LOCATION NATAANI NM COEstablished Series
TAXONOMIC CLASS: Coarse-silty, mixed, semiactive, mesic Typic Haplogypsids
TYPICAL PEDON: Nataani very fine sandy loam -- on a north facing toeslope of 2 percent at 5,200 feet elevation -- rangeland. (Colors are for dry soil unless otherwise noted. When described, the pedon was dry throughout.)
A--0 to 3 inches; light yellowish brown (10YR 6/4) very fine sandy loam, yellowish brown (10YR 5/4) moist; moderate thick platy structure parting to weak very fine granular; soft, very friable, slightly sticky and nonplastic; few fine and very fine roots; common very fine vesicular pores; 2 percent fine pebbles; violently effervescent; slightly alkaline (pH 7.8); clear smooth boundary. (2 to 4 inches thick)
2Bw--3 to 9 inches; light yellowish brown (2.5Y 6/4) loam, light olive brown (2.5Y 5/4) moist; moderate coarse subangular blocky structure; soft, very friable; slightly sticky and slightly plastic; few fine and common very fine roots; common very fine continuous tubular pores; violently effervescent; secondary calcium carbonate segregated in few fine filaments; moderately alkaline (pH 8.1); abrupt smooth boundary. (4 to 11 inches thick)
2By1--9 to 15 inches; light gray (2.5Y 7/2) gypsiferous silt loam, light yellowish brown (2.5Y 6/4) moist; moderate coarse subangular blocky structure; slightly hard, friable, slightly sticky and nonplastic; few fine and very fine roots; few very fine continuous tubular pores; secondary silt-sized gypsum crystals segregated in many fine irregularly shaped filaments, few coarse sand-sized primary gypsum crystals; strongly effervescent; slightly alkaline (pH 7.8); clear wavy boundary. (4 to 7 inches thick)
2By2--15 to 21 inches; light yellowish brown (2.5Y 6/4) gypsiferous silt loam, light olive brown (2.5Y 5/4) moist; weak coarse subangular blocky structure; soft, very friable, slightly sticky and nonplastic; few fine and common very fine roots; few very fine discontinuous tubular pores; secondary silt-sized gypsum crystals segregated in common fine irregularly shaped filaments, few coarse sand-sized gypsum crystals; slightly effervescent; moderately alkaline (pH 8.2); clear wavy boundary. (5 to 8 inches thick)
2Cy--21 to 30 inches; light yellowish brown (2.5Y 6/4) silt loam, light olive brown (2.5Y 5/4) moist; massive, platy rock structure; slightly hard, friable, slightly sticky and slightly plastic; few fine and common very fine roots; few very fine discontinuous irregularly shaped pores; 5 percent soft siltstone fragments; secondary silt-sized gypsum crystals segregated as few fine irregularly shaped filaments on undersides of fragments, few coarse sand-sized primary gypsum crystals in soft masses; slightly effervescent; moderately alkaline (pH 8.1); clear wavy boundary. (5 to 10 inches thick)
2Cr--30 inches; thinly interbedded siltstone and very fine grained sandstone bedrock.
TYPE LOCATION: San Juan County, New Mexico; on the Navajo Indian Reservation about 6 miles south of Shiprock; 2,650 feet east and 450 feet south of the northwest corner of sec. 30, T.29N., R.17W; Latitude 36 degrees 42 minutes 15 seconds N and Longitude 108 degrees 40 minutes 23 seconds W.
RANGE IN CHARACTERISTICS:
Soil moisture: Typically, the soil moisture control section is intermittently moist in some part from July to October and December to March. The soil moisture control section is dry in all parts greater than 75 percent of the time (cumulative) that the soil temperature at 20 inches is greater than 41 degrees F. Typic aridic moisture regime.
Soil temperature - 54 to 57 degrees F.
Soil depth - 20 to 40 inches to soft bedrock.
Silicate clay content, control section weighted average - 10 to 18 percent.
Reaction - slightly to moderately alkaline.
Calcium carbonate equivalent - 5 to 15 percent.
Hard rock fragments - 0 to 5 percent by volume, dominantly pebbles.
Depth to gypsic horizon - 6 to 15 inches.
A horizon - Value: 4 or 5 moist.
Chroma: 3 or 4.
Bw horizon - Hue: 7.5YR to 2.5Y.
Chroma: 2 through 4.
Texture: loam, sandy loam, or very fine sandy loam.
Sodicity, SAR: 0 to 5.
Salinity, mmhos/cm: 2 to 4.
Other features: Horizon base is too shallow or has too much evidence of carbonate accumulation to qualify as a cambic horizon.
By horizons - Hue: 10YR or 2.5Y.
Value: 6 to 8 dry, 5 to 7 moist.
Chroma: 2 through 4.
Texture: gypsiferous silt loam, gypsiferous very fine sandy loam, sandy loam, or gypsiferous sandy loam.
Sodicity, SAR: 0 to 13.
Salinity, mmhos/cm: 2 to 16.
Gypsum content: 10 to 45 percent present as both primary and secondary crystals.
Other features: 0 to 20 percent soft siltstone fragments.
C horizons - Value: 6 or 7 dry.
Chroma: 2 through 4.
Texture: silt loam or very fine sandy loam.
Sodicity, SAR: 5 to 13.
Salinity, mmhos/cm: 8 to 16.
Gypsum content: 1 to 5 percent as mostly primary crystals.
Other features: 5 to 40 percent soft, siltstone fragments.
COMPETING SERIES: There are no competitors.
GEOGRAPHIC SETTING: Nataani soils are on toeslopes of undulating plateaus. Nataani soils formed in alluvium and residuum derived from Cretaceous siltstone and very fine grained sandstone. Slopes are 1 to 5 percent. Elevation ranges from 5,000 to 5,600 feet. The mean annual precipitation is 5 to 8 inches with 35 to 60 percent falling as rain from high-intensity thunderstorms between July and September. The mean annual temperature is 51 to 54 degrees F. The average frost-free period is 140 to 160 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Gyptur, Littlehat, Persayo, Ravola, and Tsebitai soils. Gyptur soils are fine-silty, deep, and occur on adjacent summits. Littlehat soils are fine-silty and lack diagnostic subsurface horizons. Persayo soils are shallow to soft bedrock. Ravola soils are very deep, stratified, and occur on adjacent flood plains. Tsebitai soils are very deep and occur on fan terraces.
DRAINAGE AND PERMEABILITY: Well drained, slow runoff; moderate permeability.
USE AND VEGETATION: Nataani soils are used for livestock grazing. Present vegetation is Indian ricegrass, alkali sacaton, galleta, sand dropseed, and Castle Valley clover.
DISTRIBUTION AND EXTENT: Nataani soils are of small extent on the Four Corners Platform portion of the Colorado Plateau province in northwest New Mexico and southwest Colorado. MLRA 35.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Shiprock Area, Parts of San Juan County, New Mexico and Apache County, Arizona; 1993.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to a depth of about 3 inches. (A horizon)
Gypsic horizon - The zone from 9 to about 21 inches. (2By1 and 2By2 horizons)
Paralithic contact - The presence of soft sedimentary bedrock at about 30 inches.
Classified according to Keys to Soil Taxonomy Ninth Edition, 2003
ADDITIONAL DATA: The series type location was sampled for full characterization by the National Soil Survey Laboratory (NSSL) as pedon S86NM-045-006. Salinity values were also determined on three pedons, including the type location, with a wheatstone bridge. Calcium carbonate equivalence determined with a field volume calcimeter.