Composting of ornamental pruning wastes using different methods during the maturation phase.

The aim of the study was to investigate composting process of pruning wastes from cultivation of ornamental plants, using three treatments during the maturation phase. After the bio-oxidative phase (aeration rate of 0.30 L kg-1dry matter min-1) the pile was divided in three sub-piles which were i) aerated (0.20 L kg-1dry matter min-1), ii) turned every 15 days, or iii) untreated. During the composting process, temperature, oxygen concentration, electrical conductivity, carbon-to-nitrogen ratio, N-NH4+, N-NO3-, hemicellulose, cellulose contents were measured. Humification and germination indexes were also determined to evaluate the compost stability and maturity during the maturation phase. The duration of maturation phase differed within treatments: 37 days in the aerated pile, and 93 days in turned and untreated piles. Considering maturity and stability characteristics at the end of composting process, it may be concluded that forced aeration static pile, natural ventilation static pile and mechanical turning windrow applied during the maturation phase produced a stable and mature compost, but in a shorter period using forced aeration. Phytotoxicity of compost obtained with forced aeration should be verified.