  To provide sustainable digital agro-advisory services to farmers, seamless
flow of information from the farmers to the experts/expert systems, and vice
versa is required. The query generated by the farmers, which may contain
multimedia data regarding disease or pest attack in the crops is required to be
transmitted to the experts for analysis. Further, after analyzing the query, an
alert or advice from the expert system is required to be communicated back to
the farmers within some tolerable delay. However, in a country like India,
network connectivity is extremely poor in several agricultural regions which
makes the end-to-end connectivity between the farmers and the expert system
intermittent. Therefore, providing agro-advisory services to farmers in a
reasonable time becomes a challenge. In this paper, we propose a Delay Tolerant
Network (DTN) based relay application model which enables agro-advisory
services to farmers located in \emph{No-network} or \emph{Poor-network} zones.
In the proposed model, end-to-end communication has been enabled with the help
of Device to Device (D2D) communication and by introducing mobile relay nodes
which can carry the queries (responses), from (to) the poor or no network zones
to (from) the zones where communication is possible. Implementation of this
model has been presented for the tea farmers of West Bengal and Assam, which
can be extended for various other applications in future.
