Modification of properties of energy crops under Polish condition as an effect of sewage sludge application onto degraded soil.

Energy crops are one of the possible solutions for reclamation of degraded or contaminated terrain. Their cultivation requires adequate fertilization typically containing high content of organic matter, nitrogen and phosphorous. While sewage sludge may be one source of these necessary nutrients, it may also modify some plant biomass properties, such as total carbon content. In our study, we determined whether sewage sludge (containing different value of heavy metals) could be an effective fertilizer to obtain good quality energy crops (such as Miscanthus x gigantheus and reed canary grass, Phalaris arundinacea) and simultaneously play positive role for improvement of phytoremediation. The 3-year experiment was performed on degraded soil from terrain of steel mill of Czestochowa (Silesian region, Poland). During the study, it was confirmed that sewage sludge (also in combination with urea, CH4N2O) influences the mobility of Pb, Zn, Cd in soil solution, however the intensity of the process can be limited by plant species and time. Both miscanthus, and reed canary grass were characterized by the low value of bioconcentration factor (BCF), but because biomass was high, the total concentration of heavy metals in crops was comparable with hyperaccumulators. Additionally, modification of the fertilization affected energetic parameters, such as the content of carbon, S/Cl ratio, unitary CO2 emission. However, this effect was not statistically significant.