LOCATION NINEPOINT TX
Established Series
Rev: RD/LEL
01/2011
NINEPOINT SERIES
The Ninepoint series consists of very deep, well drained, moderately permeable calcareous soils. These nearly level to very gently sloping soils are on alluvial flats. They developed in silty, calcareous alluvium predominantly from limestone and mudstone. Slopes range from 0 to 3 percent. The mean annual precipitation is about 11 inches and the mean annual air temperature is about 70 degrees F.
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, hyperthermic Ustic Haplocambids
TYPICAL PEDON: Ninepoint clay loam--rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 4 inches; pale brown (10YR 6/3), clay loam, brown (10YR 4/3), moist; moderate medium subangular blocky parting to moderate fine subangular blocky structure; few fine and common very fine roots throughout; strongly effervescent; slightly alkaline (pH 7.6); clear smooth boundary (2 to 10 inches thick).
Bw1--4 to 12 inches; yellowish brown (10YR 5/4), clay loam, dark yellowish brown (10YR 4/4), moist; strong coarse subangular blocky parting to strong fine subangular blocky structure; few fine and common very fine roots throughout; common fine high continuity tubular pores; strongly effervescent; slightly alkaline (pH 7.7); clear smooth boundary.
Bw2--12 to 32 inches; light yellowish brown (10YR 6/4), clay loam, yellowish brown (10YR 5/4), moist; moderate fine prismatic parting to moderate medium subangular blocky parting to moderate fine subangular blocky structure; common very fine roots throughout; common fine high continuity tubular pores; strongly effervescent; slightly alkaline (pH 7.7); gradual smooth boundary.
Bw3--32 to 59 inches; light yellowish brown (10YR 6/4), clay loam, yellowish brown (10YR 5/4), moist; weak medium prismatic parting to weak medium subangular blocky parting to weak fine subangular blocky structure; few very fine roots throughout; common fine high continuity tubular pores; 1 percent fine white (10YR 8/1), carbonate filaments throughout; strongly effervescent; slightly alkaline (pH 7.8); gradual smooth boundary.
Bw4--59 to 80 inches; light yellowish brown (10YR 6/4), clay loam, yellowish brown (10YR 5/4), moist; weak medium prismatic parting to weak medium subangular blocky parting to weak fine subangular blocky structure; common very fine roots throughout; common fine high continuity tubular pores; strongly effervescent; slightly alkaline (pH 7.8); gradual smooth boundary.
TYPE LOCATION: Brewster County, Texas; from the junction of US Highways 90 and 385 just east of Marathon; 45.3 miles south on US Highway 385 to Terlingua Ranch Road; 4.6 miles west on Terlingua Ranch Road to junction, 3.0 miles west on graded road to junction, 0.4 mile north on trail, 110 feet west in rangeland. (Twin Peaks USGS 7.5 minute topographic quadrangle; UTM coordinates: 668885 m E, 3276330 m N, Zone 13N NAD83)
RANGE IN CHARACTERISTICS:
Soil Moisture: Ustic aridic soil moisture regime. Recieves precipitation in all months. Driest period is Novemeber through April with peak rainfall occurring May through October.
Mean annual soil temperature: 72 to 78 degrees F.
Total clay content: 25 to 45 percent
Silicate clay content: 20 to 35 percent
Calcium carbonate equivalent: less than 33 percent, generally disseminated
A horizon
Hue: 7.5YR, 10YR
Value: 5 or 6 dry, 3 or 4 moist
Chroma: 3 or 4, dry or moist
Total clay content: 27 to 45 percent
Silicate clay content: 23 to 35 percent
Calcium carbonate equivalent: 10 to 33 percent
Effervescence class: strongly to violent
Reaction: slightly to moderately alkaline
Bw horizons
Hue: 7.5YR, 10YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 3 or 4, dry or moist
Total clay content: 25 to 45 percent
Silicate clay content: 21 to 35 percent
Calcium carbonate equivalent: 20 to 30 percent
Effervescence class: strong to violent
Reaction: slightly to moderately alkaline
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Ninepoint soils are on broad, nearly level alluvial flats in a semi-bolson landscape. They formed in fine-silty alluvium of Holocene age, derived mainly from Cretaceous limestone and mudstone. Slopes are 0 to 3 percent, mostly less than 2 percent. Mean annual air temperature is 68 to 72 degrees F. Mean annual precipitation is 10 to 13 inches, and occurs as high intensity rainfall during convectional afternoon thunderstorms from June through September. Frost-free period is 240 to 280 days. Elevation is 1,800 to 3,500 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the
Blackgap (TX) and
Vieja (TX) series. Blackgap soils are less than 20 inches to limestone bedrock and occur on surrounding hills and mountains. Vieja soils are less than 20 inches to densic shale and are on low hills.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderate. Runoff is negligible on slopes less than 1 percent, and very low on 1 to 2 percent slopes.
USE AND VEGETATION: Used mainly for livestock grazing. Vegetation physiognomy is desert shrubland. Dominant woody plants are creosotebush, western honey mesquite, tarbush, whitebrush, wolfberry, allthorn, and pitaya. Grasses include tobosa, burrograss, plains bristlegrass, blue panic, and annuals.
DISTRIBUTION AND EXTENT: Southern Big Bend region of Trans-Pecos Texas; LRR D, MLRA 42, Southern Desertic Basins, Plains, and Mountains, Hot Desert Shrub LRU. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Big Bend National Park ,Brewster County, Texas, 2010. The name is from a drainageway near the type location.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 0 to 4 inches (A horizon)
Cambic horizon - the zone from 4 to 80 inches (Bw1, Bw2, Bw3, Bw4, and Bw5 horizons)
These soils were previously included in the Tornillo and Mimbres series.
Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Eleventh Edition, 2010
Moisture and temperature regimes revised for the recorrelation of Brewster County, Texas, Main part, 2/12/08, CEM
Revised for the correlation of Big Bend National Park, TX, Oct. 2010 CEM
National Cooperative Soil Survey
U.S.A.