Reference soil Nigeria 8: Plinthosol

NG008

Distribution of Plinthosols (rough estimation supplied by soilgrids)

Location: Approximately 25 m from meteorological station. Parent material: Clayey marine sediments of Tertiary and Cretaceous age (mainly kaolinite). Physiographic unit: Middle part across wide valley in flat to gently undulating Pleisto- Pliocene landscape. Land use and vegetation: Regrowth of Eupatorium odoratum after monoculture of maize. Groundwater: Saturation and temporary watertable only during and immediately after peak of rainy season at approximately 1 m or deeper. INRA classification: Sol hydromorphe peu humifere pseudogley a nappe perchee. Additional notes on profile description: Ap: Weak fine crumb structure at surface, structureless single grained below; interstitial pores in upper, tubular pores in lower part. B1, B2t and B3: Clay-humus infiltration along old root or termite channels. B3: Mottles are plinthite. References: Forbes, T.R.: A West African soil climosequence and some aspects of foodcrop potential. A thesis for the Degree of Master of Science. Cornell University, August 1975. Murdoch, G.; Moormann, F.R.: Identification of soil toposequences in the humid tropics of West Africa. Miscellaneous report No.178, Foreign and Commonwealth Office - Overseas Development Administration. Surbiton, Surrey, England 1974. Ola, S.A.: Tropical soils Of Nigeria in engineering practice, University of Benin, Benin City. Rotterdam 1983. Smyth, A.J.; Montgomery, A.F.: Soils and land use in Central Western Nigeria. Ministry of Agriculture and Natural Resources. Ibadan 1962. Vine, H.: Review of work on Nigerian soils. Report to the National Research Council, Committee on Tropical Soils. University of Leicester, June 1970.

WRB 2006:

WRB 1998:

Acric Plinthosol(Albic Abruptic)

Albi- Acric Plinthosol(Abruptic)

20-38 cm	albic horizon
38-120 cm	argic horizon
90-120 cm	plinthic horizon
	abrupt textural change

FAO-UNESCO-ISRIC 1988:

FAO-UNESCO 1974:

Dystri-

Albic Plinthosol

Plinthic Acrisol

0-20 cm	ochric A horizon
20-38 cm	albic E horizon;
38-120 cm	argic B horizon
	abrupt textural change
	plinthite

0-20 cm	ochric A horizon
30-38 cm	albic E horizon
38-120 cm	argillic B horizon
	abrupt textural change
	plinthite

Other classification

USDA-SCS (1975)

Paleustult

loamy

mixed

isohyperthermic

Classification (other)

Atan Series

Location:

Ogun State, Ikenne, IART station

Parent material

The main parent rock/ material over which the soil has been formed (1st entry)	sediment, unconsolidated
Mode of Accumulation or deposition of parent material (1st entry)	colluvial
Texture of parent material (1st entry)	sandy
Weathering status of solid rock (1st entry)	highly
Resistance against weathering (solid rock) (1st entry)	moderate
Depth1 of lithological boundary	cm
The main parent rock/ material over which the soil has been formed (2nd entry)	sediment, unconsolidated
Mode of Accumulation or deposition of parent material (2nd entry)	marine sediments
Texture of parent material (2nd entry)	clayey
Weathering status of solid rock (2nd entry)	highly
Resistance against weathering (solid rock) (2nd entry)	moderate
Soil Depth; depth to which roots can easily penetrate throughout the year	cm
Remarks on Parent Materials	clayey marine sediments of Tertiary and Cretaceous age (mainly kaolinite)

Physical

Particle size distribution:

Depth (cm)		Very Coarse Sand (%)	Coarse Sand (%)	Medium Sand (%)	Fine Sand (%)	Very Fine Sand (%)	Total Sand (%)	Coarse Silt (%)	Fine Silt (%)	Total Silt (%)	Clay (%)
0-20	:	3.1	10.1	17.9	29.9	15.5	76.5	8.4	6.5	14.9	6.5
20-38	:	2.3	9.5	17.8	31.1	15.9	76.6	9.0	8.5	17.5	6.0
38-58	:	3.1	12.0	14.4	19.9	11.5	60.9	7.0	7.7	14.7	24.4
58-90	:	2.7	9.8	12.2	18.7	11.8	55.2	8.4	8.4	16.8	28.0
90-120	:	3.1	7.5	10.2	19.2	12.5	52.5	9.8	8.9	18.7	28.7

Other physical data

Depth (cm)		Bulk Density (kg/dm³)	Spec. Surf. Area (m2/g)	COLE (cm/cm)	Water Disp. Clay (%)	Clay (%)
0-20	:	-	-	-	-	6.5
20-38	:	-	-	-	-	6.0
38-58	:	-	-	-	-	24.4
58-90	:	-	-	-	-	28.0
90-120	:	-	-	-	-	28.7

Chemical characteristics:

