Enhanced rock weathering (ERW) helps remove carbon dioxide from the atmosphere by speeding up the natural process of rock weathering to lock away carbon and to release nutrients into the soil. The Carbon Community is studying the impact of this geological process on trees, soil and forest ecosystem carbon as part of our carbon study which was launched in May 2021.
We caught up with Kat Clayton from Imperial College London to discuss why volcanic rocks are so important and why the weathering process is called ‘enhanced’.
The basalt used by The Carbon Community is a surplus by-product left over when basalt is mined for purposes such as road construction. The weathering process is called ‘enhanced’ as the rock has already been crushed before being added to the soil.
“The benefit of having crushed rock is that it’s increasing the surface area of the grains, and that increased surface area means that there's more space to react with rainwater and other elements in the soil.”
That increased surface area helps the basalt break down faster to absorb carbon molecules from the atmosphere and to release nutrients into the soil to be used by plants and microorganisms.
The short answer is no!
“What we want are volcanic rocks that have been formed deep below the earth's surface under high pressures and high temperatures, because once they then reach Earth's surface, they are very unstable, and they dissolve very quickly. They release lots of nutrients that way.”
“The kind of minerals that we would really like to have from these volcanic rocks includes things like olivine, pyroxenes, calcium rich feldspars, all of which are present in basalt rocks in particular. Calcium is something that's really important for plants and microorganisms in the soil. And so, when those minerals are dissolving in the soil, they're releasing that very crucial nutrient to be used by everything else that's in the soil as well.”
· Learn more about The Carbon Community’s carbon study
· Explainer blog and video on how we are measuring rock weathering
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