Impact of agricultural practices on plant-available silicon

Silicon (Si) is a beneficial nutrient for many plants, including major crop species. Yet, the impacts of agricultural practices on Si cycling have been hardly studied. We investigated the effects of long-term fertilizer (farmyard manure, NPK) and/or lime applications on concentrations of acetate-extractable Si (S-iacetate; i.e., potentially mobile and plant-available Si) in a Chernozem topsoil (Bad Lauchstadt, Germany). The S-iacetate concentrations were between 122 and 292 mg Si kg(-1), and thus, larger than 'critical values' considered to trigger Si limitation of plant growth. We found positive relationships between S-iacetate concentrations and soil pH, which might be explained by pH-dependence of the phytolith solubility as well as of the sorption of Si to mineral surfaces. Our data suggest that differing agricultural practices affects Si fluxes and availability in soil by affecting the soil pH.