Effects of Wollastonite Soil Application on Silicon Accumulation and Nutrient Uptake in Wetland Grasses—Insights from a Greenhouse Pot Experiment

The use of silica formed in plants might represent a promising strategy to cover the growing demand from the high-tech industry for amorphous silica. Grass species are known as strong silicon (Si) accumulating plants. In a pot experiment, we analyzed the effects of Si application (wollastonite) on biomass production, Si accumulation, and nutrient uptake of four wetland/pasture grasses (Festuca arundinacea, Lolium perenne, L. rigidum, and Phalaris arundinacea). Plants were grown in a greenhouse using organic topsoil without (natural conditions, control treatment) or with wollastonite (Si treatment) application. While we found no increase in plant biomass after Si application, Si accumulation increased four- to sevenfold. Consequently, the tested grassland species could be classified as Si excluders (Si content < 0.5%) or strong Si accumulators (Si content > 1%) when grown in Si-low or Si-rich soil. Differences in nutrient uptake were relatively small, and we found no (negative) treatment effect on plant biomass; thus, we assume no negative effects of wollastonite application on plant nutrient uptake in the short term. Our findings indicate that wollastonite application might represent a promising strategy to substantially enhance Si accumulation in wetland grasses. However, field experiments are needed to corroborate our conclusion and acquire practice-related recommendations for paludiculture farmers.