The Role of Hydrological Processes on Enhanced Weathering for Carbon Sequestration in Cropland Areas: An Application to Italy

Aiming at facing climate change, some CDR (Carbon Dioxide Removal) techniques are currently studied given their capability to sequester carbon from the atmospheric CO2 and to store it within oceans, plants, soil, or other terrestrial environments. Among them, Enhanced Weathering (EW), that acts in speeding up the chemical weathering naturally occurring in soils through the amendments of highly reactive silicate minerals, is referred to as one of the most promising. Hot and humid climates provide the best conditions for EW, since reactions are faster at high temperature, high soil water content and low soil pH. This study presents a dynamic mass balance model that explores ecohydrological, biogeochemical and olivine dissolution dynamics. Through the application of this model, which is composed of different interconnected components, it is possible to explore the role of hydrological processes on olivine dissolution and, therefore, to compute carbon sequestration rates. The model is coupled with a spatially distributed crop specific agro-hydrological model named WATNEEDS, able to solve the soil water balance at the global scale at a 5 arcminute resolution. Input of rainfall data, along with the outputs components of the soil water balance (i.e., infiltration, evapotranspiration, leaching and runoff rates) for each crop, estimated the WATNEEDS are used as input in estimating EW yields at large scale. Here a current application at the regional scale for agriculture, is proposed to explore EW yields in various cropland areas in Italy. The spatial extension of the study area, i.e., the whole Italian territory, allows to explore the EW dynamics under different climate conditions and crop and soil types, defining the importance of such factors in the EW dynamics. This allows to extract olivine dissolution dynamics in places characterized by significant differences in terms of rainfall seasonality, crop phenology, soil type and composition. A future enhancement of this study may be the application of the EW model at the global scale, so as to provide a tool to decision makers for an actual future application of EW.