An Assessment of the Effects of Applying Ash from the Thermal Disposal of Sewage Sludge for Fertilizing Energy Plants Using the Example of Giant Miscanthus (Miscanthus sinensis giganteus)

The aim of the research was to determine the possibility of using ash from the thermal utilization of municipal sewage sludge as a fertilizer in the cultivation of giant miscanthus (Miscanthus sinensis giganteus) for energy purposes. An attempt was also made to determine the optimal level of fertilization with ash from the thermal utilization of municipal sewage sludge in the commodity cultivation of miscanthus. It was assumed that the ash produced after thermal utilization of municipal sewage sludge could replace conventional mineral fertilizers. To prove the thesis, laboratory experiments of the miscanthus cultivation miscanthus were carried out. The results allowed to determine the optimal fertilization dose for miscanthus to be used in the next stage of the field research. Miscanthus does not pose a succession threat due to the method of reproduction in central Europe; therefore, its cultivation may remain under control. The research showed that for fertilization of miscanthus × giganteus crops, the ashes from thermal utilization of municipal sewage sludge could be used effectively. In experimental crops, it was shown that the optimal level of miscanthus fertilization in terms of yield was 8.32 g of ash per pot and 0.1 g of nitrogen per pot. As a result of laboratory tests, based on biometric features, the most favorable dose of ash and nitrogen fertilization from thermal utilization of municipal sewage sludge for use in field conditions was selected. The dose amounted to 3.7 t of ash∙ha−1 and 45 kg of nitrogen∙ha−1. In order to reduce the costs of cultivation, it was possible to abandon the use of nitrogen fertilizers since their omission did not cause a significant drop in yield. It is necessary to continue research in the field in order to confirm the correctness of the results obtained from laboratory tests.