Potential of pumice scraps compared to zeolitized tuff for Mn2+ release in agricultural applications

Quarry waste and by-products pose significant environmental and economic challenges for the mining industry. This study investigates the potential of pumice scraps as carriers for Mn2+ to crops for foliar fertilization. Kinetic and Isotherm modelling were performed for Mn2+-enrichment and release, and Mn2+ saturation level was compared to theoretical cation exchange capacity (CEC). Synthetic groundwater was used to simulate agricultural conditions in spraying machines. Pumice scraps were compared with more commonly studied zeolitized tuff (chabazite-rich). Despite its higher amorphous content (87.5 wt%) and lower zeolitic mineral content (analcime, 0.80 wt%), pumice exhibited greater affinity for Mn2+, achieving higher saturation percentage of the theoretical CEC than the zeolitized tuff. Pumice also demonstrated a more stable enrichment and release, making it a promising material for delivering Mn2+ to crops. The use of pumice scraps in foliar fertilization could therefore represent a new way to valorise quarry waste materials.