Spent cultivation substrate (SCS) management in circular farming systems

A spent cultivation substrate (SCS) is a growing medium which remains after the cultivation of mushrooms (SMS) or vegetables (SGS); for many years, it was considered to be a problematic waste product from farming. However, in the recent transition to sustainable, circular farming systems, it is seen as a valuable product which can be recycled. The SMS was characterized by a high organic matter content, low bulk density, high pH and soluble salt contents, and rich in macro- and micro-elements, with their contents generally decreasing in following order: K, Ca, Na, Mg, Mn, Fe, Si, Se, and Mo. The contents of heavy metals were acceptable for both SMS and SGS. SGS could potentially be used in horticulture for subsequent greenhouse vegetable cultivation, if composted/co-composted with additional waste products due to its high mineral salt content and to eliminate potential pests.