# Blockchain Applications in Agriculture: A Scoping Review
### Blockchain Technology  
According to [PERSON] [13], the agricultural sector is one of the industries with the least integration of digital technologies. Nevertheless, the use of information and communications technologies, such as blockchain, deep learning, and the Internet of Things (IoT), promise to bring digitization to agriculture and solve the above problems [14]. Specifically, blockchain, due to its decentralized nature and management, could potentially provide solutions to ensure the integrity and immutability of transactions.  
The first distributed blockchain technology was described as a fundamental component of the Bitcoin cryptocurrency [15]. This idea proved to be a success and managed to change the model of central management. The inherent features of blockchain architecture and design provide properties such as transparency, decentralisation, accessibility, autonomy, and immutability. In its original application in Bitcoin, the blockchain allowed users with only a predefined function, which was to exchange cryptocurrencies. However, that changed drastically in 2015 with the creation of Ethereum [16]. Ethereum is a blockchain system that allows anyone to build applications that will run on it. These decentralized applications are called DApps, based on smart contracts and written in high-level programming languages.  
Through smart contracts, decentralized structures can enable transactions between organizations without a central authority to be in control. Blockchain introduces the idea of \"Decentralized Autonomous Organizations\" (DAOs), where organizations can form entities where no central authority will be needed, but everything will be regulated by specific rules that they will have agreed upon and will be imposed by smart contracts [17; 18].  
The proper functioning of these DAO entities as well as the blockchain is based on consensus algorithms. The consensus protocol defines how different nodes agree on a result that will be appended to the next block [19]. It ensures security, data accuracy, and that all members follow the rules that have been set. The consensus algorithm differs, depending on the type of blockchain. Public and private blockchain use different consensus algorithms based on their requirements. The different need for trust between these types of networks defines the consensus algorithm. In public blockchains where anyone can participate, there is no trust in the network and therefore heavier consensus algorithms are needed to ensure network integrity. Consequently, variants of Proof of Work (PoW) or Proof of Stake (PoS) algorithms are used that offer fault tolerance and security but a slow transaction confirmation rate [20]. On the contrary, in private blockchains, all participants have a known identity and role, so they are governed by trust and more efficient consent algorithms can be used in terms of transaction speed. The most common of these are: the Practical Byzantine Fault-Tolerance (PBFT) and Raft consensus algorithms [21]. Finally, the need for blockchain in particular application domains has led to the recent trend of creating application-specific consensus algorithms suitable for specific tasks (e.g., IoT, supply chain, and trading) [20].