Smarter fertilization and appraisal with the drone

Don't expect a fancy office or a hangar full of equipment and flashing screens. Jan Theeven keeps it as simple as possible and we simply meet at his home. The laptop is opened to show the results of his work: a 'photograph' of a plot that reveals what you cannot see with the naked eye. It provides the farmer with essential insights.

After a career as an aerial combat engineer, Theeven wants to take a new path. But what then? "In 2016 I was at Schiphol Airport and saw the first drones on the shelf at an electronics store. I started thinking about the possibilities, such as taking aerial photos during events. But I've also always been interested in nature and agriculture and discovered that with the right equipment I could help innovate this sector." With money saved up, he purchased the drone and a multispectral camera and got the necessary licenses and certifications.

Fertilizing on demand

Theeven gets in touch with consulting firm Arvalis in 2017 that wants to do research on the fertilization needs of outdoor crops; a two-year project with 11 growers, more than 20 plots and 5 crops. Theeven provides the drone flights, per plot twice per season. One plot easily yields 200 photos, which Theeven combines into one overall image using smart software. That single image provides insight into the photosynthesis of the crop.

In order to go a step further, more research is needed. That is why Jan Theeven and Chris van Laarhoven went to LIOF to ask for financial support for their 'Precision Farming 2.0' research. Theeven: "That was quite a job, because you have to describe very well what exactly you are going to do and what the potential is. Fortunately, we eventually got the LBDF grant and were able to start September 2018."

"Tailoring fertilization can save costs, or produce higher yields or quality."

The most widely used algorithm in precision agriculture is NDVI. to inventory whether the observed spots contain living vegetation.

The multispectral camera can capture different 'layers'. Each layer tells a different story about the condition of the crop. With additional plant sap measurements on site, real meaning can be given to the different colors.

The optimal nitrogen balance

Full-field crops like leeks are challenging to grow profitably, especially with the increasingly stringent regulations set by the government. Chris van Laarhoven: "Leeks are very sensitive to an optimal nitrogen balance. In the sandy soils of Brabant and North Limburg this is a challenge. Because of its structure, a lot of nitrogen leaches into the groundwater in the form of nitrate. Leek at the same time requires relatively large amounts of nitrogen to achieve sufficient yields. However, the government is setting increasingly strict requirements for the permissible amount of nitrate in the groundwater. Moreover, over-fertilization can lead to an accumulation of nitrate in the leaves, causing the plant to produce short rather than the desired long sugars. These short sugars attract pests and fungi, which in turn require additional plant protection products. In short: growers strive for the perfect nitrogen balance, where leaching of nitrate to groundwater is limited and, on the other hand, enough nitrogen for optimal plant growth and consistent quality. Determining the right fertilization strategy varies by variety, field and soil type, but the methodology for doing so is often crude, cumbersome and expensive. If we start to better understand what leeks really need and therefore have to use less KAS (nitrogenous fertilizer, ed.), hopefully many leek growers can achieve healthy returns and continue."

"We need to get better at understanding what a crop really needs."

Impressive results

The first research results are already very interesting and encouraging for growers. In 2018, Theeven and Van Laarhoven examined the first leek plots of two growers. Due to the extreme temperatures, much more nitrate was released from the compost than normal. Despite this, the crop did not grow well in certain areas. Normally, additional fertilization with KAS is applied. The drone images also showed other poorly growing spots in the field. Van Laarhoven: "In a few places we took measurements of the plants and could see that extra foliar feed in the form of molybdenum, boron and iron was needed instead of the standard KAS. This approach saved a round of KAS spreading almost everywhere. Leaching of nitrate was also substantially less than normal. So all in all, this approach yielded better quality at significantly less cost and with less leaching!"
In 2020, results will also be known with other crops, such as potatoes.

"Tailoring fertilization yielded better quality at significantly less cost and with less leaching!"

Wildlife damage exact picture

Through EagleDrone's work on the Arvalis study, Anton Winkelmolen of GreenTechLab at the Fontys campus in Venlo also managed to find Theeven. GreenTechLab presents students with technical issues that farmers have to deal with. The issue of proper wildlife damage assessment quickly led to EagleDrone. Winkelmolen: "Wild boar or badgers can cause serious damage to a field of, for example, corn. But if the appraiser goes to the scene, he often does not get a good overall picture. After all, you can only get that from the air! Discussions about the extent of the damage are the result. With the drone images we can show exactly where and how much damage there is. With this analysis in hand, farmers can make a well-founded appeal to the Fauna Fund and receive fair compensation." Theeven: "The students of GreenTechLab have developed a piece of software that links the drone images to a calculation module. To be able to contribute to new projects like this, to meet farmers with a story and also to visit very beautiful places, that is really a wonderful combination."

Example of an overview image of wildlife damage spots on a plot of grain corn

Look also at Omroep Venlo's video on the game damage assessments >

Future

For Theeven, then, the recent projects are just the beginning. He still sees plenty of potential for agricultural and nature organizations. For Natuurmonumenten he has already charted the spread of blue-green algae and the presence of an unwanted exotic species. "Everything that can be found on the surface, I can visualize. To do this well, you need to be able to fly well and safely on the one hand, and have thorough and up-to-date knowledge of the software and equipment on the other. So I would venture to say that not many people can do what I do. Combining the results of the drone images with the measurements and expertise of substantive specialists, such as those of crop consultants, makes the results really valuable. For me, too, it is always very exciting what comes out of it: are we going to make a difference, can you really benefit from this? For the time being it's a matter of showing people what I do and what it can bring them."

More information

Agrarians, advisors and researchers: curious or got ideas for a new application? contact Eagle Drone >