Sign up for our daily Newsletter and stay up to date with all the latest news!

Subscribe I am already a subscriber

You are using software which is blocking our advertisements (adblocker).

As we provide the news for free, we are relying on revenues from our banners. So please disable your adblocker and reload the page to continue using this site.

Click here for a guide on disabling your adblocker.

Sign up for our daily Newsletter and stay up to date with all the latest news!

Subscribe I am already a subscriber

"Clearly seen relationship between too much leaf and loss of production in ProJoules "

A grower in Spain, for whom Willem van Dijk is a cultivation advisor, will start using ProJoules. This will soon make the Spanish grower the fifth grower of Willem's to use the crop planning platform. Willem and the international growers started working with the ProJoules platform for the first time in real life this year. The crop consultant shares his experiences.

Willem got to know the platform when it was still in the Excel phase. Initially, data was collected in Excel. The joules were and are leading. "The fact that I started working with it came about by chance. Growers asked about it. I know the creators of the platform and can explain to growers how it works."

Compared to the early days of ProJoules, a lot has changed. "You can't compare the platform of today with how it once started," he says. It is obvious that the platform is now available online, but that is not the only thing. "Users now have much more overview on the dashboard in ProJoules. You can also make graphs in Excel, but this is better."

Insight into cultivation strategy
The growers with whom Willem works are in Germany, the Czech Republic, Austria, and soon Spain. "I also supervise growers in England, Japan, Vietnam, and Mexico, especially remotely." Of those growers, mainly active in tomatoes and as well as some with cucumbers, growers in Austria, Germany, Mexico, and soon Spain also use ProJoules. "In the latter, I advised the growers themselves, ProJoules. In Spain, this is a completely new farm. Growers there cannot yet build on the experience of a long horticultural career. With the platform, I can give growers better insight into why they should make certain decisions. The lines in the graphs in ProJoules quickly make it clear why a certain growing strategy works or doesn't work."

Incidentally, it is not the case that growers with a lot of experience cannot also use the platform. Indeed, Willem himself also has a lot of experience, yet he gains new insights thanks to the platform. "What I have seen with my growers this year is that they can push the boundaries even more. For instance, growers started truss pruning earlier in the summer and also continued growing longer. It resulted in better production. You can also see from the data in the platform whether it pays to keep an extra fruit at the beginning of the year."

Cultivation data stays with growers
In 2021, Willem was running a trial with growers. This year the online platform started in earnest. "What's nice is that the platform continues to evolve. This morning I saw an update with CO2 figures and temperature integration in ProJoules," says Willem at the end of November. "That looks very slick, I must say." The ProJoules platform releases new updates regularly, with the aim of gaining even better insights into crops. More and more data is becoming available in the greenhouse, which ProJoules can also make use of. "Growers can make it as comprehensive as they want. That also applies to ProJoules. Growers don't have to use all the available data."

According to Willem, what appeals to growers when using the Dutch-made crop planning platform is that the crop data stays with the grower. "I have heard that several times from growers. They decide who can access the data. The data is not shared just like that. The grower also actually has to give me access to be able to look in as an adviser."

Display data from ProJoules. Click here to enlarge

More leaf picking or not?
At one of the growers Willem supervises, Drechsler, record production was achieved this year partly thanks to insights from ProJoules. "Still, we see room for further improvement," says the consultant. "At a certain point, there was too much leaf mass on the plant after all, and production took a hit. Next year, we want to be even more alert to the labor story and remove leaves on time." Already this year, German growers decided on extra leaf picking because of the insights from ProJoules. "Until early September, that pays off. It is certainly not the case that as soon as it is summer, the grower can take the head out and rest on his laurels. In autumn, a lot still needs to be done in terms of crop maintenance."

Lighting is out of the question for many growers this winter. However, adviser Willem is not any less busy than usual, partially because he also has growers in other regions. In Mexico, growers are plenty busy in December. "There, data in ProJoules shows that growers kept too many heads on for years from October to December. As a result, productions were often lower early in the new year. The planting load was too high. The advice I give now is to prune back more. Sometimes growers weren't pruning at all."

Light measurement in foil greenhouse Mexico

Light measurement
Another great insight from the platform is that growers recognize how important it is to know the amount of light in the greenhouse. "The light transmittance of a good foil greenhouse these days is sometimes very close to a glass greenhouse with all the techniques available." In Mexico, Willem also took light measurements. "We were amazed at how much light came into the greenhouse from outside. Even slightly more than with glass, but the difference was minimal. The growers there also take such insights well. They are very open and eager to learn. It's nice working with them."

There is also plenty of activity in Europe. An Austrian grower with whom Willem works is lighting, at least until Christmas. "Electricity is uncertain after Christmas. If less electricity is available, growers will light less. With ProJoules, an extra plan has then already been created with insight into what plant load the grower has to maintain. Based on the available joules, a grower should, also in a general sense, adjust plant density or pruning policy."

Looking more at joules
In Willem's opinion, growers are still not looking enough at the energy balance of the plants. "Growers still do a lot by feel and experience. Like: 'When the light outside increases, then this or that should be done.' Now, these kinds of choices are more substantiated." For the adviser, it is easy in this respect that giving advice remotely is better. "You discuss the same figures now, which is easier to talk about. Try and explain to someone why you want something in cultivation without actually being able to point it out. Now you point to a line and a week, and ProJoules shows why a certain change in direction is needed."

Using ProJoules helps growers and advisers move forward, concludes Willem. "It makes me stronger, but the client too." However, he is not afraid that he will soon no longer be needed as an adviser. "Completely autonomous cultivation is a utopia, in my opinion. Climate sensing remains necessary. A number alone does not say everything. On a computer screen, everything can look good, but when you get into the greenhouse, it can still not be quite right. Just look at Drechsler. We are super satisfied with the results there, but still, see room for profit." Willem does like to see more numbers. "For example, even more, numerical insight into a crop's foliage." By combining both insights from experience and numerical cultivation, optimal cultivation can be achieved.

For more information:

Willem van Dijk
Green Management van Dijk 
+31 612 683 871  

Publication date: