LOCATION ZACATON NMEstablished Series
TAXONOMIC CLASS: Ashy-skeletal, glassy, mesic Vitrandic Haplustepts
TYPICAL PEDON: Zacaton very cobbly ashy sandy loam--on a planar backslope sloping 45 percent to the north at 6,520 feet elevation--forestland. (Colors are for dry soil unless otherwise noted. When described on October 27, 1999, the soil was dry throughout.) Surface is covered with 25 percent gravel, 25 percent cobbles, 5 percent stones, and 10 percent boulders.
Oi--0 to 1 inch; slightly decomposed twigs, needles and cones; abrupt smooth boundary. (1 or 2 inches thick)
A--1 to 3 inches; grayish brown (10YR 5/2) very cobbly ashy sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, very friable, slightly sticky and nonplastic; common fine and many very fine roots; common fine irregularly shaped pores; 20 percent gravel, 20 percent cobbles, 5 percent stones, and 10 percent boulders; neutral (pH 7.2); abrupt smooth boundary. (2 to 3 inches thick)
Bw--3 to 9 inches; pale brown (10YR 6/3) cobbly ashy sandy loam, brown (10YR 4/3) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and nonplastic; few medium, common fine, and many very fine roots; common fine and few very fine interstitial pores; 15 percent gravel, 10 percent cobbles, and 5 percent stones; slightly alkaline (pH 7.6); clear smooth boundary. (6 to 10 inches thick)
Bk1--9 to 18 inches; pale brown (10YR 6/3) very gravelly ashy sandy loam, brown (10YR 4/3) moist; moderate fine subangular blocky structure; soft, very friable, slightly sticky and nonplastic; few coarse, common medium, common fine, and common very fine roots; few fine and common very fine interstitial pores; 30 percent gravel and 10 percent cobbles; slightly effervescent, secondary calcium carbonate segregated as few fine irregularly shaped coats on faces of peds and on rock fragments; slightly alkaline (pH 7.4); clear smooth boundary. (7 to 16 inches thick)
Bk2--18 to 32 inches; very pale brown (10YR 8/2) very cobbly ashy loam, very pale brown (10YR 7/3) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and nonplastic; few coarse, common medium, common fine, and few very fine roots; few fine and few very fine tubular pores; 15 percent gravel, 15 percent cobbles and 10 percent stones; violently effervescent, secondary calcium carbonate segregated as common fine irregularly shaped coats on faces of peds and on rock fragments; moderately alkaline (pH 8.4); abrupt smooth boundary. (14 to 29 inches thick)
Bk3--32 to 48 inches; very pale brown (10YR 7/3) cobbly ashy sandy loam, brown (7.5YR 4/4) moist, weak medium granular structure; soft, very friable, slightly sticky and nonplastic; common medium, common fine, and few very fine roots; few very fine tubular pores; 10 percent gravel, 10 percent cobbles, and 5 percent stones; strongly effervescent, secondary calcium carbonate segregated as common fine irregularly shaped coats on rock fragments; very strongly alkaline (pH 9.4); clear smooth boundary. (12 to 16 inches thick)
Bk4--48 to 63 inches; very pale brown (10YR 7/3) gravelly ashy sandy loam, yellowish brown (10YR 5/4) moist; weak medium subangular blocky structure; soft, very friable, slightly sticky and nonplastic; few medium, common fine and many very fine roots; common fine and few very fine tubular pores; 15 percent gravel and 5 percent cobbles; strongly effervescent, secondary calcium carbonate segregated as few fine irregularly shaped coats on rock fragments; very strongly alkaline (pH 9.4); gradual wavy boundary. (12 to 16 inches thick)
2Bk5--63 to 76 inches; pink (5YR 7/4) gravelly ashy loamy coarse sand, yellowish red (5YR 5/6) moist; single grain; loose, nonsticky and nonplastic; 25 percent gravel; noneffervescent matrix, slightly effervescent in few fine irregularly shaped coats of secondary calcium carbonate on rock fragments; strongly alkaline (pH 8.8); abrupt smooth boundary. (13 to 22 inches thick)
2C--76 to 102 inches; pink (5YR 8/4) gravelly ashy loamy coarse sand, yellowish red (5YR 5/6) moist; single grain; loose; nonsticky and nonplastic; 30 percent gravel; strongly alkaline (pH 8.6).
TYPE LOCATION: Bandelier National Monument, Tsankawi section, Santa Fe County, New Mexico; about 2.5 miles north of White Rock; 200 feet east and 100 feet south of the northwest corner of section 28, T.19N., R.7E.; USGS White Rock 7.5 minute topographic quadrangle; Latitude 35 degrees 51 minutes 23 seconds North and Longitude 106 degrees 12 minutes 46 seconds West, NAD 27.
RANGE IN CHARACTERISTICS: (Depths given are measured from the mineral soil surface)
Soil moisture - The soil moisture control section is moist in all parts during the 60 days following the winter solstice. It is moist in some part less than 40 percent and moist in all parts less than 25 percent of the time when the soil temperature at 20 inches is above 41 degrees F. The soils are driest in May and June. The soil moisture regime is ustic bordering on aridic.
Average annual soil temperature: 48 to 50 degrees F.
Depth to calcareous material (as visible secondary calcium carbonate): 8 to 12 inches
Depth to base of cambic horizon: 9 to 13 inches
Depth to calcic horizon: 15 to 27 inches
Lithology of rock fragments: rhyolitic tuff
Volcanic glass content: 80 to 90 percent in the coarse silt plus sand fraction
Particle-size control section:
Rock fragment content: 35 to 60 percent
Volcanic glass content: 80 to 90 percent in the coarse silt plus sand fraction
A horizon
Value: 4 or 5 dry
Chroma: 2 or 3, dry or moist
Clay content: 8 to 18 percent
Rock fragments: total range is 35 to 60 percent
15 to 25 percent gravel
15 to 25 percent cobbles
0 to 5 percent stones
5 to 10 percent boulders
Bw horizon
Value: 3 or 4 moist
Chroma: 2 or 4, dry or moist
Texture: cobbly ashy sandy loam, gravelly ashy sandy loam, and cobbly ashy loam
Clay content: 8 to 18 percent
Rock fragments: total range is 15 to 35 percent
5 to 15 percent gravel
10 to 15 percent cobbles
0 to 5 percent stones
Bk1 horizon
Value: 4 or 5 moist
Chroma: 2 to 4 dry or moist
Texture: very gravelly ashy sandy loam and very cobbly ashy sandy loam
Clay content: 8 to 18 percent
Sand content: 50 to 70 percent
Fine sand or coarser content: 40 to 60 percent
Calcium carbonate equivalent: 1 to 5 percent
Rock fragments: total range is 35 to 60 percent
25 to 35 percent gravel
10 to 20 percent cobbles
0 to 10 percent stones
Bk2 horizon
Value: 7 or 8 dry, 5 to 7 moist
Chroma: 2 or 3, dry or moist
Texture: very cobbly ashy loam or very cobbly ashy sandy loam
Clay content: 10 to 20 percent
Sand content: 50 to 70 percent
Fine sand or coarser content: 40 to 60 percent
Calcium carbonate equivalent: 15 to 25 percent
Salinity, mmhos/cm: 2 to 4
Sodicity, SAR: 5 to 13
Rock fragments: total range is 35 to 60 percent
15 to 25 percent gravel
15 to 25 percent cobbles
5 to 15 percent stones
Reaction: moderately alkaline or strongly alkaline
Lower Bk horizons
Value: 5 to 7 dry, 4 to 6 moist
Chroma: 2 to 4 dry or moist
Texture: cobbly ashy sandy loam or gravelly ashy sandy loam
Clay content: 8 to 18 percent
Sand content: 50 to 70 percent
Fine sand or coarser content: 40 to 60 percent
Calcium carbonate equivalent: 2 to 5 percent
Salinity, mmhos/cm: 2 to 4
Sodicity, SAR: 5 to 13
Rock fragments: total range is 15 to 35 percent
10 to 20 percent gravel
5 to 15 percent cobbles
0 to 10 percent stones
2Bk5 and 2C horizons
Hue: 5YR to 10YR
Value: 7 or 8 dry, 5 to 7 moist
Chroma: 1 to 4 dry, 2 to 6 moist
Texture: gravelly ashy loamy coarse sand and gravelly ashy loamy sand
Clay content: 4 to 8 percent
Calcium carbonate equivalent: 0 to 5 percent
Salinity, mmhos/cm: 0 to 2
Sodicity, SAR: 0 to 4
Rock fragments: 20 to 30 percent gravel
COMPETING SERIES: There are currently no competing series.
GEOGRAPHIC SETTING: Zacaton soils are on lower north-facing backslopes of mesas, undulating plateaus, and canyons. They formed in colluvium over residuum derived from rhyolitic tuff of the Quaternary age Bandelier Tuff formation. Slopes are 25 to 50 percent. Elevation ranges from 5,500 to 7,100 feet. The mean annual precipitation is 14 to 16 inches with about 45 percent falling as rain from high-intensity convective thunderstorms between July and September. The mean annual air temperature is 46 to 48 degrees F. The frost-free period is 120 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Abrojo, Chiminet, and Navajita soils. The Abrojo soils are coarse textured, occur on south-facing backslopes, and do not have calcic horizons. The Chiminet soils are very shallow and do not have calcic horizons. The Navajita soils are fine-loamy, have an argillic horizon, do not have a calcic horizon, and occur on footslopes and toeslopes of valley sides
DRAINAGE AND PERMEABILITY: Well drained; medium surface runoff, moderately rapid permeability
USE AND VEGETATION: Zacaton soils are used for recreation and wildlife habitat. The historic climax vegetation is Indian ricegrass, muttongrass, twoneedle pinyon, and oneseed juniper. The ecological site is Pinus edulis-Juniperus monosperma/Quercus gambeli/Bouteloua gracilis(F036XB134NM).
DISTRIBUTION AND EXTENT: Zacaton soils are of small extent on the southeastern Espanola Basin part of the Basin and Range province in northcentral New Mexico. The MLRA is 36.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Santa Fe County, New Mexico; Santa Fe Area Soil Survey Update; 2008. Zacaton is a coined name.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 1 inch to a depth of about 3 inches. (A horizon)
Cambic horizon - The zone from 3 to about 9 inches. (Bw horizon)
Calcic horizon - The zone from 18 to about 32 inches. (Bk2 horizon)
Vitrandic feature - Throughout the upper 30 inches, based on volcanic glass content (A, Bw, Bk1, and Bk2 horizons).
Particle-size control section - The zone from 11 to 41 inches (part of Bk1, Bk2, part of Bk3 horizons)
Series control section - The zone from 0 to 60 inches.
Taxonomic version: Classified according to Keys to Soil Taxonomy, Tenth Edition, 2006.