Meewisse Roses: "Thanks to PIM, my crop is more balanced."

Launched in 2023, Priva Precision Irrigation Management is now being used in around ten horticultural companies. Tom Meewisse was one of the first growers to embrace it. "I'm always open to innovation, as long as I understand what it's about and I am confident it will deliver added value. That was the case with this device. Our old measurement system was working well, although it also had some limitations. With PIM, we were able to overcome them and optimize our crop management."

Old system too limited

Before he bought the new measurement equipment, the grower based his irrigation mainly on the radiation sum, a small weighing gutter, and the amount of drain water for the entire greenhouse, which contains 4.3 hectares of Red Naomi.

"I was largely guided by the drain water volume, but with only one drainage well across more than four hectares there is a lot of delay in the data I receive from it," he explains to Priva advisor Kevin de Kok. "We also measure the EC and pH at the drainage well. Because of the delay we were actually always responding reactively. It wasn't that we had a lot of problems – experience tells you more or less how to preempt them – but there was definitely room for improvement. In particular, PIM would be able to help me set the irrigation start times more accurately. So it was an easy decision to go for it."

More accurate, more complete, and more up to date

Meewisse bought a unit that could be described as a next-generation weighing gutter. There are two substrate slabs side by side on the weighing platform. The system gives a real-time picture of the water content in the slab and its development, the drain volume, and the EC and pH of the drain water, thereby avoiding the unwanted delay. The unit is connected to the Priva Connext process computer, which the grower uses to control his irrigation.

"The equipment is more accurate than before, and the data are a lot more up to date," Meewisse says. "So we finally have an accurate picture of the water loss, or the saturation level of the slab, in the evening and at night. This determines the time you start irrigation in the morning. It works well, even in changeable weather conditions. We also work with minimum and maximum rest periods. The end time will be adjusted when I think it needs to be changed. It was 3 pm at the end of March; now it's 4 pm. It will be a little later in the summer."

Strategy adjusted

Now that the rose grower can clearly see what is happening in the slab and how much water the plants are taking up, he does not have to rely quite so much on the radiation sum. Based on the measurement data, he also took the bold step of slightly reducing the minimum rest time. This resulted in more water per cycle being given more often around noon on sunny days when transpiration is at its highest.

Less adjustment

"The irrigation pattern has visibly changed and meets the actual needs of the crop better now," he says. "Incidentally, in consultation with Priva’s cultivation advisor Peter Kamp, I waited a while before adjusting our irrigation strategy. I really have the impression that the plants are growing just that little bit better, and I have to put less effort into maintaining the right balance in the crop. You really do have to make fewer adjustments. You notice that particularly on days with changeable weather conditions."

Important indicator

When asked how PIM is perceived by other users, Kevin de Kok replies: "Very positively so far. Also by our installation partners, because the units are quick and easy to install and make ready for use for almost any substrate-based cultivation system. In a large number of crops, growers want a better and more direct understanding of the crop’s performance, for which transpiration is a key indicator. PIM definitely helps with that. I see plenty of growth potential for this measurement system, not only in roses and fruit vegetables but also in crops such as strawberry and gerbera."

Clear, real-time view of water content, drain, EC, and pH

Priva Precision Irrigation Management is a weighing device with additional sensors that connects to the climate computer. The frame, supported on legs, is equipped with a stainless steel gutter with weighing cells that carry one or two substrate slabs, a drain tank with a weighing unit (also a weighing cell), a drain pump, an EC meter, and (optionally) a pH meter. The measuring unit is connected to the Connext control computer, which is also easy to operate via a smartphone.

PIM gives the user a real-time insight into key parameters for their irrigation strategy and the root environment, such as the development of the water content in the slab, the amount of drain water, and the development of the EC and pH.