Reference soil Nigeria 20: Acrisol

NG020

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 NG020: Acrisols

BRIEF CHARACTERIZATION OF THE SOIL: Very deep, well drained reddish sandy clay derived from sandstone, with strong mottling and many horizontal tubular pores in the subsoil. Profile extends down to 390 cm.

Classification

WRB 2006

WRB 1998

Vetic- Acrisol (Alumic Profondic Clayic Rhodic)

Profondi-Vetic- Acrisol (Alumic Rhodic)

20-268 cm

argic horizon

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Chromi-Haplic Acrisol

Ferric Acrisol

0-20 cm	ochric A horizon
20-268 cm	argic B horizon

0-20 cm	ochric A horizon
20-268 cm	argillic B horizon
-	ferric

Local classification:	Owode 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
0-20	0	1.7	9.8	20.0	31.4	12.8	75.7	3.2	4.0	7.2	17.0
20-37	0	1.4	7.1	11.9	16.9	7.2	44.5	16.4	7.1	23.5	32.1
37-85	0	2.4	7.7	11.1	15.7	7.6	44.5	3.0	1.6	4.6	51.0
85-120	0	2.2	7.5	10.8	16.2	8.2	44.9	3.8	2.4	6.2	48.8
120-173	0	3.1	7.4	10.5	15.8	8.2	45	2.2	4.7	6.9	48.1
173-268	0	3.7	6.9	7.7	13.5	9.0	40.8	3.1	6.6	9.7	49.6
268-313	0	3.3	6.0	7.2	13.2	9.2	38.9	3.7	9.7	13.4	47.8
313-368	0	4.3	7.3	7.7	13.4	8.9	41.6	2.8	8.0	10.8	47.6
368-390	0	2.9	6.7	7.9	14.9	9.8	42.2	3.3	8.2	11.5	46.4

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-20	-	-	-	9.7	17.0
6-11	1.28	-	-	-	-
33-38	1.32	-	-	-	-
20-37	-	-	-	23.9	32.1
37-85	-	-	-	3.1	51.0
60-65	1.33	-	-	-	-
85-120	-	-	-	1.1	48.8
120-173	-	-	-	0.9	48.1
173-268	-	-	-	1.8	49.6
268-313	-	-	-	2.5	47.8
313-368	-	-	-	2.0	47.6
368-390	-	-	-	3.9	46.4

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
6-11	1.28	42.7	40.2	30.0	19.4	17.4	15.9	8.3	8.4
33-38	1.32	42.4	39.2	34.3	29.7	28.0	26.4	22.0	21.9
60-65	1.33	43.0	40.4	35.7	30.7	28.9	26.0	21.5	21.1

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
0-20	5.4	4.5	0.05	-	1.07	0.02	54	0.2	0.2	2.0	1.0	0.1	0.0	3.1
20-37	5.2	4.3	0.03	-	0.59	0.06	10	0.8	0.7	1.7	0.7	0.0	0.0	2.4
37-85	5.1	4.2	0.02	-	0.44	-	-	1.4	1.4	1.1	0.4	0.0	0.0	1.5
85-120	5.2	4.2	0.01	-	0.42	-	-	1.4	1.2	0.6	0.5	0.1	0.0	1.2
120-173	5.3	4.2	0.01	-	0.59	-	-	1.5	1.4	0.4	0.4	0.1	0.1	1
173-268	4.9	4.1	0.02	-	0.14	-	-	1.7	1.7	0.2	0.3	0.1	0.1	0.7
268-313	4.9	4.1	0.01	-	0.09	-	-	1.9	1.9	0.2	0.2	0.1	0.0	0.5
313-368	4.9	4.1	0.01	-	0.08	-	-	1.9	1.9	0.2	0.2	0.1	0.0	0.5
368-390	4.9	4.1	0.02	-	0.06	-	-	1.7	1.6	0.0	0.2	0.1	0.1	0.4

