Assessing biochar stability in soils in the context of climate change using a novel approach: tree ring “bomb carbon” biochar

Biochar has attracted attention for its potential to improve soil fertility and sequester carbon (C). The biochar market is expanding, both in Sweden and globally.

This project aims to address key knowledge gaps regarding biochar persistence in soil, and provide insights into its role in the turnover of soil organic matter (SOM).

Our research group have recently developed a method that builds on the accumulation of the radioactive isotope 14C in tree rings from the period when atmospheric nuclear bomb tests doubled the 14C levels in atmospheric CO2.

By making biochar of wood grown between 1963 and 1967, I have produced an isotopically labelled biochar that can be utilized to specifically study the mineralization of wood-based biochar in the soil. The feasibility of the method has been verified. I intend to utilize the method to address critical questions on biochar stability and its interactions with SOM.

I will test the effect of pyrolysis temperatures, soil temperatures and repeated freeze/thaw cycles, on biochar persistence and organic matter dynamics in soil through both lab incubations and field experiments.

The results are expected to address key knowledge gaps regarding biochar persistence in soil and provide valuable insights into its role in C sequestration.