Vermicomposting Nursery Green Waste: A Circular Economy Approach

The high variability in composition and quality of green residues, especially those derived from the nursery sector, limits their recovery and recycling. Vermicomposting (VC) is a promising sustainable technology for recycling green residues from nurseries. This transforms them into nutrient-enriched resources thanks to its ability to degrade recalcitrant materials. We tested VC using a circular economy approach to recover various green lignocellulosic residues, i.e., dry chopped green waste (GW), sawdust (SW) and woodchips (WC), from local nurseries (Pistoia, Italy). Different mixture proportions were used (100% GW, 70% GW + 30% SW, 50% GW + 50% WC, 100% WC), creating growing media that can be reused in nursery production. The physical, chemical, and biological properties of VC for each residue was monitored. To assess suitability as a growing media component, the final VC properties were verified according to Italian legislation for fertilisers (D. lgs. 75/2010), and plant growth tests were carried out to evaluate plant performance. Degradation of organic matter occurred, especially in GW (− 52%), where the reduction of enzyme activities (− 10% to − 31%) involved in the carbon and nutrient cycles, and the increase in germination index (+ 24%) suggested there was mixture stability at the end of VC. Despite some exceptions for Italian legislation, the growth test confirmed the maturity and the agronomical applicability of all mixtures. Our results show that vermicomposting would appear to be an auspicious approach for the management of lignocellulosic green residues coming from nurseries, creating an appropriate growing media component for use with a circular economy approach.