Adaptation, validation and application of the chemo-thermal oxidation method to quantify black carbon in soils

► The CTO-375 method was adapted and validated for BC analysis in soils. ► Method validation figures of merit proofed satisfactory. ► Application is shown with soil cores and topsoil temporal variability. ► BC content can be elevated in subsurface soils. ► BC contents in surface soils were largely constant over the last 25 years.