"Enhanced Weathering" for Soil Carbon Sequestration
In this era of concern about climate change, and with the accepted fact that traditional row crop agriculture is a significant contributor to the release of CO2 to the atmosphere, scientists are constantly looking for new technologies that will reduce the amount of soil-derived carbon [C] that is released from cropland acres. Scientists at the Univ. of Illinois Urbana-Champaign Institute for Sustainability, Energy, and Environment [iSEE], in cooperation with scientists from the Leverhulme Centre for Climate Change Mitigation in Sheffield, UK, have developed a new method to calculate the CO2-reduction potential of basalt rock amendments that may be added to cropland soils. Details of this process, known as “enhanced weathering”, are reported in an article titled “Improved net carbon budgets in the US Midwest through direct measured impacts of enhanced weathering” that appears in the journal Global Change Biology.
The research used to develop the technology was conducted at the Univ. of Illinois energy farm between 2016 and 2020. An article titled “Climate Win-Win: Enhanced Weathering” by iSEE Communications Specialist Julie Wurth provides a summary of the research and its meaning.
Important points about this research and its findings follow.
• Applying finely-ground basalt rock [formed from the rapid cooling of lava] to farm fields can capture significant amounts of CO2, and prevent it from being released to the surrounding atmosphere.
• With “enhanced weathering”, the rock is applied to cropland to capture C before it is released to the atmosphere. As the rock weathers, calcium and magnesium are released from it and react with dissolved CO2 in the soil to produce bicarbonate, which is harmlessly redirected to the groundwater.
• The research reported in the above-linked Global Change Biology article reports results that quantify the weathering rate and CO2 reduction potential of the basalt rock that is applied as an amendment to soil.
• According to the authors of the study, the “basalt additions, by pumping inorganic C from the atmosphere to ground water, effectively offset up to 42% of C emissions from a maize/soybean cropping system, and when paired with conservation tillage or cover cropping, could turn this cropping system into a net C sink.
• In addition to calcium and magnesium, basalt also contains phosphorus and minor nutrients that are released during weathering, and this could benefit soil fertility.
The results from this research are important to those producers who are seeking C credits that can qualify for the various Carbon programs that are available. Questions about using this product in the Midsouth are:
• What is the availability of the rock product?
• What is its cost, including purchasing, shipping, and application?
• How much of the rock should be applied per acre to realize the maximum economic benefit?
• Are there suitable alternatives to the basalt rock if it is not available or is prohibitively expensive to use for the “enhanced weathering” purpose at Midsouth locations?
Composed by Larry G. Heatherly, Aug. 2023, larryh91746@gmail.com