LOCATION WELD               CO+WY
Established Series
Rev. JWB-MLP
02/2006

WELD SERIES


The Weld series consists of very deep, well drained soils that formed in thick calcareous loess, or from silty uniform alluvium or outwash. Weld soils are on hills, uplands, or smooth plains and interfluves and have slopes of 0 to 8 percent. The mean annual precipitation is about 36 centimeters (14 inches) and mean annual temperature is 10 degrees C. (49 degrees F.) at the type location.

TAXONOMIC CLASS: Fine, smectitic, mesic Aridic Argiustolls

TYPICAL PEDON: Weld silt loam, nonirrigated cropland (Colors are for dry soil unless otherwise noted.)

Ap--0 to 13 centimeters (0 to 5 inches); grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; soft, very friable; low toughness, slightly sticky and slightly plastic; many fine roots throughout and many very fine throughout and common medium throughout; common very fine and fine moderate continuity continuous tubular pores and many very fine and fine high continuity tubular pores; neutral (ph 7.0); abrupt smooth boundary. (0 to 23 centimeters (0 to 9 inches) thick)

Bt1--13 to 25 centimeters (5 to 10 inches); brown (10YR 5/3) silty clay loam, dark brown (10YR 3/3) moist; strong medium prismatic structure parting to strong fine and medium subangular blocks; hard, firm, medium toughness, sticky and plastic; common very fine and fine low continuity tubular pores and common very fine low continuity interstitial pores; few distinct discontinuous clay films on faces of peds and in pores; neutral (pH 7.0); clear smooth boundary.

Bt2--25 to 41 centimeters (10 to 16 inches); brown (10YR 5/3) silty clay loam, dark brown (10YR 3/3) moist; moderate fine and medium prismatic structure parting to moderate fine subangular blocks; very hard, very firm, high toughness, very sticky and very plastic; many fine roots throughout and common very fine throughout and few medium throughout; common very fine moderate continuity dendritic tubular pores and common very fine and fine low continuity tubular pores; few distinct discontinuous clay films on vertical and horizontal faces of peds; common medium cylindrical soft masses of carbonate pedogenic between peds; slightly effervescent on faces of peds and in pores; slightly alkaline (pH 7.4); clear wavy boundary. (The combined thickness of the Bt horizon is 51 to 152 centimeters (20 to 60 inches)

Btk--41 to 64 centimeters (16 to 25 inches); light brownish gray (10YR 6/2) silty clay loam, brown (10YR 5/3) moist; weak coarse prismatic structure parting to moderate fine and medium subangular blocky; hard, firm, medium toughness, sticky and plastic; many fine roots throughout and common very fine throughout and few medium throughout; common very fine moderate continuity dendritic tubular pores and common very fine and fine moderate continuity tubular pores; few distinct patchy light gray (10YR 7/2), dry, carbonate coats and very few faint patchy clay films in root channels and/or pores; few fine irregular soft carbonate threads pedogenic throughout; violently effervescent on faces of peds and in pores; moderately alkaline; clear wavy boundary. (8 to 30 centimeters (3 to 12 inches) thick)

Bk--64 to 91 centimeters (25 to 36 inches); light brownish gray (10YR 6/2), silt loam, grayish brown (10YR 5/2), moist; weak coarse prismatic structure; soft, very friable, low toughness, slightly sticky and slightly plastic, common very fine and fine roots throughout; common very fine low continuity vesicular pores and common very fine and fine low continuity tubular pores and few very fine low continuity dendritic tubular pores; few fine irregular soft carbonate threads pedogenic throughout; violently effervescent on faces of peds and in pores, moderately alkaline, gradual smooth boundary. (13 to 30 centimeters (5 to 12 inches) thick)

BC--91 to 152 centimeters (36 to 60 inches); light brownish gray (10YR 6/2), very fine sandy loam, brown (10YR 5/3), exterior, moist: weak medium prismatic structure; soft, very friable, low toughness, slightly sticky and slightly plastic; common very fine and fine roots throughout; common very fine low continuity tubular pores; few fine irregular soft carbonate threads pedogenic throughout; violently effervescent on faces of peds; moderately alkaline; gradual wavy boundary. (20 to 76 centimeters (8 to 30 inches) thick)

C--152 to 203 centimeters (60 to 80 inches); pale brown (10YR 6/3), very fine sandy loam, brown (10YR 5/3), moist; massive; soft, very friable, low toughness, slightly sticky and slightly plastic; common fine roots throughout; common very fine low continuity tubular pores; few fine irregular soft carbonate threads pedogenic throughout; violently effervescent on faces of peds; moderately alkaline.

