Reference soil Democratic Republic of the Congo 02: Ferralsol

CD002

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 CD002: Ferralsols

WEATHER: Dry season, dry for at least two weeks. VEGETATION AND LAND USE: Hévéa from the 1930's, rejuvenated once (7 or 8 years ago). Tree rows, about 1m wide, clean, very few litter. MINERALOGY: Kaolinite, goethite, quartz. SURFACE DRAINAGE: dendritic, medium dense. ADDITIONAL NOTES ON PROFILE DESCRIPTION: O - fresh and decomposing organic matter and roots (many living). AB - cutans: matrans? - pores: also many micro to fine interstitial. B1 - cutans: bridges. - pores: also many micro to fine interstitial. - roots: also very few medium. B2 - cutans: bridges; contain iron oxides and hydroxides besides clay. B3 - cutans: bridges. Mottles from 12 to 154cm depth are possibly decomposing concretions. Structure from 12 to 94cm depth has a tendancy to porous massive; strong columnar when dry.

Classification

WRB 2006

WRB 1998

Haplic- Ferralsol (Hyperdystric Xanthic)

Xanthi-Hyperdystric- Ferralsol

17-152 cm

ferralic horizon

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Hyperdystri-Xanthic Ferralsol

Xanthic Ferralsol

34-154 cm	ferralic B horizon
4-34 cm	ochric A horizon
-	ferralic

34-154 cm	oxic B horizon
4-34 cm	ochric A horizon

Local classification:	Sol ferrallitique fortement désaturé jaune

Other classification

USDA-SCS (1975)

Haplorthox udic 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
4-12	-	1.5	17.1	31.6	22.3	3.9	76.4	1.8	0.8	2.6	21.1
12-34	-	0.4	14.5	32.1	21.3	3.9	72.2	2.2	0.5	2.7	24.5
34-64	-	0.3	14.5	32.2	20.4	3.4	70.8	1.6	1.0	2.6	26.5
64-94	-	0.6	15.7	30.8	18.8	3.2	69.1	1.1	1.7	2.8	28.0
94-114	-	0.4	14.1	32.5	20.4	3.3	70.7	1.7	1.1	2.8	26.6
130-150	-	0.6	15.3	30.5	19.4	3.5	69.3	1.5	1.0	2.5	28.3

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
4-12	-	-	-	10.6	21.1
15-20	1.283	-	-	-	-
12-34	-	-	-	14.5	24.5
30-60	1.461	-	-	-	-
34-64	-	-	-	17.8	26.5
90-110	1.363	-	-	-	-
64-94	-	-	-	21.2	28.0
94-114	-	-	-	3.4	26.6
130-150	1.46	-	-	0.5	28.3

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
15-20	1.283	42.3	39.2	30.8	22.3	20.2	18.3	13.6	12.5
30-60	1.461	37.7	35.8	30.4	25	23.3	21.7	14.4	13.0
90-110	1.363	37.3	33.4	27.5	22.1	20.9	19.1	15.9	14.4
130-150	1.46	38.0	35.3	29.9	24.8	22.7	20.7	15.6	14.4

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
4-12	4.1	3.6	0.09	-	1.26	0.09	14	1.5	1.1	0	0	0.1	0.1	0.2
12-34	4.4	3.8	0.04	-	0.50	0.04	13	1.2	0.9	0	0	0	0	-
34-64	4.3	3.8	0.04	-	0.37	0.03	12	1.2	1.1	0	0	0	0	-
64-94	4.3	3.9	0.03	-	0.26	-	-	1.2	0.9	0	0	0	0.1	0.1
94-114	4.5	4.0	0.02	-	0.17	-	-	0.9	0.7	0	0	0	0	-
130-150	4.4	4.0	0.03	-	0.14	-	-	0.9	0.7	0	0	0	0	-

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 %
4-12	4	5.0	-	4.4	-	22	2
12-34	-	4.3	-	1.8	-	21	0
34-64	-	3.8	-	1.3	-	29	0
64-94	3	3.7	-	0.9	-	24	3
94-114	-	3.3	-	0.6	-	21	0
130-150	-	3.1	-	0.5	-	23	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
4-12	-	-	-	0	0	1.4	0.2	-	-	-	0.1
12-34	-	-	-	0	0	1.6	0.2	-	-	-	0
34-64	-	-	-	0.1	0	1.8	0.2	-	-	-	0.2
64-94	-	-	-	0.1	0	1.8	0.2	-	-	-	0.1
94-114	-	-	-	0	0	1.7	0.2	-	-	-	0.1
130-150	-	-	-	0	0	1.8	0.2	-	-	-	0.1

