Reference soil Rwanda 08: Ferralsol

RW008

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 RW008: Ferralsols

Classification: sombric Kurorthox The profile description: B: Coatings resembling clay films are visible with 10x. Coarse fragments in pockets. Bth1: Many continuous prominent-very thick brown to dark brown (7.5YR4/4) skeletans over argillans on vertical ped faces. Bth2: Many discontinuous faint-thin 5YR2/1 and 5YR3/4 clay films bridging sand grains. The described argillans are black 5YR2/1. The described "mottles" are ground colors. Small pockets of skeletan material (oxic) penetrates the upper part of Bth material. Cr1: Common continuous prominent-thin yellowish red (5YR5/8) clay films bridging sand grains. Described argillans are dark reddish brown (2.5YR3/4). Cr2: Few discontinuous faint-thin dark reddish brown (5YR3/2) clay films on vertical and horizontal ped faces. Few fine mica flakes present. Bth3: Clay films are thicker and more continuous on vertical ped faces. They appear as films and bridges on structural aggregates but are thinner. Slides: 9961 - 9968.

Classification

WRB 2006

Acric- Ferralsol (Sombric Humic Alumic Clayic)

72-190 cm	argic horizon
9-72 cm	ferralic horizon

72-190 cm	argic horizon
9-72 cm	ferralic horizon

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Humi-Haplic Ferralsol rudic

Humic Ferralsol

0-9 cm	ochric A horizon
72-190 cm	argic B horizon
9-72 cm	ferralic B horizon
-	strongly humic

0-9 cm	ochric A horizon
72-190 cm	argillic B horizon
9-72 cm	oxic B horizon
-	high organic matter content in B horizon

Local classification:	Kibinja Series

Other classification

USDA-SCS (1975)

Sombrihumox udic clayey kaolinitic isothermic

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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
0-9	4	19.7	9.4	13.0	11.8	4.3	58.2	5.4	4.8	10.2	31.6
9-44	5	22.4	9.0	10.2	9.1	3.6	54.3	6.7	2.3	9	36.7
44-72	36	35.9	6.9	7.8	6.9	3.4	53.5	4.3	3.6	7.9	43.3
72-100	48	20.2	5.3	4.9	4.7	3.0	37	3.7	2.4	6	58.3
100-190	35	16.8	5.3	4.5	5.6	3.5	30.6	3.6	6.9	9.5	62.2

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-9	1.64	-	0.012	-	31.6
9-44	1.48	-	0.016	-	36.7
44-72	1.61	-	0.008	-	43.3
72-100	1.56	-	0.010	-	58.3
100-190	1.67	-	0.013	-	62.2

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
0-9	1.64	-	-	-	-	-	-	-	9.0
9-44	1.48	-	-	-	-	-	-	-	10.9
44-72	1.61	-	-	-	-	-	-	-	13.6
72-100	1.56	-	-	-	-	-	-	-	16.7
100-190	1.67	-	-	-	-	-	-	-	18.5

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
0-9	5.0	3.7	-	-	1.65	0.13	13	11.1	2.2	1.0	0.6	0.2	0.1	1.9
9-44	4.5	3.5	-	-	1.03	0.07	15	11.2	2.9	0.3	0.2	0.1	0.1	0.7
44-72	4.9	3.7	-	-	1.00	0.07	14	13.8	2.5	2.0	0.3	0.0	0.1	2.3
72-100	4.8	3.7	-	-	0.64	0.05	14	9.5	2.7	1.8	0.3	0.1	0.1	2.2
100-190	4.8	3.9	-	-	0.80	0.05	16	7.6	3.4	1.7	0.3	0.1	0.1	2.2

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 %
0-9	19	9.9	31	5.8	13	22	1
9-44	8	8.6	23	3.6	11.9	34	1
44-72	20	9.1	27	3.5	16.1	27	1
72-100	26	8.2	18	2.2	17	26	1
100-190	25	6.5	19	2.8	9.2	28	1

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
0-9	9.0	26	0.08	0.2	0.00	1.1	0.3	0.3	0.2	-	0.2
9-44	9.0	28	0.07	0.2	0.01	1.2	0.4	0.4	0.2	-	0.2
44-72	9.3	44	0.08	0.3	0.01	1.4	0.4	0.6	0.3	-	0.2
72-100	9.3	39	0.09	0.3	0.02	1.8	0.4	0.6	0.2	-	0.2
100-190	9.2	45	0.09	0.3	0.01	1.9	0.4	0.1	0.1	-	0.3

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
0-9	-	-	-	4.1	-	-	-	-	-
9-44	-	-	-	3.9	-	-	-	-	-
44-72	-	-	-	4.2	-	-	-	-	-
72-100	-	-	-	4.1	-	-	-	-	-
100-190	-	-	-	4.1	-	-	-	-	-

