Environmental and Agronomic Evaluation of Containerized Substrates Developed from Sewage Sludge Compost for Ornamental Plant Production

A life cycle assessment (LCA) evaluation of the aerobic and manufacturing processes of nursery growing media and a growth analysis of Bougainvillea in protected environment have been realized in order to evaluate the environmental and agronomical quality of a compost coming from urban sewage sludge and green waste. The LCA has enabled the environmental impact evaluation of both the compost and the growing media; the analysis has been done considering a composting process lasting 120 days, made by a firm specialized in waste recovery. The structures and equipment together with all the inputs and outputs, both energy-related and coming from the composting matter, have been considered. The transport of the composted waste and the materials used to produce the media has been evaluated. In order to produce the growing media, the compost has been mixed with draining material at the 30% of the volume. The remaining 70% has been obtained mixing peat and compost in the percentages of 0%, 25%, 40%, 55%, and 70% of the total volume. The Bougainvillea plants have been grown for 150 days and fertirrigated with a different nutrient solution according to the growing media compost percentage. The electric conductivity of the nutrient solution and, therefore, its fertilizing ability, was inversely proportional to the growing media compost content. The growing media physical and chemical characteristics have been determined. Regarding the LCA analysis, the peat substratum productive process is the most impacting; this because of the peat extraction process and its transport from the north east of Europe to Southern Italy. At the end of the cultivation trial, the best ornamental performance has been obtained using the compost-based growing media compared to only peat.