Reference soil Samoa 05: Cambisol

WS005

Cambisols occur mainly in the temperate and boreal regions of the world, where the soil’s parent material is still young or where low temperatures slow down the processes of soil formation.

Characteristics

Soils having either a cambic horizon (a horizon showing evidence of alteration with respect to the underlying material), or a mollic horizon overlying a subsoil, which has a base saturation of less than 50 percent in some part within 100 cm from the soil surface, or one of the following diagnostic horizons within the specified depth: an andic, vertic, or vitric horizon starting between 25 and 100 cm; a (petro-)plinthic or salic horizon starting between 50 and 100 cm, in absence of loamy sand or coarser textures above these horizons.

Distribution of Cambisols (rough estimation supplied by soilgrids)

Reference soil WS005: Cambisol

A fine latosolic soil at south end of banana fertilizer trial, consisting of "collo-alluvium" derived from clcareous tuff. In the B2 horizon saprolite is present (colour dry 5 YR 3/3). (The precipitation data of Lotofaga are only APPROXIMATE values; additional climatic data: 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)

Physical characteristics

Particle size distribution

Depth (cm)	Gravel % v/v	very coarse sand % w/w	coarse sand % w/w	medium sand % w/w	fine sand % w/w	very fine sand % w/w	Total sand % w/w	coarse silt % w/w	fine silt % w/w	Total silt % w/w	Clay % w/w
0-15	-	1.1	1.3	1.6	5.8	5.8	15.6	24.2	22.3	46.5	37.9
15-30	-	0.3	0.5	1.6	8.9	6	17.3	23.8	23.3	47.1	35.8
30-45	-	0.3	0.2	0.9	6.5	6.7	14.6	16.6	23.1	39.7	45.7
45-60	-	0.2	0.3	0.8	6.2	6.7	14.2	19.6	20.9	40.5	45.4
60-75	-	0.3	0.3	0.6	5.9	7.2	14.3	20.5	24.5	45	40.7
75-90	-	0.2	0.2	0.7	5.4	5.8	12.3	19.7	25.7	45.4	42.4

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-15	-	-	-	-	37.9
15-30	-	-	-	-	35.8
30-45	-	-	-	-	45.7
45-60	-	-	-	-	45.4
60-75	-	-	-	-	40.7
75-90	-	-	-	-	42.4

Chemical data

Depth (cm)	pH H2O	pHKCl	EC 1: 2.5 dS/m	CaCO3 % w/w	C % w/w	N %	C / N	Exch. Acid cmol(c)/kg	Exch. Al cmol(c)/kg	Ca cmol(c)/kg	Mg cmol(c)/kg	K cmol(c)/kg	Na cmol(c)/kg	Sum Cations cmol(c)/kg
0-15	5.6	4.9	0.25	-	2.82	0.29	10	-	-	36.8	8.0	1.1	0.4	46.3
15-30	5.6	4.6	0.26	-	1.42	0.14	10	-	-	38.6	20.0	0.8	0.6	60
30-45	6.1	4.4	0.21	-	1.10	0.11	10	-	-	40.6	21.6	0.5	0.7	63.4
45-60	5.8	4.4	0.19	-	0.83	0.10	8	-	-	43.0	22.6	0.5	0.5	66.6
60-75	6.1	4.3	0.14	-	0.70	0.07	10	-	-	42.0	21.7	0.5	0.5	64.7
75-90	5.9	4.3	0.16	-	0.58	0.06	10	-	-	40.6	23.0	0.4	1.0	65

Depth (cm)	Base sat. %	CEC soil cmol(c)/kg	CEC clay cmol(c)/kg	CEC org cmol(c)/kg	ECEC cmol(c)/kg	Al sat. %	ESP %
0-15	64	72.2	191	9.9	-	-	-
15-30	75	79.6	222	5	-	-	-
30-45	76	83.1	182	3.9	-	-	-
45-60	79	84	185	2.9	-	-	-
60-75	79	81.8	201	2.4	-	-	-
75-90	77	84	198	2.0	-	-	-

Depth (cm)	pH NaF	P Retention %	ODOE	Al o % w/w	Si o % w/w	Fe d % w/w	Al d % w/w	Fe p % w/w	Al p % w/w	C p % w/w	Fe o % w/w
0-15	8.6	-	-	0.66	0.45	2.46	0.31	0.06	0.05	-	1.55
15-30	8.5	-	-	0.78	0.45	2.52	0.34	0.05	0.03	-	1.64
30-45	8.4	-	-	0.87	0.45	2.98	0.39	0.13	0.13	-	2.18
45-60	8.5	-	-	0.94	0.5	3.03	0.42	0.11	0.12	-	2.32
60-75	8.5	-	-	0.93	0.45	2.97	0.41	0.2	0.26	-	2.19
75-90	8.5	-	-	0.89	0.35	2.73	0.39	0.19	0.25	-	2.04

