Reference soil Gabon 01: Ferralsol

GA001

Ferralsols occur in tropical and subtropical regions of the world, mainly on old and stable land surfaces.

Characteristics

Soils having a ferralic horizon (strongly weathered horizon with low-activity clays and very low amounts of weatherable minerals) between 25 and 200 cm from the soil surface. They lack a nitic horizon (a horizon with strongly developed, nut-shaped structure) and do not have a layer which fulfils the requirements of an argic horizon and which has, in the upper 30 cm, 10 percent or more water-dispersible clay.

Distribution of Ferralsols (rough estimation supplied by soilgrids)

Reference soil GA001: Ferralsols

A deep rooting (>180 cm) soil with many fine pores, derived from precambrian metamorphites (Leptynite); mineralogical features: kaolinite and goethite. Site situated in primary tropical forest with irregular forest floor and high biological activities (termites, earthworms, insects) and a thin (5mm) layer of decomposing litter. In the lower parts of the profile iron concretions appear; additional climate data: insolation (h).

Classification

WRB 2006

WRB 1998

Haplic- Ferralsol (Hyperdystric Clayic Xanthic)

Xanthi-Hyperdystric- Ferralsol

7-300 cm

ferralic horizon

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Dystri-Xanthic Ferralsol

Xanthic Ferralsol

0-20 cm	ochric A horizon
7-300 cm	ferralic B horizon

0-20 cm	ochric A horizon
7-300 cm	oxic B horizon

Local classification:	Sol ferrallitique jaune, fortement désaturé, typique

Other classification

USDA-SCS (1975)

Haplorthox udic clayey isohyperthermic

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
0-7	-	1.4	7.4	13.6	12.2	3.0	37.6	3.4	2.8	6.2	56.2
7-20	-	1.7	8.2	12.0	10.4	3.0	35.3	3.5	2.4	5.9	58.8
50-65	-	5.3	11.1	10.2	8.6	2.6	37.8	2.7	2.3	5	57.2
120-135	-	5.5	11.3	10.5	8.4	2.6	38.3	2.2	2.8	5	56.7
185-200	-	6.9	10.8	9.1	8.0	2.7	37.5	2.7	1.9	4.6	57.9
270-285	-	9.6	10.0	7.6	7.2	2.5	36.9	2.9	2.3	5.2	57.8

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-7	-	81	-	23.5	56.2
10-15	1.17	-	-	-	-
7-20	-	68	-	30.5	58.8
50-65	1.34	62	-	0.0	57.2
120-135	-	59	-	0.0	56.7
185-200	1.35	58	-	0.0	57.9
270-285	-	59	-	0.0	57.8

Other physical data

Depth (cm)	Bulk density kg/dm³	pF 0 % v/v	pF 1.0 % v/v	pF 1.5 % v/v	pF 2.0 % v/v	pF 2.3 % v/v	pF 2.7 % v/v	pF 3.4 % v/v	pF 4.2 % v/v
10-15	1.17	47.7	43.6	38.0	32.6	29.5	29.1	25.2	23.4
50-65	1.34	46.0	45.6	42.0	38.4	35.1	38.4	28.1	26.0
185-200	1.35	45.6	45.4	40.7	36.1	32.9	32.5	28.1	26.8

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
0-7	3.3	3.2	0.60	-	3.27	0.24	14	4.5	3.3	0.2	0.2	0.2	0.2	0.8
7-20	3.6	3.4	0.75	-	1.88	0.12	16	3.5	2.9	0.2	0.0	0.1	0.0	0.3
50-65	4.2	3.8	0.08	-	0.61	0.06	10	2.3	2.0	0.2	0.0	0.0	0.1	0.3
120-135	4.3	3.9	0.05	-	0.36	-	-	1.8	1.6	0.0	0.0	0.0	0.1	0.1
185-200	4.5	3.9	0.04	-	0.27	-	-	1.7	1.6	0.0	0.0	0.0	0.1	0.1
270-285	4.8	4.1	0.03	-	0.26	-	-	1.2	1.1	0.0	0.1	0.0	0.0	0.1

