LOCATION PROSSER WA+OREstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Xeric Haplocambids
TYPICAL PEDON: Prosser very fine sandy loam - grassland. (Colors are for dry soil unless otherwise noted.)
A--0 to 4 inches; grayish brown (10YR 5/2) very fine sandy loam, dark grayish brown (10YR 4/2) moist; weak fine granular structure; soft, very friable; nonsticky and nonplastic; many roots; neutral (pH 7.2); abrupt smooth boundary. (3 to 6 inches thick)
Bw1--4 to 15 inches; brown (10YR 5/3) very fine sandy loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; slightly hard, very friable; nonsticky and nonplastic; many roots; common very fine tubular pores; slightly alkaline (pH 7.6); clear wavy boundary.
Bw2--15 to 24 inches; light brownish gray (10YR 6/2) very fine sandy loam, dark grayish brown (10YR 4/2) moist; massive; slightly hard, friable; nonsticky and nonplastic; many roots; common very fine tubular pores; moderately alkaline (pH 8.0); clear wavy boundary. (Combined thickness of the Bw horizon is 7 to 26 inches)
Bk--24 to 30 inches; light brownish gray (10YR 6/2) very fine sandy loam, dark grayish brown (10YR 4/2) moist; massive; slightly hard, friable; nonsticky and nonplastic; many roots; many very fine tubular pores; slightly effervescent; moderately alkaline (pH 8.2); abrupt smooth boundary. (0 to 12 inches thick)
2R--30 inches; basalt; discontinuous lime-silica coatings.
TYPE LOCATION: Adams County, Washington; about 2 miles northwest of Othello; 500 feet south and 100 feet east of the northwest corner of section 28, T. 16 N., R. 29 E., W.M.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 50 to 56 degrees F. These soils are usually dry in all parts between depths of 4 and 12 inches following summer solstice and are moist during the winter and spring. Depth to the Bk horizon, when present, is 10 to 30 inches. Depth to a lithic contact ranges from 20 to 40 inches. The soil has 5 to 12 percent clay and is 15 to 30 percent sand coarser than very fine sand including gravel in the particle-size control section.
The A horizon has value of 5 or 6 dry, 3 or 4 moist and chroma of 2 to 4 dry and moist. Reaction is neutral or slightly alkaline.
The Bw horizon has value of 5 or 6 dry, 3 or 4 moist and chroma of 2 to 4 dry and moist. Texture is silt loam or very fine sandy loam. Reaction is slightly alkaline or moderately alkaline.
The Bk horizon (when present) has value of 5 to 7 dry, 3 to 5 moist, and chroma of 2 to 4 dry and moist. Texture is silt loam or very fine sandy loam. Calcium carbonate equivalent is 1 to 15 percent. In some pedons, this horizon contains a few gravel or cobbles. The only zone of lime accumulation in some pedons, is a thin cap on the top of the bedrock.
COMPETING SERIES: These are the
Bijorja,
Chedehap,
Clems,
Drewsey,
Haybourne,
Heist,
Irrigon,
McClenden,
Rebel,
Royal,
Scooteney,
Vining, and
Wiehl series.
Bijorja soils 20 to 40 inches to a paralithic contact (granodiorite)
Chedehap soils greater than 60 inches to bedrock
Clems soils greater than 60 inches to bedrock
Drewsey soils greater than 60 inches to bedrock
Haybourne soils greater than 60 inches to bedrock
Heist soils greater than 60 inches to bedrock
Irrigon soils 20 to 40 inches to a paralithic contact (tuffaceous sandstone
McClenden soils greater than 45 inches to bedrock
Rebel soils greater than 60 inches to bedrock
Royal soils greater than 60 inches to bedrock
Scooteney soils greater than 60 inches to bedrock
Vining soils 20 to 40 inches to a lithic contact (basalt)
Wiehl soils 20 to 40 inches to a paralithic contact (sandstone)
GEOGRAPHIC SETTING: Prosser soils formed mainly in loess and in glaciofluvial sediments with a minor component of volcanic ash. These soils are on hillslopes, benches, and plateaus at elevations of 300 to 2,400 feet. Slopes range from 0 to 60 percent. Summers are hot and dry, and winters are cool and moist. The mean annual precipitation is 6 to 10 inches. The average January temperature is 28 degrees F. and the average July temperature is 72 degrees F. The mean annual temperature is 48 to 54 degrees F. The frost-free season is 135 to 210 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Burke, Ephrata, Koehler, Quincy, Shano, Starbuck, and Warden soils. Burke soils are on uplands and have a duripan. Ephrata soils are on terraces and are coarse-loamy over sandy or sandy-skeletal. Koehler soils are on terraces, sandy and have a duripan. Quincy soils are on dunes and terraces and are sandy and deep. Shano soils on uplands and Warden soils on terraces and both are more than 40 inches deep. Starbuck soils are on benches and have a lithic contact at a depth of 12 to 20 inches.
DRAINAGE AND PERMEABILITY: Well drained; very slow to rapid runoff; moderate permeability.
USE AND VEGETATION: Prosser soils are used mainly for grazing and for growing irrigated crops. The native vegetation is bluebunch wheatgrass, Sandberg bluegrass, and big sagebrush.
DISTRIBUTION AND EXTENT: Southeastern and south-central Washington and north-central Oregon. MLRA 7. The soil is moderately extensive.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Benton County, Washington, 1916.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 0 to 4 inches
Cambic horizon - the zone from 4 to 24 inches
Lithic contact -the zone beginning at 30 inches
Particle-size control section - the zone from 10 to 30 inches