Reference soil Nigeria 21: Phaeozem

NG021

Phaeozems occur all over the world, but especially on the more moist side of the steppe regions, bordering Chernozems.

Characteristics

Soils having a mollic horizon (deep, brownish or blackish surface horizon with a significant accumulation of organic matter and high base saturation); a base saturation of 50 percent or more between 25 and 100 cm from the soil surface; a calcium carbonate-free soil matrix at least to a depth of 100 cm from the soil surface, or to a contrasting layer between 25 and 100 cm; no diagnostic horizons other than an albic, argic, cambic or vertic horizon, or a petrocalcic horizon in the substratum.

Distribution of Phaeozems (rough estimation supplied by soilgrids)

Reference soil NG021: Phaeozems

BRIEF CHARACTERIZATION OF THE SOIL: Moderately deep, well drained brown sandy clay, derived from gneiss, with hard spherical magniferous concretions in the subsoil.

Classification

WRB 2006

WRB 1998

Luvic-Ferralic- Phaeozem (Clayic Chromic)

Chromi-Luvic- Phaeozem

25-175 cm	argic horizon
-	ferralic

ferralic

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Ferrali-Luvic Phaeozem

Luvic Phaeozem

0-25 cm	mollic A horizon
25-175 cm	argic B horizon

0-25 cm	mollic A horizon
25-175 cm	argillic B horizon
-	ferralic

Local classification:	Iwo Series

Other classification

USDA-SCS (1975)

Haplustalf ustic sandy over loamy 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
0-25	0	3.1	6.3	14.4	27.3	15.2	66.3	9.1	12.2	21.3	12.4
25-55	0	6.2	8.3	13.1	20.8	11.9	60.3	6.9	13.6	20.5	19.1
55-84	51	13.3	10.7	9.8	11.5	6.4	51.7	3.6	8.1	11.7	36.6
84-109	0	10.3	7.6	6.8	9.4	6.4	40.5	7.5	11.9	19.4	40.2
109-135	0	5.9	5.3	4.9	8.1	6.6	30.8	8.9	17.4	26.3	42.9
135-175	0	4.2	5.7	5.2	8.6	6.8	30.5	6.6	18.2	24.8	44.8
175-225	0	5.5	4.0	3.9	8.4	6.3	28.1	5.4	21.2	26.6	45.4
225-264	0	3.7	4.2	4.5	9.3	6.6	28.3	5.5	24.2	29.7	41.9
264-300	0	4.1	3.5	4.4	9.7	6.7	28.4	5.6	25.1	30.7	40.9
300-345	0	3.7	2.6	4.4	11.3	9.0	31	4.1	30.9	35	34.0
345-435	0	3.7	5.1	9.1	18.0	11.3	47.2	2.8	25.3	28.1	24.7

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-25	-	-	-	6.3	12.4
7-12	1.34	-	-	-	-
25-55	-	-	-	14.0	19.1
55-84	-	-	-	13.4	36.6
84-109	-	-	-	0.0	40.2
109-135	-	-	-	1.5	42.9
135-175	-	-	-	0.0	44.8
175-225	-	-	-	1.7	45.4
225-264	-	-	-	1.4	41.9
264-300	-	-	-	2.5	40.9
300-345	-	-	-	11.0	34.0
345-435	-	-	-	15.8	24.7

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
7-12	1.34	41.4	37.3	27.1	20.7	18.3	15.8	10.0	7.7

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
0-25	5.9	5.2	0.05	-	0.81	0.07	12	0.1	0.0	3.0	0.9	0.2	0.0	4.1
25-55	5.8	4.8	0.02	-	0.32	0.04	8	0.1	0.0	2.2	0.9	0.1	0.0	3.2
55-84	5.6	4.9	0.02	-	0.36	0.04	9	0.1	0.0	2.8	1.5	0.1	0.0	4.4
84-109	5.5	4.8	0.01	-	0.15	0.03	5	0.1	0.0	1.8	1.7	0.1	0.0	3.6
109-135	5.5	4.9	0.01	-	0.14	0.02	7	0.1	0.0	2.0	2.0	0.1	0.3	4.4
135-175	5.5	4.8	0.01	-	0.09	0.02	5	0.2	0.0	2.2	2.1	0.1	0.0	4.4
175-225	5.5	5.0	0.02	-	0.06	0.02	3	0.1	0.0	2.4	3.2	0.2	0.0	5.8
225-264	5.9	5.2	0.02	-	0.02	0.01	2	0.0	0.0	2.6	3.8	0.2	0.1	6.7
264-300	5.8	5.1	0.02	-	0.08	0.01	8	0.1	0.0	3.1	5.4	0.2	0.1	8.8
300-345	5.8	4.7	0.02	-	0.06	0.02	3	0.2	0.0	4.4	8.2	0.3	0.3	13.2
345-435	5.9	4.1	0.02	-	0.03	0.01	3	0.6	0.2	8.4	12.4	0.3	0.1	21.2