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
9-44	-	-	-	very weak to weak	-	-	very strong	weak	-	-	very weak to weak	-
44-72	-	-	-	very weak to weak	-	-	very strong	very weak to weak	-	-	-	very weak to weak
72-100	-	-	-	very weak to weak	-	-	very strong	weak	-	-	-	-
100-190	-	-	-	very weak to weak	-	-	very strong	weak	-	-	-	-

Profile description

Ah 0-9 cm	dark yellowish brown (10YR 4/4, dry) dark brown (7.5YR 3/4, moist)slightly gravelly sandy clay,moderate coarse platy parting to moderate fine and medium crumb,slightly hard firm slightly sticky plastic,common and fine medium vesicular pores and common fine and medium tubular pores,common very fine and fine and common medium roots,few fine gravel Quartz fragments,non calcareous,abrupt wavy boundary to,
Bo 9-44 cm	(dark) brown (7.5YR 4/4, dry) dark reddish brown (5YR 3/4, moist)gravelly clay,moderately coherent massive parting to moderate medium crumb,slightly hard firm slightly sticky plastic,patchy thin clay cutans,common to many fine and medium vesicular pores and common many fine and medium tubular pores,common very fine and fine and common medium roots,few fine gravel Quartz fragments,non calcareous,clear irregular boundary to,
Boh 44-72 cm	(dark) brown (7.5YR 4/4, dry) dark reddish brown (5YR 3/3, moist)(5YR 2/2, dry) and (5YR 3/4, dry) ,(5YR 2/2, moist) and (5YR 2/4, moist),gravelly clay,moderate very coarse prismatic parting to moderate medium and coarse crumb,moderate medium and coarse crumb,slightly hard firm slightly sticky plastic,slightly hard very friable slightly sticky plastic,many mottles (5 YR 2/4),broken thin clay cutans on horizontal and vertical pedfaces cutans,common micro to medium vesicular and tubular pores,common fine and medium roots,few micro roots,common fine gravel Quartz,many fine gravel rock and quartz few medium gravel,non calcareous,abrupt irregular boundary to,
72-100 cm	yellowish red (5YR 5/8, dry) (5YR 4/8, moist)(5YR 2/1, dry) and (5YR 3/4, dry) and (5YR 4/8, dry),(5YR 2/1, dry) and (5YR 2/4, dry) and (5YR 3/8, dry),very gravelly clay,moderate very coarse subangular blocky,moderate medium and coarse subangular blocky,slightly hard friable very sticky plastic,very hard firm slightly sticky plastic,many mottles (5 YR 2/4) and many mottles (5 YR 3/8),continuous thin clay cutans on horizontal and vertical pedfaces cutans,broken thin clay cutans on horizontal and vertical pedfaces,common fine medium vesicular and tubular pores,few very fine and fine vesicular pores and few fine and medium tubular pores,few micro and few fine roots,many fine gravel rock and quartz and few medium gravel fragments,many fine gravel rock and quartz few and fine gravel,non calcareous,gradual irregular boundary to,
100-190 cm	Invalid Code: (5YR 2/1, moist) and (5YR /3/2 moist) and (2.5YR 4/8, moist) ,Invalid Code: (5YR 2/2, dry) and (5YR 3/2, dry) and (2.5YR 4/8, dry) (2.5YR 2/6, moist) and (7.5YR 5/8, moist) dark red (2.5YR 3/6, dry) and (7.5YR 6/8, dry),gravelly sandy clay,gravelly clay,weak medium subangular blocky,moderate very coarse subangular blocky,very hard friable very sticky plastic,extremely hard firm slightly sticky plastic,many mottles (5 YR 3/2) and many mottles (2.5 YR 4/8),many mottles (7.5 YR 5/8),broken thin clay cutans on horizontal and vertical pedfaces,broken thin clay cutans on vertical pedfaces,few fine to medium vesicular pores and few very fine and medium tubular pores,few micro to fine vesicular pores and few micro to fine tubular pores,few micro and few fine roots,common fine gravel quartz fragments and few mica flakes,common fine gravel quartz fragments,non calcareous,

Kind 1 (parent material) ; Parker (eds), 1984	granite
Mode of accumulation or deposition of parent material	residual material
Soil Depth	72cm
Texture of parent material	clayey
Weathering Resistance	high
General characterization of the status of weathering of solid rock	highly

Occurrence of soil aggradation (McDonald et al., 1984)	absent
Intensity of the soil erosion type	slight
Soil erosion type	sheet
Slope stability	stable

Land use or vegetation in the immediate vicinity of the site	woodland, grazed
Remarks on Land Use / Vegetation	VEGETATION: Eucalyptus plantation. LAND USE: Crops: bananas and maize.

Altitude	1785m
Physiographic Unit	crest of interfluve in hills
Physiographic position of the site	crest
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	plateau
Slope	3%
Form of the slope surrounding the site	convex
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	hilly

Drainage class ; FAO (2006) - Guidelines for soil description	well
Dry From - To	0-190cm
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
Microrelief pattern	none
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 Rwanda 08: Ferralsol

Characteristics

Reference soil RW008: Ferralsols

Classification