Plant and microbial growth as affected by growing media interacting with spent mushroom compost

Mushroom (Agaricus bisporus) and oyster (Pleurotus ostreatus) cultivation generates a vast amount of by-product after the harvest of edible products in the form of used compost, so called spent mushroom composts (SMC) or spent oyster substrate (SOS). In Europe, more than three million tons of SMC are produced every year as a byproduct from mushroom cultivation. The management of SMC and SOS has thus become an increasing challenge from an environmental point of view. This spent material has been utilized as growing media, bio-fertilizers, in bioremediation and as a tool to control plant diseases. They have, therefore, a great potential to be implemented in primary food production. The current study investigated the impact of SMC or SOS amendment to peat on plant and microbial growth. The achieved results indicated increased flower and yield potential after SMC amendment to peat compared with SOS. Assessment of microflora in the substrate highlighted higher amount of beneficial microbial groups such as Pseudomonas, in peat and SMC mixtures compared to the ones with peat and SOS.