LOCATION CALDWELL WA+IDEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Cumulic Haploxerolls
TYPICAL PEDON: Caldwell silt loam, cultivated. (Colors are for dry soils unless otherwise stated.)
Ap--0 to 9 inches, grayish brown (10YR 5/2) silt loam, very dark gray (10YR 3/1) moist; weak coarse platy structure parting to weak fine granular; slightly hard, friable, slightly sticky and slightly plastic; many roots, common fine tubular pores; neutral (pH 6.8); abrupt smooth boundary. (6 to 10 inches thick)
A--9 to 17 inches, dark gray (10YR 4/1) silt loam, black (10YR 2/1) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; hard, friable, moderately sticky and slightly plastic; common roots; common fine tubular pores; common organic staining; neutral (pH 7.2); clear smooth boundary. (7 to 9 inches thick)
ABt--17 to 26 inches, dark gray (10YR 4/1) heavy silt loam, very dark gray (10YR 3/1) moist; moderate medium prismatic structure parting to moderate medium angular blocky; hard, slightly firm, moderately sticky and moderately plastic; common roots; many fine tubular pores; few faint patchy clay films on faces of peds; few distinct organic stains on faces of peds; few faint silica coatings on vertical faces peds; neutral (pH 7.2); clear smooth boundary. (7 to 10 inches thick)
Bt--26 to 39 inches, gray (10YR 5/1) silty clay loam, very dark gray (10YR 3/1) moist; moderate medium prismatic parting to moderate medium angular blocky structure; hard, firm, moderately sticky and moderately plastic; common roots; common fine tubular pores; few faint patchy clay films on faces of peds; few distinct silica coatings on faces of peds; neutral (pH 7.2); abrupt smooth boundary (10 to 15 inches thick)
Btg--39 to 54 inches, light brownish gray (2.5Y 6/2) silty clay loam, very dark grayish brown (2.5Y 3/2) moist; massive; hard, firm, moderately sticky and moderately plastic; few roots; few fine tubular pores; few faint clay films on faces of peds; many fine prominent yellowish brown (10YR 5/6) moist, masses of iron accumulation with clear boundaries, and few fine prominent brown (7.5YR 4/4) moist, masses of iron accumulation with sharp boundaries in the matrix; neutral (pH 7.2); abrupt smooth boundary. (14 to 20 inches thick)
BCg--54 to 61 inches, light brownish gray (2.5Y 6/2) light silty clay loam, dark grayish brown (2.5Y 4/2) moist; massive; hard, firm, moderately sticky and moderately plastic; no roots; few fine tubular pores; common fine masses of iron accumulation throughout; neutral (pH 7.0).
TYPE LOCATION: Whitman County, Washington - 400 feet west and 200 feet north of the southeast corner of section 15, T. 15 N., R. 45 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature at 20 inches ranges from 48 to 50 degrees F. The Caldwell soils are saturated at certain seasons of the year but are dry for 45 to 60 consecutive days in all parts between 4 and 12 inches in most years. The mollic epipedon is 20 to 38 inches and may include part of the Bw or Bt horizon. Depth to aquic conditions with chroma of 2 or less and redox concentrations is 30 to 40 inches.
The A and AB horizons have value of 3 to 5 dry, 1 to 3 moist and chroma of 1 to 3 moist and dry. It has 18 to 27 percent clay. Reaction is slightly acid to slightly alkaline.
The Bw or Bt horizon has hue of 10YR or 2.5Y, value of 4 to 6 dry, 2 to 4 moist and chroma of 1 to 3 moist and dry. Texture is silt loam or silty clay loam. It has 20 to 35 percent clay. The structure of the Bt ranges from weak to moderate prismatic. Faint to distinct discontinuous clay films are on vertical faces of some peds. Reaction is neutral to moderately alkaline.
The Bwg or Btg horizon and BCg horizon have hue of 10YR or 2.5Y, value of 4 to 7 dry, 2 to 4 moist and chroma of 1 to 4 moist or dry. Texture is silty clay loam or heavy silt loam. It has 20 to 35 percent clay. Redoximorphic features range from faint to distinct with colors ranging from 5YR to 10YR hues. Small pockets of volcanic ash and basalt pebbles are in the lower part of some profiles. Reaction is neutral to moderately alkaline.
Cg horizon present in some pedons
COMPETING SERIES: These are the Harana, Jett, Keigley, Loupence, Red Rock, Rustico and Snow series. Harana soils are strongly alkaline in the A horizon and are dry for more than 60 consecutive days. Jett and Keigley soils are calcareous and do not have aquic conditions within 40 inches. Loupence and Rustico soils have an aridic soil moisture regime. Red Rock soils are calcareous in the C horizon and do not have aquic conditions within 40 inches. Snow soils do not have aquic conditions with chroma of 2 or less within 40 inches.
GEOGRAPHIC SETTING: Caldwell soils are and in flood plains and drainageways. Slope ranges from 0 to 8 percent. The soils formed in fine-silty alluvium derived primarily from loess, with minor amounts of volcanic ash in the upper part. Elevations are 1,700 to 2,600 feet. The climate is characterized by warm dry summers and cool moist winters. The mean annual precipitation is 18 to 23 inches. The mean annual temperature is 47 to 49 degrees F. The frost-free period is about 100 to l35 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These include Konert, Latah, Naff, Palouse, and Thatuna soils. Konert soils have a fine textured argillic horizon and are on flood plains. Latah soils have albic horizon, a fine textured argillic horizon and are on low terraces and in drainageways. Naff and Thatuna soils do not have redox depletions or reduced matrix with a chroma of 2 or less and are on loess hills. Palouse soils have a regular decrease in organic carbon, do not have redoximorphic features and are on loess hills.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained. Permeability is moderately slow.
USE AND VEGETATION: These soils are used mainly for cropland. Small grains, peas, lentils, legumes and grass hay, and pasture are common crops. Native vegetation consisted of giant wildrye, sedge, bluegrasses, rushes, willow, hawthorne, cattails, redtop, iris, and aspen.
DISTRIBUTION AND EXTENT: Southeastern Washington and western Idaho; MLRA 9. Series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Boise area, Idaho - 1901.
REMARKS: Diagnostic horizons and features recognized in this pedon include:
Mollic epipedon - the zone from 0 to 39 inches (Ap, A, ABt and Bt horizons)
Cumulic feature - the zone from 0 to 31 inches (Ap, A, and ABt horizons) having an irregular decrease in organic carbon with depth.
Cambic horizon - the zone from 39 to 54 inches (Btg horizon) with evidence of oriented clay but failing to meet the required clay increase.
Oxyaquic feature - the zone from 39 to 61 inches having aquic conditions and chroma of 2 or less with redox concentrations.
Particle-size control section - the zone from 10 to 40 inches
This description reflects a change in classification as of 5/00 from fine-silty, mixed, mesic Cumulic Haploxerolls to fine-silty, mixed, superactive, mesic Cumulic Haploxerolls.