The Geugrag series are members of the fine, mixed, mesic family of Anthraquic Hapludalfs [Hydragric Anthrosols (Eutric Oxyaquic) classified by WRB]. These soils have dark gray silt loam Ap horizons with yellowish red mottles, dark gray clay loam BAg horizons with strong brown mottles, dark yellowish brown silty clay loam Bt1 horizons with light olive brown mottles, yellowish brown clay Bt2 horizons with grayish brown mottles, and gray clay Btg horizons with yellowish brown mottles. They occur on continental river terraces.

Typifying Pedon: Geugrag silt loam-paddy rice (Colors are for moist soil).

  Slope: 0-2%

  Elevation: 6 m above m.s.l.

  Soil moisture regime: Udic

  Soil temperature regime: Mesic

  Parent material: Old alluvium

  Diagnostic features: An occhric epipedon from a depth of 0 to 13 cm and an argillic horizon from a depth of 23 to 140 cm (An anthraquic horizon from a depth of 0 to 23 cm and an argic horizon from a depth of 23 to 140 cm by WRB).

  Described by: Song, K. C., S. J. Jung, and D. C. Noh,  29 March, 2006.

Ap  - 0 to 13 cm. Dark gray (10YR 4/1) silt loam; common fine to medium distinct yellowish red (5YR 5/6) mottles; structureless, puddled; firm, sticky and plastic; common fine rice roots; common fine to medium pores; abrupt smooth boundary.

BAg - 13 to 23 cm. Dark gray (2.5Y 4/1) clay loam; common fine to medium prominent strong brown (7.5YR 5/6) mottles; moderate prismatic structure; firm, very sticky and very plastic; common fine rice roots; common fine to medium pores; clear smooth boundary.

Bt1  - 23 to 46 cm. Dark yellowish brown (10YR 4/6) silty clay loam; common fine faint  light olive brown (2.5YR 5/4) mottles; moderate coarse prismatic structure; very firm, very sticky and very plastic; thick continuous clay cutans; few fine rice roots; few fine pores; clear smooth boundary.

Bt2 - 44 to 70 cm. Yellowish brown (10YR 5/6) clay; common fine to medium faint grayish brown (2.5YR 5/2) mottles; strong coarse angular blocky structure; very firm, very sticky and very plastic; thick continuous clay cutans; few fine rice roots; common fine to medium pores; clear wavy boundary.

Btg - 70 to 104 cm. Gray (5Y 5/1) clay; common fine to medium prominent yellowish brown (10YR 5/6) mottles; strong angular blocky structure; very firm, very sticky and very plastic; few fine to medium rice roots; common fine to medium pores; clear smooth boundary.

BCtg - 104 to 140 cm. Olive gray (5Y 5/2) clay; common fine to medium prominent light olive brown (2.5Y 5/6) mottles; weak prismatic structure; firm, sticky and plastic; no roots; few fine pores; clear smooth boundary.

Cg – 140 to 180 cm

  The typifying pedon has an ochric epipedon from a depth of 0 to 13 cm, an argillic horizon from a depth of 23 to 140 cm, and has a base saturation (by sum of cations) of 35% or more at 125 cm below the upper boundary of the argillic horizon. That can be classified as Alfisol. It has aquic conditions for some time in normal years in one or more horizons within 50 cm of the mineral soil surface, but does not have 50 percent or more redox depletions with chroma of 2 or less within the upper 12.5 cm of the argillic horizon. Therefore it can be classified as Udalf. It meets the requirements of Hapludalf. It has anthraquic condition and keys out as Anthraquic Hapludalf.

  Typifying pedon has more than 35% clay at the particle-size control section and has mesic soil temperature regime. Therefore it can be classified as fine, mixed, mesic family of Anthraquic Hapludalf.

Type Location: About 400 meters south-west of the Crossroads between No. 712 and No. 714 road, Wolseong Dong, Gimje city, Jeollabug Do (126^o 54' 50.6", 35^o 46' 50.7").

Range in Characteristics: These soils ochric epipedons and argillic horizons. Solum thickness ranges from more than 100 cm and the Cg horizon thickness ranges from two to three meters or more. Reaction ranges from strongly to slightly acid, generally increasing slightly with depth. Base saturation is more than 60 percent. Ap horizons are gray, grayish brown, dark grayish, or brown silt loam or silty clay loam with yellowish brown, dark yellowish brown, or strong brown mottles. Bt horizons are yellowish brown, dark yellowish brown, brown, or dark brown silty clay or silty clay loam with light gray to gray mottles. Btg horizons are gray silty clay loam or clay loam with yellowish brown or dark yellowish brown mottles and usually black or dark brown soft manganese concretions.

Competing Series and Their Differentiae: These are the Chogye, Paju, and Chilgog seires. The Chogye series are on low mountain foot slopes derived from old-colluvial materials. The Paju series occur on low river terraces derived from basaltic materials. The Chilgog series occur on mountain foot slopes derived from acid crystalline rocks and have fine loamy texture class.

Setting: The Geugrag soils occur on level to nearly level slightly dissected low river terraces where dominant slopes range less than 2 percent.

Principal Associated Soils: These soils occur at lower elevations and have more yellow hues than the redder Hwadong and Bancheon soils. They are at higher elevations than the grayer Honam, Sugye, or Hamchang soils.

Drainage and Permeability: The Geugrag soils occupy the worse drained portions of the moderately well drained class. They are very slowly permeable and runoff is slow. The artificially controlled water table fluctuates between 100 and 150 cm during most seasons.

Use and Vegetation: Most areas are used for flooded paddy rice during the summer and about half for non irrigated barley during the winter months.

Distribution and Extent: The Geugrag soils are of small extent and occur in the river terraces mostly in the western and southern parts of Korea.

Series Established: Gwangsan Gu, Gwangju city, 1966. Revised, Gimje city, Jeollabug Do, 2006.

Laboratory data sheets of typifying pedon.