Field-scale evidence for soil organic carbon response to enhanced rock weathering

Enhanced rock weathering (ERW) is as a measure to remove carbon dioxide from the atmosphere. ERW refers to an artificial acceleration of the natural reaction of silicate-bearing rocks with atmospheric carbon dioxide forming carbonates in the soil - thereby removing carbon dioxide from the atmosphere. The added rock material also changes the physical-chemical soil environment which potentially can have long-lasting impact on the functioning of the ecosystem. For example, it could lead to changes the carbon present in soils, which could provide further carbon dioxide removal or increased greenhouse gas emissions which would accelerate man-made climate change.

In a new study in Global Change Biology, we show that ERW cause changes in soil organic carbon which exceed the carbon dioxide removed by ERW - providing first field evidence for an additional carbon dioxide removal. After two years of ERW in a rubber plantations more carbon dioxide had been sequestered in organic matter than was captured by silicate weathering reaction. This was because of an up-regulation of the so-called mineral carbon pump which leads to formation of stable soil organic matter forms from plant residues. This is in contrast to findings in irrigated cropland field trials in California, USA, where the mineral carbon pump was inhibited by ERW. 

While the few studies disagree about the direction of the response of soil carbon to ERW, they demonstrate that such changes cannot be omitted and must be included in assessments of the carbon dioxide removal by ERW. 

Xu, Tongtong, et al. "Enhanced silicate weathering accelerates forest carbon sequestration by stimulating the soil mineral carbon pump." Global change biology 30.8 (2024): e17464.
APA