Reference soil Nigeria 19: Phaeozem

NG019

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 NG019: Phaeozems

BRIEF CHARACTERIZATION OF THE SOIL: Very deep well drained red sandy clay, derived from sandstone, with mottling in the subsoil. Tubular pores. Few woody and many fibrous roots at the surface.

Classification

WRB 2006

WRB 1998

Luvic-Ferralic- Phaeozem (Clayic Chromic)

Chromi-Luvic- Phaeozem

25-165 cm	argic horizon
-	ferralic

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Ferrali-Luvic Phaeozem

Luvic Phaeozem

0-25 cm	mollic A horizon
25-165 cm	argic B horizon
-	ferralic

0-25 cm	mollic A horizon
25-165 cm	argillic B horizon
-	ferralic

Local classification:	Alagba Series

Other classification

USDA-SCS (1975)

Tropudalf udic sandy over clayey 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
0-25	0	2.1	11.2	18.4	23.7	9.3	64.7	1.8	5.7	7.5	27.8
25-60	0	1.9	9.2	14.5	18.9	9.3	53.8	4.5	2.9	7.4	38.8
60-100	0	2.0	7.8	10.8	13.3	7.4	41.3	8.5	1.5	10	48.8
100-130	0	2.1	7.1	10.0	13.6	7.9	40.7	3.1	2.6	5.7	53.6
130-165	0	2.3	6.6	9.3	13.5	8.0	39.7	2.5	3.8	6.3	53.9
165-240	0	2.7	7.0	8.5	12.0	8.1	38.3	3.1	3.6	6.7	55.0
240-310	0	2.1	6.5	8.0	11.5	8.7	36.8	2.7	4.5	7.2	56.0
310-365	0	2.6	6.8	8.2	11.7	8.3	37.6	3.9	4.9	8.8	53.5
365-410	0	3.7	7.2	7.9	11.8	8.5	39.1	3.0	3.0	6	54.8

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-5	1.23	-	-	-	-
0-25	-	-	-	17.1	27.8
25-60	-	-	-	32.2	38.8
50-55	1.41	-	-	-	-
60-100	-	-	-	37.5	48.8
100-130	-	-	-	17.5	53.6
130-165	-	-	-	1.5	53.9
165-240	-	-	-	3.5	55.0
240-310	-	-	-	2.6	56.0
310-365	-	-	-	2.1	53.5
365-410	-	-	-	1.0	54.8

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
0-5	1.23	46.2	43.5	33.7	26.2	24.0	22.1	17.4	16.7
50-55	1.41	39.4	37.5	35.3	32.3	30.9	29.1	25.5	25.3

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	7.3	6.8	0.15	1.9	2.20	0.10	22	-	-	15.8	2.1	0.0	1.4	19.3
25-60	7.4	6.3	0.05	0.6	0.58	0.06	10	-	-	5.8	1.1	0.0	0.8	7.7
60-100	7.4	6.3	0.04	0.8	0.32	0.05	6	-	-	3.9	1.1	0.0	0.6	5.6
100-130	7.1	6.3	0.04	0.5	0.23	0.04	6	-	-	3.1	1.4	0.0	0.5	5
130-165	7.2	6.4	0.04	0.6	0.16	-	-	-	-	3.1	1.5	0.3	0.0	4.9
165-240	7.5	6.8	0.06	0.5	0.12	-	-	-	-	2.8	2.1	0.4	0.0	5.3
240-310	7.5	6.8	0.05	0.5	0.06	-	-	-	-	2.2	2.2	0.5	0.0	4.9
310-365	7.5	6.8	0.05	0.5	0.07	-	-	-	-	1.9	1.4	0.7	0.0	4
365-410	7.5	6.7	0.05	0.4	0.09	-	-	-	-	2.1	1.0	0.8	0.0	3.9

