CARBON CLEANSE: Agricultural liming answers to climate change, researchers say

Daniel Piamonte

As cities choke on carbon smog and farmlands suffer under scorching heat, one overlooked farming technique is digging up fresh hope—agricultural liming.  

In the fight for a greener world, this centuries-old soil treatment is an ally that cleanses carbon emissions and locks it into the Earth.

Researchers from the Yale Center for Natural Carbon Capture at Yale University revealed that liming, when applied properly, offers a simple, soil-deep solution in combating climate change. 

Plowing greater purpose

With the growing demand for agricultural products, farmers are often dependent on fertilizers to hasten crop growth. However, the utilization of fertilizers pose adverse effects—excessive application can hinder plant growth and increase acidity in soil. 

As remedy, farmers apply lime, primarily calcium carbonate (CaCO₃),  to neutralize acidity and restore soil balance.

Even so, the Intergovernmental Panel for Climate Change (IPCC), estimates that all the carbon in lime is eventually released as carbon dioxide—leading some to blame liming for added emissions.

However, a recent study challenged this view.

Researchers from Yale noted that it’s not lime itself, but rather the presence of strong acids in the soil—like nitric and sulfuric acids from fertilizers and pollution—that causes carbon dioxide emissions during the liming process.

In fact, in low-acid conditions, lime doesn’t emit carbon dioxide at all. Instead, it reacts with carbon dioxide  to form bicarbonate, a stable compound that stays in the soil. This process allows liming to act as a natural carbon removal.

“It is the reaction of acidity with the carbonate that creates carbon dioxide emissions, not the addition of the lime itself,” explained Tim Jesper Suhrhoff, lead researcher from the same university.

Digging through data

Researchers combined historical records from the Mississippi River Basin, and ran detailed computer modeling to investigate the long-term effects of liming, fertilizer use, and industrial pollution.

The study found that industrial pollution from fossil fuel burning and widespread nitrogen fertilizer use since the 1930s have sharply increased soil acidity, which current lime application has yet to fully neutralize.

Contrarily, the popularization of liming in the 1930s significantly improved capacity of agricultural lands in removing CO₂, with soil-based carbon removal now estimated at about 75% of its theoretical maximum.

Despite its benefits, liming is penalized, since policies assume that it contributes to carbon emissions. However, doing so will only worsen soil acidity—hampering plant growth and lowering crop yield.

“By penalizing liming, rather than the addition of acids, we are targeting the wrong driver and potentially losing the other benefits that liming can bring, in terms of increased yields and lower nitrous oxide emissions,” emphasized Suhrhoff.

With this, researchers are hoping for policy reform that links carbon emissions to supplementing acid fertilizers, not liming.

Climate comeback

The researchers recommend another greener approach in capturing carbon. 

First, neutralize soil acidity with a large amount of silicate rock, then safely apply lime. This maximizes CO2 removal from the atmosphere while allowing farmers to reap other benefits of liming, such as greater crop yields and healthier soil condition. 

“We have known for a long time that liming is great for farmers and global food security. What we show here is that over longer timescales, it is also an efficient way to remove CO2 from the atmosphere,” noted Suhrhoff.

As of now, this research is being presented at the Goldschmidt Conference in Prague, one of the world’s leading forums on Geochemistry. 

In a world where climate catastrophes loom closer each year, the study sparks global discussion on the role of sustainable agriculture in climate change mitigation.

Indeed, carbon cleansing through lime hints that some climate solutions to a greener future are simply right under our feet all along.