Current tracking systems that are being implemented in the agricultural supply chain involve the following challenges: centralized control, lack of agreed data standards, data reliability, and data ownership. To address these challenges, we are creating a blockchain-based traceability system. This system relies on the strength of blockchain whereby product information can be stored and retrieved and can never be altered. This brings about the much-needed transparency and reliability in the supply of items in the chain. Our approach uses Ethereum, a decentralized blockchain platform that supports smart contracts and decentralized applications. We also introduce a reputation-based smart contract scheme, which motivates network nodes to provide traceability data. Additionally, we have analyzed the performance of our system and applied it appropriately. The results show significant improvements in query efficiency, personal information protection, and information accuracy and reliability in agricultural supply chain management.