Enhanced silicate weathering in agricultural rice paddies: maximisation of soil carbon sequestration and crop production, while reducing the overall greenhouse gas emissions

In order to limit global warming to the well below 2C of the United Nations Paris Agreement, model projections indicate that both rapid decarbonisation and the implementation of negative emission technologies (NETs) that ensure long-term stable carbon (C) sequestration will be required.

Among NETs, enhanced weathering (EW) of silicate rocks can remove CO2 from the atmosphere, while potentially delivering co-benefits for agriculture (e.g. reduced nitrogen losses, increased yields, increased drought and salinity resistance) and reducing the overall greenhouse gas (GHG) emissions from this activity.

Thus, EW application may be of special interest on rice paddies since they: emit large quantities of methane (up to 11 % of global CH4 emitted); have high water demands and might face drought episodes due to climate change; and are exposed to salinity stress in Europe since they are cultivated in coastal areas.

Although some studies have studied the effects of silicate waste on rice paddies, none of them have combined natural silicate rocks and waste simultaneously.

Moreover, quantification of inorganic C sequestration through EW and the potential risks in terms of heavy metal contamination have rarely been assessed.

The main goal of EWRECA is to develop an agricultural management practice for rice paddies that (i) minimises the GHG emissions, while maximising (ii) rice production (biomass and quality), and (iii) C sequestration.

Moreover, EWRECA aims to re-use crushed concrete fines, an artificial silicate from construction waste, thus enhancing material circular economy.

To achieve this objective, a mesocosm field experiment will be set up applying different agricultural management treatments. Responses on GHG emissions, plant biomass and soil microbial communities will be assessed over two growing seasons.

Overall, this project will generate valuable scientific results that will be of interest for national, European and global strategic actions in agricultural systems.