LOCATION MALABON OREstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, mesic Pachic Ultic Argixerolls
TYPICAL PEDON: Malabon silty clay loam, cultivated. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 7 inches; very dark brown (10YR 2/2) silty clay loam, dark grayish brown (10YR 4/2) dry; strong very fine granular structure; hard, friable, slightly sticky and slightly plastic; many very fine roots; many irregular pores; moderately acid (pH 5.6); clear smooth boundary. (6 to 11 inches thick)
AB--7 to 12 inches; dark brown (7.5YR 3/2) silty clay loam, dark grayish brown (10YR 4/2) dry; weak fine subangular blocky and strong very fine granular structure; hard, friable, moderately sticky and moderately plastic; many very fine roots; many very fine and few fine tubular pores; very dark brown (10YR 2/2) coatings on peds; slightly acid (pH 6.1); clear wavy boundary. (0 to 15 inches thick)
Bt1--12 to 19 inches; dark brown (10YR 3/3) silty clay, dark grayish brown (10YR 4/2) dry; moderate medium subangular blocky and moderate very fine granular structure; hard, firm, moderately sticky and moderately plastic; common very fine roots; common fine and very fine and few medium tubular pores; many prominent very dark grayish brown (10YR 3/2) clay films on faces of peds and along pores; slightly acid (pH 6.3); clear wavy boundary. (6 to 20 inches thick)
Bt2--19 to 29 inches; dark brown (10YR 3/3) silty clay, brown (10YR 5/3) dry; moderate medium and very fine subangular blocky structure; very hard, firm, moderately sticky and moderately plastic; common very fine roots; common very fine and few medium tubular pores; many prominent dark brown (7.5YR 3/2) clay films on faces of peds and along pores; slightly acid (pH 6.5); clear wavy boundary. (8 to 20 inches thick)
BCt--29 to 42 inches; brown (10YR 4/3) silty clay loam, brown (10YR 5/3) dry; weak coarse subangular blocky structure; very hard, firm, slightly sticky and moderately plastic; common very fine roots; common fine and medium tubular pores; common prominent dark brown (7.5YR 3/2) clay films on faces of peds and along pores; neutral (pH 6.8); clear wavy boundary. (0 to 20 inches thick)
2C--42 to 60 inches; brown (10YR 4/3) clay loam, brown (10YR 4/3) dry; massive; hard, friable, slightly sticky and slightly plastic; few very fine roots; few fine tubular pores; neutral (pH 6.9).
TYPE LOCATION: Lane County, Oregon; about 1,950 feet west and 1,950 feet north of the SE corner of section 12, T. 15 S., R. 5 W. Willamette Meridian, Harrisburg, Oregon. USGS 7.5 minutes quad. Latitude 44 degrees, 16 minutes, 43 seconds N.; and Longitude 123 degrees, 14 minutes, 13 seconds W. NAD 27.
RANGE IN CHARACTERISTICS: The soil is usually moist but is dry in all parts between 4 and 12 inches during the summer for 45 to 60 consecutive days within MLRA 2 but ranges to 90 days in MLRA 5. The mean annual soil temperature ranges from 52 to 55 degrees F. The pscs has 35 to 45 percent clay. The solum is 40 to 60 inches thick and has 0 to 5 percent gravel. Up to 15 percent gravel are in some horizons in some pedons. The mollic epipedon is 20 to 30 inches thick. Hue is 10YR or 7.5YR.
The A horizon has value of 2 or 3 moist, 4 or 5 dry and chroma of 2 or 3 moist and dry. It has 27 to 35 percent clay and 0 to 5 percent gravel. Reaction is moderately acid or slightly acid.
The AB or BA horizon, when present, has value of 2 or 3 moist, 4 or 5 dry and chroma of 2 or 3 moist and dry. Texture is silty clay loam or silty clay with 35 to 45 percent clay. Reaction is moderately or slightly acid.
The Bt horizon has value of 3 moist to 20 inches or more, and 3 or 4 below 20 inches, value of 4 or 5 dry and chroma of 2 or 3 moist, 3 or 4 dry. Texture is silty clay loam or silty clay with 35 to 45 percent clay and 0 to 5 percent gravel. Reaction is moderately acid to neutral.
The BCt horizon, when present, has 30 to 45 percent clay.
The 2C horizon, where present, has value of 3 or 4 moist, 4 to 6 dry and chroma of 3 or 4 moist and dry. Texture is silty clay loam, clay loam, loam or gravelly loam and may be stratified with sandy clay loam and fine sandy loam in some pedons. It has 0 to 30 percent gravel. Reaction is slightly acid or neutral.
COMPETING SERIES: These are the Darby, Dixonville, Mart, and Silverton series. Darby soils have a mollic epipedon 30 to 50 inches thick and are darker colored by 1 or 2 units of value in the upper part of the argillic horizon. Dixonville soils have a paralithic contact at a depth of 20 to 40 inches. Silverton soils have a lithic contact at 20 to 40 inches. Mart soils have a mean annual soil temperature of 48 to 52 degrees F.
GEOGRAPHIC SETTING: Malabon soils are dominantly on stream terraces but are also recognized on high flood plains in some areas. Elevation is 100 to 1,100 feet. Slopes are 0 to 3 percent. The soils formed in loamy and clayey alluvium from mixed materials. The summers are warm and dry and the winters are cool and moist. The mean annual precipitation is 30 to 60 inches. The mean January temperature is 39 to 40 degrees F. and the mean July temperature is 65 to 67 degrees F. The mean annual temperature is 50 to 55 degrees F. The frost-free season is 160 to 235 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Awbrig, Clackamas, Conser, Courtney, Oxley, Salem, and the competing Darby, Coburg, and Redbell soils. Awbrig and Conser soils are poorly drained and occur in depressions and on low terraces. Courtney soils are poorly drained and occur in depressions. Clackamas and Oxley soils are somewhat poorly drained. In addition, Clackamas soils have a very gravelly or extremely gravelly C horizon. Oxley soils are loamy-skeletal. Clackamas and Oxley soils occur on terraces. Darby soils occur on footslopes. Coburg soils occur on high flood plains and terraces. Redbell soils occur on low terraces.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderately slow permeability. Areas of Malabon soils on high flood plains are subject to rare to occasional flooding for brief periods from December to March.
USE AND VEGETATION: These soils have wide use for growing orchard, berry, vegetable, small grain, hay, pasture, and grass seed crops. Natural vegetation is Douglas fir, Oregon white oak, blackberry, Pacific poison-oak, other shrubs, and grasses.
DISTRIBUTION AND EXTENT: Stream terraces of the Willamette Valley and Umpqua Valley, Oregon; MLRA 2, 5. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Benton County Area, Oregon, 1970.
REMARKS: Diagnostic horizons and features include:
Mollic epipedon - the zone from 0 to 29 inches (Ap, AB, Bt1, Bt2 horizons)
Argillic horizon - the zone from 12 to 42 inches (Bt1, Bt2, and BCt horizons)
Particle-size control section - the zone from 12 to 32 inches
The Malabon soils are found on the high and low Winkle geomorphic surfaces as recognized in the Willamette Valley, Oregon. Those soils associated with the low Winkle surface have a flooding hazard.
The Mart soils as defined in Washington are very similar. More investigation is needed to adequately separate.
ADDITIONAL DATA: Characterization data for one pedon 67Oreg. 20-15(1-6), by OSU and published in Soil Science, Volume 109, No.5, 1970.