Elemental composition of the soil

Depth (cm)	Al2O3 % w/w	CaO % w/w	Fe2O3 % w/w	K2O % w/w	MgO % w/w	Na2O % w/w	SiO2 % w/w	TiO2 % w/w
0-15	12.1	2.23	15.6	0.82	6.54	-	45.6	4.5
15-30	14.1	2.12	17.1	0.60	6.07	-	43.9	4.8
30-45	15.2	1.82	17.8	0.54	5.15	-	43.3	4.99
45-60	15.2	1.7	17.3	0.45	5.75	-	41.2	4.81
60-75	15.4	1.69	17.6	0.49	6.73	-	42.2	4.95
75-90	15.8	1.72	18.2	0.49	4.64	-	43.6	5.08

Depth (cm)	Al2O3/Fe2O3 mol/mol	LOI % w/w	MnO2 % w/w	P2O5 % w/w	SiO2 / Al2O3 mol/mol	SiO2/Fe2O3 mol/mol	SiO2 / R mol/mol
0-15	1.2	12.3	0.23	0.40	6.4	7.8	3.5
15-30	1.3	11.1	0.22	0.42	5.3	6.8	3.0
30-45	1.3	11.0	0.22	0.43	4.8	6.5	2.8
45-60	1.4	13.7	0.21	0.41	4.6	6.3	2.7
60-75	1.4	10.4	0.21	0.41	4.7	6.4	2.7
75-90	1.4	10.2	0.22	0.40	4.7	6.4	2.7

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-15	-	-	-	-	-	-	-	-	strong	-	-	-
15-30	-	-	-	-	-	-	-	-	strong	-	-	-
30-45	-	-	-	-	-	-	-	-	strong	-	-	-
45-60	-	-	-	-	-	-	-	-	strong	-	-	-
60-75	-	-	-	-	-	-	-	-	strong	-	-	-
75-90	-	-	-	-	-	-	-	-	strong	-	-	-

Profile description

Ah 0-15 cm	(dark) brown (7.5YR 4/2, dry) very dark greyish brown (10YR 3/2, moist)silty clay,strong medium and coarse subangular blocky,hard friable slightly sticky plastic,few very fine fine continuous tubular vertical pores,clear boundary to,
E 15-30 cm	dark yellowish brown (10YR 3/4, moist)silty clay,strong medium and coarse subangular blocky,hard friable sticky very plastic,few very fine medium continuous tubular vertical pores,gradual boundary to,
Bt 30-60 cm	(dark) brown (7.5YR 4/4, dry) dark yellowish brown (10YR 3/4, moist)silty clay,strong medium and coarse subangular blocky,slightly hard firm very sticky very plastic,broken thick clay on pedfaces cutans,few very fine medium continuous tubular vertical pores,gradual boundary to,
Bw1 60-90 cm	dark yellowish brown (10YR 3/4, dry) dark yellowish brown (10YR 3/4, moist)silty clay,weak coarse subangular blocky,hard friable very sticky plastic,broken thin clay on pedfaces cutans,few very fine fine continuous tubular vertical pores,diffuse boundary to,
Bw2 90-120 cm	yellowish brown (10YR 5/4, dry) dark yellowish brown (10YR 4/4, moist)silt loam,massive,hard friable slightly sticky plastic,few very fine continuous tubular vertical pores,gradual boundary to,
C 120-140 cm	yellowish brown (10YR 5/4, dry) dark yellowish brown (10YR 4/4, moist)massive,slightly hard,

Kind 1 (parent material) ; Parker (eds), 1984	basic tuff
Mode of accumulation or deposition of parent material	fluvial
Remarks on Parent Materials	calcareous tuff

Intensity of the soil erosion type	slight
Soil erosion type	sheet

Major crops	coconut
Remarks on Land Use / Vegetation	Bananas with grass, weeds and pandanus

Altitude	45m
Slope	20%
Slope Aspect	north
Form of the slope surrounding the site	concave
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	hilly

Drainage class ; FAO (2006) - Guidelines for soil description	well
Moist From - To	0-20cm
Wet From To	20-140cm

Rock outcrop class (FAO (2006) - Guidelines for soil description)	none
Evidence of salt; Soil Survey Manual USDA, 1951	non-saline
Surface stoniness class (FAO (2006) - Guidelines for soil description)	none

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Reference soil Samoa 05: Cambisol

Characteristics

Reference soil WS005: Cambisol

Classification