News » 10.06.2025 - NL: Shared water supply to aid growers in dry periods

Anyone who climbed the communal water basin in Berlikum, Friesland, in mid-May after several months without rain will see calmly rippling water. This year, there is still plenty of water available in the 45,000 m2 basin, which is a reassurance for the Dutch growers who see their individual rainwater basins visibly becoming emptier in mid-May.

Those who make the climb will also see some orange 'balls' floating in the basin. These are used to maintain good water quality, similar to how growers use the USAF™ cavitating ultrasonic transmitters from Ultramins on their farms.

Communal bassin of Gietwater Berlikum

50 cubic meters per hour
For pepper grower Jaap Vink of Vink Sion, tomato grower Theo van der Kaaij of Kaaij Kwekerij, and tomato grower Marco van Overbeek of Gardener's Pride, the presence of the communal water basin in their greenhouse area has long been unremarkable, even though it is rare elsewhere. The communal basin has been there since the Frisian greenhouse area was set up in early 2000.

Policymakers required the creation of a communal basin, which became a "showpiece of sustainability" benefiting both growers and the environment. New growers in the area were required to use water from this basin, leading to the signing of purchase contracts. Despite this, individual basins were eventually developed over the years, as there was always a need for more quality irrigation water.

The two basins of Gietwater Berlikum are filled with osmosis water.

Since the development, several companies using greenhouses have made changes. Some growers have stopped their previous activities or switched to new ones. Among them are Jan and Frans Zeinstra, who used to grow tomatoes but no longer use their greenhouses for tomato cultivation. Along with Vink Sion and Kaaij, they remain part of Gietwater Berlikum. Gardener's Pride is also a participant in the shared water supply.

The initial plan was to fill the communal basin with 100 cubic meters of purified surface water per hour, but this didn't meet the growers' water quality expectations. Now, the basin is filled with osmosis water instead. Users collectively draw 50 cubic meters per hour, while 30 cubic meters of osmosis water are added each hour. This means the basin level decreases gradually. However, this isn't an issue because there are fewer users now, and rain allows growers to rely on their individual basins as needed.

Previously, attempts were also made to use water via ultrafiltration, but that project was not successful.

The first transmitters
The latest measure to enhance and maintain water quality in the communal basin is the installation of USAF cavitating ultrasonic transmitters from Ultramins. The Zeinstra brothers were the first in the are to use these transmitters in their own basins. After installing the USAF transmitters in their basins, silos, and daily supplies, they observed significant improvements. "In the first 2 weeks, there was slightly more pollution because the transmitters were clearing the algae and biofilm. Within 4 weeks, we saw the water was much clearer, and the biofilm and algae were gone. The water has become much more transparent and cleaner everywhere."

Eric van Velzen (Ultramins) and Jaap Vink with Vink Sion at the company's individual basin.

Urgency or prevention
The experiences of the Zeinstra brothers caught the attention of their colleagues in Friesland. In mid-May, we visited the area, and the three major users of the communal basin shared their insights. It became clear that, due to dry conditions this year, the communal basin is playing a more significant role in the growers' irrigation strategies compared to last year.

In the wet spring of 2024, pepper grower Jaap required "almost no" water from the communal basin. Unlike his colleagues who grow tomatoes and have higher water needs, pepper cultivation demands less. Additionally, Jaap recycles all his water, and his use of extra screens reduces evaporation from the greenhouse. "I don't throw away a drop of water," he emphasizes.

Before relocating his business to Friesland, Jaap operated in a horticultural area between near the Westland greenhouse area. Unlike in Friesland, Jaap only had personal basins there and did not disinfect the water. He continued this practice during his initial years in Friesland until an issue arose, after which, he switched to using a UV disinfectant.

Eric van Velzen, business development manager at Ultramins, recognizes the image. At Ultramins, they see two types of customers, he notes. "Growers for whom the investment in our system is urgent due to problems and growers for whom it's about prevention. Jaap falls into that latter group."

Regarding the communal basin, there had been complaints about "gray" water quality. However, the installation of transmitters from Ultramins helped improve the water quality at Gietwater Berlikum.

Take into account more frequent, longer droughts
At Vink Sion, the transmitters float in a 6,000-square-meter water basin. In the area, tomato growers, concerned about the spread of the Tomato brown rugose fruit virus (ToBRFV) since 2019, have opted to place the transmitters in other parts of their irrigation systems.

