LOCATION THREADGILL NMEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, active, mesic Ustic Haplocalcids
TYPICAL PEDON: Threadgill silt loam--rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 5 inches; dark yellowish brown (10YR 4/4) silt loam, dark brown (10YR 3/3) moist; moderate fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine and common fine roots; many fine and very fine pores; strongly effervescent; slightly alkaline; clear smooth boundary. (3 to 5 inches thick)
Bk1--5 to 12 inches; brown (7.5YR 5/4) silty clay loam, dark brown (7.5YR 4/4) moist; weak medium subangular blocky structure; hard, friable, sticky and plastic; common very fine and fine roots; many very fine and fine pores; strongly effervescent; few fine masses of calcium carbonate; moderately alkaline; clear smooth boundary. (5 to 8 inches thick)
Bk2--12 to 18 inches; light brown (7.5YR 6/4) silty clay loam, brown (7.5YR 5/4) moist; moderate medium subangular blocky structure; hard, friable, sticky and plastic; few fine and very fine roots; common fine and very fine pores; violently effervescent; common fine masses of calcium carbonate; moderately alkaline; clear smooth boundary. (4 to 8 inches thick)
Bk3--18 to 36 inches; light brown (7.5YR 6/4) silty clay loam, brown (7.5YR 5/4) moist; weak coarse prismatic structure parting to weak medium subangular blocky; hard, friable, sticky and plastic; few fine and very fine roots; common fine and very fine pores; violently effervescent; many fine and few medium masses of calcium carbonate; moderately alkaline; gradual smooth boundary. (8 to 19 inches thick)
Bk4--36 to 60 inches; light brown (7.5YR 6/4) silty clay loam, brown (7.5YR 5/4); massive; hard, friable, sticky and plastic; few fine masses of calcium carbonate; violently effervescent; moderately alkaline.
TYPE LOCATION: Chaves County, New Mexico; 10 feet south of the road in the SE1/4, SW1/4, Sec. 18, T. 5 S., R. 21 E.
RANGE IN CHARACTERISTICS:
Soil Moisture: Intermittently moist in some part of the soil moisture control section December through March and May through September.
Soil Temperature: 56 to 59 degrees F.
Depth to secondary carbonates: 3 to 5 inches
A horizon:
Hue: 7.5YR or 10YR
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 2 to 4
Bk horizon:
Hue: 7.5YR or 10YR
Value: 5 to 7 dry, 4 to 6 moist
Chroma: 3 or 4
Texture: silty clay loam or clay loam with 27 to 35 percent clay
Calcium carbonate equivalent: 15 to 25 percent
COMPETING SERIES: There are no competing series in the same family. A very similar soil is the Willard series. Willard soils are in the superactive cation exchange activity class. In addition, Willard soils have discontinuities of lacustrine deposits within 40 inches of the surface and contain horizons with gypsum accumulation.
GEOGRAPHIC SETTING: Threadgill soils are on fan terraces. Slope ranges from 0 to 5 percent. They formed calcareous alluvium derived from limestone. Average annual precipitation is 10 to 12 inches. Average annual temperature ranges from 55 to 57 degrees F., and the average frost-free period ranges from 180 to 190 days. Elevation ranges from 4,200 to 4,700 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Asparas, Darvey, Deama, Gabaldon, and Pastura soils. Asparas soils have a mollic epipedon and an argillic horizon. Darvey soils have a fine-loamy control section. Deama and Pastura soils are shallow. Gabaldon soils have a mollic epipedon 20 inches or more thick.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderately slow. Runoff is low on slopes less than 1 percent and medium on 1 to 5 percent slopes.
USE AND VEGETATION: Rangeland. The present vegetation is mainly tobosa, blue grama, silver bluestem, and walkingstick cholla.
DISTRIBUTION AND EXTENT: South central New Mexico. Threadgill soils are of minor extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Chaves County (North Part), New Mexico, 1981.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: 0 to 5 inches. (A horizon)
Calcic horizon: 12 to 60 inches. (Bk horizons)
ADDITIONAL DATA: NSSL and NMSU; Sample No. 379NM-5-7.