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 %
0-7	6	12.6	22	11.4	-	26	2
7-20	4	6.7	11	6.6	-	43	0
50-65	5	6.1	11	2.1	-	33	2
120-135	2	5.6	10	1.3	-	29	2
185-200	2	5.4	9	0.9	-	30	2
270-285	2	4.9	8	0.9	-	22	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
0-7	-	-	-	0.12	0.02	2.35	0.44	-	-	-	0.26
7-20	-	-	-	0.11	0.02	3.13	0.56	-	-	-	0.21
50-65	-	-	-	0.13	0.02	2.95	0.54	-	-	-	0.09
120-135	-	-	-	0.12	0.02	2.72	0.52	-	-	-	0.04
185-200	-	-	-	0.11	0.03	2.64	0.52	-	-	-	0.03
270-285	-	-	-	0.11	0.03	2.73	0.53	-	-	-	0.03

Depth (cm)	CaSO4.2H2O %	P Bray mg/kg	P Olsen mg/kg	pH CaCl2	clay_noncarbonate % w/w	clay_carbonate % w/w	phosphorus4 mg/kg	phosphorus1 mg/kg	total_sulfur % w/w
0-7	-	-	18.6	-	-	-	-	-	-
7-20	-	-	6.9	-	-	-	-	-	-
50-65	-	-	6.7	-	-	-	-	-	-

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-7	-	-	very weak to weak	weak to medium	-	-	very strong	-	-	very weak	-	-
7-20	-	-	very weak to weak	weak to medium	-	-	very strong	-	-	very weak	-	-
50-65	-	-	very weak to weak	weak to medium	-	-	very strong	-	-	very weak to weak	-	-
120-135	-	-	very weak to weak	weak to medium	-	-	very strong	-	-	very weak	-	-
185-200	-	-	very weak to weak	weak to medium	-	-	very strong	-	-	very weak	-	-
270-285	-	-	very weak to weak	weak to medium	-	-	very strong	-	-	very weak	-	-

Sand mineralogy

Depth (cm)	Heavy Frac. sand % w/w	K-Feldspar % w/w	Light Fra. sand % w/w	Opaque % w/w	Plagioclase % w/w	Quartz % w/w
120-135	2.9	-	97.1	94	-	100

Minerals

Depth (cm)	Grenate % w/w	Grossular % w/w	Muscovite % w/w	Rutile % w/w	Sillimanite % w/w	Spinel % w/w
120-135	-	-	-	8	1	-

Profile description

Ah 0-7 cm	very dark greyish brown (10YR 3/2, moist)clay,strong very fine subangular blocky to strong fine and medium crumb,very friable sticky plastic,many micro very fine interstitial pores and many coarse exped and inped tubular pores,many very fine to coarse roots,non calcareous,clear smooth boundary to,
7-20 cm	yellowish brown (10YR 5/4, moist)clay,moderate to strong very fine and fine subangular blocky,firm sticky plastic,many very fine and fine interstitial pores and few medium exped and inped tubular pores,many very fine to coarse roots,non calcareous,gradual irregular boundary to,
Bo1 20-70 cm	yellowish brown (10YR 5/8, moist)clay,weak medium subangular blocky to moderate very fine and fine subangular blocky,firm very sticky plastic,many very fine and fine exped and inped tubular pores,common very fine and fine and common medium roots,non calcareous,diffuse smooth boundary to,
Bo2 70-300 cm	yellowish brown (10YR 5/8, moist)clay,weak medium angular blocky to moderate fine angular blocky,firm very sticky plastic,many very fine and fine exped and inped tubular pores,few very fine and fine roots,non calcareous,

Kind 1 (parent material) ; Parker (eds), 1984	basic gneiss
Mode of accumulation or deposition of parent material	residual material
Remarks on Parent Materials	Precambrian leptynite
Texture of parent material	clayey
Weathering Resistance	moderate
General characterization of the status of weathering of solid rock	highly

Land use or vegetation in the immediate vicinity of the site	(semi-)natural vegetation
Remarks on Land Use / Vegetation	VEGETATION: humid tropical forest (protected)
Status of vegetation; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	primary
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	evergreen forest

Altitude	530m
Physiographic Unit	site on top of plateau
Physiographic position of the site	flat
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	plateau
Slope	2%
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	undulating

Drainage class ; FAO (2006) - Guidelines for soil description	well
Flooding frequency (FAO, 1986)	never
Kind of ground water table (USDA, 1979)	no groundwater table observed
Estimated permeability (class) of least permeable part of the profile	moderate
Estimated run off (class)	medium

Evidence of alkali ; Soil Survey Manual USDA, 1951	non-alkaline
Surface cracking	no cracks observed
Slaking of aggregates by tillage, rainfall or frost (USDA/SCS, 1979)	no surface slaking/crusting observed
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 Gabon 01: Ferralsol

Characteristics

Reference soil GA001: Ferralsols

Classification