide cracks extend from the surface to 20 inches or more, pressure faces and slickensides are present below 2 inches.
Reaction: slightly or moderately alkaline
A horizon
Hue: 2.5YR or 5YR
Value: 3 or 4 dry
Calcium carbonate equivalent: 5 to 10 percent
Salinity: EC of 2 to 4 mmhos/cm
Sodicity: SAR of 0 to 5
BC and Bss horizons
Hue: 2.5YR or 5YR
Value: 3 or 4 dry
Chroma: 3 or 4 moist
Texture: clay or silty clay
Calcium carbonate equivalent: 5 to 10 percent
Salinity: EC of 2 to 4 mmhos/cm
Sodicity: SAR of 0 to 5
2Bss horizon
Hue: 7.5YR or 10YR
Value: 3 or 4 dry
Chroma: 3 or 4 moist
Calcium carbonate equivalent: 5 to 10 percent
Salinity: EC of 2 to 4 mmhos/cm
Sodicity: SAR of 0 to 5
COMPETING SERIES: These are the Catman (NM), Kyle (SD), Mcnary (AZ), Swanboy (SD), and Twotop (SD) series. Mcnary soils have hues of 7.5YR and yellower and are derived from basalt. Catman soils have hues of 10YR and yellower. Kyle, Swanboy, and Twotop soils all have hues of 2.5Y, are in LRR-G and are more moist in May and June.
GEOGRAPHIC SETTING: The Venzuni soils formed in alluvium, fan alluvium, and stream alluvium derived from red bed shale of the Chinle Formation and the Glen Canyon Undivided Group. Venzuni soils are on alluvial fans on valley sides and stream terraces on valley floors. Slopes are 1 to 6 percent. Elevations range from 6,700 to 7,600 feet. The mean annual temperature is 46 to 54 degrees F., and the mean annual precipitation is 12 to 16 inches. The frost free period is 100 to 135 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bryway, Galzuni, Nutreeah, Silcat, Toldohn and Vessilla soils. The Bryway, Galzuni, and Nutreeah soils have argillic horizons and are fine textured. The Silcat soils have colors more yellow than 10YR. Toldohn and Vessilla soils are less than 20 inches to bedrock.
DRAINAGE AND PERMEABILITY: Well drained, low to very high runoff, and very slow permeability.
USE AND VEGETATION: This series is used for livestock grazing. The present vegetation is rabbitbrush, western wheatgrass, sleepygrass, and blue grama.
DISTRIBUTION AND EXTENT: West central New Mexico. MLRA 35, LRR-D. This series is of small extent.
MLRA OFFICE RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: McKinley County Area, New Mexico; McKinley County and Parts of Cibola and San Juan Counties, 2001.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: The zone from 0 to 2 inches. (A horizon)
Vertic properties: The presence of slight gilgai, pressure faces and slickensides, and cracks 0.5 inches wide that extend from the surface to 20 inches or more. The cracks remain open for more than 90 cumulative days but less the 150 days per year. (Discrepancies between moisture regime of surrounding soils and period of open cracks are under study. The moisture regime of surrounding soils was used for classification until study results are received.)
Classified according to Soil Taxonomy Second Edition, 1999; Keys to Soil Taxonomy Tenth Edition, 2006.