Martin Houben (BKU): 'Fully SKAL in ten years, but preferably tightening PlanetProof'

ARTICLE

MARKET & CURRENT AFFAIRS

Hein van Iersel, Monday 30 June 2025

265 sec

Amara's law in practice: ICT, data and mechanization serving the tree nursery

Few people will be familiar with Amara's law. It states that people generally overestimate what can change technologically in three years, but underestimate what is almost inevitably going to happen in ten years. This principle also seems to apply to the tree nursery sector. Director Martin Houben of Boomkwekerij Udenhout explains the technological and strategic choices he makes at the intersection of ICT, data, and mechanization, and the practical obstacles he encounters along the way.

Martin Houben

Houben aims to make his tree nursery fully organic within ten years. 'We are currently planning to expand by about four hectares of SKAL-certified nursery each year.' However, a few things need to happen first. For Houben, the biggest challenge lies in practical feasibility. This mainly concerns eliminating herbicides and developing the right hoeing machines. That is, to say the least, a challenging path with many obstacles. 'In 2024, for example, it was so wet that hoeing was hardly possible. Then you want to be able to correct with chemicals. Within SKAL, that is of course not allowed.'
Rather than switching to 100% organic and SKAL, Houben would prefer to eliminate herbicides within PlanetProof. 'That way you retain room to intervene in emergency situations while still drastically reducing the use of crop protection products. At present, we no longer spray for insect and fungal infestations. Only in cases of truly problematic infestations, such as early and severe powdery mildew, do I want to keep the option to intervene.'

'In 2024, it was so wet that hoeing was hardly possible. Then you want to be able to correct with chemicals'

At the same time, Houben acknowledges and observes that customers and society in general show a clear preference for SKAL. Houben: 'Black-and-white distinctions simply work better for tenders, but I believe the honest story is more nuanced. We already hardly use crop protection products, and I expect to be able to say the same about herbicides before too long if we can deploy better hoeing machines. The winter spraying is particularly important for us.'

'Black-and-white distinctions simply work better for tenders, but I believe the honest story is more nuanced'

trial and error

To reduce dependence on chemicals, Boomkwekerij Udenhout heavily invests in mechanization. This includes the use of autonomous vehicles. Houben has been working with an Aigro Up implement carrier for two years. 'It works perfectly on dry and flat terrain.' After the pilot, Aigro adapted the implement carrier. The latest version has four-wheel drive and can both mow and hoe, equipped with small hoeing tines. 'This version is more robust and can also handle fields with root ball holes. The working method on the farm will also change. That requires a new type of operator who is both technically skilled and agronomically knowledgeable.'

The latest version of the Aigro-Up has four-wheel drive and is equipped with hoeing tines

water: from drainage to storage

Whereas waterlogging used to be mainly a matter of drainage, Houben now wants to retain and reuse the surplus. 'We receive an average of 900 mm of precipitation per year, but only need 600 mm. We no longer want to drain the remaining 300 mm through ditches but store it in deeper underground layers.'
For this purpose, he and fellow growers in Udenhout want to start a trial with controlled drainage and underground water storage in a bubble several meters below the surface. The water can be filtered through biofilters or activated carbon before being pumped down. So far, according to Houben, the water boards are cautious about this idea. 'They fear contamination, while we can demonstrate that we hardly use any crop protection or artificial fertilizers anymore. With the pilot, we want to involve the water board and province and possibly prove that we, as tree growers, can actually contribute to groundwater replenishment. It's a win-win situation.'

headstrong

'Tree growers have a reputation for being headstrong, and rightly so,' says Houben. 'You have to be willing to experiment and take risks.' At the same time, Houben believes that the major themes—sustainability, data, mechanization—require collaboration. 'Everyone does their own thing, but we need to connect more. These themes are too large and complex to solve alone. You also need industry, which develops the technology we require for sustainability.'
As an example, he mentions recent innovations in harvesting machines. 'For years, nothing changed; now suddenly several new systems are coming to market. That shows that collective pressure from the sector triggers action. Manufacturers also need scale. You can't develop an entirely new technology for just one tree nursery.'

tree wrapper

One such innovation is the Tree Wrapper. Houben: 'Damcon has introduced the Tree Wrapper, and competitors are also working on it. We hope a feasible application for our type of soil will be available soon. This technology automatically wraps root-balled trees with biodegradable material, saving labor and improving efficiency. For now, it only works with smaller root ball sizes. It's important for us to experiment next year with larger root ball sizes and create root balls in (loamy) sandy soil. I expect rapid development in this area. You often see that such developments don't originate within a single company but through collaboration between growers, suppliers, and technicians.'

acceleration: from six to five years

With all the developments Udenhout is working on, it should be possible to reduce the standard cultivation period from six to five years. 'That's possible if you grow smarter. With soil scans, weather sensors, drip irrigation, and targeted fertilization, you can optimize growth.' Labor registration also plays a role. Houben: 'With HortiTime from Joost Sterke we record activities per plot. But ultimately, we want to calculate the labor cost for each individual tree. That's also important for cost price calculations. This requires further data integration. For last year's planting, we already recorded per tree who the spindle supplier was and, for example, whether it is on its own roots. I expect customers will soon routinely ask for this. Consider, for example, the issue of graft incompatibility.'

data: who is in control?

Digitization not only helps with cultivation but also with business operations. 'We already use AI to prepare quotes faster. Last year we were able to issue 15 percent more quotes, and this year I expect another 10 percent growth.'
Another form of digitization is using stem diameter measurements to accurately map inventory. Our stem diameter measurement project, in collaboration with AgroWizard, is one of five projects awarded funding within AgroBOTS 3 of High Tech NL.
Nevertheless, there are concerns. Who owns all this data? Suppliers want to use the data to improve their own algorithms through learning. I understand that, but we must maintain control.' Therefore, together with universities and platforms such as GreenTechPort Brabant, work is being done on guidelines and infrastructure for safe and fair data sharing. 'You need to be able to share data for innovation, but under certain conditions.'

bumps along the road

The interview with Houben is coming to an end, also because Houben receives a notification on his mobile phone that one of the autonomous mowers has generated an error message. And since this interview takes place on the Friday after Ascension Day, Houben is on call. It's a fitting illustration that the path toward more automation and robotization comes with many bumps. Fortunately, we can combine the error message with the photography. Ten minutes later, we free the Aigro Up mower from a root ball hole and send it back on its way. Houben expects these kinds of malfunctions to be a thing of the past with the new four-wheel drive Aigro Up.

interview series

In this series of interviews, the trade journal Boom in Business talks to several tree growers about how they respond to societal pressure, technological development, and sustainability, and how they work on their innovation strategy at the intersection of data, ICT, and mechanization. Martin Houben of Boomkwekerij Udenhout kicks off the series.

This article was previously published on June 30, 2025 on the Boom In Business website.

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