AI for Monitoring, Reporting and Verification of Biochar Carbon Market

Moonshot Award

Patent or Technology Development

Abstract

Pyrogenic carbon (pyC) is a leading pathway for durable soil carbon storage, but quantifying its permanence is difficult, mostly obtained by incubating fresh biochar. We addressed this by pairing incubation kinetics with the radiocarbon record of pyC that has already persisted in soil. Across 17 soils sampled by A, B, and C horizon (51 samples) from five major U.S. soil orders, we combined 35-day incubations with ¹³C-labeled microbial and straw amendments, radiocarbon dating, elemental composition, and Random Forest modeling to link mineralization, age, and composition. Radiocarbon ages spanned modern to ~34,000 years and increased with depth. pyC mineralized roughly seven-fold slower than co-occurring native soil organic carbon, and neither mineralization rate nor H/C ratio varied significantly with age, indicating no loss of stability over millennia. Exchangeable calcium, pH, depth, and nitrogen outranked intrinsic char chemistry as predictors of age, implicating mineral and metal interactions in persistence .These results provide direct, multi-millennial evidence that pyC durability does not decline with time, informing permanence accounting for soil carbon removal.