Machinery

Background

Automating weeding in iceberg lettuce

Can robotisation solve the capacity problem of inter-row hoeing? Dutch iceberg lettuce grower Nico Knibbe takes up the challenge.

Nico Knibbe of Mts Knibbe and Boerma in Wieringerwerf, the Netherlands likes to try new things. He and his brothers are young entrepreneurs facing large investments, so sustainability is of great importance.

Automate weeding in iceberg lettuce

Talking about precision agriculture and the objective within the Dutch precision farming project NPPL, in which Knibbe is taking part, the building plan of a new potato sorter is put aside. Various models of robots and robot tractors appear on Nico’s computer screen. The aim is to automate weeding in iceberg lettuce. A second goal is to reduce usage of herbicides. Achieving the goals in the first phase depends on establishing the right contacts with suppliers. The aim is to demonstrate prototypes in May of this year.

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Nico Knibbe is looking at robots that can automatically hoe weeds in his iceberg lettuce plots. - Photos: Jan Willem Schouten
Nico Knibbe is looking at robots that can automatically hoe weeds in his iceberg lettuce plots. - Photos: Jan Willem Schouten

Camera-operated weeder

This year, Knibbe will grow 120 hectares of iceberg lettuce. Since 2016, he has been working with the Steketee IC Knibbe, a camera-operated weeder. This machine works not only close to the rows, but also between the plants in the row. “However, we only do that in problem areas. When there is little weed, we use a regular hoe,” says Knibbe.

3 hectares per day

He would prefer to use the camera-controlled machine on the entire plot, but the driving speed is too low. In addition, technical defects occurred regulary. “We managed to achieve an average of 3 hectares per day and a total of 120 hectares in three years. It is still highly questionable whether a robot has a higher driving speed, but the idea behind robotisation is that the robot weeder continues working day and night and that labour is saved. How this all works out in practice remains to be seen.”

Wageningen University & Research researcher Bram Veldhuisen helps Knibbe make the right choice when it comes to investing in a robot weeder. The arable farmer knows all too well that several suppliers are developing new technology and he wants to join in on time.

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Nico Knibbe has for several years now been using a camera-operated Steketee IC weeder.
Nico Knibbe has for several years now been using a camera-operated Steketee IC weeder.

Dino from NAÏO Technologies

Just like drones when they first appeared in the fields, robots appeal to the imagination. Dino from NAÏO Technologies now appears on Knibbe’s computer screen. Apparently this weeder is doing well in iceberg lettuce. However, the working width will have to be adjusted from 1.80 meters to 2.25 meters.

Comments on robots are also made. The hoeing mechanism is different from the Steketee IC, which in the first place requires getting used to. Above all, Knibbe wants to experience how much time he spends positioning and setting the weed robot. Can the weed robot find the plants, do various GPS systems exchange the data?

Safety

Knibbe: “It should have a camera that sends a signal to my phone when things go wrong.” In addition, according to Veldhuisen, safety is an issue. “Safety must be guaranteed. It is not yet clear how the robots guarantee this.” Knibbe will not be slowed down by this. “If I would do that, nothing would ever happen.”

Also read: Demystifying robots for use by everyday farmers

Autonomous tractor

The option closest to current practice is to have the Steketee IC towed by an autonomous tractor. Knibbe knows that systems are being developed by various companies, such as Gotrac GPS and Probotic systems. Most work on a pre-prepared route and that is not what he is looking for.

“GPX solutions is developing a system where a so-called Preplan is being made in advance on the computer. This Preplan contains lines, turning points and sequence of actions, such as PTO on and hydraulics on or off.” This system is intended for the Fendt 200 and 300 series, says Knibbe. The Greenbot by Precision Makers, a stand-alone autonomous tractor, does not have his preference.

Precision spraying

Last year Knibbe invested in a new Amazone sprayer. The boom is equipped with multiple nozzle holders at 50 centimeters. These form the sections. The AmaSwift system makes it possible to choose a spraying nozzle depending on the application. Only two adjustments are required to spray precisely on the plant row or just on bare soil shortly after crop emergence.

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The boom on the new Amazone sprayer is equipped with multiple nozzle holders at 50 centimeters distance.
The boom on the new Amazone sprayer is equipped with multiple nozzle holders at 50 centimeters distance.

Knibbe: “The bridge system on the nozzle holder where the delivery is guided to nozzles at 25 centimeters is available. I’m still waiting for the right type. In addition, I need AmaSelect Row to set the correct sections in the computer.” Once this has been done, he wants to start using this system for treating phytophthora in potatoes.

The expected savings vary from 33% in soil herbicides to 66% with the first spraying of the crop. “We also do it because customers within Global-Gap ask us to. We have no evidence yet of a better yield and improvement of soil life.”

Variable rate spraying recommendations

When Veldhuisen shows the possibilities of Akkerweb as a model that supports decisions, Knibbe is glued to the screen. So much research has been done in the cultivation of potatoes that, provided that the user can enter cultivation registration and other data, variable rate spraying recommendations result from it.

For example, a phytophthora application has been developed by Wageningen University & Research and Agrifirm, but there are also, for example, haulm killing applications. Knibbe: “Apparently this is mainly known to trading partners. I think it would be appropriate to stretch a spraying schedule, for example ” He immediately creates an account. He can obtain data from his crop registration in Cropvision.

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Nico Knibbe is more than willing to invest in new technology. He won't let technical challenges slow him down. "If I would do that, nothing would ever happen."
Nico Knibbe is more than willing to invest in new technology. He won't let technical challenges slow him down. "If I would do that, nothing would ever happen."

All robotisation components available

Bram Veldhuisen of Wageningen University and Research (WUR) has been given the task of making all known knowledge about robotisation and especially its possibilities available to farmers. For the Dutch NPPL project, he followed all developments online and in practice. Many robots are developed internationally, he explains. Videos can often be found on Youtube. Most are uploaded by the suppliers. “Companies show robots working in ideal conditions. It is usually not that easy in practice.”
Knibbe must experience the effectiveness of hoeing, the user-friendliness and safety in particular. Veldhuisen follows, among others, the AgroIntelli Robotti, the Greenbot and Dino from NAÏO Technologies. “We have to learn in the field how to set up the robot in such a way that it finds the plants. Do the GPS systems match and what if they don‘t? We also have to experience how to bring the robot to the field and to what extent you have to stay with it. The Dino robot is equipped with a hoe by NAÏO Technologies. As an arable farmer, you have to become familiar with that type of hoe.“
Like the Greenbot, the AgroIntelli Robotti is an autonomous tractor equipped with a lifting mechanism for attaching implements. The Robotti fits around the implement. Therefore it cannot pull Knibbe’s Steketee IC.
Then there’s the difference in drivetrains. “A Robotti has a diesel engine, the Dino is equipped with an electric motor and a battery. Growers need to know how long they want to run the machine, what the costs are of fuel, refueling or of an extended battery package.”

Bram Veldhuisen of Wageningen University & Research (WUR) is an expert in the field of robotisation in agriculture. According to him, farmers need to experience in practice how robots really work.
Bram Veldhuisen of Wageningen University & Research (WUR) is an expert in the field of robotisation in agriculture. According to him, farmers need to experience in practice how robots really work.

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