‘Switching to diffused ALBARINO glass reaps multiple benefits’

Larger fruits that ripen faster, and more generative growth. For Schenkeveld, this the greatest added value of growing under diffused glass. At the Schenkeveld Schiphol site, where the first greenhouses opened in the autumn of 2017, the operators opted for Cultilene’s ALBARINO Mid Haze glass with double AR coating especially because of the special hydrophilic anti-reflection coating – which leaves the glass structure intact.

Schenkeveld Schiphol is by common consent a prestige project. The company’s growth means that Schenkeveld will eventually require over 40 hectares of glass, directly along the A4 motorway, just outside Schiphol Airport. “The Westland, where our roots lie and where we now grow almost 40 hectares of tomatoes, did not have enough space to realise our growth ambitions,” says Rokien Schenkeveld. “That’s why we had to look further, leading us to PrimA4a, a greenhouse horticultural development area near Schiphol. There was room here to set up a large-scale company, in an easily accessible location with optimal utilities.”
Schenkeveld Schiphol will eventually include four greenhouses of eleven hectares each, with a central processing area in the middle. “Half of this so-called ‘cloverleaf’ has been realised,” says Schenkeveld. “In October 2017, the North greenhouse and the processing area became operational. The East greenhouse joined them in October 2018. This second greenhouse should have gone into production a year earlier, but the discovery of numerous bombs from the Second World War caused a considerable delay in the construction process. Current plans have the West and South greenhouses up and operating in 2021, creating a total area of 44 hectares at this location. The area is reserved entirely for the large truss tomato variety, Merlice.”

Careful deliberations

Before beginning construction, Schenkeveld focused extensively on the design and layout of the new greenhouse complex. The glass for the greenhouse formed a crucial part of the plans. “Diffused glass is the trend today; we couldn’t ignore that,” says Berry Baruch, Growing Manager at Schenkeveld. “However, we had no prior experience with it and we wanted to plan carefully. We therefore contacted the WUR and fellow growers, who had already had experience with diffused glass. Their experiences did not lie. WUR studies showed that diffused glass results in more and better distributed light in the greenhouse. As a result, fellow companies achieved an increase in production of 3-5%. In the end, this is what won us over. At Schenkeveld, we continuously strive for further optimisation while ensuring we do not take on too much risk.”

AR coating as a decisive factor

Once the choice for diffused glass was made, the next question to answer was what type of diffused glass was most suitable for Schenkeveld’s growing situation and the crop. “We had no doubt that we would choose diffused glass with a double anti-reflection coating,” says Baruch. “With such a coating you reduce reflection and the light transmission increases. Many coatings are applied via etching, a process whereby a chemical agent is used to treat the glass, changing the structure and creating unevenness. Dirt easily adheres to the glass, cleaning is more difficult, and needs to be done regularly. However, Cultilene’s anti-reflection coating – a Sol-Gel Coating – helps address these problems. The coating is sprayed onto the glass and then heated so that the coating and glass fuse. The structure of the glass is therefore not affected, and the surface is smoother, ensuring that light transmission remains constant for many years. That was the most important reason for choosing Cultilene ALBARINO glass.”

Best of both worlds

Schenkeveld chose ALBARINO Mid Haze glass, with a haze factor of 50%. In concrete terms, this means that part of the incident light is spread out. “Almost all tomato companies in the Netherlands opt for mid haze, with advantages including diffused light combined with high light transmission. Thanks in part to the double anti-reflection coating, we achieve a light transmission of 96%. In short, we combine the best of both worlds,” says Baruch. “According to the WUR, although high haze glass helps achieve higher production, the winter months also have less light. We worried that we would then harvest far too many kilos in the summer, whereas it is also important for us to achieve good production in the winter.”

Larger tomatoes, faster ripening

The crucial question is what the practical benefits of investing in diffused ALBARINO glass will be. Baruch doesn’t mince his words; he sees a clear added value in several areas. “The biggest gain is that the light penetrates deeper into the crop, reaching the lower and intermediate fruit. This has a positive effect on photosynthesis, which results mainly in larger tomatoes, and fruit which ripens faster. On average, we harvest here ten days earlier than in the Westland. We also see that pollination with bumblebees is achieved more easily. Perhaps that’s because the heads don’t get as warm because of less direct radiation.”
Baruch cannot yet say whether the diffused glass also increases production. “The previous growing year’s dry, warm summer made it incomparable with other years. But the fact remains we still had a reasonable production run. It’s likely that the glass choice also plays a role. In a normal year, I expect that ALBARINO diffused glass should be able to produce 3-5% more.”

Satisfied

The fact that the diffused glass used with the Merlice crop resulted in a more generative growth came something as a surprise to Baruch. “The variety survived the winter better than expected. That’s a positive, but for that reason we should have focussed a little more on growth last year. The crop was too large. We hope to find the right balance in the coming years. You really have to learn how to grow under diffused glass; perhaps I didn’t spend enough time thinking about this. But the choice for diffused ALBARINO glass has proved to be the right one; it reaps multiple benefits.”

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