Reference soil Samoa 03: Dystric Cambisol

WS003

Distribution of Cambisols (rough estimation supplied by soilgrids)

A shallow soil, situated in steeply dissected mountainous foothills of andesitic origin, affected by severe erosion. Below 15cm saprolite appears (coloured 2,5 YR 4/0 and 3/0 moist). The C1 horizon is coloured 10 YR 3/3 and 2,5 YR 4/2; vegetation: tamarine, cocoa and breadfruit trees, taro, sensitive weed (vao fefe; Mimosa pudica); climatic data of Utumapu: xa - precipitation 1975 Temperature(C): Faleolo Airport: Time Mean Max Min years Jan 26.7 30.3 24.0 1975-77 Jul 25.9 29.9 23.9 1974-76

FAO-UNESCO-ISRIC 1988:

FAO-UNESCO 1974:

Lithi-

Dystric Cambisol

lithic phase

0-0 cm	cambic B horizon
0-0 cm	ochric A horizon

0-0 cm	cambic B horizon
0-0 cm	ochric A horizon

Other classification

USDA-SCS (1975)

Humitropept

fine

mixed

isohyperthermic

Classification (other)

Vailele clay and bouldery clay

Location:

Upolu Island, Vailele-uta banana trial behind WESTEC plantation

Physical

Particle size distribution:

Depth (cm)		Gravel (%)	Very Coarse Sand (%)	Coarse Sand (%)	Medium Sand (%)	Fine Sand (%)	Very Fine Sand (%)	Total Sand (%)	Coarse Silt (%)	Fine Silt (%)	Total Silt (%)	Clay (%)
0-15	:	-	0.4	0.4	0.3	0.5	0.7	2.3	11.6	30.8	42.4	55.4
15-30	:	-	0.1	0.2	0.2	0.3	1.3	2.1	25.5	31.6	57.1	41
30-65	:	-	0.1	0.1	0.1	0.6	4.3	5.2	42.6	37.7	80.3	14.6

Other physical data

Depth (cm)		Bulk Density (kg/dm³)	Spec. Surf. Area (m2/g)	COLE (cm/cm)	Water Disp. Clay (%)	Clay (%)
0-15	:	-	-	-	-	55.4
15-30	:	-	-	-	-	41
30-65	:	-	-	-	-	14.6

Chemical characteristics:

Depth (cm)		pH H2O	pH KCl	EC 1 : 2.5 (mS/cm)	CaCO3 (%)	Org. C (%)	Org. N (%)	C / N	Exch. Acid (cmol/kg)	Exch. Al (cmol/kg)	Ca (cmol/kg)	Mg (cmol/kg)	K (cmol/kg)	Na (cmol/kg)	Sum Cations (cmol/kg)
0-15	:	3.7	4.1	0.56	-	5.46	0.47	12	-	-	2.6	3.0	0.1	0.1	5.8
15-30	:	3.6	4.0	0.3	-	1.78	0.06	30	-	-	1.2	1.1	0.1	0.2	2.6
30-65	:	5.1	4.0	0.54	-	0.13	0.01	13	-	-	0.4	0.7	0.1	0.4	1.6

Depth (cm)		CEC Soil (cmol/kg)	CEC Clay (cmol/kg)	CEC Org (cmol/kg)	ECEC (cmol/kg)	Base sat. (%)	Al sat. (%)	ESP (%)
0-15	:	34.4	62	19.1	-	17	-	-
15-30	:	24.8	60	6.2	-	10	-	-
30-65	:	21.3	146	0.5	-	8	-	-

Depth (cm)		pH NaF	P Retention (%)	ODOE	Melanic Index	Fe o (wt%)	Al o (wt%)	Si o (wt%)	Fe d (wt%)	Al d (wt%)	Fe p (wt%)	Al p (wt%)	C p (wt%)
0-15	:	9.2	-	-	-	1.67	0.75	0.1	6.75	1.28	1.09	0.65	-
15-30	:	9.8	-	-	-	0.53	0.57	0.1	6.33	1.08	0.5	0.36	-
30-65	:	10	-	-	-	0.45	0.57	0.1	6.9	0.87	0.02	0.18	-

Elemental composition of the clay:

Depth (cm)		SiO2 (wt%)	Al2O3 (wt%)	Fe2O3 (wt%)	CaO (wt%)	MgO (wt%)	K2O (wt%)	Na2O (wt%)	TiO2 (wt%)
0-15	:	35.2	30.8	15.3	0.04	0.37	0.03	-	2.99
15-30	:	38.5	32.8	13.7	0.02	0.35	0.02	-	2.64
30-65	:	33.7	27.5	19.5	0.14	0.92	0.14	-	3.6

Depth (cm)		MnO2 (wt%)	P2O5 (wt%)	Ign.Loss clay (wt%)	Total clay (%)	SiO2 / Al2O3 (mol/mol)	SiO2 / Fe2O3 (mol/mol)	SiO2 / R (mol/mol)	Al2O3 / Fe2O3 (mol/mol)
0-15	:	0.08	0.51	14.6	99.9	1.9	6.1	1.5	3.2
15-30	:	0.07	0.43	13.9	102.5	2	7.5	1.6	3.8
30-65	:	0.3	0.9	13.5	100.2	2.1	4.6	1.4	2.2

Elemental composition of the soil:

