Yam production in Nigeria Wikipedia
Yam is grown on free draining, sandy and fertile soil, after clearing the first fallow. Land is prepared in the form of mound or ridge or heap of 1 metre (3 ft 3 in) height. The yams recommended for such soil conditions in Nigeria are white yam or white guinea yam (Discorea rotundata) and water yam or yellow yam (Discorea alata).