Photo credit: ILVO
Growing media include any materials other than soil used as a horticultural substrate for plant rooting and cultivation in a confined volume, as part of controlled environment agriculture. These growing media are used for growing vegetables, fruits and ornamentals in a range of hydroponic systems in greenhouses. Peat is widely used as major constituent in growing media but is controversial due to damage to peatlands and greenhouse gas emissions at harvesting.
Biochar can be used in growing media blends as fertilizer or for improving plant growth, disease suppression, and as a sustainable (partial) replacement of peat. Biochar is one of the products of pyrolysis, i.e., heating of biomass with no or limited presence of air. It can be produced from a wide variety of feedstocks, ranging from lignocellulosic materials (as wood, reed, and grass) to nutrient rich waste streams as manure.
Biochar contains nutrients originating from the feedstock, which can potentially be released by use in growing media. Next to that, biochar addition can alter the pH of the growing media, which influences nutrient mobility and availability.