Depth (cm)		pH H2O	pH KCl	EC 1 : 2.5 (mS/cm)	CaCO3 (%)	Org. C (%)	Org. N (%)	C / N	Exch. Acid (cmol/kg)	Exch. Al (cmol/kg)	Ca (cmol/kg)	Mg (cmol/kg)	K (cmol/kg)	Sum Cations (cmol/kg)
0-20	:	5.9	4.9	0.08	-	0.84	0.07	12	0.1	0.0	1.6	0.3	0.1	2
20-38	:	5.5	4.4	0.04	-	0.34	0.03	11	0.2	0.1	0.8	0.0	0.1	0.9
38-58	:	4.7	3.8	0.02	-	0.29	0.03	10	1.3	0.8	0.5	0.0	0.1	0.6
58-90	:	4.5	3.7	0.03	-	0.22	0.03	7	1.6	1.1	0.4	0.0	0.1	0.5
90-120	:	4.6	3.7	0.02	-	0.15	0.03	5	2.6	2.0	0.0	0.0	0.0	-

Depth (cm)		CEC Soil (cmol/kg)	CEC Clay (cmol/kg)	CEC Org (cmol/kg)	ECEC (cmol/kg)	Base sat. (%)	Al sat. (%)
0-20	:	5.8	-	2.9	-	34	-
20-38	:	3.8	-	1.2	-	24	-
38-58	:	7.5	-	1.0	-	8	-
58-90	:	3.6	-	0.8	-	14	-
90-120	:	8.1	-	0.5	-	-	-

Elemental composition of the clay:

Depth (cm)		SiO2 (wt%)	Al2O3 (wt%)	Fe2O3 (wt%)	CaO (wt%)	MgO (wt%)	K2O (wt%)	Na2O (wt%)	TiO2 (wt%)
0-20	:	48.7	29.4	6.00	0.08	0.37	0.50	-	2.52
20-38	:	51.3	27.8	5.6	0.01	0.33	0.54	-	3.32
38-58	:	45.8	32.8	6.3	0.00	0.33	0.36	-	1.65
58-90	:	43.4	31.2	5.8	0.02	0.25	0.34	-	1.47
90-120	:	45.3	33.0	5.8	0.01	0.27	0.32	-	1.54

Depth (cm)		MnO2 (wt%)	P2O5 (wt%)	Ign.Loss clay (wt%)	Total clay (%)	SiO2 / Al2O3 (mol/mol)	SiO2 / Fe2O3 (mol/mol)	SiO2 / R (mol/mol)	Al2O3 / Fe2O3 (mol/mol)
0-20	:	0.10	0.40	12.6	100.67	2.8	21.6	2.5	7.7
20-38	:	0.13	0.33	11.9	101.26	3.1	24.3	2.8	7.8
38-58	:	0.02	0.13	13.3	100.69	2.4	19.3	2.1	8.2
58-90	:	0.02	0.08	13.3	95.88	2.4	19.9	2.1	8.4
90-120	:	0.01	0.07	13.1	99.42	2.3	20.8	2.1	8.9

Elemental composition of the soil:

Depth (cm)		SiO2 (wt%)	Al2O3 (wt%)	Fe2O3 (wt%)	CaO (wt%)	MgO (wt%)	K2O (wt%)	Na2O (wt%)	TiO2 (wt%)
0-20	:	94.0	2.5	1.0	0.04	0.01	0.48	-	1.14
20-38	:	94.5	2.3	1.0	0.01	0.01	0.53	-	1.19
38-58	:	85.4	8.7	2.1	0.01	0.01	0.48	-	1.26
58-90	:	83.0	10.0	2.8	0.01	0.02	0.47	-	1.28
90-120	:	81.5	10.5	4.0	0.01	0.01	0.47	-	1.34

Depth (cm)		MnO2 (wt%)	P2O5 (wt%)	LOI (wt%)	SiO2 / Al2O3 (mol/mol)	SiO2 / Fe2O3 (mol/mol)	SiO2 / R (mol/mol)	Al2O3 / Fe2O3 (mol/mol)
0-20	:	0.04	0.02	2.1	63.8	250.2	50.8	3.9
20-38	:	0.03	0.01	1.2	69.7	251.6	54.6	3.6
38-58	:	0.02	0.03	3.6	16.7	108.3	14.4	6.5
58-90	:	0.02	0.03	3.9	14.1	78.9	12.0	5.6
90-120	:	0.02	0.03	4.1	13.2	54.2	10.6	4.1

Clay mineralogy:

Depth (cm)		Kaolinite	Mica / illite	Vermiculite	Chlorite	Smec	Halloysite	Mixed layer	Quar	Feldspar	Gibbsite	Goethite	Hematite
0-20	:	strong	-	-	-	-	-	weak	weak to medium	-	-	-	-
20-38	:	strong	-	-	-	-	-	weak	weak to medium	-	-	-	-
38-58	:	very strong	-	-	-	-	-	weak	very weak to weak	-	-	-	-
58-90	:	very strong	-	-	-	-	-	weak	very weak to weak	-	-	-	-
90-120	:	very strong	-	-	-	-	-	weak	very weak to weak	-	-	-	-

