Reference soil Nigeria 12: Acrisol

NG012

Acrisols occur dominantly in the wetter parts of the tropics and subtropics and the warm temperate regions in relatively young landscapes.

Characteristics

Soils having an argic horizon (a subsurface horizon with distinct higher clay content than the overlying horizon), which has a cation exchange capacity of less than 24 cmolc per kg in some part, either starting within 100 cm from the soil surface, or within 200 cm from the soil surface if the argic horizon is overlain by loamy sand or coarser textures throughout. They have a base saturation (total amount of Ca, Mg, K and Na with respect to the cation exchange capacity) of less than 50 percent in the major part between 25 and 100 cm from the soil surface

Distribution of Acrisols (rough estimation supplied by soilgrids)

Reference soil NG012: Acrisols

Brief description of the profile: Deep, well drained, red sandy clay loam with an increase of clay with depth and a soft plinthic horizon from 64 cm onwards blocked by hard plinthite at 130 cm depth; horizontation is gradual, structural development is weak. Parent material: Migmatites and granites of the basement complex. Land use and vegetation: Pure Isoberlinia woodland, grasscover mainly consisting of Andropogon gayanus. Additional notes on profile description: B2t: Mottles distinct, black and yellowish. B3: Between 100 - 130 cm fairly hard plinthite; texture as indicated only in the softer parts of the horizon. "Rhodoxic" (USDA) tentative subgroup. Climate data source: Agroclimatological data Africa 1, FAO. Rome 1984.

Classification

WRB 2006

WRB 1998

Plinthic-Cutanic- Acrisol (Epieutric Chromic)

Chromi-Plinthic- Acrisol

100-130 cm	petroplinthic horizon
36-130 cm	argic horizon
64-100 cm	plinthic horizon

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Chromi-Plinthic Acrisol

Plinthic Acrisol

0-16 cm	ochric A horizon
36-130 cm	argic B horizon
-	plinthite

0-16 cm	ochric A horizon
36-130 cm	argillic B horizon
-	plinthite

Local classification:	Upper series Borgu Game Res.

Other classification

USDA-SCS (1975)

Plinthustult ustic 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
0-10	-	6.8	18.1	19.1	21.3	9.1	74.4	10.7	5.1	15.8	9.7
10-30	-	10.3	19.9	19.6	16.6	5.4	71.8	7.5	4.8	12.3	16.0
30-60	-	9.3	15.9	10.9	9.0	4.7	49.8	8.4	7.3	15.7	34.5
60-85	-	9.3	13.8	7.7	8.3	4.2	43.3	8.4	10.8	19.2	37.4

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-10	-	-	-	-	9.7
10-30	-	-	-	-	16.0
30-60	-	-	-	-	34.5
60-85	-	-	-	-	37.4

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
0-10	6.5	5.6	0.19	-	0.90	0.09	10	-	-	1.4	0.6	0.2	0.0	2.2
10-30	5.9	4.7	0.06	-	0.42	0.03	14	-	-	0.6	0.6	0.1	0.0	1.3
30-60	5.1	4.2	0.12	-	0.23	0.03	8	-	-	0.2	0.3	0.2	0.0	0.7
60-85	5.3	4.3	0.03	-	0.16	0.02	8	-	-	0.6	0.5	0.2	0.0	1.3

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 %
0-10	76	2.9	30	3.2	-	-	0
10-30	93	1.4	9	1.5	-	-	0
30-60	21	3.3	10	0.8	-	-	0
60-85	38	3.4	9	0.6	-	-	0

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-10	-	-	-	weak to medium	-	-	very strong	weak	-	weak	-	-
10-30	-	-	-	weak to medium	-	-	very strong	weak	-	weak	-	-
30-60	-	-	-	weak to medium	-	-	very strong	weak	-	very weak to weak	-	-
60-85	-	-	-	weak to medium	-	-	very strong	weak	-	very weak to weak	-	-

Trace elements

Depth (cm)	As mg/kg	Ba mg/kg	Cd mg/kg	Co mg/kg	Cr mg/kg	Cu mg/kg	Mn mg/kg
0-10	-	-	-	6	19	8	752
10-30	-	-	-	9	22	10	422
30-60	-	-	-	14	22	12	418
60-85	-	-	-	12	20	16	427
85-120	-	380	-	14	31	18	618

Depth (cm)	Mo mg/kg	Ni mg/kg	Pb mg/kg	Sr mg/kg	V mg/kg	Zn mg/kg
0-10	-	8	6	-	-	13
10-30	-	9	14	-	20	-
30-60	-	11	6	-	-	17
60-85	-	12	18	-	-	20
85-120	-	12	32	-	-	15

Profile description

Ah 0-16 cm	brown (7.5YR 5/4, dry) dark reddish brown (5YR 3/4, moist)sandy loam,weak fine subangular blocky,very friable (moist) slightly plastic,common fine and medium tubular pores,common fine and medium roots,non calcareous,gradual smooth boundary to,
Bw1 16-36 cm	(5YR 8/8, dry) red (2.5YR 4/8, moist)slightly gravelly sandy clay loam,weak fine subangular blocky,firm slightly sticky plastic,broken thin clay cutans,few tubular pores,common fine roots,frequent small spherical ferruginous concretions,frequent fine gravel strongly weathered lithorelicts fragments,non calcareous,gradual smooth boundary to,
Bw2 36-64 cm	reddish yellow (5YR 6/8, dry) red (2.5YR 4/6, moist)sandy clay loam,weak fine subangular blocky,firm slightly sticky plastic,broken thin clay cutans,common fine tubular pores,non calcareous,gradual smooth boundary to,
Btv 64-100 cm	reddish yellow (5YR 6/8, dry) red (2.5YR 4/8, moist)sandy clay,weak angular blocky,firm sticky plastic,distinct mottles,broken moderately thick clay cutans,few to common tubular pores,few small ferruginous concretions,few fine gravel lithorelics fragments,plinthite pans,non calcareous,clear wavy boundary to,
BCvm 100-130 cm	gravelly sandy clayvery frequent small ferruginous concretions,petroferric pans,non calcareous,

Kind 1 (parent material) ; Parker (eds), 1984	coarse-grained igneous rock
Mode of accumulation or deposition of parent material	colluvial
Remarks on Parent Materials	migmatite and granite of the Basement Complex
Texture of parent material	sandy clay
Texture of parent material (second entry)	stony
Weathering Resistance	moderate
General characterization of the status of weathering of solid rock	highly

Land use or vegetation in the immediate vicinity of the site	(semi-)natural vegetation
Remarks on Land Use / Vegetation	Pure Isoberlinia woodland, grasscover mainly consisting of Andropogon gayanus
Status of vegetation; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	primary
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	woodland

Altitude	300m
Physiographic Unit	slightly rolling landscape
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.	hill
Slope	5%
Slope Aspect	south-east
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	rolling

Drainage class ; FAO (2006) - Guidelines for soil description	well
Flooding frequency (FAO, 1986)	never
Kind of ground water table (USDA, 1979)	no groundwater table observed
Moist From - To	0-180cm
Estimated permeability (class) of least permeable part of the profile	slow
Estimated run off (class)	medium

Evidence of alkali ; Soil Survey Manual USDA, 1951	non-alkaline
Micro relief type: small-scale differences in relief in the direct vicinity of the site (FAO, 1986)	level
Evidence of salt; Soil Survey Manual USDA, 1951	non-saline

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Reference soil Nigeria 12: Acrisol

Characteristics

Reference soil NG012: Acrisols

Classification