Study Shows Limestone Locks Carbon, Boosts Yields

Adding crushed limestone (calcium carbonate) to farmland can help remove carbon dioxide from the atmosphere each year while also improving soil health and boosting crop production, according to a recent study led by Yale University and published in Nature Water.

Limestone is already widely used on Irish farms to correct soil acidity and support plant growth. The study found that it also has the potential to store carbon for thousands of years by producing bicarbonate when it interacts with the soil. This bicarbonate can wash into rivers and oceans, where it helps lock away carbon for the long term.

Noah Planavsky, associate professor at Yale and co-author of the study, explained that applying multiple tonnes of limestone per acre could remove billions of tonnes of carbon dioxide globally by the end of the century. Using limestone alongside other soil amendments could help turn farmland into a carbon sink rather than a source.

The research also points out that nitrogen fertilisers can create acid in the soil, which releases carbon. Adding enough limestone to neutralise this acid helps the soil hold on to carbon instead.

Liming also brings other benefits. The bicarbonate that reaches the ocean can help raise ocean pH, supporting shellfish and marine life that are important to Ireland’s coastal communities.

Peter Raymond, biogeochemistry professor at Yale and co-director of the Yale Center for Natural Carbon Capture, said that adjusting liming practices on farms offers a natural way to capture carbon while improving soil health and crop yields.