Reference soil Gabon 04: Ferralsol

GA004

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 GA004: Ferralsols

A well drained, extremely deep soil (> 180cm) with a lot of biological activities (termites, earthworms), derived from precambrian sandstone. Due to human influence (burning), there is only secondary vegetation consisting mainly (80 %) of herbs and grasses. Charcoal fragments can be found at 40 cm of depth and in top layer. Besides, there are dark mottles of organic matter in 2nd, 3rd and 4th horizon. In Bws1 horizon 3 bands of humus/clay (3mmm thick) appear; additional climatic data: insolation (hours).

Classification

WRB 2006

WRB 1998

Acric-Geric- Ferralsol (Alumic Xanthic)

Geri-Acric- Ferralsol (Alumic Xanthic)

19-150 cm

ferralic horizon

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Alumi-Xanthic Ferralsol

Xanthic Ferralsol

0-19 cm	ochric A horizon
19-150 cm	ferralic B horizon

19-150 cm

ochric A horizon

Local classification:	Sol ferrallitique, fortement désaturé, faiblement apprauvi

Other classification

USDA-SCS (1975)

Haplorthox udic loamy kaolinitic 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
0-10	-	0.2	5.7	40.7	27.4	4.2	78.2	2.6	1.4	4	17.9
10-19	-	0.2	4.8	39.9	29.9	4.2	79	3.8	0.3	4.1	17.1
20-40	-	0.3	4.9	33.7	28.1	4.3	71.3	3.8	0.0	3.8	24.9
40-65	-	0.2	5.0	31.1	25.1	4.4	65.8	4.5	0.0	4.5	29.7
70-90	-	0.4	4.1	31.1	28.2	4.7	68.5	3.5	0.9	4.4	27.0
110-140	-	0.2	3.8	29.3	29.1	5.0	67.4	3.8	1.1	4.9	27.6

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-10	-	-	-	3.2	17.9
10-15	1.20	-	-	-	-
30-35	1.26	-	-	-	-
10-19	-	-	-	5.8	17.1
20-40	-	-	-	9.6	24.9
45-50	1.28	-	-	-	-
40-65	-	-	-	11.1	29.7
75-80	1.24	-	-	-	-
70-90	-	-	-	0.0	27.0
110-140	-	-	-	0.0	27.6

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	1.20	52.9	50.0	36.7	23.4	19.7	18.4	8.2	7.8
30-35	1.26	49.7	48.0	36.3	24.6	21.7	20.3	12.1	10.7
45-50	1.28	45.1	42.5	33.3	24.2	21.1	19.5	12.9	9.1
75-80	1.24	45.6	43.2	31.4	19.6	16.5	15.0	11.2	11.0

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
0-10	5.3	4.5	0.14	-	2.73	0.15	18	0.2	0.2	3.5	0.5	0.2	0.0	4.2
10-19	5.2	4.2	0.03	-	1.04	0.07	15	0.9	0.9	0.6	0.0	0.0	0.0	0.6
20-40	4.8	4.1	0.03	-	0.71	0.05	14	1.1	1.1	0.2	0.0	0.1	0.0	0.3
40-65	4.8	4.2	0.02	-	0.44	-	-	1.1	1.1	0.2	0.0	0.0	0.0	0.2
70-90	4.9	4.2	0.01	-	0.29	-	-	0.8	0.9	0.4	0.0	0.0	0.1	0.5
110-140	4.7	4.2	0.02	-	0.28	-	-	1.0	0.9	0.2	0.0	0.0	0.0	0.2

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 %
0-10	43	9.8	55	9.6	-	2	0
10-19	26	2.3	13	3.6	-	39	0
20-40	17	1.8	7	2.5	-	61	0
40-65	11	1.8	6	1.5	-	61	0
70-90	42	1.2	4	1.0	-	75	8
110-140	13	1.6	6	1.0	-	56	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
0-10	-	-	-	0.16	0.01	1.03	0.35	-	-	-	0.07
10-19	-	-	-	0.10	0.00	0.97	0.30	-	-	-	0.07
20-40	-	-	-	0.09	0.01	1.46	0.39	-	-	-	0.09
40-65	-	-	-	0.10	0.01	1.55	0.55	-	-	-	0.07
70-90	-	-	-	0.10	0.01	1.31	0.41	-	-	-	0.04
110-140	-	-	-	0.09	0.01	1.39	0.45	-	-	-	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
0-10	-	-	47.9	-	-	-	-	-	-
10-19	-	-	2.9	-	-	-	-	-	-

