This study builds on existing conceptual frameworks and published studies on agricultural extension, to unpack the efficiency and effectiveness of different communication channels.

Focusing on studies from low-and-middle income countries, to draw lessons for sub-Saharan Africa, findings show that there is a huge variability in estimates of both cost efficiency and effectiveness of different agricultural extension communication channels. This is attributed to various factors including the enabling environment, quality of the communication channel or the relevance and quality of messaging. Although value-for-money considerations are important, there is a risk that over-emphasis on cost efficiency can undermine delivery of real change. Reaching a large audience can be achieved but unless attention is paid to information quality and context, and whether mass reach channels are appropriate, positive benefits associated with the uptake of good agricultural practices will not be achieved.

Given these findings, the purpose of communication should precede the choice of communication channels based on cost efficiency and cost effectiveness. A combination of communication channels allows for larger reach and increases overall effectiveness of extension campaigns as multiple types of communication channels have complementarity and are synergistic thus better able to trigger behavioural change. This justifies extension campaign strategies that combine different channels for different types of communication.