## 4 Literature Review and Related Work
### Distributed Ledger Solutions (2016-Today)
[PERSON] studied the complexity and the problems of China's agriculture sector, concluding that poor organization is a very limiting issue [22]. Considering this, the proposed dual blockchain system consists of a user information chain and a transaction chain. The user information chain is used to record and store the user information of the agricultural business enterprises in the public service platform, while the transaction chain is used to record and store all transaction data. Results of the conducted trials of the proposed framework show that the double-chain solution not only ensures the transparency and security of transaction information and the privacy of enterprise information, but can also significantly improve the credibility of the public service platform and the overall system efficiency. [PERSON] et al. propose another interesting idea regarding the agriculture supply chain and the use of Industry 4.0 principles [85]. [PERSON] et al. refer to the idea of food democracy, according to which consumers are considered as citizens and the food not as a good but as a civil right. The authors advertise the idea of voluntary traceability and combine it with Industry 4.0 technologies. Their proposal concentrates on a framework consisting of a big data platform for handling collected data. This enables maintaining data paternity with respect to the supply chain operator and traceability towards the product. The significance of the voluntary traceability is highlighted, focusing on the volume and the quality of the data collected for each product, as well as the need for a big data platform to handle them. [PERSON] et al. propose an integrated solution of a blockchain platform named AgriBlockIoT in the agriculture supply chain [23]. AgriBlockIoT is a fully distributed system which uses the blockchain technology in combination with IoT devices in order to collect and distribute traceability data. The proposed solution was tested with two different blockchain platforms, namely Ethereum and Hyperledger Sawtooth. Trial results showed that Ethereum performed considerably better compared to Hyperledger Sawtooth, in terms of latency, CPU and network usage. AgriBlockIoT enables the integration of IoT and blockchain technologies, creating transparent, fault-tolerant, immutable and auditable records which can be used for an agri-food traceability system. Furthermore, [PERSON] et al. propose another system based on blockchain and IoT technologies for the agriculture supply chain [60]. Specifically, the authors try to combine the technologies of blockchain, IoT, low-power wide-area network (LPWAN) and existing enterprise resource planning (ERP). The proposed platform, which aims to solve food safety and trust issues of the traditional agri-food supply chain, involves all parties within a typical agriculture supply chain ecosystem. In 2018, many more articles on the application of blockchain technology into the agriculture supply chain were published. A number of researchers ([5; 24; 25; 26; 27; 28; 33; 34; 46; 52; 65; 86]) propose similar solutions regarding the integration of blockchain in the agriculture supply chain with small scale differentiations. [PERSON] et al. [27; 52] propose the FTSCON (Food Trading System with Consortium blockchain), an automated merchant transaction mechanism for the agri-food supply chain. FTSCON improves transaction security and privacy protection by using smart contracts and a consortium (private) blockchain which is more efficient than a public one in terms of financial cost and computational power. [PERSON] et al. [28] introduce the Harvest Network, a blueprint to build a \"farm to fork\" food traceability application, where they combine the Ethereum blockchain and IoT devices with GS1 message standards. The Harvest Network introduces the idea of tokenized smart contracts, in which the contract is not subject to global consensus and does not have to be validated by the entire network, but instead is only be processed by dynamically sized node clusters, thus improving efficiency.