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 %
0-25	76	5.4	44	2.8	-	0	0
25-55	68	4.7	25	1.1	-	0	0
55-84	77	5.7	16	1.3	-	0	0
84-109	63	5.7	14	0.5	-	0	0
109-135	70	6.3	15	0.5	-	0	5
135-175	62	7.1	16	0.3	-	0	0
175-225	62	9.4	21	0.2	-	0	0
225-264	77	8.7	21	0.1	-	0	1
264-300	93	9.5	23	0.3	-	0	1
300-345	99	13.4	39	0.2	-	0	2
345-435	139	15.2	62	0.1	-	1	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
0-25	-	-	-	0.05	0.00	0.95	0.15	-	-	-	0.11
25-55	-	-	-	0.07	0.02	1.55	0.21	-	-	-	0.15
55-84	-	-	-	0.12	0.02	2.41	0.36	-	-	-	0.14
84-109	-	-	-	0.12	0.05	3.72	0.46	-	-	-	0.11
109-135	-	-	-	0.13	0.05	4.01	0.46	-	-	-	0.09
135-175	-	-	-	0.12	0.05	4.34	0.49	-	-	-	0.09
175-225	-	-	-	0.10	0.05	4.40	0.43	-	-	-	0.08
225-264	-	-	-	0.10	0.05	4.13	0.42	-	-	-	0.06
264-300	-	-	-	0.10	0.05	4.28	0.43	-	-	-	0.07
300-345	-	-	-	0.08	0.05	3.66	0.39	-	-	-	0.09
345-435	-	-	-	0.08	0.05	1.67	0.15	-	-	-	0.09

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-25	-	very weak	very weak	weak to medium	-	-	very strong	weak to medium	-	-	-	-
25-55	-	very weak	very weak	weak to medium	-	-	very strong	weak to medium	-	-	-	-
109-135	-	-	very weak	weak to medium	-	-	very strong	weak to medium	-	-	-	-
175-225	-	-	very weak	weak to medium	-	-	very strong	weak	-	-	-	-
264-300	-	-	-	weak to medium	-	-	very strong	weak	-	-	-	-
345-435	-	-	-	very weak	-	-	very strong	very weak to weak	-	-	weak to medium	-

Profile description

Ap 0-25 cm	very dark greyish brown (10YR 3/2, dry)loamy sand,weak medium crumb,loose friable non plastic,few fine discontinuous exped and inped interstitial random pores,many medium roots,non calcareous,gradual wavy boundary to,
25-55 cm	(dark) brown (7.5YR 4/4, dry)sandy loam,moderate medium crumb,slightly hard friable non plastic,few fine roots,few medium angular hard manganiferous concretions,few fine gravel strongly weathered quartz fragments,non calcareous,gradual wavy boundary to,
Bt1 55-84 cm	reddish brown (5YR 4/4, dry)very gravelly sandy clay loam,moderate medium subangular blocky,slightly hard friable slightly sticky,few very fine discontinuous exped and inped interstitial oblique pores,few medium angular hard manganiferous concretions,few fine gravel weathered mica fragments,non calcareous,gradual smooth boundary to,
Bt2 84-109 cm	yellowish red (5YR 4/6, dry)sandy clay loam,moderate medium subangular blocky,very hard firm slightly plastic,few (2-5%) fine faint diffuse mottles 10R6/8 (light red),few fine discontinuous exped and inped tubular vertical pores,few fine roots,few medium spherical hard manganiferous concretions,few fine gravel fresh mica and few medium gravel fresh quartz fragments,non calcareous,gradual irregular boundary to,
Bt3 109-135 cm	yellowish brown (10YR 5/8, dry)sandy clay,strong medium subangular blocky,very hard firm slightly plastic,few fine discontinuous exped and inped tubular vertical pores,few fine roots,few small spherical hard manganiferous concretions,few fine gravel fresh mica fragments,non calcareous,gradual irregular boundary to,
135-175 cm	yellowish brown (10YR 5/8, dry)sandy clay,strong medium subangular blocky,very hard firm slightly plastic,few fine continuous inped tubular vertical pores,few fine roots,few fine gravel fresh mica fragments,non calcareous,

Kind 1 (parent material) ; Parker (eds), 1984	gneiss
Mode of accumulation or deposition of parent material	residual material
Remarks on Parent Materials	intermediate gneiss
Soil Depth	84cm
Texture of parent material	sandy clay
Weathering Resistance	moderate
General characterization of the status of weathering of solid rock	partially or moderately

Major crops	cassava
Land use or vegetation in the immediate vicinity of the site	arable farming
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	shifting - fallow bush
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 forest

Altitude	240m
Physiographic Unit	slope
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.	low hill
Slope	5%
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	0-175cm
Flooding frequency (FAO, 1986)	never
Kind of ground water table (USDA, 1979)	no groundwater table observed

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 Nigeria 21: Phaeozem

Characteristics

Reference soil NG021: Phaeozems

Classification