The Ora series are members of the medial, mixed, thermic family of Andic Humudepts [Cambic Umbrisols (Humic Hyperdystric Siltic) classified by WEB]. These soils have dark brown gravelly silt loam Ap horizons, dark brown gravelly silt loam AB horizons, dark brown gravelly silt loam Bw1 horizons, dark yellowish brown gravelly silt loam Bw2 horizons, and dark yellowish brown gravelly silt loam BC horizons. They occur on lava plains and are derived from pyroclastic materials.

Typifying Pedon: Ora gravelly silt loam-upland crops (Colors are for moist soil).

  Slope: 7-15%

  Elevation: 219 m above m.s.l.

  Soil moisture regime: Udic

  Soil temperature regime: Thermic

  Parent material: Pyroclastic materials

  Diagnostic features: An umbric epipedon from a depth of 0 to 35 cm and a cambic horizon from a depth of 35 to 92 cm (An umbric horizon from a depth of 0 to 35 cm and a cambic horizon from a depth of 35 to 92 cm by WRB).

  Described by: Song, K. C., D. C. Noh, and S. J. Jung,  15 June, 2011.

Morphological properties of typifying pedon.

Ap  - 0 to 20 cm. Dark brown (10YR 3/3) gravelly silt loam; weak fine to medium granular structure; friable, slightly sticky and slightly plastic; common fine to medium roots; common fine to medium pores; 10% gravels; clear smooth boundary.

AB - 20 to 35 cm. Dark brown (10YR 3/3) gravelly silt loam; moderate medium to coarse subangular blocky structure; friable, slightly sticky and slightly plastic; common fine to medium roots; common fine to medium pores; 10% gravels; clear smooth boundary.

Bw1 - 35 to 67 cm. Dark brown (10YR 3/3) gravelly silt loam; weak fine to medium subangular blocky structure; friable, slightly sticky and slightly plastic; common fine to medium roots; common fine to medium pores; few worm holes; 15% gravels; clear wavy boundary.

Bw2 - 67 to 92 cm. Dark yellowish brown (10YR 3/4) gravelly silt loam; weak fine to medium subangular blocky structure; friable, slightly sticky and slightly plastic; few fine roots; few fine pores; 20% gravels; clear smooth boundary.

BC - 92 to 160 cm. Dark yellowish brown (10YR 4/4) gravelly silt loam; weak fine to medium subangular blocky structure; friable, slightly sticky and slightly plastic; few fine roots; common fine to medium pores; 25% gravels.

  The typifying pedon has an umbric epipedon from a depth of 0 to 35 cm and a cambic horizon from a depth of 35 to 92 cm. That can be classified as Inceptisol. It has an udic soil moisture regime and keys out as Udept. It has an umbric epipedon and keys out as Humudept. It has, throughout one or more horizons with a total thickness of 18 cm or more within 75 cm of the mineral soil surface, a fine-earth fraction with both a bulk density of 1.0 g/cm³ and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling more than 1.0. It can be classified by Andic Humudept. The typifying pedon has medial particle-size class, mixed mineralogy class, and thermic soil temperature regime. Therefore it can be classified as medial, mixed, thermic family of Andic Humudept.

Type Location: About 400 meters south-west of the Namhag Bridge, Yeon Dong, Jeju city, Jeju Do (126° 31' 30.7'', 33° 27' 39.3'').

Range in Characteristics: These soils have umbric epipedons and an argillic horizons. Solum thickness ranges from 100 to 200 cm and depth to hard rock is more than 3 meters. Reaction is medium to slightly acid. Base saturation is less than 60 percent. A horizons are dark brown or very dark grayish brown gravelly silt loam. Bw horizons are dark brown, dark grayish brown, or dark yellowish brown gravelly silt loam, loam, or silty clay loam. C horizons are dark brown or dark yellowish brown gravelly silt loam or silty clay loam. The content of coarse fragments ranges from 10 to 35 percent.

Competing Series and Their Differentiae: These are the Sara and Jeju soils. The Sara soils have medial over cindery texture class. The Jeju soils are belonged to Andic Palehumults.

Setting: The Ora soils are developed on gently sloping to moderately steep lava plains and are derived from pyroclastic materials. Slope ranges from 2 to 30 percent and 2 to 15 percent slopes are predominant.

Principal Associated Soils: The Jeju, Bongseong, Gueom, and Donggwi soils are associated with the Ora soils. They occur on similar physiographic positions.

Drainage and Permeability: Well drained. Permeability is moderately slow. Runoff is medium.

Use and Vegetation: Most of these soils are used for upland crops such as barley, sweet potato, oil vegetables, potato, and the remaining areas are grass land growing grass and shrub.

Distribution and Extent: The Ora soils are of moderate extent and are distributed on lava plains of the northeastern parts in Jeju Do.

Series Established: Jeju city, Jeju Do, 1975. Revised, Jeju city, Jeju Do, 2011.

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) - - - - - - - - - - -
0-20	Ap	22.9	71.6	5.5			41.3	30.3	0.9	1.5	1.2	1.2	0.7
20-35	BA	21.1	72.5	6.4			36.7	35.8	1.3	1.9	1.4	1.4	0.4
35-67	Bw1	19.3	73.1	7.5			35.2	37.9	1.9	2.3	1.6	1.3	0.4
67-92	Bw2	21.1	71.8	6.0			32.6	39.2	1.6	2.1	1.2	0.9	0.2
92-160	BC	25.3	64.9	9.8			24.6	40.3	2.5	3.7	2.0	1.3	0.3

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

0-20

5.32

20-35

4.61

35-67

3.96

67-92

1.75

92-160

1.17

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

0-20

1.35

0.66

56.6

20-35

1.43

0.59

76.9

35-67

1.52

0.68

54.1

67-92

1.08

0.67

52.0

92-160

0.91

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
0-20	4.0	1.5	0.6	0.2	6.2	35.5	0	41.7	30.8	6.2	0
20-35	3.2	1.1	0.4	0.2	4.8	36.6	1.0	41.4	39.2	5.8	17.2
35-67	1.9	0.6	0.2	0.2	2.9	38.8	0.7	41.7	29.4	3.6	19.4
67-92	2.0	1.4	0.2	0.3	3.9	23.9	0.8	27.9	23.9	4.7	17.0
92-160	2.1	2.1	0.1	0.6	5.0	21.9	0	26.8	23.1	5.0	0

Depth (cm)	(Base Sat)		CO3 as	Res	P Ret	(------ pH ------)				Acid Oxalate Extraction
	Sum	NH4-	CaCO3			NaF	KCl	CaCl2	H2O	Opt	Al	Fe	Si
		OAc	˂2mm					.01M		Den
	5C3	5C1	6E1g	8E1		8C1d		8C1f	8C1f	8J	6G12	6C9a	6V2
	---- Pct ----			ohms/cm	Pct		1: 1	1: 2	1: 1		- Pct of ˂2mm -
0-20	15.0	20.2			55.2		4.6	5.0	5.6		0.60	0.92	0.09
20-35	11.5	15.8			82.6		4.5	4.9	5.5		1.13	1.38	0.20
35-67	6.9	9.7			91.9		4.5	4.8	5.7		1.53	1.32	0.40
67-92	14.1	16.4			86.0		4.5	4.9	6.0		0.97	1.04	0.17
92-160	18.5	21.6			83.7		5.0	5.0	6.1		1.01	1.15	0.18