  The agricultural sector is still lagging behind from all other sectors in
terms of using the newest technologies. For production, the latest machines are
being introduced and adopted. However, pre-harvest and post-harvest processing
are still done by following traditional methodologies while tracing, storing,
and publishing agricultural data. As a result, farmers are not getting deserved
payment, consumers are not getting enough information before buying their
product, and intermediate person/processors are increasing retail prices. Using
blockchain, smart contracts, and IoT devices, we can fully automate the process
while establishing absolute trust among all these parties. In this research, we
explored the different aspects of using blockchain and smart contracts with the
integration of IoT devices in pre-harvesting and post-harvesting segments of
agriculture. We proposed a system that uses blockchain as the backbone while
IoT devices collect data from the field level, and smart contracts regulate the
interaction among all these contributing parties. The system implementation has
been shown in diagrams and with proper explanations. Gas costs of every
operation have also been attached for a better understanding of the costs. We
also analyzed the system in terms of challenges and advantages. The overall
impact of this research was to show the immutable, available, transparent, and
robustly secure characteristics of blockchain in the field of agriculture while
also emphasizing the vigorous mechanism that the collaboration of blockchain,
smart contract, and IoT presents.
