Microbiological research makes greenhouse horticulture waterproof

New insights for a microbially healthy water system in the greenhouse

New techniques make it possible to determine the microbial community in irrigation water, or to very rapidly show the presence of pathogens in the water. This offers greenhouse horticulturalists the possibility of creating ideal conditions for greenhouse crops and to act early in the event of the presence of pathogens in drain-water. In an article for Glastuinbouw Waterproof, Patrick Smeets and Marcelle van der Waals describe methods to achieve a microbially healthy system in the greenhouse.

Growers face big challenges as a consequence of several developments concerning water and greenhouse horticulture. The emission-free greenhouse and freshwater shortages are for instance driving the need for extensive recirculation and the reuse of water from greenhouse horticulture, cities and industry. This can on the one hand create risks for plant and human health, but it also can offer opportunities for an improved water quality in the greenhouse. A good, protective microbial community in the irrigation water of course promotes healthy plant growth during cultivation.


The recirculation of drain-water and the reuse of residual water streams can lead to the introduction and dissemination of pathogens for humans and plants. The current regulations are however directed mostly to human health and the environment. The risks to plant health still receive little attention. For example, E. coli monitoring in decontaminated water provides only limited safeguards for plant health. This is because many pathogens are more resistant to decontamination than E. coli. Moreover, the presence of E. coli is barely connected to pathogens for plants. Research on the role and the manageability of the microbial community in water and biofilm contributes to the safe recirculation and use of residual streams in the greenhouse. It also increases crop yields.

Irrigation water safety

In various Dutch and international projects, such as Organische stof in recirculatiewater voor sturing microbiële diversiteit en functionaliteit (OSIRES) [Organic material in recirculation water for microbial diversity and functionality management (OSIRES)], KWR is researching – together with partners including Wageningen University & Research, Stichting Control Food and Flowers, and Glastuinbouw Nederland – the safety of recirculated irrigation water, and the management and safeguarding of residual streams. In this process, KWR draws on knowledge and techniques built up over many years’ experience in the monitoring of drinking water safety.


The Water Quality and Health team will be present at the HortiContact trade fair (March 5-7 in Gorinchem) to provide all the information about achieving a microbially healthy water system in greenhouse horticulture.

You can register directly through this link.