Interested in the experiences of neighboring growers, Kaaij Kwekerij, a tomato grower, initially installed transmitters in its own rainwater basin, followed by the daily storage silo. Now, transmitters are present in all basins and daily storage silos. Theo notes: "The only place without transmitters is our waste drainage silo."

For irrigating their tomato crops, the company uses a combination of water from both the communal basin and their own water supplies. By utilizing water from Gietwater Berlikum, the tomato growers can avoid fully depleting their own basins during a dry spring. "This year, we started using water from the communal basin in March, whereas last year, we didn't need to switch until much later."

In mid-May, a new 8-hectare greenhouse will be constructed for Kaaij Kwekerij, and the water supply system will be further expanded, including enlarging one of the basins. This expansion will help the growers maintain their goal of having 1,000 cubic meters of water supply per hectare of greenhouse.

A new greenhouse is being build for Kaaij Kwekerij

"This dry year is one you hesitate to document but must consider," says Theo. The option to draw water from the communal basin has become especially valuable. "The trend seems to be towards drier conditions, so we need to plan for larger water reserves."

In 2024, Kaaij Kwekerij began using the USAF transmitters for the first time. The growers quickly noticed the impact on the hydrogen peroxide they were using. "We typically use a low dosage of hydrogen peroxide up to 10 ppm, but 2 to 3 weeks after installing the transmitters, the hydrogen peroxide was no longer detectable. Ultramins explained that this happened because the transmitters, in combination with the hydrogen peroxide, were effectively breaking down the biofilm, which proved true. The quality of the irrigation water now looks excellent, and we measure our usual hydrogen peroxide levels again. We can even reduce our hydrogen peroxide usage since the Ultramins transmitters make it more effective."

Eric van Velzen and Theo van der Kaaij checking out the water quality in the bassin of Gietwater Berlikum

Cleaner filters
One of Gardener's Pride's locations in the area, acquired from a colleague eight years ago, relies entirely on water from the communal reservoir. The company supports the decision to invest in Ultramins transmitters for the communal reservoir. "Since we started using the transmitters, the filters at our location, which solely depends on water from the communal reservoir, have improved. We don't have to backwash them as often due to reduced contamination."

For Gardener's Pride's other locations, the growers' cooperative Oxin Growers invested in USAF transmitters using SIG&F subsidy funding for their member. Now, transmitters are installed in the grower's individual water basins, daily storage silos, and even in the waste drainage silo.

For the waste drainage silo, the USAF MT 600 Watt, the most powerful transmitter in the Ultramins range, was selected. Eric van Velzen from Ultramins explains: "The capacity needed is determined by a company's water supply requirements on the hottest day. This approach ensures that there is always sufficient capacity."

Grower Marco is satisfied with the performance of the transmitters across his Frisian locations. "Thanks to the investment Oxin Growers made for us, the UV disinfectant is now running more consistently, and the T10 values have improved." By using transmitters at various points in his irrigation systems, he's achieved double water treatment in multiple areas. "I can't think of anything else I would need to do here."

USAF™ MT 600 Watt, the most powerful transmitter in Ultramins' range, in silo at Gardener's Pride

Frisian growers set a good example
Ultramins now provides USAF cavitating ultrasonic transmitters in over 50 countries. Eric remains surprised at how often the importance of water is underestimated. "Water flows through your greenhouse like a train, stopping at every station. In horticulture, we focus heavily on above-ground activities, but it's crucial to pay special attention to what occurs underground as well."

The growers in the north of the Netherlands understand the importance of high-quality irrigation water and have collaborated both collectively and individually to enhance water quality. They find the irrigation water from the communal basin satisfactory, as the filters remain clean and the water is clear. Theo and Eric confirm this after double-checking with a bottle sample.

Eric advises that it's a good idea to occasionally remove sediment from the bottom of the basin. If extreme drought causes the communal basin to empty this year, it would be the perfect opportunity to do so. However, the growers aim to keep the basin filled and the irrigation water clean. With the help of the USAF cavitating ultrasonic transmitters, they've successfully managed this, as issues with algae, biofilm, and pathogens in the water are now a thing of the past.
 

Source:www.floraldaily.com

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