Ground volcanic rock, when applied to agricultural fields, might play a pivotal role in capturing atmospheric carbon, potentially counteracting global warming. A collaborative study by Cornell University and the University of California, Davis in arid areas found that this technique efficiently sequestered carbon in the soil, even amidst severe droughts.
This mechanism operates as rainwater absorbs carbon dioxide from the air and subsequently interacts with volcanic rock to trap it. While this rock weathering process naturally spans millions of years—too lengthy to combat global warming—it can be drastically expedited by grinding the rock into fine particles and mixing it with soil.
Prior studies suggest that if global farmlands adopted this enhanced rock weathering, they could potentially sequester 215 billion tons of carbon dioxide over the next 75 years. Yet, until now, the method hasn’t been tested in dry landscapes.
To address this, the researchers conducted experiments on a dormant cornfield spanning five acres in the Sacramento Valley. Here, they dispersed ground rock, specifically metabasalt and olivine. Metabasalt stems from the cooling and solidifying of lava on the earth’s crust, whereas olivine is a mineral present in certain igneous rocks.
During the winter of 2020–2021, they gathered data. This period marked a severe drought in California, with precipitation levels dropping to 41% below the norm—a condition potentially unfavorable for rock weathering.
The researchers aimed to ascertain if this approach was viable in arid conditions and to validate the accuracy of their measurement techniques for assessing its global carbon storage potential. It’s noteworthy that drylands constitute 41% of the earth’s land area, a percentage likely to increase due to climate shifts.
A recent study revealed that plots treated with crushed rock retained 0.15 tons more carbon dioxide per hectare than untreated sections. While rock weathering rates might vary across locations, extracting such an amount of carbon from all Californian farms equates to taking 350,000 cars off the highways annually.
