Identification of microbial life in sustainable and disease suppressive growing media : the role of beneficial microorganisms

Our current understanding of the microbial communities inhabiting growing media is limited. However, techniques such as phospholipid fatty acid analysis, metabarcoding and shotgun metagenomics are increasingly used to analyze and understand microbial life in growing media and therefore they are starting to fill the knowledge gap. Using these techniques in the interreg2seas project Horti-BlueC (www.horti-bluec.eu ), we try to understand the microbiological processes involved in sustainable growing media based on plant fibers, chitin and biochar. In sustainable growing media, peat is (partially) replaced and/or the use of chemical fertilizers and plant protection products is reduced. Plant fibers include defibrated miscanthus straw, flax shives and reed. Chitin is produced from shell fish waste such as crab and shrimps shells. Biochar (charred material) is rich in carbon and is produced from organic material such as wood, spent growing media and the woody fraction of green waste. We showed that adding biochar to peat mainly changes the bacterial community, whereas plant fibers and chitin mainly change the fungal community of the growing media. By changing the microbiome of the growing media, these new amendments might reduce the impact of horticulture on the environment and contribute to a circular-based economy