The Hyocheon series are members of the fine loamy, mixed, mesic family of Typic Endoaqualfs [Fluvic Gleyic Hydragric Anthrosols (Eutric) classified by WRB]. These soils have moderately thick dark grayish brown silt loam Ap horizons and moderately deep olive gray or dark gray silty clay loam Btg horizons. Cg horizons are dark gray silty clay loam with ferrous carbonate mottles. These soils are in local valleys adjacent to broad alluvial plains.

Typifying Pedon: Hyocheon silt loam-rice paddy (Field description Gwangsan Gun profile No. 86; colors are for moist soil).

  Slope: 0-2%

  Elevation:  m above m.s.l.

  Soil moisture regime: Aquic

  Temperature regime: Mesic

  Parent material: Local alluvium

  Diagnostic features: An ochric epipedon from a depth of 0 to 21 cm and an argillic horizon from a depth of 47 to 95 cm (An anthraquic horizon from a depth of 0 to 21 cm and a hydragric horizon from a depth of 21 to 95 cm by WRB).

Morphological properties of typifying pedon.

Ap1 - 0 to 9 cm. Olive gray (5Y 4/2) silt loam; common fine prominent yellowish red (5YR 4/8) mottles; structureless, puddled; friable, sticky and plastic; few very fine pores; many fine roots; abrupt smooth boundary; pH 5.5.

Ap2 - 9 to 21 cm. Dark grayish brown (2.5Y 4/2) loam; common fine to medium prominent strong brown (7.5YR 5/8) mottles; weak coarse platy structure; firm, sticky and plastic; few fine root holes; common fine roots; clear smooth boundary; pH 7.0.

BAg1 - 21 to 32 cm. Olive gray (5Y 4/2) clay loam; common coarse distinct dark grayish  brown (10YR 4/ ) inprism mottles; moderate coarse prismatic structure breaking to moderate coarse and medium subangular blocky; firm, sticky and plastic; very thin gray clay cutans; clear smooth boundary; pH 6.5.

BAg2 - 32 to 47 cm. Olive gray (5Y 5/2) clay loam; many coarse prominent strong brown (7.5YR 5/6) inprism mottles; moderate very coarse prismatic structure breaking to moderate coarse subangular blocky; firm, sticky and plastic; thin discontinuous olive gray (5Y 4/2) clay cutans; very few fine roots; clear smooth boundary; pH 6.5.

Btg - 47 to 77 cm. Gray (5Y 5/1) silty clay loam; few fine very dark brown (10YR 2/2) manganese mottles and many coarse and medium strong brown (7.5YR 5/6) inprism mottles; moderate very coarse prismatic structure breaking to moderate coarse and medium subangular blocky; firm, very sticky and very plastic; thin continuous gray clay cutans; common medium root holes; very few fine roots; clear smooth boundary; pH 6.5.

BCtg - 77 to 95 cm. Dark gray (5Y 4/1) silty clay loam; common fine prominent strong brown (7.5YR 5/6) and pale yellow (5Y 7/3) ferrous carbonate inprism mottles; very weak very coarse prismatic structure; firm, very sticky and very plastic; patchy thin gray clay cutans in common medium root holes and on prism faces; clear smooth boundary; pH 6.5.

Cg  - 95 to 120 cm. Dark gray (5Y 4/1) silty clay loam; few fine to medium white ferrous carbonate mottles and soft in mass concretions; structureless, massive; firm, very sticky and very plastic; pH 6.5.

Type Location: About 200 meters south of the Provincial Office of Rural Development on the PORD Experiment Station, Nongseong Dong, Seo Gu, Gwangju City.

Range in Characteristics: These soils have ochric epipedons and argillic horizons. The solum thickness ranges from 50 to 100 cm. Reaction is slightly acid to neutral throughout and ferrous carbonate mottles occur below 50 to 100 cm. Ap horizons are 20 to 30 cm thick dark grayish brown or gray silt loam or loam with mottles. Btg horizons are olive gray, gray, or dark grayish brown clay loam or silty clay loam with strong brown, yellowish brown, or yellowish red mottles. Cg horizons are dark gray, olive gray, or grayish brown silty clay loam, silty clay, silt loam or loam with yellow to white ferrous carbonate mottles and soft concretions.

Competing Series and Their Differentiae: These are the Sinheung, Jisan, Honam, Yanggog and Agog soils. The Sinheung and Jisan soils lack ferrous carbonate. The Honam soils have fine clayey textures and lack ferrous carbonate. The Yanggog soils are formed from sandstone and conglomerate source materials. The Agog soils have darker epipedon and occur high mountainous regions. 

Setting: Level to nearly level local valley alluvial plains. Slopes are less than 2 percent.

Principal Associated Soils: The Honam, Sugye and Geugrag soils are associated on broad alluvial plains. The Jisan, Baeggu, and Yongji soils are associated in local valley areas. The Gwangsan, Jeonnam, Songjeong and similar soils are associated in uplands.

Drainage and Permeability: Imperfectly drained. Permeability is slow or very slow. Runoff is moderately slow or slow. Depth to the ground water table ranges between about 50 and 100 cm.

Use and Vegetation: Most of these soils are used for flood irrigated rice during the wet summer and non irrigated barley during the dry winter and spring seasons.

Distribution and Extent: The Hyocheon series are of small extent and occur only in the south-western parts of the country.