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
4-12	-	-	11.9	-	-	-	-	-	-
12-34	-	-	6.8	-	-	-	-	-	-
34-64	-	-	3.2	-	-	-	-	-	-

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
4-12	-	very weak	-	weak	-	-	very strong	-	very weak	-	-	-
34-64	-	very weak	-	weak	-	-	very strong	-	very weak	-	-	-
130-150	-	very weak	-	weak	-	-	very strong	-	very weak	-	-	-

Profile description

O 0-4 cm	(dark) brown (7.5YR 4/2, dry) (dark) brown (7.5YR 4/2, moist)organic leaves slightly,loamy sand,moderate fine and medium subangular blocky,hard friable slightly sticky slightly plastic,no cutans,many micro medium tubular pores and many medium interstitial pores,no inclusions,charcoal fragments,non calcareous,non calcareous,clear smooth boundary to,abrupt smooth boundary to,
12-34 cm	strong brown (7.5YR 4/6, dry) (dark) brown (7.5YR 4/4, moist)sandy loam,weak fine and medium subangular blocky,hard very friable sticky plastic,few (2-5%) medium faint diffuse 2.5YR5/8 (red) mottles,many micro fine tubular few medium interstitial pores,charcoal inclusions,non calcareous,diffuse smooth boundary to,
Bo1 34-64 cm	(7.5YR 4/5, moist)sandy loam,weak medium subangular blocky,hard very friable sticky plastic,few (2-5%) medium faint diffuse mottles (2.5YR 5/8),patchy thin clay and humus cutans between sand grains,many micro fine tubular few medium interstitial pores,few medium roots,no inclusions,no fragments,non calcareous,diffuse smooth boundary to,
Bo2 64-94 cm	(7.5YR 4.5/6, moist)sandy clay loam,weak coarse subangular blocky structure,very friable sticky plastic,few (2-5%) medium faint diffuse mottles (2.5YR 5/8),patchy thick clay and sesquioxide cutans between sand grains,many micro fine tubular pores and many fine interstitial pores,no inclusions,no fragments,non calcareous,gradual smooth boundary to,
Bo3 94-154 cm	(7.5YR 5/7, moist)sandy clay loam,weak coarse subangular blocky parting to weak very fine and fine subangular blocky structure,very friable sticky plastic,few (2-5%) medium faint diffuse mottles (2.5YR 5/8),patchy clay and sesquioxide cutans between sand grains,many micro fine tubular pores and many fine interstitial pores,no inclusions,no fragments,non calcareous,

Kind 1 (parent material) ; Parker (eds), 1984	sediment, unconsolidated
Mode of accumulation or deposition of parent material	eolian mixed / undifferentiated
Remarks on Parent Materials	Pleistocene
Texture of parent material	loamy

Major crops	rubber
Land use or vegetation in the immediate vicinity of the site	plantation forestry
Remarks on Land Use / Vegetation	VEGETATION: Plantation; tree-cover 50%, fern cover 100%. LANDUSE: Hévéa from the 1930's. rejuvenated once (7 or 8 years ago).Tree rows about 1 m wide, clean, very few litter.

Altitude	460m
Physiographic Unit	Upland-riv.plateau, 80m above river
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.	plateau
Slope	4%
Slope Aspect	north
Form of the slope surrounding the site	convex
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	undulating

Drainage class ; FAO (2006) - Guidelines for soil description	well
Dry From - To	0-10cm
Flooding frequency (FAO, 1986)	never
Kind of ground water table (USDA, 1979)	no groundwater table observed
Moist From - To	10-150cm
Estimated permeability (class) of least permeable part of the profile	high
Estimated run off (class)	slow

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
Microrelief Height: variation in height	400
Micro relief type: small-scale differences in relief in the direct vicinity of the site (FAO, 1986)	termite/ant mounds
Microrelief pattern	isolated
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 Democratic Republic of the Congo 02: Ferralsol

Characteristics

Reference soil CD002: Ferralsols

Classification