LOCATION TOCITO NM COEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, active, calcareous, mesic Typic Torriorthents
TYPICAL PEDON: Tocito silt loam -- on a fan terrace sloping 2 percent to the north at 4,910 feet elevation -- irrigated cropland. (Colors are for dry soil unless otherwise noted.)
Ap--0 to 6 inches; pale brown (10YR 6/3) silt loam, brown (10YR 4/3) moist; weak thick platy structure parting to moderate medium granular; soft, very friable, slightly sticky and slightly plastic; many very fine roots; common very fine tubular pores; strongly effervescent; moderately alkaline (pH 8.2); clear smooth boundary. (2 to 6 inches thick)
AB--6 to 12 inches; pale brown (10YR 6/3) clay loam, dark grayish brown (10YR 4/2) moist; moderate medium subangular blocky structure; slightly hard, friable, sticky and plastic; many fine and common very fine roots; common fine and very fine tubular pores; strongly effervescent; moderately alkaline (pH 8.0); clear wavy boundary. (0 to 10 inches thick)
By--12 to 16 inches; pale brown (10YR 6/3) silty clay loam, brown (10YR 5/3) moist; moderate coarse subangular blocky structure; hard, friable, sticky and plastic; common fine and very fine roots; few fine and common very fine tubular pores; secondary silt-sized gypsum crystals segregated in few fine irregularly shaped accumulations on ped faces and as filaments; strongly effervescent; moderately alkaline (pH 7.9); clear wavy boundary. (4 to 10 inches thick)
Cy1--16 to 28 inches; light brownish gray (10YR 6/2) silt loam, brown (10YR 5/3) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few medium and very fine roots; few fine and common very fine tubular pores; few lamina of very fine sandy loam; secondary silt-sized gypsum crystals segregated in very few fine irregularly shaped filaments; strongly effervescent; moderately alkaline (pH 8.0); clear smooth boundary.
Cy2--28 to 49 inches; pale brown (10YR 6/3) clay loam, brown (10YR 5/3) moist; massive; hard, firm, sticky and plastic; few medium and very fine roots; few fine and very fine tubular pores; few lamina of silt loam; secondary silt-sized gypsum crystals segregated in very few fine irregularly shaped filaments; strongly effervescent; moderately alkaline (pH 8.0); clear smooth boundary.
Cy3--49 to 70 inches; pale brown (10YR 6/3) silty clay loam, brown (10YR 5/3) moist; massive; hard, firm, sticky and plastic; few very fine roots; few fine and very fine tubular pores; few lamina of silt loam, secondary silt-sized gypsum crystals segregated in very few fine irregularly shaped filaments; strongly effervescent; moderately alkaline (pH 8.0); (Combined thickness of the C horizons is more than 40 inches)
TYPE LOCATION: San Juan County, New Mexico; on the Navajo Indian Reservation about 2 miles west of Shiprock, on the Navajo Community College farm; 1,000 feet west and 950 feet north of the southeast corner of sec. 27, T.30N., R.18W; Latitude 36 degrees 46 minutes 49 seconds N and Longitude 108 degrees 43 minutes 18 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. Typic aridic moisture regime.
Soil temperature - 54 to 57 degrees F.
Rock fragments - usually none, but some pedons have up to 15 percent fine gravel in thin subhorizons.
A horizon
Value: 5 or 6 dry, 4 or 5 moist.
Texture: silt loam or very fine sandy loam.
Calcium carbonate equivalent: 5 to 10 percent.
AB horizon
Value: 5 or 6 dry, 4 or 5 moist.
Chroma: 2 or 3.
Texture: clay loam or loam.
Salinity, mmhos/cm: 2 to 4.
Sodicity, SAR: 0 to 5.
Calcium carbonate equivalent: 5 to 10 percent.
By horizon
Value: 5 or 6 dry, 4 or 5 moist.
Chroma: 2 through 4.
Texture: silty clay loam or clay loam.
Salinity, mmhos/cm: 2 to 4.
Sodicity, SAR: 0 to 5.
Calcium carbonate equivalent: 5 to 10 percent.
Gypsum content: 1 to 5 percent.
Cy horizons
Value: 5 through 7 dry, 4 through 6 moist.
Chroma: 2 through 4.
Texture: stratified very fine sandy loam to silty clay loam. Salinity, mmhos/cm: 4 to 8.
Sodicity, SAR: 0 to 13.
Calcium carbonate equivalent: 10 to 15 percent.
Gypsum content: 1 to 5 percent.
Other features: horizons containing gypsum do not contain enough gypsum, are too thin to qualify as gypsic horizons.
COMPETING SERIES: there are no competing series.
GEOGRAPHIC SETTING: Tocito soils are on low stream terraces and fan terraces of probable early Holocene age. Tocito soils formed in stratified alluvium derived from Cretaceous siltstone and shale. Slopes are 1 to 3 percent. Elevation ranges from 4,800 to 5,300 feet. The mean annual precipitation is 5 to 8 inches with 35 to 60 percent falling as rain from high-intensity convective 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 Bebeevar, Gyptur, Littlehat, Notal, and Persayo soils. Bebeevar soils are sandy and occur on adjacent flood plains. Gyptur soils have gypsic horizons and are strongly saline-sodic. Littlehat soils are moderately deep to soft bedrock and occur on adjacent uplands. Notal soils are fine textured. Persayo soils are shallow to soft bedrock on adjacent uplands.
DRAINAGE AND PERMEABILITY: Well drained, medium runoff; moderately slow permeability. Flooding frequency ranges from none to rare.
USE AND VEGETATION: Tocito soils are used for livestock grazing and irrigated cropland and pasture. Present vegetation is alkali sacaton, galleta, mound saltbush, Russian thistle, ribscale, black greasewood and bottlebrush squirreltail. Corn and alfalfa are the main cultivated crops.
DISTRIBUTION AND EXTENT: Tocito soils are of small extent on the Four Corners Platform portion of the Colorado Plateau province in northwest New Mexico. MLRA 35.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: San Juan County, New Mexico, Shiprock Area Soil Survey, 1993.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from the soil surface to a depth of about 6 inches. (Ap horizon)
Entisol feature - the lack of diagnostic subsurface horizons. This soil contains segregated gypsum in the BCy and C horizons, but does not contain segregated calcium carbonate. The soil is stratified, but does not demonstrate irregular organic carbon distribution. This soil seldom floods but has the potential to flood in unusual storms.
ADDITIONAL DATA: Salinity values were determined on four pedons, including the type location, with a Wheatstone bridge. In addition, percent gypsum, electrical conductivity, and particle-size were determined on the typifying pedon through reference samples by the BIA soils laboratory in Gallup, NM.
Classified according to Soil Taxonomy Second Edition, 1999; Keys to Soil Taxonomy Tenth Edition, 2006.