Enhanced weathering in the US Corn Belt delivers carbon removal with agronomic benefits

Abstract

Terrestrial enhanced weathering (EW) of silicate rocks, such as crushed basalt, on farmlands is a promising scalable atmospheric carbon dioxide removal (CDR) strategy that urgently requires performance assessment with commercial farming practices. We report findings from a large-scale replicated EW field trial across a typical maize-soybean rotation on an experimental farm in the heart of the United Sates Corn Belt over 4 y (2016 to 2020). We show an average combined loss of major cations (Ca 2+ and Mg 2+ ) from crushed basalt applied each fall over 4 y (50 t ha −1 y −1 ) gave a conservative time-integrated cumulative CDR potential of 10.5 ± 3.8 t CO 2 ha −1 . Maize and soybean yields increased significantly ( P < 0.05) by 12 to 16% with EW following improved soil fertility, decreased soil acidification, and upregulation of root nutrient transport genes. Yield enhancements with EW were achieved with significantly ( P < 0.05) increased key micro- and macronutrient concentrations (including potassium, magnesium, manganese, phosphorus, and zinc), thus improving or maintaining crop nutritional status. We observed no significant increase in the content of trace metals in grains of maize or soybean or soil exchangeable pools relative to controls. Our findings suggest that widespread adoption of EW across farming sectors has the potential to contribute significantly to net-zero greenhouse gas emissions goals while simultaneously improving food and soil security.

Convergent evidence for temperature-dependent emergence of silicification in terrestrial plants

“…The Si cycle is crucial for regulating the Earth's carbon cycle 69 . Silicate weathering xes CO 2 from the atmosphere; a process that is increasingly implemented in agroecosystems to provide bene ts for both carbon sequestration and crop yields [70][71][72] . Plants enhance silicate weathering through various mechanisms 73 , especially if Si demand increases, and our ndings on the link between plant silici cation and changes in the Earth's climate provide new clues regarding the interactions between Si and C cycling over geological timescales 13 .…”

Soil cation storage as a key control on the timescales of carbon dioxide removal through enhanced weathering

“…2), Jq feed and Jq diss are deployment (spreading) and dissolution fluxes of feedstock θ (mol m −2 y −1 ), respectively, and Δ denotes the flux difference between scenarios with and without feedstock deployment. Mechanistically, this metric corresponds to time-integrated solid-phase approaches for tracking on-field rates of CDR [Beerling et al, 2024;Kantola et al, 2023;Reershemius et al, 2023;Reershemius and Suhrhoff, 2023]. In short, these techniques rely on measuring mobile cations and immobile elements in soil before and after feedstock application and using these measurements to estimate loss of base cations from applied feedstock.…”

Iron Chelation in Soil: Scalable Biotechnology for Accelerating Carbon Dioxide Removal by Enhanced Rock Weathering

“…This is important for nutrients whose availability is pH-dependent (e.g., Fe, , Mo, Cu, Zn, Si , etc.). Because basalt-amended soils typically experience an increase in pH, ,, the use of fixed pH-extractants is not suitable. Second, water is sufficiently mild to avoid weathering the basalt during the extraction procedure unlike other extractants (e.g., DTPA-based extraction, 0.5 N acetic acid-based extraction, etc.).…”

“…The reacted solution was obtained by slowly pipetting from the side opposite to where the grain pellet formed. In the second phase, the basalt was reacted with 10 mL of filter-sterilized Fe-LCM 3 medium containing either siderophores [1,5,10,20, and 40 μM desferrioxamine B mesylate (DF) or 1−40 μM DF equivalents as measured by the CAS assay of malleobactin/pyochelin mixture or pyoverdine/pyochelin mixture] or disodium citrate (citrate content of 40−300 μM), also including a control treatment (only fresh Fe-LCM 3 medium without added chelators). After 90 h, the reacted solution was pipetted out into a fresh tube as described above.…”

“…1,2,4,5 Concerns over possible trace metal accumulation in soils have been raised 7 but agricultural EW trials in the U.S. show no evidence of trace metal accumulation either in soils (pore water, exchange sites) or grains over four years of treatment. 1 In response to the growing scientific evidence base, EW is scaling rapidly through worldwide expansion of commercial activities with significant purchases of the resulting carbon removal credits on the voluntary carbon markets (e.g., Microsoft, Stripe). 4,8 Here, we focus on the manipulation of chelator activity in soil as a potential route to increasing the efficiency of EW and its resulting carbon removal.…”