キャッサバの導入に関する一考察

東部ナイジェリアの例

抄録

It has been said that there was no problem of food production in Nigeria until the 1960's. This country could produce enough food to satisfy her domestic demand which had increased very rapidly in coincidence with the rapid growth of population. Accordingly, numerous studies have been devoted to discover a mechanism of rapid food production.
An influential hypothesis set up mainly by economists and agricultural economists is the land-surplus-economy model which postulates that the increased food production in Nigeria may have been achieved by the mobilization of unused or underutilized land with relatively small additional labor input. On the other hand, some geographers have assumed that the growth of food production can be achieved by land-intensive cultivation techniques which have been developed without a change in farm implements.
In this paper, the author attempts to clarify the process of the growth of cassava production in Eastern Nigeria, hopefully, in support of the latter explanation. Originally, cassava was introduced from tropical America. It was considered to be a food inferior to yam. When farmers began to cultivate cassava, they had to change land-use pattern (increased inter- or mixed-cropping, use of manure, more developed crop complex). The author believes that they could manage it with relatively small additional input and that this is why farmers could feed a larger population under traditional methods of cultivation before the 1960's, particularly in Eastern Nigeria.