BLOCKCHAIN-POWERED AGRICULTURAL CARBON CREDIT MARKETPLACE: A Verifier-Attested Architecture for Smallholder Credit Generation, Buffering, and Trading

Agriculture has the potential to deliver substantial amounts of verified carbon removals, but smallholders rarely participate: costs of certification are fixed per project, evidence of soil carbon is challenging to elicit and verify, and tokenized-credit markets to date are thin and fragmented. This paper describes a blockchain-based marketplace where agricultural credits are both issued and exchanged within a unified platform to ensure supply chain integrity. The design involves farmer-side evidence capture, digitalization with conservative uncertainty discounts, a k-of-n quorum of accredited verifiers, batch-minted tokens that encode quality information, a buffer pool for reversals, and an escrowed order-book market that settles on-chain and delists in a national registry. As the implementation of the system has yet to happen, the attributes of the system are assessed in terms of mathematical models in which parameters are determined beforehand. Through Merkle batching, transaction costs decrease from 24,000 to 46 gas units for every record at the batch size of 1,000. A quorum consisting of 5 out of 9 members results in a reduction of the risk of accepting a false proof by 100 times to 0.09% if 10% of the validators are compromised. Detection of spatial overlaps allows for the identification of parcels that are being enrolled multiple times with respect to the GPS discrepancies below 5 meters with recall worth at least 99.4%. The aggregated project would require 446 ha under the assumption of baseline conditions instead of 1,713 ha to achieve cost-effectiveness, while the buffer cost percentages of 15 to 30% could be required depending on the level of risks. The results are entirely hypothetical and should be interpreted as scenarios rather than measurements in any deployed system.