The official term is aeroponics: the roots hang in the air and are fed tiny droplets of water containing nutrients.
The potato plants are now two and a half months old and they are thriving, as are their roots. Smits is testing what drop size gives the best results. Cultivation using mist has various advantages, explains Smits. When potatoes are grown in soil there is a lack of oxygen in the soil that slows down growth. Potatoes grown in mist also don’t suffer from soil diseases and persistent pests such as nematodes. Another benefit is that the plants can be grown close together; Smits thinks 20 plants per square metre would work.
The only negative aspect of Smits’ experiment is that the tubers are not growing that well. ‘That’s my own fault. I created the perfect environment for plant growth in this greenhouse but two weeks ago I discovered the plants form tubers when they are under stress. Now I’ve reduced the nutrients in the water droplets. That creates some stress but I also need to do something with the day-night cycle and mechanical stress to encourage tuber growth.’
Smits thinks aeroponic spuds have a future. ‘They are already being grown on a small scale in greenhouses in Switzerland, and this method is starting to make financial sense in the Netherlands too. There is less land available for growing potatoes and prices are going up, whereas the technology for aeroponics is becoming cheaper.’
Price of land for growing potatoes is going up while this technique is becoming cheaper
Potatoes can be grown in mist in greenhouses or outdoors. This method uses 95 per cent less water than cultivation in fields, says Smits. The use of pesticides can be reduced by 100 per cent in greenhouses and 80 per cent outdoors (where Phytophthora and Colorado beetles are a problem). He is still doing the calculations on the profitability of one hectare of potatoes grown in mist.