Silicon (Si) effects on mineral nutrient status in plants are not well investigated. It is known that Si has a beneficial effect on plants under stressed conditions. The aim was to make a state of the art investigation of the Si influence: (1) on nutrient availability in four different soil types, namely clayish, sandy, alum shale and submerged soil; and (2) on accumulation of various nutrients in maize, lettuce, pea, carrot and wheat growing in hydroponics. Soil was treated with K₂SiO₃ corresponding to 80 and 1000 kg Si ha⁻¹ and the nutrient medium with 100, 500, 1000 and 5000 μM Si. In general, Si effects were similar in all analyzed plant species and in all soil types tested. Results showed that, in soil, Si increased the availability of Ca, P, S, Mn, Zn, Cu and Mo and that of Cl and Fe tended to increase. The availability of K and Mg was not much affected by Si. Uptake from solution of S, Mg, Ca, B, Fe, and Mn increased; N, Cu, Zn and K decreased; P decreased/increased; and Cl and Mo was not influenced. Translocation to shoot of Mg, Ca, S, Mn, and Mo increased; Fe, Cu and Zn decreased; and K, P, N, Cl and B was not affected. It was concluded that, if plants had been cultivated in soil, Si-maintained increased availability of nutrients in the soil solution would probably compensate for the decrease in tissue concentration of those nutrient elements. The study shows that Si also influences the nutrient uptake in non-stressed plants.

In our previous work, we used Salix viminalis in the field to decontaminate agricultural soils containing cadmium. Our aim in the current study was to determine whether S. viminalis could decrease the levels of heavy metals, arsenic, polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in industrial soil at a former workshop site. The site was planted with S. viminalis cuttings in July 2003. Soil samples were collected yearly from 2005 to 2015 and analysed for heavy metals, arsenic, PCBs and PAHs. The results showed that 21% of chromium, 30% of arsenic, 54% of cadmium, 61% of zinc, 62% of copper, 63% of lead, 87% of nickel, 53% of PCBs and up to 73% of PAHs were removed from the soil after 10 years of S. viminalis treatment. After just 1 year of Salix cultivation, a significant decrease was observed in most of the contaminants in the soil. The reduction in contaminants was linear at first but slowed down after a few years. The number of years prior to a slow-down in rate of removal differed between the contaminants. This study concludes that S. viminalis can be used for the phytoremediation of contaminated industrial soil and that the rate of decontamination differs between substances.