Can arbuscular mycorrhizal fungi speed up carbon sequestration by enhanced weathering?

Societal Impact Statement Mitigating climate change and increasing agricultural sustainability are twin challenges society faces in the upcoming decades. One measure that can contribute to reducing atmospheric CO2 is enhanced weathering through application of ground silicates. Here we propose that mycorrhizal fungi may critically contribute to the success of enhanced weathering in agricultural systems. Fundamental lab-based experiments now need to go hand in hand with real-world field trials, with the goal to optimize both decarbonization and environmental sustainability of agricultural ecosystems. Arbuscular mycorrhizal fungi have significantly contributed to weathering of the earth's surface since their evolutionary origin 400-500 million years ago. They have been a key player in the global carbon cycle over geological timescales. In order to reach the global warming targets as agreed at the Paris summit in 2015, implementation of negative emission technologies is necessary. Among the options, one of the simplest is enhanced weathering, where silicate rock is ground into small particles to enhance weathering rate. Here we synthesize the ways by which mycorrhizal fungi interact with these particles when applied to agricultural fields, and suggest they may stimulate weathering by various direct and indirect mechanisms. We conclude that because the intensity with which mycorrhiza interact with soil is tightly related to plant provisioning of photosynthates in exchange for soil-derived nutrients, weathering rates and hence carbon sequestration are likely to increase with agricultural activities that stimulate plant reliance on and investment in arbuscular mycorrhizal fungi.

Automated summary

Mitigating climate change and increasing agricultural sustainability are twin challenges society faces in the upcoming decades. Enhanced weathering through ground silicates can reduce atmospheric CO2, with arbuscular mycorrhizal fungi potentially playing a key role in this process. Stimulating plant reliance on and investment in these fungi may lead to increased weathering rates and carbon sequestration in agricultural ecosystems.