Observations on induced diffusion of innovations as a component of tropical agricultural extension systems

In designing extension systems, answers to the question ‘How many extension agents are needed?’ are always given. The question is, in practice, answered intuitively and this paper enquires whether economically optimal answers are conceivable. It appears that, so long as farmers vary in their propensity to innovate, there probably are least-cost solutions to the question in respect of specific projects. The underlying theory is complex and the treatment presented here is simplified, perhaps oversimplified. In discussion, the importance of diffusion processes as an agent of innovative change is emphasised.