C_Macci.mp4

Recording of presentations at the Suricates project closing conference

Title : Composting’s potentiality for the recovery of green wastes and sediments in nursery sector as growing media

Authors : Cristina MACCI12, Francesca VANNUCCHI12, Serena DONI1 , Davide MANZI1 , Irene ROSELLINI1 , Manuele SCATENA1 , Stefano LUCCHETTI3 , Grazia MASCIANDARO12, Eleonora PEUZZI12 1Research Institute on Terrestrial Ecosystems (IRET), CNR, Via Moruzzi 1, 56124 Pisa, Italy 2NBFC: National Biodiversity Future Center, Palermo 90133, Italy 3Agri Vivai s.r.l. Via Vecchia Casalina, 118/G, Pistoia 51100, Italy * Corresponding author e-mail: cristina.macci@cnr.it

Summary :

This study's main goal was to show that co-composting can be a useful valorization strategy for recycling two different types of wastes, green residues (green urban wastes and Posidonia oceanica) and decontaminated sediments, in nursery sector as growing media, being the search for alternative substrates to peat increasingly necessary. Posidonia is one of the main endemic marine plants and in every spring season leaves of it reach coastlines. Removal and disposal of these accumulations pose several economic and environmental problems, with primary destination is the landfill.

Sediments (S) from a small-regulated stream located in an urban area of Čejkovice (Czech Republic) and green waste (GW) biomass collected from local agriculture were co-composted in the following ratio: 75%S:25%GW(S75), 50%S:50%GW (S50), 25%S:75%GW (S25), for about 7 months. Instead, posidonia (PO), green wastes and remediated sediments come from Port of Livorno were mixed in the ratio of 20%PO:80%GW (SP0), 10%PO:80%GW:10%S (SP10); 20%PO:60%GW:20%S (SP20), and co-composted for about 6 months.

In all piles, excepted for that with the highest content of sediments (S75 and SP20), the bio-oxidative phase (mesophilic and thermophilic periods) was reached, while only in pile S50, S25 and SP0 the temperature exceeded 55°C, recommended temperature for maximizing the material sterilization. The compost stability and maturity were reached in all the co-composting piles by the decrease and stabilization of organic matter content, electrical conductivity, microbial activity, and the increase of humification rate.

In addition, the level of germination tests found in all mixtures was not phytotoxic for seed germinations (higher than 50%, the threshold value expressing phytotoxicity). All the obtained composts responded to the main characteristics for composting and growing media preparation provided by national and international regulations, with some expectation in terms of bulk density and total organic carbon. In addition, some of the acquired co-composts were employed alone or associated with another organic substrates as growing media in the nursery industry in comparison to traditional peat, and similar outcomes in terms of plant growth and physiology were seen across the studies. Our findings demonstrate the possibility of the co-composting process as a different approach to managing decontaminated sediments and green wastes to create a growing media for peat replacement (preferably not more than 50%) while also being consistent with the circular economy approach.

Acknowledgements:This work was supported by LIFE AGRISED (LIFE17 ENV/IT/269) and Fondazione Cassa di Risparmio di Pistoia e Pescia projects.