TYPE LOCATION: Washington County, Colorado; 39 degrees 55 minutes 48.2 seconds North and 103 degrees 19 minutes 44.4 seconds West.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature 51 centimeters (20 inches): 9 to 13 degrees C. (48 to 55 degrees F.)
Mean summer soil temperature: 15 to 24 degrees C. (59 to 75 degrees F)
Mollic epipedon: 18 to 48 centimeters (7 to 19 inches)
Depth to calcareous material: 20 to 51 centimeters (8 to 20 inches) in virgin profiles
Calcium carbonate equivalent: less than 15 percent in the C horizon but may exceed this amount in thin strata in some parts of some pedons
Organic carbon content mollic epipedon: 0.8 to 3 percent and decreases uniformly with depth, reaching levels of 0.2 percent or less within a depth of 127 centimeters (50 inches)
Exchangeable sodium percentage: usually less than 3 percent in the solum and does not exceed 14 percent in any horizon as much as 4 inches thick within the solum
Exchangeable sodium percentage C horizon: generally higher than in the solum and may exceed 15 percent in some pedons
Content of coarse fragments: typically less than 2 percent, ranges from 0 to 15 percent in the solum
C horizon: may have 0 to 25 percent pebbles
Soil temperature 20 inches: 5 degrees C. (41 degrees F.) or higher for about 200 to 240 days
Moisture control section: moist in some part of the when soil temperature at 51 centimeters (20 inches) is 5 degrees C. (41 degrees F.) or higher for about 56 to 152 days.

A horizon:
Hue: 5Y to 7.5YR
Value: 4 or 5, and 2 or 3 moist
Chroma: 2 or 3
Structure: usually granular but subangular blocky in some pedons
Rupture Resistance: soft or slightly hard
Reaction: neutral or slightly alkaline (pH 6.6 to 7.8)

Bt horizon
Hue: 5Y to 7.5YR
Value: 4 to 7, and 3 to 6 moist
Chroma: 2 to 5
Texture: silty clay, or silty clay loam
Clay content: 35 to 50 percent
Silt content: 20 to 55 percent
Sand content: 5 to 50 percent, less than 15 percent being fine or coarser sand
Structure: prismatic structure but angular blocky structure in some pedons
Reaction: neutral or slightly alkaline (pH 6.6 to 7.8), in the upper part and slightly alkaline or moderately alkaline in the lower part

C horizon:
Hue: 5Y to 7.5YR
Value: 6 to 8, 5 or 6 moist
Chroma: 2 to 4
Texture: loam or silt loam with less than 27 percent clay
Texture in some pedons below 40 inches: fine sandy loam
Reaction: moderately alkaline or strongly alkaline (pH 8.0 to 8.6)

COMPETING SERIES: These are the Ashfork, Bethune, Blackpipe, Boneek, Boquillas, Chapin, Collbran, Collide, Emigrant, Huggins, Kube, Leyden, Loma, Nuncho, Nunn, Querc, Raku, Rednun, Richfield, Ryus, Savo, Showlow, Standley, Thunderbird, and Wormser series.
Asfork soils are at 1524 to 1829 meters (5000 to 6000 feet) elevation
Bethune, Blackpipe, Boquillas, Emigrant, Huggins, Leyden, and Querc soils have a paralithic contact at depths of 51 to 102 centimeters (20 to 40 inches).
Boneek and Kube soils have a paralithic contact at depths of 102 to 152 centimeters (40 to 60 inches).
Ashfork, Chapin, Thunderbird and Wormse soils have a lithic contact at depths of less than 102 centimeters (40 inches).
Collide and Rednun soils have hues of 2.5YR or 5YR in the control section.
Loma and Ryus soils are calcareous throughout.
Nuncho soils are usually dry when the soil temperature at a depth of 51 centimeters (20 inches) is 5 degrees C. (41 degrees F.) or greater.
Nunn soils contain rock fragments typically less than 5 percent and range from 0 to 15 percent.
Raku soils are in a warmer temperature zone.
Richfield soils have a warmer soil temperature.
Savo soils have a mean annual temperature of 48 degrees F. or less.
Showlow soils average more than 15 percent rock fragments below the Bt horizon.
Standley soils average 15 to 35 percent rock fragments in the control section.
Torreon soils are derived from basalt and have calcic horizons above a depth of 40 inches.

GEOGRAPHIC SETTING:
Landform: on hills, plains and interfluves
Slopes: 0 to 8 percent
Parent material: thick calcareous silty eolian materials or from silty uniform alluvium or outwash
Mean annual precipitation: 28 to 41 centimeters (11 to 16 inches),peak periods of precipitation occurring in the spring and early summer months
Mean annual temperature: 7 to 12 degrees C. (45 to 53 degrees F.)
Mean summer temperature: 14 to 23 degrees C. (57 to 73 degrees F.)

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Adena and Colby soils.
Adena soils have a very thin solum and an ochric epipedon.
Colby soils lack an argillic horizon.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage: well drained
Runoff: low
Saturated hydraulic conductivity: moderately low

USE AND VEGETATION: They are used as native pastureland or for dry or irrigated cropland.
Native vegetation is blue grama and western wheatgrass.

DISTRIBUTION AND EXTENT: Present known distribution limited to eastern Colorado and Wyoming. Series is of large extent. MLRA's 67 and 69.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado

SERIES ESTABLISHED: Fort Collins Area, Colorado 1927.

REMARKS: Diagnostic horizons and features recognized in this pedon:
Mollic epipedon: 0 TO 25 centimeters (0 to 10 inches) after mixing
Argillic horizon: 13 to 38 centimeters (5 to 15 inches)

Changes in classification from lab findings (94CO121-001), field testing, transects to reflect actual field conditions

Last updated by the state 1998

Modified format by LRM in 1/2006 to include metric conversion and change permeability to saturated hydraulic conductivity.


National Cooperative Soil Survey
U.S.A.