LOCATION NILLO TX
Established Series
Rev. LEL/JLR/ACT
10/2013
NILLO SERIES
The Nillo series consists of very deep, well drained, slowly permeable soils on ephemeral stream floodplains. These nearly level soils formed in Holocene-age alluvium derived mainly from tuff of the Duff and Pruett Formations. Slope ranges from 0 to 2 percent. The mean annual precipitation is about 330 mm (13inches) and the mean annual air temperature is about 18.3 degees C (65 degrees F).
TAXONOMIC CLASS: Fine-silty, mixed, superactive, calcareous, thermic Ustic Torrifluvents
TYPICAL PEDON: Nillo silty clay - rangeland. (Colors are for dry soil unless otherwise stated.)
A -- 0 to 8 cm (0 to 3 inches); grayish brown (10YR 5/2) silty clay, dark brown (10YR 3/3) moist; weak medium platy parting to moderate fine subangular blocky and moderate fine granular structure; hard, firm, very sticky and very plastic; common very fine and fine roots; strongly effervescent; moderately alkaline; abrupt smooth boundary (0 to 20 cm or 0 to 8 inches thick)
C1 -- 8 to 30 cm (3 to 12 inches); light brown (7.5YR 6/3) stratified loam, brown (7.5YR 5/3) moist; massive; slightly hard, very friable, slightly sticky, slightly plastic; common fine and few medium roots; many bedding planes evident; many thin strata of coarser and finer textured materials 3 to 38 mm (1/8 to 1 1/2 inches) thick; strongly effervescent; moderately alkaline; abrupt smooth boundary (15 to 41 cm or 6 to 16 inches thick)
C2 -- 30 to 66 cm (12 to 26 inches); light brown (7.5YR 6/3) stratified loam, brown (7.5YR 4/3) moist; massive; slightly hard, friable, moderately sticky and moderately plastic; common fine and few medium roots; many bedding planes; many thin strata of coarser and finer textured materials; strongly effervescent; moderately alkaline; abrupt wavy boundary (0 to 40 cm or 0 to 16 inches thick)
Ab -- 66 to 81 cm (26 to 32 inches); grayish brown (10YR 5/2) clay loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; few fine roots; common very fine tubular pores; strongly effervescent; moderately alkaline; gradual smooth boundary (13 to 36 cm or 5 to 14 inches thick)
Bwb -- 81 to 117 cm (32 to 46 inches); grayish brown (10YR 5/2) clay loam, brown (10YR 4/3) moist; weak coarse prismatic parting to moderate medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few fine roots; common very fine tubular pores; strongly effervescent; moderately alkaline; clear smooth boundary
Bkb1 -- 117 to 140 cm (46 to 55 inches); brown (7.5YR 5/3) clay loam, brown (7.5YR 4/3) moist; weak fine and medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; very few prominent friable, moderately sticky, moderately plastic; very few prominent discontinuous white (10YR 8/1) calcium carbonate coats on surfaces of peds; few calcium carbonate threads; 2 percent subrounded igneous gravel; violently effervescent; strongly alkaline; gradual wavy boundary
Bkb2 -- 140 to 168 cm (55 to 66 inches); brown (7.5YR 5/3) clay loam, brown (7.5YR 4/3) moist; weak medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; very few fine and few medium roots; common fine calcium carbonate masses; 9 percent calcium carbonate equivalent; violently effervescent; strongly alkaline; gradual smooth boundary (combined thickness of Bwb horizons range from 38 to 100 cm or 15 to 40 inches thick)
Bkb3 -- 168 to 203 cm (66 to 80 inches); brown (7.5YR 5/3) clay loam, brown (7.5YR 4/3) moist; weak fine and medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; common fine calcium carbonate masses; violently effervescent; strongly alkaline; gradual smooth boundary (0 to 23 cm or 0 to 9 inches thick)
TYPE LOCATION: Presidio County, Texas; from the junction of U.S. Highways 90 and 67 in Marfa, 7.2 miles south-southwest on U.S. Highway 67 to intersection with FM 169, 24.4 miles south on FM 169 to Plata, 3.2 miles south on Casa Piedra road to intersection with Puerto Portillo Road, 7.6 miles east and south on Puerto Potrillo road Road to intersection with ranch road, 1.1 miles southeast on ranch road to junction, 1.1 miles east on ranch road to junction, 1.7 miles east on ranch road to junction, 2.7 miles south-southeast on ranch road, then 600 feet west of road in range. USGS 7.5 minute topographic quadrangle: McKinney Mountain, Texas; Latitude: 29 degrees, 46 minutes, 23 seconds North; Longitude: 103 degrees, 48 minutes, 1 second West; NAD83; UTM coordinates 615844 m E, 3294335 m N, Zone 13, NAD83.
RANGE IN CHARACTERISTICS:
Soil moisture: Intermittently moist in the soil moisture control section during July-September. The soil is moist for less than 90 cumulative days during the growing season in the control section. Ustic aridic soil moisture regime.
