Reference soil Nigeria 25: Phaeozem

NG025

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 NG025: Phaeozems

BRIEF CHARACTERIZATION OF THE SOIL: Deep, moderately well drained reddish sandy loam, derived from gneiss, with quartz fragments in the subsoil.

Classification

WRB 2006

WRB 1998

Luvic-Ferralic- Phaeozem (Chromic)

Chromi-Luvic- Phaeozem

0-42 cm	mollic horizon
42-66 cm	argic horizon
-	ferralic

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Ferrali-Luvic Phaeozem

Luvic Phaeozem

0-42 cm	mollic A horizon
42-66 cm	argic B horizon
-	ferralic

0-42 cm	mollic A horizon
42-66 cm	argillic B horizon
-	ferralic

Local classification:	Balogun Series

Other classification

USDA-SCS (1975)

Tropudalf udic sandy over 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
0-13	0	7.4	15.9	17.9	15.2	6.3	62.7	6.3	9.5	15.8	21.5
13-42	0	7.6	13.7	15.1	17.2	8.4	62	6.0	11.4	17.4	20.7
42-66	0	4.3	11.5	13.8	14.7	7.6	51.9	7.4	10.8	18.2	29.8
66-103	0	5.4	14.9	16.4	15.1	7.1	58.9	8.3	13.4	21.7	19.3
103-160	0	5.8	14.9	15.9	15.0	7.4	59	7.1	14.4	21.5	19.6

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-13	-	-	-	10.6	21.5
13-42	-	-	-	57.6	20.7
42-66	-	-	-	22.5	29.8
66-103	-	-	-	1.5	19.3
103-160	-	-	-	0.5	19.6

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
0-13	6.7	6.0	0.16	-	2.62	0.24	11	0.1	0.0	14.8	2.7	0.2	0.0	17.7
13-42	6.5	5.1	0.04	-	0.75	0.07	11	0.0	0.0	4.2	1.0	0.1	0.1	5.4
42-66	5.6	4.1	0.01	-	0.43	0.04	11	0.5	0.5	2.2	1.4	0.0	0.1	3.7
66-103	5.7	4.3	0.02	-	0.12	0.02	6	1.4	1.2	0.4	0.7	0.0	0.1	1.2
103-160	6.1	4.0	0.01	-	0.12	0.01	12	1.5	0.7	0.2	0.7	0.0	0.1	1

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 %
0-13	105	16.8	78	9.2	-	0	0
13-42	65	8.3	40	2.6	-	0	1
42-66	66	5.6	19	1.5	-	9	2
66-103	24	4.9	25	0.4	-	24	2
103-160	21	4.7	24	0.4	-	15	2

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
0-13	-	-	-	0.10	0.00	1.89	0.19	-	-	-	0.10
13-42	-	-	-	0.10	0.00	1.52	0.26	-	-	-	0.10
42-66	-	-	-	0.16	0.00	2.37	0.19	-	-	-	0.10
66-103	-	-	-	0.08	0.00	2.00	0.19	-	-	-	0.08
103-160	-	-	-	0.08	0.00	1.92	-	-	-	-	0.08

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-13	-	-	very weak to weak	weak	-	-	very strong	very weak to weak	weak	-	very weak	-
13-42	-	-	very weak to weak	weak	-	-	very strong	very weak to weak	weak	-	very weak to weak	-
42-66	-	-	very weak to weak	weak	-	-	very strong	very weak	weak	-	very weak to weak	-
66-103	-	-	very weak	weak	-	-	strong	very weak	weak	-	very weak to weak	-
103-160	-	-	very weak	weak	-	-	strong	very weak	weak	-	very weak	-

Profile description

Ap 0-13 cm	dark brown (7.5YR 3/2, moist)sandy loam,moderate fine crumb,very friable non sticky non plastic,many fine discontinuous exped and inped interstitial random pores,many fine and medium roots,few fine gravel strongly weathered quartz fragments,non calcareous,clear wavy boundary to,
13-42 cm	dark brown (7.5YR 3/2, moist)sandy loam,moderate medium crumb,friable slightly sticky non plastic,few fine discontinuous exped interstitial oblique pores,many very fine and fine roots,few fine gravel strongly weathered quartz fragments,non calcareous,clear wavy boundary to,
Bt 42-66 cm	dark red (2.5YR 3/6, moist)sandy clay loam,moderate medium subangular blocky,firm slightly sticky slightly plastic,many fine roots,few fine gravel weathered quartz fragments,non calcareous,clear wavy boundary to,
66-103 cm	red (2.5YR 5/6, moist)sandy loam,moderate medium subangular blocky,friable sticky slightly plastic,few fine roots,few fine gravel fresh quartz fragments,non calcareous,clear wavy boundary to,
CB 103-160 cm	red (2.5YR 5/6, moist)sandy loam,moderate medium subangular blocky,loose non sticky non plastic,few fine gravel fresh quartz fragments,non calcareous,

Kind 1 (parent material) ; Parker (eds), 1984	gneiss
Mode of accumulation or deposition of parent material	slope wash
Remarks on Parent Materials	intermediate gneiss
Soil Depth	103cm
Texture of parent material	loamy
Weathering Resistance	moderate
General characterization of the status of weathering of solid rock	partially or moderately

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	100m
Physiographic Unit	slope
Physiographic position of the site	lower 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	8%
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	moderately well
Flooding frequency (FAO, 1986)	never
Kind of ground water table (USDA, 1979)	no groundwater table observed
Moist From - To	0-160cm

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 25: Phaeozem

Characteristics

Reference soil NG025: Phaeozems

Classification