(a) Draw an outline map of Nigeria. On the map, locate and name: (i) three major soil zones (ii) an important crop associated with each zone; (iii) an impor...

(a) Outline map of Nigeria: soil zones, crops and towns

The map below shows three major soil zones and their associated crops. Kano and Ibadan are the two towns located in the northern sandy-soil zone and the southern forest-soil zone respectively.

(b) Characteristic features of two soil zones

1. Northern zone of sandy soils

• It occurs mainly in the far northern part of Nigeria, where the climate is arid or semi-arid.
• It is formed under low rainfall and sparse vegetation.
• The soil is loose, friable and porous, with coarse sand grains and a sandy-loam texture.
• It is easy to cultivate and is generally well drained.
• It contains little humus and has low water-holding capacity, so it dries out rapidly.
• It is not heavily leached because rainfall is relatively low.
• It supports crops such as groundnut, millet, cotton and maize, especially where moisture is adequate.

2. Interior zone of lateritic soils

• It is widespread in the interior and Middle Belt of Nigeria.
• It develops under alternating wet and dry tropical conditions and is commonly reddish or brownish in colour.
• Its red colour results from iron compounds; it also contains aluminium compounds.
• It is heavily leached by rainfall and is therefore generally of medium fertility unless manure or fertiliser is added.
• It is sticky when wet but hard and compact when dry, and may become relatively impervious.
• It supports food crops such as yam, cassava, cocoyam and maize.