Series Established: Gwangju City, Jeollanam Do, 1966.

Laboratory data sheets of typifying pedon.

Depth (cm)	Horizon	( --- Total ---)			(-- Clay --)		(-- Silt --)		(------- Sand -------)
		Clay	Silt	Sand	Fine	Coarse	Fine	Coarse	VF	F	M	C	VC
		LT	.002	.05	LT	LT	.002	.02	.05	.10	.25	.5	1
		.002	- .05	- 2	.0002	.002	- .02	- .05	- .10	- .25	- .50	- 1	- 2
		- - - - - - - - - - - Pct of ˂ 2mm (3A1) - - - - - - - - - - -
0-9	Ap1	25.6	50.6						5.2	7.7	4.9	4.3	1.7
9-21	Ap2	25.4	47.8						1.4	4.8	9.7	8.1	2.1
21-32	BAg1	27.9	45.3						4.5	7.6	5.8	5.6	3.3
32-47	BAg2	29.3	42.7						4.2	7.5	6.5	6.7	3.1
47-77	Bg	36.8	45.5						2.6	4.8	4.0	4.1	2.2
77-95	BCg	32.3	47.7						3.2	5.3	4.5	4.8	2.2
95-120	Cg	33.4	53.2						2.6	3.6	2.8	2.8	1.6

Depth (cm)

Coarse Fractions(mm)

˃2mm

Orgn

Total

Extr

Total

(-- Dith -Cit --)

Weight

Wt

C

N

P

S

Extractable

2-5

5-20

20-75

.1-75

Pct of

Fe

Al

Mn

Whole

6A1c

6B3a

6S3

6R3a

6C2b

6G7a

6D2a

Pct of ˂ 75mm (3B1)

Soil

Pct ˂ 2mm

g/kg

Pct of ˂ 2mm

0-9

1.62

9-21

1.37

21-32

0.74

32-47

0.30

47-77

0.72

77-95

1.01

95-120

1.30

Depth (cm)	Ratio/Clay		Atterberg		( Bulk Density )			COLE	(- Water Content -)				WRD
	CEC	1500	Limits		Field	33	Oven	Whole	Field	10	33	1500	Whole
		kPa	LL	PI	Moist	kPa	Dry	Soil	Moist	kPa	kPa	kPa	Soil
	8D1	8D1	4P1	4P	4A3a	4A1d	4A1h	4D1	4B4	4B1c	4B1c	4B2a	4C1
			Pct ˂0.4mm		- - g/cc - -			cm/cm	-- Pct of ˂2mm --				cm/cm
0-9							1.02				38.9	15.5
9-21							1.02				35.8	15.7
21-32							1.40				34.4	16.9
32-47							1.40				35.4	15.8
47-77							1.21				40.5	20.2
77-95					-		-				35.4	15.4
95-120					-		1.14				37.2	16.4

Depth (cm)	( NH4OAc Extractable Bases )					Acid-	Extr	(----- CEC -----)			Al
	Ca	Mg	K	Na	Sum	ity	Al	Sum	NH4-	Bases	Sat
	5B5a	5B5a	5B5a	5B5a	Bases			Cats	OAc	+ Al
	6N2e	6O2d	6Q2b	6P2b		6H5a	6G9a	5A3a	5A8b	5A3b	5G1
	- - - - - - - - - - - - meq / 100g - - - - - - - - - - - -										Pct
0-9	6.00	2.20	0.40	0.40					11.6
9-21	7.00	2.40	0.18	0.38					11.1
21-32	8.70	3.80	0.08	0.35					11.5
32-47	7.90	3.40	0.10	0.28					10.6
47-77	7.60	4.00	0.13	0.25					12.9
77-95	5.60	3.00	0.08	0.18					10.9
95-120	5.80	3.20	0.08	0.15					12.6

Depth (cm)	(Base Sat)		CO3 as	Res	Cond	(------ pH ------)				Acid Oxalate Extraction
	Sum	NH4-	CaCO3			NaF	KCl	CaCl2	H2O	Opt	Al	Fe	Si
		OAc	˂2mm					.01M		Den
	5C3	5C1	6E1g	8E1	8I	8C1d		8C1f	8C1f	8J	6G12	6C9a	6V2
	---- Pct ----			ohms/cm	dS/m		1: 1	1: 2	1: 1		- Pct of ˂2mm -
0-9		77.6					3.9		4.9
9-21		89.7					4.3		5.2
21-32		112.4					5.5		6.6
32-47		110.2					5.5		6.7
47-77		92.9					4.6		5.7
77-95		81.3					4.1		5.5
95-120		73.3					4.0		5.2

Depth (cm)	Elemental Analysis of Clay							3/	Free	Mn
	H2O	Igni	SiO2/	SiO2	Fe2O3	Al2O3	K2O	CEC	Fe2O3
	%	loss %	R2O3	%	%	%	%	me/100g	%	ppm
0-9			1.94	44.72	8.88	33.54	2.18	30.03
9-21			-	-	-	-	-	-
21-32			1.91	43.88	9.97	32.56	1.70	29.02
32-47			1.88	43.61	9.71	33.09	1.89	-
47-77			1.99	45.48	8.68	33.24	1.55	27.52
77-95			2.19	47.36	6.25	22.77	1.94	28.52
95-120			-	-	-	-	-	-

3/ Versene Metbod, 1 N CaCl2 Saturated, 1 N NaCl Extracted