[Effect of enhanced silicate minerals weathering on carbon sequestration by plant-soil systems in rice fields]

Successive crop harvest results in soil silicon (Si) loss, which constantly reduces soil available Si. Agricultural measures that can increase the availability of soil Si are in urgent need in agroecosystems. Enhanced weathering of silicate minerals can effectively replenish soil Si, which will promote plant uptake of Si, formation of plant phytolith occluded carbon (PhytOC), and the sequestration of atmospheric CO₂. In addition, the process of silicate mineral weathering can promote soil carbon (C) sequestration. In this study, we applied silicate mineral wollasto-nite powder to rice fields in Liaoning Province to investigate effects of the enhanced weathering process on soil available Si, changes in phytolith carbon (PhytOC) content in plant-soil systems, and the content of various soil C forms. The results showed that the application of wollastonite powder could significantly increase the available Si content in the surface soil (53%), promote rice dry biomass production (12% increase in rice grains and 4% increase in straw), increase the phytOC content (4% increase in rice grains and 26% increase in straw), which together resulted in 25% increase in phytOC production fluxes. The application of wollastonite powder tended to increase both inorganic and organic C content in the soil, resulting in 13% increases of soil total C content. In summary, enhanced weathering of silicate minerals could effectively increase soil available Si in paddy soil, promote rice Si absorption and phytOC formation, and enhance soil CO₂ sequestration, achieving the effect of coordinated carbon sequestration from both above- and below-ground.