Reference soil Nigeria 06: Nitisol

NG006

Nitisols occur mainly in the tropics and subtropics, as well as in areas with a Mediterranean type of climate. They are associated with basic rocks (e.g. basalts) or hard limestone or dolomite deposits.

Characteristics

Soils having a nitic horizon (a horizon with pronounced nut-shaped soil structure and significant amount of active iron) within 100 cm from the soil surface, and gradual to diffuse horizon boundaries between the surface and the underlying horizons. They do not have a ferric, plinthic or vertic horizon within 100 cm from the soil surface.

Distribution of Nitisols (rough estimation supplied by soilgrids)

Reference soil NG006: Nitisols

Physiographic unit: In a wide valley in a flat to gently undulating Pleisto-Pliocene terrace landscape. Visible sand grains throughout the profile most commonly subrounded, many rounded. INRA classification: Sol ferralitique peu desature apprauvi modal Additional notes on profile description: A2: Fine and medium inped pores plus some medium tubular pores. B22t: Pores gradually diminishing; locally moderately thick cutans and faunal channels. Brief description of the soil: Deep, red clayey soil with a sandy surface soil up to 30 cm. Ikenne toposequence, profile no. 080. Profile forms part of IITA-LRD-ISM Co-operative Program. Worm casts at the surface; subterranean termite chambers, up to 15 cm in several places of the profile. Pieces of pottery scattered through upper 50 cm. 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. Murduch, G.; Moormann, F.: Identification of soil toposequences in the humid tropics of West Africa. Foreign and Commonwealth Office - Overseas Development Administration, miscellaneous report 178. 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.

Classification

WRB 2014

Nitisol

FAO-UNESCO-ISRIC 1974

Eutric Nitosol

Local classification:	Alagba Series

Other classification

USDA-SCS (1975)

Paleustalf udic clayey kaolinitic isohyperthermic

Profile description

Ah 0-13 cm	dark reddish brown (5YR 3/3, moist)sandy loam,moderate fine crumb,very friable slightly sticky non plastic,many medium interstitial pores and common tubular random pores,gradual smooth boundary to,
E 13-30 cm	dark reddish brown (5YR 3/4, moist)sandy loam,weak medium subangular blocky parting to fine crumb,very friable slightly sticky non plastic,common fine interstitial pores and many inped tubular random pores,gradual smooth boundary to,
BE 30-45 cm	dark reddish brown (2.5YR 3/4, moist)sandy clay loam,weak to moderate fine subangular blocky,friable slightly sticky slightly plastic,patchy thin unspecified on pedfaces cutans,many fine inped tubular random pores and common inped tubular random pores,gradual smooth boundary to,
Bt1 45-105 cm	dark red (2.5YR 3/6, moist)sandy clay,moderate fine subangular blocky,firm slightly sticky plastic,broken thin unspecified on pedfaces cutans,many fine inped tubular random pores,diffuse smooth boundary to,
Bt2 105-150 cm	dark red (2.5YR 3/6, moist)sandy clay,moderate fine subangular blocky,firm slightly sticky plastic,broken thin unspecified cutans,common fine inped tubular random pores,few channels,

Depth1	400cm
Mode of accumulation or deposition of parent material	marine sediments
Remarks on Parent Materials	uniform in lithology
Texture of parent material (second entry)	clayey
General characterization of the status of weathering of solid rock	highly

Land improvements ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	land clearing
Land use or vegetation in the immediate vicinity of the site	fallow
Remarks on Land Use / Vegetation	Eupatorium odoratum after clearing
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	shifting - fallow grass
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)	grassland

Altitude	26m
Physiographic Unit	see remarks
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%
Slope Aspect	south-west
Form of the slope surrounding the site	straight
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	flat or almost flat

Flooding frequency (FAO, 1986)	never
Kind of ground water table (USDA, 1979)	no groundwater table observed
Moist From - To	0-150cm
Estimated permeability (class) of least permeable part of the profile	high

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Reference soil Nigeria 06: Nitisol

Characteristics

Reference soil NG006: Nitisols

Classification