Land-based enhanced rock weathering (ERW) is a biogeochemical carbon dioxide removal (CDR) strategy aiming to accelerate natural geological processes of carbon sequestration through application of crushed silicate rocks, such as basalt, to croplands and forested landscapes. However, the efficacy of the approach when undertaken with basalt, and its potential co-benefits for agriculture, require experimental and field evaluation. Here we report that amending a UK clay-loam agricultural soil with a high loading (10 kg m-2) of relatively coarse-grained crushed basalt significantly increased the yield (21 ± 9.4%, s.e.) of the important C4 cereal Sorghum bicolor under controlled environmental conditions, without accumulation of potentially toxic trace elements in the seeds. Yield increases resulted from the basalt treatment after 120 days without P- and K- fertilizer addition. Shoot silicon concentrations also increased significantly (26 ± 5.4%, s.e.), with potential benefits for crop resistance to biotic and abiotic stress. Elemental budgets indicate substantial release of base cations important for inorganic carbon removal and their accumulation mainly in the soil exchangeable pools. Geochemical reactive transport modelling, constrained by elemental budgets, indicated CO2 sequestration rates of 2-4 t CO2 ha-1, 1 to 5 years after a single application of basaltic rock dust, including via newly formed soil carbonate minerals whose long-term fate requires assessment through field trials. This represent an approximately 4-fold increase in carbon capture compared to control plant-soil systems without basalt. Our results build support for ERW deployment as a CDR technique compatible with spreading basalt powder on acidic loamy soils common across millions of hectares of western European and North American agriculture.
|Number of pages||19|
|Journal||Global Change Biology|
|Early online date||21 Apr 2020|
|Publication status||Published - 1 Jun 2020|
Bibliographical note© 2020, The Authors(s).
- enhanced mineral weathering
- carbon dioxide removal
Mark Edward Hodson
- Environment and Geography - Anniversary Professor