Emission-free cultivation is possible. Wageningen UR's Greenhouse Horticulture and a consortium of companies has already shown this over the past few years with trials on stone wool, with cucumber and pepper crops. Last year, they also showed that buffered and rinsed coco substrate is also suitable for emission-free cultivation. But what about non-buffered coco substrates? And non-rinsed coco?
Retaining nitrogen
On June 8th, a trial with high-wire cucumber crop was started on this subject. The cucumbers (variety High Power) are placed in two sections. In one section, the coco substrate was buffered and rinsed prior to cultivation. At the discharge of the rinsed water, sodium was removed from the substrate. "But in this rinse water there are also nitrates present, which contain nitrogen, which can be used again in cultivation," as the researchers know. "Therefore, we use non-buffered coco substrate in the other section, so that nitrogen remains in the recirculation system."
It is very important to watch the fertilizer ratio in the irrigation water. In particular, the proportion of sodium in the nutritional-EC must be monitored.
The first fruits were harvested on June 23. And as yet, the crop is looking quite good, according to researchers. "The section with rinsed coco is slightly more generative, caused by a slightly higher EC in the nutrients. The crop in the non-rinsed section looks slightly fresher. The EC in the nutrients will be reduced slightly in both sections, in order to lower the EC in the drainage water. The crop could open a little more in each section, therefore 1 cup per m2 will be removed."
Emission-free cultivation
In the emission-free cultivation sections, two types of filtration filters are used this season. A MT-IBA filter is used. This type of Fiber Filtration filter uses thousands of wound fiber coils and can filter up to 0.4 μm of particles from the water. The filter removes floating substances, unwanted organisms, but leaves nutrients in the water. The second filter is a flatbed filter. Drainage water is passed over a filter cloth (35 μm, 35 g/m2 cloth), that traps the dirt and the filtered water passes through. This type of filter is supplied by Moor Filtertechniek.
Follow the findings of the researchers here, available only in Dutch.