LOCATION CHILICOTAL TX
Established Series
Rev. RAC/JLR/ACT
11/2014
CHILICOTAL SERIES
The Chilicotal series consists of very deep, well drained, moderately permeable soils that formed in loamy gravelly piedmont sediments from igneous mountains. These soils are on gently undulating to strongly rolling fan remnants and alluvial fans. Slopes range from 1 to 50 percent.
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, thermic Ustic Haplocalcids
TYPICAL PEDON: Chilicotal very gravelly fine sandy loam, rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 2 inches; brown (7.5YR 5/4) very gravelly fine sandy loam, brown (7.5YR 4/4) moist; weak fine granular structure; slightly hard, very friable; many roots; 40 percent igneous gravel; very slightly effervescent; moderately alkaline; abrupt smooth boundary (1 to 3 inches thick).
Bw--2 to 7 inches; brown (7.5YR 5/4) very gravelly loam, brown (7.5YR 4/4) moist; weak fine subangular blocky structure; slightly hard, friable; common roots; 45 percent igneous gravel; few fine threads and films of calcium carbonate; slightly effervescent; moderately alkaline; clear smooth boundary (3 to 17 inches thick).
Bk1--7 to 14 inches; brown (7.5YR 5/4) very gravelly loam, brown (7.5YR 4/4) moist; weak fine subangular blocky structure; slightly hard, friable; common roots; 45 percent igneous gravel, 5 percent igneous cobbles, patchy coatings of calcium carbonate on undersides of coarse fragments; common threads and films of calcium carbonate; strongly effervescent; moderately alkaline; clear smooth boundary. (4 to 12 inches thick)
Bk2--14 to 28 inches; brown (7.5YR 5/4) very gravelly loam, brown (7.5YR 4/4) moist; weak fine subangular blocky structure; slightly hard, friable; common roots; 55 percent igneous gravel; underside of coarse fragments covered with coatings of calcium carbonate; common threads and films of calcium carbonate; strongly effervescent; moderately alkaline; clear wavy boundary (0 to 20 inches thick).
Bk3--28 to 40 inches; light brown (7.5YR 6/4) extremely gravelly loam, brown (7.5YR 5/4) moist; weak very fine granular structure; very hard, friable; few roots; 65 percent igneous gravel, 5 percent igneous cobbles, patchy coatings of calcium carbonate on underside of coarse fragments; violently effervescent; moderately alkaline; clear smooth boundary (7 to 20 inches thick).
Bk4--40 to 51 inches; pink (7.5YR 7/4) extremely gravelly sandy loam, brown (7.5YR 5/4) moist; weak very fine granular structure; slightly hard, very friable; few roots; 60 percent igneous gravel with thick coatings of calcium carbonate; violently effervescent; moderately alkaline; clear smooth boundary (8 to 30 inches thick).
Bk5--51 to 61 inches; pink (7.5YR 7/4) extremely gravelly sandy loam, brown (7.5YR 5/4) moist; weak very fine granular structure; slightly hard, friable; few roots; 70 percent igneous gravel with patchy coatings of calcium carbonate; violently effervescent; moderately alkaline; abrupt smooth boundary (8 to 10 inches thick).
Bk6--61 to 80 inches; pink (7.5YR 7/4) extremely gravelly sandy loam, light brown (7.5YR 6/4) moist; weak very fine granular structure; extremely hard, very friable, roots penetrate only between peds; 65 percent igneous gravel, 5 percent igneous cobbles; violently effervescent; moderately alkaline.
TYPE LOCATION: Brewster County, Texas. From the Big Bend National Park headquarters at Panther Junction; 3.2 miles west on paved road; 2.9 miles north on Grapevine Hills Road; 400 yards west of road Latitude: 29 degrees, 21 minutes, 57 seconds North; Longitude: 103 degrees, 13 minutes, 31 seconds West.
RANGE IN CHARACTERISTICS:
Solum thickness: greater than 80 inches
Depth to the calcic horizon: 6 to 20 inches
Texture of the control section: sandy loam, fine sandy loam, loam, sandy clay loam, clay loam
Average clay content of the control section: 15 to 30 percent
Rock fragment content of all horizons: 20 to 90 percent
Rock fragment content of the particle-size control section (weighted average): 35 to 70 percent
Calcium carbonate equivalent of the control section: 10 to 50 percent, but averages 10 to 40 percent
Soil moisture: The soil has an aridic moisture regime that borders an ustic regime. Ustic aridic moisture regime.
