Guiding Methodologies for Soil Processing and Analyses to Support Rigorous Soil Carbon Accounting

This white paper examines how laboratory soil processing methods influence the accuracy and consistency of soil organic carbon measurements used in carbon markets, climate reporting, and soil health assessments. Researchers compared multiple processing techniques—including sieving, grinding, drying, and carbon quantification methods—across agricultural soils and eight external laboratories. The findings demonstrate that inconsistent laboratory procedures can significantly affect soil carbon results. The paper provides practical recommendations for standardizing laboratory methodologies, improving reproducibility, reducing variability, and strengthening confidence in soil carbon accounting for researchers, policymakers, carbon credit programs, and sustainability initiatives.