NL: Exceptional weather good test case pepper trial 2SaveEnergyKas

For the 'Peaks without peaks' project, in the 2SaveEnergy greenhouse in Bleiswijk there is a test ongoing to establish how pepper crops deal with temporary lower temperatures and changing conditions. The recent winter weeks turned out to be a good test case.

Researchers Arie de Gelder and Frank Kempkes: "The weather was unprecedented during recent weeks. An exceptional amount of light for the time of the year and to end a pretty cold wind, according to some, a ‘Siberian Bear’. Ideal conditions for learning how we should deal with the peaks in our energy use in our pepper testing."

"And then the gauge is indicating only 0.54 m3/m2 at the end of the week. In practice, you will hear other sounds, and when you have removed your foil and have only one screen in a single roof greenhouse, then in such a week you run very rapidly to 1.5m3/m2. What have we now learned in this week? Insulation helps immensely and insulating in the greenhouse we use a double roof (glass-foil), a double aluminized cloth and a transparent cloth. Result: with a heating tube of 30 degrees Celsius (with a double 51mm net) it remains at 18 degrees inside while outside it is -8 with a biting wind. Then at 9:00am with rapidly increasing radiation, to open the aluminum cloths, at 10:00am the transparent cloth and the tube is already out. We cultivate with the knowledge of 'Next Generation Growing', so we only generate heat on demand."

"At 12 o'clock we already have to open a crack at 27 degrees, because the sun is doing very well. By closing the screens in time in the afternoon, we retain the heat well so that the tube is not needed again until around 8 o'clock. So actually we did not have a peak in energy consumption during last week, the sun did the job. Don’t we have any peaks? Surely we do, Saturday, February 3, there was a peak. Two degrees, windy and with those wintery showers. Our daily consumption was then much higher than the coldest and windiest day of last week. In order to simulate the peak usage, in February we have limited the tube heating at 22 degrees Celsius during the night for a week, and yes, then it gets too cold: 15 instead of the desired 18 degrees."

"In the recently held large supervisory committee meeting, we also discussed what kind of effect on the crop all this has or had. Some large flowers, but then again normal with good setting.

Deformed Fruits? So far, four have been found in the greenhouse. The state of the crop was to their satisfaction. Of course there is always discussion and so many people mean so many wishes. The choices that we have made so far, for the time being seem to turn out well. With all the light, the setting was not really the biggest problem. Maybe unburden the plant somewhat by cutting a green fruit? The first setting (3rd node) and second setting (5th node) are close together and require a continuous high level of assimilates. Now for the coming period to retain a plant with sufficient growth and have a peak in production."