Phalaenopsis growers are looking for a method to achieve good quality and production with lower emissions of fertilizers. This can be achieved by adding Controlled Released Fertilizers (CRF) to the pot at the start of the cultivation, according to research by the Business Unit Greenhouse Horticulture of Wageningen University & Research. CRF coated granules are added at the start of the cultivation and deliver a small but certain amount of fertilizer to the plant daily.
Phalaenopsis potplants are grown in a bark substrate and the fertilizers are added to the water the plant receives by sprinkling from above. The result is that a large amount of the fertilizers do not end up in the pot but on the ground. From 2027, however, emissions in Netherlands must be close to zero: all the drain water must be collected and reused.
The use of CRF Granules
WUR investigated the use of CRF granules in the pot to lower the emission of fertilizers . From the start of the cultivation, the coated CRF granules deliver a small but certain amount of fertilizer to the plant daily for 16 to 18 months, which is tailored to what the plant needs every day. As a result, less fertilizers need to be added to the top irrigation. Moreover, all the water that fell next to the pot and drained from the bottom of the pot was collected and reused with the next watering. The research took place at a growers site were all plants were treated in the same way. . The cultivation results were compared with those of four reference companies.
Production and quality were found to be comparable and the shelf life of the plants fertilized with CRF was rated "excellent". The granules replaced the application of fertilizers by sprinkling to a large extent - namely about half. Together with the collection and reuse of all the drain water, the emission was almost 0: with the new fertilization, the growers already comply with the rules for 2027. Moreover, the granules are active longer than the cultivation lasts. This means that fertilizers are also released when the consumer has bought the plant.
Reuse of drain water
The reuse of drain water did not cause any problems during the study. However, there are other growers for whom full recirculation can cause cultivation problems (especially with root growth). These problems are unrelated to the kind of fertilizers used. The cause of these problems is not yet known. That is why WUR is researching the problems that can arise with full recirculation in a new research project.
The research into lowering emissions with CRF was funded by the STOWA (Foundation for Applied Research Water Management) and the crop cooperative Potorchidee, and was supported by Pannekoek Orchideeën, the Phalaenopsis growers association of the Netherlands, the reference companies, ICL Specialty Fertilizers, Van Os Research, Glastuinbouw Nederland, Lentse & Slingerland Potgrond, Anthura, Floricultura and Delphy.
The research report can be found on glastuinbouwwaterproof.nl.