Dutch brothers Leo and Maarten van Erkel cultivate large-flowered cut cymbidium on perlite in containers on 15,000 m2. Except for 10 weeks, from mid-June to end of August, orchids are harvested throughout the year. Last year, the groundsheet of one of two rainwater basins with a capacity of 4,500 m3 was renewed and also a tarpaulin was placed to prevent algae growth in the water.
Sodium level
"The cymbidium crop always had an exemption for the recycling of drainage water because of salt sensitivity of the crop and low EC in the fertilizer," Maarten van Erkel says. Meanwhile emission standards do apply for cymbidium and research has started to determine at what sodium level adverse effects on crop growth will occur. The brothers are members of the Cut-Cymbidium Crop Cooperative, where tests with different sodium programs have been running for three years.
Mobile purification
The cymbidium grower: "In these trials there is sodium accumulation in the irrigation water, but in practice it is not so bad. Because we do not re-circulate, the sodium content is hardly increasing. If this would be the case, we would flush more and would discharge into the sewer. If next year it will be necessary to purify the water, we're going to do it with a mobile water treatment plant. If purification would be needed too frequently or if mobile purification is too expensive, we'll look for another solution."
Collection system for drainage water
Still many cymbidium growers let the drain water soak into the ground and need to invest heavily in a system for collecting drain water. "Because the greenhouse is never empty, it is expensive to install the system. The greenhouse requires leveling, making of sloping surfaces and then covering with plastic foil or hanging the foil to the potted plant cultivation system," says the grower.
"In the cultivation of roses on rockwool we already had a system for collecting drain water, otherwise we would walk deeply in the mud because we are here at a very low level. Twelve years ago we switched to growing cymbidium, and adapted the draining system at the same time. We now benefit from it. The plants are placed approximately 15 cm above the ground on a fixed gauze bed system with a gutter system underneath."
Disinfection of irrigation water
At the greenhouse, a QuickScan purification was carried out to get a complete overview of all water flows, so it became clear what had to be done. Van Erkel: "This summer we are going to disinfect the drain water from viruses, fungi and bacteria to be able to recycle. We are still discharging into the sewer, but next year that is no longer permitted. The condensate will be stored in the rainwater basin and the basin water will be disinfected as well."
Source: Glastuinbouw Waterproof