Tomatoworld

About Tomatoworld

Tomatoworld, an information and education centre located in the Westland region of the Netherlands, has a 1,200m² show greenhouse where 40 different tomato varieties are grown for demonstration purposes. For the past two years, Ab van Marrewijk has been responsible for managing all aspects of the greenhouse climate to keep production running smoothly.

“Our facility allows customers to see how different varieties perform under various conditions. Visitors are also able to try samples and do taste tests to find out which varieties they prefer,” says Van Marrewijk.

Up until 2020, Tomatoworld attracted around 8,000 visitors a year from all over the globe. But then the pandemic broke out, causing a dramatic fall in visitor numbers. “So we needed to find a new purpose. After reviewing the options, we decided to shift our focus to research instead,” he continues. “Our technical partners were immediately enthusiastic about the idea because it would enable them to test new ideas in practice.”

Living lab for innovation

Today, Tomatoworld has become a ‘living lab’ for innovation. For instance, it has recently conducted live testing of a new tomato harvesting robot from Japan, and the greenhouse is fitted with many other kinds of state-of-the-art technology including an energy screen, a Hoogendoorn IIVO climate computer and numerous cameras and sensors collecting all kinds of data. This provides valuable insights into crop strategies for partners such as substrate suppliers including Saint-Gobain Cultilene, as well as being beneficial for Tomatoworld’s own tomato production activities.

“Having been involved in the horticultural industry for several decades, a few years ago I learned about the Plant Empowerment philosophy from Peter van Weel, one of the authors of the book,” explains Van Marrewijk. “The focus on optimizing the plant’s natural balances by using data in combination with the laws of physics and plant physiology really appealed to my own way of thinking. Once we got the new climate computer in early 2021, I realized that we now had all the necessary information at our fingertips, so this was the ideal opportunity to put Plant Empowerment into practice and explore the effects. Since then, teams from two of the Plant Empowerment Implementation Partners, Hoogendoorn and LetsGrow, have been helping me to use the computer to closely monitor factors such as temperature, humidity and water in order to improve the balance.”

Sensor-driven screening strategy

In May 2021, this was supported by the installation of a new lighter-coloured energy screen at Tomatoworld to replace the existing dark screen, plus three new temperature sensors: above the screen, below the screen in between the heads, and at the base of the plants. The combination of the new energy screen with the sensor data enabled Van Marrewijk to adapt his screening schedule: “We applied the new way of thinking from the book and started using the energy screen to influence the temperature and humidity in the greenhouse. For example, now that I can see the temperature above the screen, I can decide whether the coldness might affect the heads. If it’s too cold then I won’t open the screen at all, or I will only open it very gradually.”

Additionally, Van Marrewijk explains that the computer helps him to keep the evaporation going: “You don’t want the humidity to drop below around 60%, so if I see that the levels are starting to fall, I will close the screen to 80%. This causes the humidity to rise so that the heads become active again. But even when the air humidity is normal, if you  open the windows when it is very cold outside, you can get condensation on fruits, leaves and stem. With the naked eye, you can only see condensation on the fruits, not the leaves and the stem, so that’s another way that the data comes in useful.

Also, in the past, the plants used to suffer burnt leaves at the top of the head in the spring. By keeping the screen closed every night to maintain a higher temperature at the head, it now makes it easier for the all-important calcium to reach the top of the plant. And thanks to the lighter colour of the screen, I can now keep it closed until 10 or 11 a.m. rather than sunrise, which helps to save a lot of energy.”

Mineral balance

Besides helping Van Marrewijk to implement a new screening strategy, the Plant Empowerment principles have also enabled him to take a new approach to irrigation and the EC. “Now that I’m able to see precisely what’s happening in the substrate thanks to the sensors, I can work more precisely in terms of what time I start watering and how long I carry on for,” he comments. “Should I give a little bit more at the end of the day, yes or no? And what about the mineral balance in the water? After all, changing one mineral can have a negative effect on another. That’s why we’re currently running a nutrient trial on three different varieties, each on two different substrates. We take two samples from each variety – one from the top and one from the bottom of the plant – every two weeks to compare the performance and influence of different recipes and approaches.”

No chemicals

As another benefit of the Plant Empowerment philosophy, the grower mentions plant health: “I’ve noticed that the crop is stronger, because we’ve had less of a problem with insects and disease. For example, I didn’t see any signs of Botrytis at all until October 2021, and that’s only because I reduced the heating because the energy prices shot up. In fact, I only had to spray once last year. For me, that’s proof that it’s possible to grow a crop without using chemicals if you use this new way of thinking to focus on plant health.”

Feeding the world

Van Marrewijk admits to being surprised by the results so far, and he is now keen to see the outcome of applying the Plant Empowerment philosophy for the whole of the new season, which was planted in late January 2022. “The results of this approach have been amazing: we had a very fresh, bright and colourful crop with good production levels all summer long, despite not focusing on the data until halfway through the cycle. We now have everything in place right from the start of the new season, so we expect to get even more information than last year and use it to our full advantage.”

In the past, as a show greenhouse, the focus was on quality and appearance – it was mainly about creating the ‘wow’ factor, he says. But in view of Tomatoworld’s research role for its partners, Van Marrewijk is also interested in investigating other benefits of Plant Empowerment such as production levels, plant health and energy savings. “After all, growers will increasingly be impacted by many factors, including the scarcity of water and essential minerals, rising energy prices and the labour shortage. Meanwhile, the ever-growing world population is set to hit the ten billion mark by 2050 and all those stomachs need feeding.” In this context, he believes the philosophy can also make a key contribution to tackling the huge global challenge that lies ahead.

“All this data can be used to develop a very precise crop strategy tailored to each specific variety, no matter where you are in the world. Therefore, I absolutely believe that the new way of thinking presented in the Plant Empowerment philosophy can help growers everywhere to increase their production per square metre so that we can tackle this global challenge together,” he concludes.

Interested in learning more about data-driven growing?

Are you interested in learning more about autonomous and data-driven growing in line with the Plant Empowerment philosophy? We organize different activities to stimulate cooperation and knowledge exchange, such as webinars, workshops, partner- and member meetings. For more information about the webinars check here.