Recirculation, circular fertilizers and resilience: the potential of growing media systems for circular production

Current thinking about circularity and sustainability is used to identify i) recirculation of drainage water, ii) circular fertilisers, and iii) resilience control as growing media related areas with a wider societal meaning. The objectives are to find to which extent circularity can be realized and how growing media and compost research can serve transition to a more circular horticulture. Recirculation of drainage water increases water use efficiency by 50%, nutrient use efficiency by 60% and eliminates the emission of water borne chemical agents. The challenge remains as still 90% of the global area of growing media systems does not yet use available techniques to realize full recirculation. The global use of more circular fertilisers, including plant, animal and human wastes, can stop depletion of natural reserves and diffuse emission of nutrients. It is argued that the combination of irrigation techniques and the use of growing media offer horticulture both opportunity and reasons to lead in the production of circular fertilisers, being either soluble or slow release. Resilient growing media facilitate cultivation without chemical agents, without disinfection before reuse and without continuous disinfection of recirculating water. We identify methodological improvements still needed to safely progress on this road. The importance of growing media based cultivation is put in perspective of the global production of food and ornamentals.