The effect of harvest frequency on yielding and quality of energy raw material of reed canary grass grown on municipal sewage sludge

The four-year-lasting field experiment located on loamy clay aimed at determination of yielding and biofuel characteristics of reed canary grass ‘Bamse’ variety cultivated at different doses of municipal sewage sludge (0, 10, 20, 40, 60 Mg ha−1 DM). In the experiment, three frequencies of energy feedstock harvesting were used: a one-harvest management system (in autumn), a two-cut regime (in spring and autumn), and a three-cut regime (in spring, summer, and autumn) in order to determine which of them has the best advantage of yielding potential obtained at application of sewage sludge. It was found out that application of 40 Mg ha−1 DM of sludge resulted in the highest yield of biomass. The content and bioaccumulation index of macronutrients in plants increased along with the increasing dose of applied sewage sludge, reaching the maximum at 60 Mg ha−1 DM. Biomass was characterized by favourable parameters: net calorific value in the range of 15.2–16.1 MJ kg−1 as well as low ash (5.5%–7%) and sulphur (0.11%–0.24%) mass fractions. The most favourable was the single harvesting run in late autumn as well as the two-cut regime. In the cultivation of reed canary grass for energy purposes, excessive amounts of swaths of biomass should be avoided in order to prolong plant growth on the field, increase accumulation of dry matter, lower the moisture content, and at the same time reduce the mineral content. Application of increasing doses of sewage sludge positively affected soil physico-chemical properties as well. •Reed canary grass yield significantly depended on municipal sewage sludge dose.•Application of 40 Mg ha−1 of sludge DM resulted in the highest yield of biomass.•Single harvesting and two-cut regime has the best advantage of yielding potential.•Increasing doses of sewage sludge positively affected biomass and soil properties.