Effect of Rock Phosphate on Zn and Fe Bioavailability and Accumulation by Salix smithiana in Heavily Contaminated Soil

High biomass production Salix smithiana was proved as the plant able to accumulate substantial amount of Cd and Zn in aboveground biomass. Nevertheless, in heavily contaminated soils (mainly by Zn) willows can suffer from chlorosis because of Fe deficiency induced by excess of Zn amount. Method such as chemophytostabilization seems like very good measure for planting willows in such heavily contaminated soil. In our experiments we evaluated effect of rock phosphate on changes in Zn and Fe bioavailability and accumulation of these elements by willows together with the willows growth on heavily contaminated soil. Addition of rock phosphate reduced plant-available Zn concentrations in soils resulting in significant decrease of Zn content in leaves. In the case of Fe, however, its contents in the leaves significantly decreased as well, although the mobile portion of Fe in soil remained unchanged. Yield of aboveground biomass in rock phosphate treatment was not significantly different in comparison to the control. After the first vegetation period, we can conclude that reduction of Zn contents in willows after rock phosphate application did not lead to suppress of Fe deficiency and improvement of willow growth in heavily contaminated soil.