The Gapo series are members of the loamy skeletal, mixed, mesic family of Typic Fluvaquents [Fluvic Gleyic Hydragric Anthrosols (Eutric) classified by WRB]. These soils have dark grayish brown loam Ap horizons with brown mottles, grayish brown very gravelly sandy loam Cg1 horizons with dark yellowish brown mottles, and very dark gray very gravelly sandy clay loam Cg2 horizons. They are developed on fluvio-marine plains.

Typifying Pedon: Gapo loam-rice paddy (Colors are for wet soil).

  Slope: 0-2%

  Elevation: 1 m above m.s.l.

  Soil moisture regime: Aquic

  Soil temperature regime: Mesic

  Parent material: Fluvio-marine deposits

  Diagnostic features: An ochric epipedon from a depth of 0 to 15 cm (An anthraquic horizon                       from a depth of 0 to 15 cm and hydragric horizon from a depth of 15 to                      62 cm by WRB).

  Described by: Song, K. C., D. C. Noh, and B. K. Hyun,  30 Jan., 2013.

Ap  - 0 to 15 cm. Dark grayish brown (2.5Y 4/2) loam; few fine prominent brown (7.5YR 4/3) mottles; structureless, puddled; slightly sticky and slightly plastic; many fine to medium roots; no pores; 5% fine gravels; clear smooth boundary.

Cg1 - 15 to 62 cm. Grayish brown (2.5Y 5/2) very gravelly sandy loam; common fine to medium distinct dark yellowish brown (10YR 4/4) mottles; structureless, massive; slightly sticky and slightly plastic; few fine roots; no pores; 60% gravels and cobbles; abrupt wavy boundary.

Cg2 - 62 to 150 cm. Very dark gray (Gley 1 3/N) very gravelly sandy clay loam; structureless, massive; sticky and slightly plastic; no roots; no pores; 70% gravels and cobbles.

  The typifying pedon has an ochric epipedon from a depth of 0 to 15 cm. But it does not have other diagnostic horizons. Therefore it can be classified as Entisol. It has aquic conditions for some time in normal years in a layer at a depth between 40 and 50 cm below the mineral soil surface, has a texture class finer than loamy fine sand and, in 50% or more of the matrix, chroma of 2 or less and redox concentrations. That can be classified as Aquents. It has a slope of less than 25% and an organic-carbon content (Holocene age) of 0.2% or more at a depth of 125 cm below the mineral soil surface. That can be classified as Fluvaquent. Also it meets the requirements of Typic Fluvaquent. The typifying pedon has loamy skeletal particle-size class and mesic soil temperature class, and can be classified as sandy skeletal, mixed, mesic family of Typic Fluvaquent.

Type Location: About 500 meters west of Deogchon Noinhoegwan, Garyeo Ri, Georyu Myeon, Goseong Gun, Gyeongsangnam Do (128^o 21' 7.4'', 34^o 59' 49.2'').

Range in Characteristics: These soils have ochric epipedons. Depth to hard rock is more than 3 meters. Reaction is medium acid to neutral. These soils have more than 35 percent of coarse fragments throughout the profile. Ap horizons are thin olive gray, gray, dark gray or dark grayish brown loam or slit loam with strong brown mottles. C horizons are dark olive gray, dark gary, or very dark gray very gravelly silt loam, loam, or sandy loam.

Competing Series and Their Differentiae: These are the Gupo, Yulpo, and Yeosu soils. The Gupo soils have coarse loamy texture class and contain shell fragments in the subsoils. The Yulpo soils have fine loamy texture class and contain plenty shell fragments throughout the profile. The Yeosu soils have fine texture class.

Setting: The Gapo soils occur on fluvio-marine plains mainly southern coastal parts of the country. The slopes range from 0 to 2 percent.

Principal Associated Soils: These are the Mangyeong, Gwangpo, Munpo, Dapyeong and Gupo soils in similar positions.

Drainage and Permeability: Poorly drained; rapid permeability; slow runoff.

Use and Vegetation: The Gapo soils are used only for rice paddy.

Distribution and Extent: These soils are relatively small extent distributed on fluvio-marine plains.

Series Established: Changwon city, Gyeongsangnam Do, 1976. Revised, Goseong Gun, Gyeongsangnam Do, 2013.

Laboratory data sheets of typifying pedon.