Influence of Fertilization With the use of Biomass Ash and Sewage Sludge on the Chemical Composition of Jerusalem Artichoke Used for Energy-Related Purposes

The experiment was based on two factors: 4-levels of fertilization with ash from biomass - 0; I - 4.28; II - 8.57; III - 12.85 t^ha-1 and 2-levels of fertilization with sewage sludge: 0; 1–30.3 t^ha-1. The experimental plant was Jerusalem artichoke (Helianthus tuberosus L.), Gigant cultivar. The contents of nitrogen tended to increase in response to fertilization with sewage sludge and to decrease with a growing dosage of fertilization with biomass ash. The use of municipal sewage sludge as a fertilizer did not produce visible changes in the contents of six macronutrients (carbon, phosphorus, potassium, sulfir, calcium and magnesium) in overground part of Jerusalem artichoke. The use of ash at the dose of 12.8 t^ha-1 resulted in an increase in potassium contents in the plants, to the level of 5.63 g K^kg-1 during the first year of trials and the trend was continued in the second year. Biomass chemical stability in 2-year experiment was noted except the content of nitrogen, cadmium and lead which were increasing while the level of sewage sludge increased. The content of zinc, copper, lead and cadmium in overground part of Jerusalem artichoke did not exceed the threshold values defined for wood pellets and briquettes by the standards set forth by DIN 51731 1996–10.