LOCATION GAGIL FM+PBEstablished Series
TAXONOMIC CLASS: Fine, sesquic, isohyperthermic Typic Haploperox
TYPICAL PEDON: Gagil silty clay loam - on a 15 percent convex slope in a degraded anthropic savannah. When described (4/16/80), the soil was moist throughout. (Colors are for moist soils unless otherwise noted. All textures are apparent field textures.)
A1--0 to 4 inches; dark brown (7.5YR 4/4) silty clay loam, brown (7.5YR 5/4) dry; moderate fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine roots; many very fine tubular and interstitial pores; approximately 2 percent by volume subrounded quartslike sand grains; few dark brown (7.5YR 4/4) wormcasts; strongly acid (pH 5.2, 1:1 water); clear wavy boundary. (4 to 6 inches thick)
B21--4 to 8 inches; yellowish red (5YR 4/6) silty clay; moderate medium angular blocky structure parting to moderate fine angular block; firm, slightly sticky and plastic; few very fine and fine roots; many very fine tubular and interstitial pores; many thin waxy coatings on faces of peds and lining pores; very few vesicular gibbsite concretions .2 to .4 inch in size; strongly acid, (pH 5.1, 1:1 water); gradual wavy boundary. (4 to 9 inches thick)
B22--8 to 18 inches; yellowish red (5YR 4/6) silty clay; moderate medium angular blocky structure parting to moderate fine angular blocky; firm, slightly sticky and plastic; few very fine and fine roots; many very fine and fine tubular and interstitial pores and few medium tubular pores; many thin waxy coatings on faces of peds and lining pores; very few vesicular gibbsite concretions .2 to .4 inch in size; approximately 2 percent by volume moderately hard saprolitic pebbles .2 to .8 inch in size; strongly acid (pH 5.3, 1:1 water); clear wavy boundary. (6 to 10 inches thick)
C--18 to 59 inches; variegated strong brown (7.5YR 4/6) and dusky red (10R 3/3) silty clay loam, many spots and streaks of dark greenish gray (5BG 4/1), olive gray (5Y 5/2), yellowish brown (10YR 5/4), and red (10R 5/6); firm, slightly sticky and slightly plastic; many very fine and common fine tubular pores following fractures; strongly acid (pH 5.4, 1:1 water).
TYPE LOCATION: Tomil Municipality, Yap Island, Yap State, Federated States of Micronesia; from intersection of road to Faniff and road to Tomil-Gagil, head 1,640 feet ENE. on road, then about 164 feet S. of road; lat. 9 degrees 33 minutes 19 seconds N. and long. 138 degrees 8 minutes and 3 seconds E.
RANGE IN CHARACTERISTICS: The thickness of the solum ranges from 16 to 22 inches.
The A horizon has moist color with hue of 5YR or 7.5YR, and chroma and value of 3 or 4. The apparent field texture is silty clay loam, silty clay, or extremely gravelly loam. The horizon is 0 to 10 percent solid spheroidal iron concretions .1 to .2 inch in size. Organic matter content ranges from 0.5 to 4 percent. Reaction in 1:1 water is strongly acid to slightly acid.
The B2 horizon has moist color of 5YR 4/4, 4/6, 4/8, or 5/8 or of 7.5YR 5/8. The apparent field texture is silty clay loam, silty clay, or clay with calculated (2.5 x 15-bar water) clay content of 55 to 90 percent. The horizon is 0 to 5 percent solid spheroidal iron concretions .1 to 2 inches in diameter. Reaction in 1:1 water is very strongly acid to medium acid.
The C horizon has moist variegated colors with hue of 10R, 2.5YR, 7.5YR, 10YR, 5Y, or 5BG, value of 3 through 8, and chroma of 1 through 8. It has an apparent field texture of silty clay loam, silty clay, or clay with a calculated (2.5 x 15-bar water) clay content of 35 to 80 percent. Reaction in 1:1 water is very strongly acid to medium acid.
COMPETING SERIES: These are the Ngardok, Ngatpang, and Palau series. Ngardok soils have mixed mineralogy. Ngatpang and Palau soils have halloysitic mineralogy.
GEOGRAPHIC SETTING: Gagil soils are on sideslopes and ridgetops of uplands. Slopes are 2 to 50 percent. These soils formed in residuum derived from highly weathered volcanic breccia and tuff. Elevation ranges form 3 to 197 feet. The mean annual temperature is 81 degrees F., and does not vary by more than 34 degrees F from month to month. Mean annual maximum temperature is 88 degrees F., and mean annual minimum is 75 degrees F. Mean annual rainfall is about 122 inches and varies from about 90 to 149 inches from year to year with the driest months of February, March, and April averaging 6 inches per month.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Gitam, Rumung, Weloy, and Yap soils. Gitam, Rumung, and Weloy soils are underlain by schist, have an argillic horizon, and a high base saturation. Yap soils have a higher organic-matter content, base saturation, fertility status, and are typically under broadleaf evergreen forest vegetation.
DRAINAGE AND PERMEABILITY: Well drained; slow through rapid runoff; moderately rapid permeability.
USE AND VEGETATION: Most areas are idle land used for watershed. The vegetation is degraded anthropic savannah consisting of poor stands of mainly Gleichenia linearis and Nepenthes mirabilis with scattered shrubs.
DISTRIBUTION AND EXTENT: Gagil soils are inextensive in Yap.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Gagil Municipality, Yap Island and State, Federated States of Micronesia, 1981.
REMARKS: Gagil soils have a perudic moisture regime. The surface layer becomes dry for short periods particularly during the months of February, March, and April. Irrigation is required during these months, in most years, on most shallow-rooted crops.