Silicon dissolution kinetics of fresh and aged oil palm phytoliths
My Master thesis will contribute to better understanding of the reactivity and dissolution kinetics of plant phytoliths extracted from oil palm biomass and topsoils in soil solutions. We expect that conversion of rainforest into oil-palm plantations disrupts the natural terrestrial silicon (Si) cycle and increases dissolved Si output from the system, until the newly established land cover reaches equilibrium with respect to Si cycling. It is yet unknown, how oil palms as Si accumulating plants affect the cycling of Si by taking up dissolved Si from soil solution and accumulating it in their aboveground biomass in small silica particles (phytoliths). Several studies confirmed that Si released during mineral weathering and phytolith dissolution is largely taken up by vegetation and converted to phytoliths before being returned to the soil by litter decomposition. Under tropical climate, the contribution of plants and thus phytoliths to Si dynamics in the soil is more important compared to temperate or boreal vegetation. We expect, that phytoliths of oil palms considerably affect the Si cycle by producing larger amounts of phytoliths that are returned to the soil by piling up palm fronds that decompose and release oil-palm phytoliths to the soil. Dissolution experiments may contribute to a better understanding how fast Si from oil-palm phytoliths is returned to the soil.