Elemental composition of the clay

Depth (cm)	SiO2 % w/w	Al2O3 % w/w	Fe2O3 % w/w	CaO % w/w	MgO % w/w	K2O % w/w	Na2O % w/w	TiO2 % w/w
70-90	27.8	37.7	13.4	0.00	0.09	0.21	0.02	2.45
110-140	26.6	38.6	13.2	0.00	0.09	0.21	0.05	2.39

Depth (cm)	MnO2 % w/w	P2O5 % w/w	Ign.Loss clay % w/w	Total Clay % w/w	SiO2/Al2O3 mol/mol	SiO2/Fe2O3 mol/mol	SiO2 / R mol/mol	Al2O3/Fe2O3 mol/mol
70-90	0.02	0.24	17.0	98.93	1.3	5.5	1	4.4
110-140	0.02	0.23	17.1	98.49	1.2	5.4	1	4.6

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-10	-	very weak to weak	weak to medium	weak to medium	-	-	strong	-	-	very weak	-	-
10-19	-	very weak to weak	strong	weak to medium	-	-	strong	-	-	very weak	-	-
20-40	-	very weak to weak	strong	weak to medium	-	-	strong	-	-	very weak	-	-
40-65	-	very weak to weak	strong	weak to medium	-	-	strong	-	-	very weak	-	-
70-90	-	very weak to weak	strong	weak to medium	-	-	strong	-	-	very weak	-	-
110-140	-	very weak to weak	strong	weak to medium	-	-	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
110-140	0.1	-	99.9	82	-	100

Minerals

Depth (cm)	Anatase % w/w	Andalusite % w/w	Apatite % w/w	Augite % w/w	Biotite % w/w	Hornblende (basaltic) % w/w
110-140	9	-	-	-	-	-

Depth (cm)	Grenate % w/w	Grossular % w/w	Muscovite % w/w	Rutile % w/w	Sillimanite % w/w	Spinel % w/w
110-140	-	-	-	11	-	-

Profile description

Ah1 0-10 cm	very dark grey (10YR 3/1, moist)loamy sand,single grain to moderate medium crumb,loose very friable non sticky non plastic,many micro to fine pores,many very fine and many medium roots,non calcareous,clear smooth boundary to,
Ah2 10-19 cm	dark yellowish brown (10YR 3/4, moist)loamy sand,single grain to weak subangular blocky,very friable slightly sticky non plastic,common(5-15%) fine distinct clear mottles (10 YR 3/1),many micro to fine exped and inped pores,common very fine and common medium roots,non calcareous,clear irregular boundary to,
BA 19-40 cm	dark yellowish brown (10YR 4/6, moist)sandy loam,weak medium subangular blocky,very friable slightly sticky slightly plastic,few (2-5%) fine distinct clear mottles,many micro very fine exped and inped pores,few fine and few coarse roots,non calcareous,gradual irregular boundary to,
Bo1 40-67 cm	yellowish brown (10YR 5/8, moist)sandy clay loam,weak fine and medium subangular blocky,very friable sticky plastic,few (2-5%) fine distinct clear mottles,patchy clay and humus cutans,many micro and very fine pores,few fine roots,non calcareous,diffuse smooth boundary to,
Bo2 67-150 cm	(10YR 5.5/8, moist)sandy clay loam,porous massive to weak medium and coarse subangular blocky,very friable sticky plastic,many micro and very fine pores,few fine roots,non calcareous,

Kind 1 (parent material) ; Parker (eds), 1984	non calcareous sandstone
Mode of accumulation or deposition of parent material	residual material
Remarks on Parent Materials	Upper Precambrium
Texture of parent material	loamy
Weathering Resistance	high
General characterization of the status of weathering of solid rock	highly

Land improvements ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	burning
Land use or vegetation in the immediate vicinity of the site	hunting and fishing
Remarks on Land Use / Vegetation	VEGETATION: Dicranopteris linearis. LAND USE: Burnt annually
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	shifting
Status of vegetation; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	secondary
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	semi-deciduous shrub

Altitude	215m
Physiographic Unit	upland
Physiographic position of the site	upper slope
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	hill
Slope	4%
Slope Aspect	west
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 04: Ferralsol

Characteristics

Reference soil GA004: Ferralsols

Classification