As Jenny Aker says, there's more data than you might think on the impact of agricultural market information systems. In Module 9 of the ICT in Agriculture Sourcebook, on page 208 (see: http://www.ictinagriculture.org/ictinag/sites/ictinagriculture.org/files/final_Module9.pdf) there is an aggregated summary of around a dozen different impact studies, showing the impact on prices for farmers, traders and consumers.

But there is a bigger issue here which I would summarise as "Why are mobile agricultural information systems not scaling up as expected?" The reasons for this are complex, but I think they have to do with fragmentation of the market -- by mobile operating system, by crop type, by system, by periodicity of information etc. These type of fragmentation issues are typical of relatively less mature markets and I think we will see better growth prospects once consolidation in the marketplace occurs