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	108	17.9	64	7.7	-	-	8
25-60	101	7.6	20	2.0	-	-	11
60-100	102	5.5	11	1.1	-	-	11
100-130	139	3.6	7	0.8	-	-	14
130-165	107	4.6	9	0.6	-	-	0
165-240	113	4.7	9	0.4	-	-	0
240-310	132	3.7	7	0.2	-	-	0
310-365	111	3.6	7	0.2	-	-	0
365-410	93	4.2	8	0.3	-	-	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
0-25	-	-	-	0.27	0.08	1.49	0.25	-	-	-	0.17
25-60	-	-	-	0.16	0.03	2.16	0.29	-	-	-	0.12
60-100	-	-	-	0.11	0.03	2.68	0.33	-	-	-	0.09
100-130	-	-	-	0.11	0.03	2.78	0.36	-	-	-	0.08
130-165	-	-	-	0.08	0.03	2.68	0.33	-	-	-	0.08
165-240	-	-	-	0.11	0.03	2.84	0.34	-	-	-	0.05
240-310	-	-	-	0.08	0.03	2.96	0.36	-	-	-	0.04
310-365	-	-	-	0.08	0.03	2.64	0.33	-	-	-	0.04
365-410	-	-	-	0.08	0.03	2.26	0.27	-	-	-	0.03

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-25	very weak	-	-	weak	-	-	very strong	-	-	very weak to weak	-	-
25-60	weak	-	-	weak	-	-	very strong	-	-	very weak	-	-
60-100	weak	-	-	weak	-	-	very strong	-	-	very weak	-	-
100-130	weak	-	-	weak	-	-	very strong	-	-	very weak	-	-
130-165	weak	-	-	weak	-	-	very strong	-	-	very weak	-	-
165-240	weak	-	-	weak	-	-	very strong	-	-	very weak	-	-
240-310	very weak to weak	-	-	weak	-	-	very strong	-	-	very weak	-	-
310-365	-	-	-	weak	-	-	very strong	-	-	very weak	-	-
365-410	-	-	-	weak	-	-	very strong	-	-	very weak	-	-

Profile description

Ap 0-25 cm	very dark grey (5YR 3/1, dry)sandy loam,moderate medium subangular blocky,hard friable non sticky non plastic,many coarse discontinuous exped and inped tubular random pores,many very fine to coarse roots,slightly calcareous (0-2%),gradual smooth boundary to,
25-60 cm	weak red (2.5YR 4/2, dry)sandy clay loam,moderate medium subangular blocky,hard firm non sticky non plastic,many coarse discontinuous exped and inped tubular random pores,many medium roots,slightly calcareous (0-2%),gradual smooth boundary to,
Bt1 60-100 cm	red (2.5YR 4/6, dry)sandy clay,strong medium subangular blocky,hard firm slightly sticky slightly plastic,few fine continuous inped tubular horizontal pores,few fine roots,slightly calcareous (0-2%),gradual smooth boundary to,
Bt2 100-130 cm	red (2.5YR 4/6, dry)sandy clay,strong medium subangular blocky,firm slightly sticky slightly plastic,many medium continuous exped and inped tubular horizontal pores,few fine roots,slightly calcareous (0-2%),gradual smooth boundary to,
Bt3 130-165 cm	red (2.5YR 4/6, dry)sandy clay,strong medium subangular blocky,firm slightly sticky slightly plastic,few fine continuous inped tubular horizontal pores,few fine roots,slightly calcareous (0-2%),gradual smooth boundary to,

Kind 1 (parent material) ; Parker (eds), 1984	sandstone
Mode of accumulation or deposition of parent material	colluvial
Soil Depth	165cm
Texture of parent material	sandy clay
Weathering Resistance	moderate
General characterization of the status of weathering of solid rock	highly

Occurrence of soil aggradation (McDonald et al., 1984)	absent
Slope stability	stable

Land use or vegetation in the immediate vicinity of the site	fallow
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	35m
Physiographic Unit	slope
Physiographic position of the site	middle 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	7%
Form of the slope surrounding the site	straight
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	undulating

Drainage class ; FAO (2006) - Guidelines for soil description	well
Dry From - To	0-165cm
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 19: Phaeozem

Characteristics

Reference soil NG019: Phaeozems

Classification