New research shows that agricultural reserves, a process of adding lime to the soil, can remove CO2 from the atmosphere rather than causing carbon emissions.
Researchers at Yale University’s Yale Natural Carbon Capture Center were discovered based on over 100 years of data and detailed computer modeling from the Mississippi River basin.
They found that air pollution and the addition of acidity in the form of fertilizers is a major factor in CO2 emissions from the soil.
Calculating emissions based on acidic inputs indicates that emissions may be underestimated in some cases, and the possibility of reducing agricultural restrictions is overlooked.
Carbon emissions in agriculture
Agriculture is one of the largest greenhouse gas emissions sectors, with a significant proportion of soil-related agricultural emissions.
The Intergovernmental Panel on Climate Change (IPCC) calculates that all carbon in lime is released as CO2 when added to agricultural soils and reduced acidity, but some countries use low numbers.
How agricultural restrictions release CO2 from soil
When lime is added to the soil, it reacts with carbonic acid to produce bicarbonate, calcium and magnesium. When strong acids are present in soils such as nitric acid or sulfuric acid, these react with bicarbonate to produce carbonic acid, which releases CO2.
Lead author, Dr. Tim Jesper Souhoff, the center of the Yale Natural Carbon Capture Center, said, “It is the reaction to acidity with carbonates that generates CO2 emissions, not the agricultural restrictions themselves.
“In the absence of strong acids, the riser does not lead to emissions, and in reality removes CO2 from the atmosphere through the formation of bicarbonate.”
He added: “Continuing to add acidity to the soil will react with the remaining natural alkaline pools to create emissions. By punishing farming restrictions rather than acidic additions, you could target the wrong driver and lose other benefits that could potentially result from reriding.
Removal is done at 75% of the maximum rate
Researchers used data from the Mississippi River basin collected since 1900 to calculate the impact of agriculture on air pollution, fertilizer use, and CO2 emissions.
This data shows that industrial pollution from fossil fuel combustion and the increasing use of nitrogen fertilizer since the 1930s have produced high levels of acidity in the soil.
Since the 1930s, when limestone applications to farmlands increased significantly, both the effectiveness and efficiency of carbon dioxide removal have also increased, as shown in river records and model results.
Researchers estimated today that removal occurs at about 75% of the theoretical maximum velocity.
Calling for policy reforms on agricultural emissions
Based on their results, researchers are calling for a rethinking of policy on agricultural emissions, with emissions related to the addition of acid fertilizers rather than lime.
But they emphasize that this needs to be handled with caution.
“For a long time, we have known that Liming is perfect for farmers and global food security,” explained Dr. Suhrhoff.
“What we’re showing here is that it’s also an efficient way to remove CO2 from the atmosphere, more than a longer timescale. Before adding large amounts of silicate rock to neutralize acidity, it may be the best strategy to limit emissions and get the additional benefits that Liming offers.”
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