Biochar stability scores from analytical pyrolysis (Py-GC-MS)

Abstract

The long-term stability of biochar in soil is key for carbon capture and storage and soil amelioration. Yet, its assessment is hampered by the long time-horizons needed to actually probe biochar’s stability. Therefore, quick and reliable estimation methods are sought. Analytical pyrolysis (Py-GC-MS) offers a quick tool to predict biochar’s stability in soil, if adequate and validated metrics can be extracted from it. This work derives and validates stability scores from biochar pyrograms and advanced data analysis. The stability scores were benchmarked by comparison with other stability metrics (Edinburgh stability tool, fixed carbon content and atomic H/C ratio). Calibration of the stability scores with these stability metrics had an R2 between 0.61 and 0.95; validation resulted in R2 between 0.59 and 0.72. Overall, this work illustrates how Py-GC-MS can lead to simple and adequate predictors of biochar stability.