A and Bw horizons
Hue: 7.5YR, 10YR
Value: 4 to 6, dry or moist
Chroma: 2 to 6, dry or moist
Organic matter content: 0.8 to 2 percent
Calcium carbonate equivalent: 2 to 40 percent
Reaction: moderately alkaline
Average organic carbon in the upper 16 inches is high relative to the sand to clay ratio.
Bk horizons
Hue: 7.5YR, 10YR
Value: 4 to 7, dry or moist
Chroma: 1 to 6, dry or moist
Reaction: moderately alkaline in the upper part to strongly alkaline in the lower part
Calcium carbonate equivalent: 15 to 50 percent
Below 40 inches most pedons have underlying layers of varying thickness, fine earth texture, and size and content of coarse fragments.
COMPETING SERIES: These are the
Gallen (NM),
Gilland (TX),
Polar (TX),
Powerline (AZ), and
Tombstone (AZ) series. Gallen and Tombstone soils have less than 18 percent clay in the control section. In addition, Gallen soils are in the
Pecos-
Canadian
Plains and Valleys and are more moist in
May and June. Gilland soils are moderately deep. Polar soils are in the Central Rolling Red Plains and are more moist in May and June. Powerline soils are moderately deep to bedrock.
GEOGRAPHIC SETTING: These soils are on piedmont slopes, fan remnants, and alluvial fans below igneous hills and mountains. Slopes along ridges range from 1 to 10 percent, and on side slopes from 5 to about 50 percent. The soils formed in loamy gravelly sediments from succeeding erosional sediments that built up these piedmont slopes. At the type location, the rounded gravel is of several kinds of igneous rock. Mean annual air temperature ranges from 60 to 68 degrees F. and mean annual precipitation ranges from about 8 to 16 inches with most occurring during the late summer and early fall months. Frost- free period ranges from 210 to 250 days and elevation ranges from 2,500 to 5,500 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Chamberino,
Holguin,
Lajitas,
Monterosa, and
Paisano soils. Chamberino soils have high organic carbon relative to the sand/clay ratio, but are not in areas that border the ustic moisture regime. Holguin soils are very shallow and shallow over conglomerate rock. Lajitas soils are less than 20 inches thick over igneous bedrock and are on hillsides. Paisano soils are shallow to a petrocalcic horizon. Monterosa soils are less than 20 inches to a petrocalcic horizon and are on plane and weakly convex ridges.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderate.
Runoff is very low on 1 to 3 percent slopes, low on 3 to 5 percent slopes, and medium on slopes greater than 5 percent.
USE AND VEGETATION: Livestock grazing and wildlife habitat. Grasses in most areas are mainly chino grama, slim tridens, black grama, and threeawns with woody vegetation of lechuguilla, creosotebush, skeletonleaf goldeneye, catclaw, sotol, yucca, and ceniza.
DISTRIBUTION AND EXTENT: West Texas in MLRA 42. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Brewster County, Texas; 1982
REMARKS: Diagnostic horizon and features recognized in this pedon are:
Ochric epipedon - the zone from 0 to 2 inches (A horizon)
Calcic horizon - the zone from 14 to 80 inches (Bk2, Bk3, Bk4, Bk5, Bk6 horizons)
Classified according to Soil Taxonomy Second Edition, 1999; Keys to Soil Taxonomy, Twelfth Edition, 2014.
Update and revision for recorrelation of Brewster County, TX, Main Part, 2/8/08, CEM
Revised for the correlation of Big Bend National Park, TX, Oct. 2010, CEM
Revised for the correlation of Hudspeth County, Texas (Main Part) and Culberson County, Texas (Main Part); July, 2012, NMS
Revised for the correlation of Presidio County, Texas ; Oct, 2012, WWJ
Revised for the correlation of White Sands Missile Range, New Mexico; October, 2014, NMS
ADDITIONAL DATA: Texas A&M University - Lab sample S80TX-043-11
National Cooperative Soil Survey
U.S.A.