Exchangeable sodium percentage: 15 to 25 percent
Sodium Adsorption Ratio: 15 to 25
Depth to a buried soil: 20 to 40 inches (51 to 102 cm)
Surface mantle above the buried soil:
Texture of the surface mantle above the buried soil: fine sandy loam, silty clay, very fine sandy loam, loam, silt loam, clay loam or silty clay loam
Clay content: 10 to 45 percent
Upper part of the buried soil:
Texture of the upper part of the buried soil: clay loam, silty clay loam, silty clay, or clay
Clay content: 27 to 55 percent
A horizon
Hue: 7.5YR, 10YR
Value: 5 to 6 dry, 3 or 4 moist
Chroma: 2 to 4, dry or moist
Texture: loam sandy clay loam, or clay loam, or silty clay but ranges to heavier or lighter textures depending on size of drainageway and drainage area producing sediments
C horizon
Hue: 7.5YR, 10YR
Value: 5 to 6 dry, 4 or 5 moist
Chroma: 2 to 4, dry or moist
Texture: fine sandy loam, very fine sandy loam, loam, silt loam, or silty clay loam
Clay content: 10 to 35 percent
Bedding planes and thin strata of variable textures are evident in most pedons
Ab horizon
Hue: 7.5YR, 10YR
Value: 3 to 5, dry or moist
Chroma: 2 or 3, dry or moist
Texture: clay loam, silty clay loam, clay, silty clay
Clay content: 25 to 55 percent
Bwb horizon
Hue: 5YR, 7.5YR, 10YR
Value: 4 or 5, dry or moist
Chroma: 2 to 4, dry or moist
Texture: clay loam, silty clay loam, silty clay, clay
Clay content: 30 to 55 percent
Calcium carbonate equivalent: less than 15 percent
Bkb horizon
Hue: 5YR to 10YR
Value: 4 or 5, dry or moist
Chroma: 2 to 4, dry or moist
Texture: clay loam, silty clay loam, silty clay, clay
Clay content: 30 to 55 percent
Calcium carbonate equivalent: less than 15 percent
COMPETING SERIES: These are the
Crowflats (NM) and
Riveroad (AZ) series. Crowflats and Riveroad soils have exchangeable sodium percentage less than 15 percent and do not have buried horizons.
GEOGRAPHIC SETTING: Nillo soils are on ephemeral stream Holocene-age floodplains of ephemeral streams. They are associated with channels that receive overbank floodwaters once in 7 to 20 years for a duration of less than 2 days. Nillo soils formed in stratified loamy and clayey alluvium derived from tuffaceous rocks of the Duff and Pruett Formations. Slope ranges from 0 to 3 percent. Mean annual precipitation ranges from 305 to 380 mm (12 to 14 inches). Mean annual air temperature ranges from 16.7 to 19.4 degrees C (62 to 68 degrees F). Frost-free period ranges from 210 to 260 days, and elevation ranges from 1,070 to 1,525 m (3,500 to 5,000 feet).
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Gemelo and
Straddlebug soils. Gemelo soils have less than 18 percent clay and 15 to 35 percent rock fragments in the particle size control section. They are on late-Holocene fan aprons. Straddlebug soils have between 18 and 35 percent clay and more than 15 percent coarser fine sand in the particle-size control section. They are on alluvial flats and stream terraces that do not receive overbank floodwaters because stream channels are large enough to transport peak flows.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is slow. Runoff is medium on 0 to 1 percent slopes, and high on 1 to 2 percent slopes.
USE AND VEGETATION: This soil is used for livestock grazing and wildlife habitat. Woody species consist of creosotebush, tarbush, and western honey mesquite. Grasses in the understory include giant sacaton, sideoats grama, alkali sacaton, tobosa grass, blue grama, plains bristlegrass, cane bluestem, Arizona cottontop, and vine mesquite.
DISTRIBUTION AND EXTENT: LRR-D, MLRA 42, Southern Desertic Basins, Plains, and Mountains, Desert Grassland LRU. Far West Texas. MLRA 42. The soil is of minor extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Presidio County, Texas, 1997. The name is coined.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 0 to 8 cm (0 to 3 inches) (A horizon)
Buried soil - the zone from 66 to 200 cm (26 to 80 inches) (Ab, Bwb1, Bwb2, Bkwb1, and Bkb2 horizons)
Cambic horizon - the zone from 81 to 200 cm (32 to 80 inches) (Bwb and Bkb horizons)
Ustic feature - the soil has an aridic moisture regime that borders the ustic moisture regime.
Fluventic feature - the soil has an irregular decrease in organic carbon content with depth.
Superactive cation activity class - CEC to percent clay ratio is 0.60 or greater. This is assumed from the abundant zeolitic minerals in the Duff and Pruett Tuffs.
Classified according to Keys to Soil Taxonomy, Eleventh Edition, 2010
Update and revisions for re-correlation of Brewster County, Texas, Main Part, 2/12/08, CEM
Revised for the correlation of Presidio County, Texas; Oct, 2012, WWJ
Revised for the correlation of the SDJR - MLRA 42 - Nillo silty clay, 0 to 3 percent slopes, occasionally flooded project, September 2013, LJG2
ADDITIONAL DATA:
Laboratory data is available for the typifying pedon, S93TX-377-005, from Texas A&M University Soil Characterization Laboratory.
National Cooperative Soil Survey
U.S.A.