The Soil Organic Carbon Knowledge Graph (SOCKG) enhances robust soil carbon modeling, which is crucial for voluntary carbon markets. These markets create incentives for climate-friendly practices by encouraging the retention of carbon in soil, reducing atmospheric carbon levels. Industry sectors, like energy and transportation, purchase carbon credits to offset unavoidable emissions, while farmers and land managers are rewarded for adopting practices that increase soil organic carbon (SOC). For these markets to function effectively, it is essential to have advanced soil carbon modeling technologies that accurately measure SOC content, predict changes, and link those changes to specific agricultural practices. High-quality data is central to this process. By integrating siloed data into a cohesive knowledge graph, linking it to broader datasets, and establishing infrastructure for its sustainability, SOCKG can play a transformative role in enabling and accelerating the growth of this emerging market.