Depth (cm)		SiO2 (wt%)	Al2O3 (wt%)	Fe2O3 (wt%)	CaO (wt%)	MgO (wt%)	K2O (wt%)	Na2O (wt%)	TiO2 (wt%)
0-15	:	24.1	24.2	23.5	0.15	1.02	0.03	-	5.65
15-30	:	28.7	25.6	23.9	0.05	1.18	0.02	-	5.63
30-65	:	30.1	25.2	25.6	0.03	1.72	0.01	-	6.06

Depth (cm)		MnO2 (wt%)	P2O5 (wt%)	LOI (wt%)	SiO2 / Al2O3 (mol/mol)	SiO2 / Fe2O3 (mol/mol)	SiO2 / R (mol/mol)	Al2O3 / Fe2O3 (mol/mol)
0-15	:	0.25	0.40	20.7	1.7	2.7	1.0	1.6
15-30	:	0.21	0.33	14.3	1.9	3.2	1.2	1.7
30-65	:	0.37	0.63	10.9	2	3.1	1.2	1.5

Clay mineralogy:

Depth (cm)		Kaolinite	Mica / illite	Vermiculite	Chlorite	Smec	Halloysite	Mixed layer	Quar	Feldspar	Gibbsite	Goethite	Hematite
0-15	:	weak to medium	-	-	-	-	-	-	-	-	weak	weak	-
15-30	:	weak to medium	-	-	-	-	-	-	-	-	weak	weak	-
30-65	:	weak to medium	-	-	-	-	-	-	-	-	weak	weak

Profile description:

Ah 0-15 cm	dark brown (7.5YR 3/2, dry) dark brown (7.5YR 3/2, moist), silty clay, strong fine and medium subangular blocky, very hard friable slightly sticky slightly plastic, common fine continuous exped tubular horizontal pores slightly porous (<40 vol%), clear wavy boundary to,
B 15-30 cm	dark yellowish brown (10YR 3/4, dry) dark brown (10YR 3/3, moist), silty clay slightly gravelly, moderate fine subangular blocky to moderate coarse subangular blocky, slightly hard very friable slightly sticky slightly plastic, few fine continuous exped random pores slightly porous (<40 vol%), few medium gravel weathered andesite fragments, clear wavy boundary to,
C1 30-110 cm	light brownish grey (10YR 6/2, dry) (2.5YR 3/no, moist), sandy clay, massive, very hard very firm slightly sticky slightly plastic, (10YR 3/4) and (2.5YR 4/2), few very fine pores slightly porous (<40 vol%), dominant fresh andesite fragments, abrupt wavy boundary to,
C2 110-120 cm	light brown (7.5YR 6/4, dry) dark reddish brown (5YR 3/3, moist), silty clay, massive, soft firm slightly sticky slightly plastic, no pores slightly porous (<40 vol%), abrupt wavy boundary to,
C3 120-140 cm	strong brown (7.5YR 5/8, dry) yellowish red (5YR 4/6, moist), silt, hard firm slightly sticky slightly plastic, no pores slightly porous (<40 vol%),

The main parent rock/ material over which the soil has been formed (1st entry)	fine-grained intermediate igneous rock
Mode of Accumulation or deposition of parent material (1st entry)	residual material
Texture of parent material (1st entry)
Weathering status of solid rock (1st entry)	partially or moderately
Depth1 of lithological boundary	30 cm
The main parent rock/ material over which the soil has been formed (2nd entry)
Resistance against weathering (solid rock) (2nd entry)
Soil Depth; depth to which roots can easily penetrate throughout the year	30 cm
Remarks on Parent Materials	andesite

Soil erosion type (1st entry)	sheet
Intensity of the soil erosion type (1st entry)	severe
Occurrence of soil aggradation	absent
Slope Stability	locally unstable

Current land use at the site	mixed farming
Major crops
Main type of irrigation	no irrigation
Rotation scheme	crop rotation scheme not relevant
Vegetation Type;The natural vegetation at the site
Status of vegetation
Remarks on Land Use / Vegetation	tamarind, cocoa & breadfruit trees, taro

The altitude of the soil profile relative to mean sea level, specified in meters	150 m asl
Regional landform	mountain
Topography of the surrounding country	steeply dissected
Physiographic Unit in the immediate surrounding of the site	mountainous foothills
The slope refers to the inclination of the land immediately surrounding the site. The measured or estimated slope angle is specified to the nearest per cent	33 %
The physiographic position of the site where the profile is located
Form of the slope surrounding the site	concave
Slope Aspect of the site	south

Depth of groundwater table	cm
Groundwater Top	cm
Groundwater Bottom	cm
Kind of groundwater table	no groundwater table observed
Top Stagnating Layer	cm
Bottom Stagnating Layer	cm
Runoff	very rapid
Flooding frequency	never
Estimated permeablity (class) of least permeable part of the profile	moderate
Drainage Class	well
To Drainage Class
Moisture conditions of the profile: dry from -to	0-15 cm
Moisture conditions of the profile: moist from -to	15-110 cm
Wet From - To	110-120 cm

Microrelief type: small-scale differences in relief in the direct vicinity of the site
Microrelief Pattern	none
Microrelief Height
Rockiness	little rocky
Stoniness	fairly stony
Average size of stones
Shape of stones (on average)
Cracks	no cracks observed
Slaking of aggregates by tillage, rainfall or frost	no surface slaking/crusting observed
Evidence of salt	non-saline
Evidence of alkali	non-alkaline

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Reference soil Samoa 03: Dystric Cambisol