LOCATION MCGOWAN WAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Vitrandic Haploxeralfs
TYPICAL PEDON: McGowan ashy loam - forested on a 9 percent southwest-facing slope at an elevation of 2,480 feet. (Colors are for dry soil unless otherwise noted.)
Oi--0 to 1 inch; needles, twigs, and leaves.
A1--1 to 5 inches; light brown (7.5YR 6/4) ashy loam, dark brown (7.5YR 3/4) moist; weak fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine and common fine roots; many very fine irregular pores; 20 percent shot-like aggregates; moderately acid (pH 6.0); clear smooth boundary.
A2--5 to 11 inches; brown (7.5YR 5/4) ashy loam, dark brown (7.5YR 3/4) moist; weak fine subangular blocky structure parting to weak fine granular; slightly hard, friable, slightly sticky and slightly plastic; many very fine and common fine roots; many very fine irregular pores; 10 percent shot-like aggregates; moderately acid (pH 6.0); clear smooth boundary. (Combined thickness of the A horizon is 7 to 10 inches.)
BAt--11 to 16 inches; brown (7.5YR 5/4) clay loam, dark brown (7.5YR 3/4) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine, common fine, and few medium roots; many fine irregular pores; few gravel; few faint clay films in pores; moderately acid (pH 5.8); clear smooth boundary. (5 to 16 inches thick)
Bt1--16 to 27 inches; brown (7.5YR 5/4) clay loam, dark brown (7.5YR 3/4) moist; weak medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common very fine roots; many fine irregular and few fine tubular pores; few gravel; few faint clay films in pores; moderately acid (pH 5.8); gradual smooth boundary.
Bt2--27 to 43 inches; brown (7.5YR 5/4) clay loam, dark brown (7.5YR 3/4) moist; moderate medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common very fine, few fine and few coarse roots; many fine irregular pores; 5 percent gravel; few distinct clay films on faces of peds and in pores; moderately acid (pH 5.9); clear smooth boundary. (Combined thickness of the 2Bt horizon is 30 to more than 60 inches.)
Bt3--43 to 61 inches; brown (7.5YR 5/4) clay loam, dark brown (7.5YR 3/4) moist; weak fine subangular blocky structure; hard, firm, slightly sticky and moderately plastic; few very fine roots; many fine irregular pores; 5 percent paragravel; few faint clay films on faces of peds and in pores; moderately acid (pH 5.8).
TYPE LOCATION: Klickitat County, Washington; about 7 miles northwest of Lyle; 800 feet north and 1,800 feet east of the southwest corner, section 29, T. 4 N., R. 12 E. Latitude 45 degrees, 48 minutes, 00 seconds N. and Longitude 121 degrees, 20 minutes, 06 seconds W.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 47 to 51 degrees F. The soil moisture control section is dry in all parts for 45 to 60 consecutive days within the 4 months that follow the summer solstice in 6 or more years out of 10. Volcanic ash influence is 7 to 14 inches thick and has an estimated moist bulk density of 1.10 to 1.30 g/cc, volcanic glass content of 5 to 30 percent, acid oxalate extractable aluminum plus one-half iron of 1.0 to 2.0 percent, phosphate retention of 50 to 75 percent, and 15 bar water retention of 8 to 12 percent. Clay content in the particle-size control section ranges from 18 to 33 percent. Base saturation ranges from 50 to 60 percent. Rock fragments in the particle-size control section range from 0 to 10 percent gravel 2 to 4 mm in size. Below 40 inches rock fragments range from 0 to 20 percent paragravel, 0 to 15 percent gravel and 0 to 10 percent cobbles.
The A horizon has hue of 5YR to 10YR, value of 4 to 6 dry and chroma of 2 to 4 dry and moist.
The BAt horizon has hue of 5YR and 7.5YR, value of 4 to 6 dry, 3 or 4 moist and chroma of 3 or 4 dry and moist. Texture is ashy loam, loam or clay loam.
The Bt horizon has hue of 5YR or 7.5YR, value of 4 to 6 dry, 3 or 4 moist and chroma of 4 to 6 dry and moist. Texture is loam or clay loam.
COMPETING SERIES: This is the Kephart series. Series with a similar classification except isotic mineralogy are the Bernhill and Underwood soils. Agnew soils have a mean annual soil temperature of 51 to 53 degrees F. have redox depletions and concentrations within 20 inches. Bernhill soils have 10 to 35 percent rock fragments in the particle-size control section and are dry for 60 to 75 consecutive days. Kephart soils are dry for 90 to 130 consecutive days. Underwood soils have 5 to 30 percent paragravel within the particle-size control section.
GEOGRAPHIC SETTING: McGowan soils are on plateaus at elevations of 500 to 2,500 feet. Slopes are 2 to 15 percent. They developed in colluvium and residuum from basalt with an influence of volcanic ash in the surface. Summers are warm and dry and winters are cool and wet. The mean annual precipitation is 35 to 45 inches. The average January temperature is 29 degrees F. and the average July temperature is 65 degrees F. The mean annual temperature is 45 to 50 degrees F. The frost-free season is 120 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Chemawa, Fanal and Husum soils. Chemawa soils are ashy. Fanal soil have a mollic epipedon. Husum soils are ashy-skeletal.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderate permeability.
USE AND VEGETATION: These soils are used for timber production, cropland, grazeable woodland, wildlife habitat and some urban development. The principal farm crops are orchards, small grains and hay and pasture. Native vegetation is Douglas-fir and grand fir with an understory of vine maple, creambush oceanspray, cascade Oregon-grape and common snowberry.
DISTRIBUTION AND EXTENT: Klickitat County, Washington; MLRA 6. The series is moderately extensive.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Klickitat County, Washington, 2003.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 1 to 11 inches
Argillic horizon the zone from 11 to 61 inches
Particle-size control section - the zone from 11 to 31 inches
Vitrandic feature - the zone from 1 to 11 inches
Laboratory data supports isotic mineralogy from 1 to 11 inches and mixed mineralogy from 11 to 61 inches. The series concept would have been considered as isotic mineralogy if lab data for type location was not available.
Depth to diagnostic horizons and features are measured from the top of the first mineral layer.
More investigation is needed in differentiating significant differences between the McGowan and Underwood series.
ADDITIONAL DATA: Partial laboratory data available for this soil NSSL pedon number 40A0989,
40A0990, and 87P0056.