Paessler et al. (2026): Is biomass yield increase a potential indicator for CDR performance of enhanced weathering?
Dirk Paessler, Jens S. Hammes, Ingrid Smet and Anna A. Stoeckel, IN: ResearchGate (preprint), https://doi.org/10.13140/RG.2.2.19883.50723
Enhanced weathering (EW) of alkaline feedstocks such as natural rocks or industrial by-products is a promising approach to remove CO₂ from the atmosphere. Finely ground feedstock, containing silicate and/or carbonate minerals, is spread on fields. When rain and CO₂ form carbonic acid it dissolves these minerals, which releases base cations and nutrients into the soil and also increases soil pH. The beneficial effects of rock dusts like lime on yields have been appreciated by farmers for centuries. For CDR projects crop yield increase is a welcome co-benefit, while the main desired effect is that the cations from the dissolving rock accompany bicarbonate ions in the leachate waters, which can be measured as increase in total alkalinity (TA). This carbon transport is essentially a way of capturing carbon from the air, a climate mitigation approach that is currently challenged by the high cost of MRV. When assessing the above-ground biomass and leachate data from the 2023/2024 greenhouse experiment, the authors have observed a significant correlation between the two. A significant increase in TA export of the rock-dust-treated pots almost always coincided with a significant increase in biomass. But the data does not yet allow the authors to understand what is the cause, and what is the effect. To fill this knowledge gap they published a call for proposals in October in which they offered their sample archive to labs for further investigation.