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 %
0-20	54	5.7	34	3.7	-	4	0
20-37	44	5.5	17	2.1	-	13	0
37-85	33	4.5	9	1.5	-	31	0
85-120	34	3.5	7	1.5	-	34	0
120-173	27	3.7	8	2.1	-	38	3
173-268	20	3.5	7	0.5	-	49	3
268-313	19	2.6	5	0.3	-	73	0
313-368	16	3.1	7	0.3	-	61	0
368-390	14	2.8	6	0.2	-	57	4

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
0-20	-	-	-	0.10	0.02	1.01	0.18	-	-	-	0.08
20-37	-	-	-	0.13	0.03	1.71	0.27	-	-	-	0.10
37-85	-	-	-	0.13	0.03	2.18	0.37	-	-	-	0.10
85-120	-	-	-	0.13	0.03	2.05	0.29	-	-	-	0.09
120-173	-	-	-	0.13	0.03	2.20	0.31	-	-	-	0.08
173-268	-	-	-	0.11	0.03	2.39	0.33	-	-	-	0.05
268-313	-	-	-	0.10	0.03	2.55	0.39	-	-	-	0.03
313-368	-	-	-	0.08	0.03	2.40	0.34	-	-	-	0.03
368-390	-	-	-	0.08	0.05	2.40	0.34	-	-	-	0.03

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-20	weak to medium	-	-	weak to medium	-	-	very strong	-	-	very weak	-	-
20-37	weak to medium	-	-	weak to medium	-	-	very strong	-	-	-	-	-
37-85	weak	-	-	weak to medium	-	-	very strong	-	-	-	-	-
85-120	weak	-	-	weak to medium	-	-	very strong	-	-	-	-	-
120-173	weak	-	-	weak	-	-	very strong	-	-	very weak to weak	-	-
173-268	very weak	-	-	weak	-	-	very strong	-	-	very weak	-	-
268-313	very weak	-	-	weak	-	-	very strong	-	-	very weak	-	-
313-368	very weak	-	-	weak	-	-	very strong	-	-	very weak	-	-
368-390	very weak	-	-	weak	-	-	very strong	-	-	very weak	-	-

Profile description

Ap 0-20 cm	(dark) brown (7.5YR 4/2, dry)sandy loam,weak medium crumb,soft very friable,many medium discontinuous exped and inped tubular random pores,many coarse roots,non calcareous,gradual wavy boundary to,
BA 20-37 cm	yellowish red (5YR 4/6, dry)sandy clay loam,strong medium subangular blocky,very hard friable slightly plastic,many medium discontinuous exped and inped tubular random pores,many coarse roots,non calcareous,clear smooth boundary to,
Bt1 37-85 cm	dark reddish brown (2.5YR 3/4, moist)sandy clay,strong medium subangular blocky,firm slightly plastic,few (2-5%) medium faint clear mottles 2.5Y5/6 (light olive brown),many medium discontinuous exped and inped tubular horizontal pores,many medium roots,non calcareous,gradual smooth boundary to,
Bt2 85-120 cm	red (2.5YR 4/6, moist)sandy clay,moderate medium subangular blocky,very firm slightly plastic,common (5-15%) medium faint clear 2.5Y6/6 mottles (olive yellow),many fine continuous inped tubular horizontal pores,many medium roots,non calcareous,gradual smooth boundary to,
Bt3 120-173 cm	red (2.5YR 4/6, moist)sandy clay,moderate medium subangular blocky,very firm slightly plastic,common (5-15%) coarse distinct clear mottles 2.5Y6/6 (olive yellow),many fine continuous inped tubular horizontal pores,many fine roots,non calcareous,gradual smooth boundary to,
Bt4 173-268 cm	red (2.5YR 4/6, moist)sandy clay,moderate medium subangular blocky,very firm slightly plastic,common (5-15%) coarse distinct clear mottles 2.5Y6/6 (olive yellow),many fine continuous inped tubular horizontal pores,non calcareous,

Kind 1 (parent material) ; Parker (eds), 1984	sandstone
Mode of accumulation or deposition of parent material	slope wash
Soil Depth	173cm
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	30m
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	4%
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	0-37cm
Kind of ground water table (USDA, 1979)	no groundwater table observed
Moist From - To	37-390cm

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 20: Acrisol

Characteristics

Reference soil NG020: Acrisols

Classification