Mineral sand:

Depth (cm)		Heavy Frac. Sand (wt%)	Light Frac. Sand (wt%)	Quartz (wt%in lf)	K-Feldspar (wt%in lf)	Plagioclase (wt%in lf)	Rest (wt%in lf)	Opaque (wt%in lf)
0-20	:	1.6	98.4	94	4	2	-	79
20-38	:	-	-	-	-	-	-	-
38-58	:	1.6	98.4	96	1	3	-	73
58-90	:	1.7	98.3	97	2	1	-	78
90-120	:	1.9	98.1	98	0	2	-	77

Minerals:

Depth (cm)		Anatase (wt%)	Andalusite (wt%)	Hornblende basaltic (wt%)	Brookite (wt%)	Epidote (wt%)	Rutile (wt%)	Sillimanite (wt%)	sillimanite (f) (wt%)	Staurolite (wt%)	Tourmaline (wt%)	Zircone (wt%)
0-20	:	-	1	5	-	7	4	6	2	-	-	-
20-38	:	-	-	-	-	-	-	-	-	-	-	-
38-58	:	3	1	3	-	3	4	7	1	-	-	-
58-90	:	2	-	1	-	3	7	8	-	-	-	-
90-120	:	5	-	2	1	4	8	5	3	-	-	-

Profile description:

Ap 0-20 cm	brown (10YR 5/3, moist), sandy loam, weak fine crumb and single grain, very friable, common fine interstitial pores and common fine tubular pores, many fine and common medium roots, few termite channels, non calcareous, clear wavy boundary to,
E 20-38 cm	brown (10YR 5/3, moist), sandy loam, weak fine subangular blocky, very friable non sticky non plastic, many fine inped tubular random pores and common medium inped tubular random pores, many fine and few medium roots, few termite channels, non calcareous, clear wavy boundary to,
2Bt1 38-61 cm	brown (7.5YR 5/4, moist), sandy clay loam, moderate fine subangular blocky, firm slightly sticky slightly plastic, common (5-15%) fine faint mottles and common (5-15%) medium faint mottles, patchy thin cutans on pedfaces, many fine inped tubular random pores and common medium inped tubular random pores, few medium roots, few termite channels, non calcareous, clear wavy boundary to,
2Bt2 61-93 cm	brown (10YR 5/3, moist), sandy clay loam, moderate fine subangular blocky, firm slightly sticky slightly plastic, patchy thin cutans in root channels and pores, many fine inped tubular random pores and few medium inped tubular random pores, common fine and few medium roots, few channels, non calcareous, gradual wavy boundary to,
2BCv 93-180 cm	light brownish grey (10YR 6/2, moist), slightly gravelly sandy clay, weak medium subangular blocky, firm slightly sticky slightly plastic, many (15-40%) medium prominent sharp mottles (2.5YR 3/6) and many (15-40%) coarse prominent mottles (2.5YR 3/6), patchy thin cutans in root channels and pores, common fine inped tubular random pores, common fine roots, very few large ferruginous nodules, few termite channels, plinthite pans, non calcareous,

Current land use at the site	fallow
Major crops
Main type of irrigation
Rotation scheme
Vegetation Type;The natural vegetation at the site	grassland
Status of vegetation	secondary
Remarks on Land Use / Vegetation	Regrowth of Eupatorium Odoratum after monoculture of maize

The altitude of the soil profile relative to mean sea level, specified in meters	26 m asl
Regional landform	valley
Topography of the surrounding country	flat or almost flat
Physiographic Unit in the immediate surrounding of the site	side slope
The slope refers to the inclination of the land immediately surrounding the site. The measured or estimated slope angle is specified to the nearest per cent	1 %
The physiographic position of the site where the profile is located	middle slope
Form of the slope surrounding the site	straight
Slope Aspect of the site	south

Depth of groundwater table	100 cm
Groundwater Top	cm
Groundwater Bottom	cm
Kind of groundwater table	apparent
Top Stagnating Layer	cm
Bottom Stagnating Layer	cm
Runoff	medium
Flooding frequency	never
Estimated permeablity (class) of least permeable part of the profile	slow
Drainage Class	imperfect
To Drainage Class
Moisture conditions of the profile: dry from -to	cm
Moisture conditions of the profile: moist from -to	0-180 cm
Wet From - To	cm

Microrelief type: small-scale differences in relief in the direct vicinity of the site	level
Microrelief Height
Rockiness
Stoniness
Average size of stones
Shape of stones (on average)
Slaking of aggregates by tillage, rainfall or frost
Evidence of salt	non-saline
Evidence of alkali	non-alkaline

Soil erosion type (1st entry)
Occurrence of soil aggradation
Slope Stability

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Reference soil Nigeria 8: Plinthosol