Machinery

Background

Blades and hoes key to camera-controlled mechanical weeding

Camera-controlled hoes form a new challenge for growers. During a demonstration of the Ferrari Remoweed and the Robovator visitors could see how camera-controlled mechanical weeders work. It’s a matter of fine-tuning and tinkering with blades and hoes.

The event, where the 2 camera-controlled mechanical weeders were demonstrated, was organised in the Netherlands and hosted by Maatschap P&M Laan and cauliflower and cabbage grower Erik Botman. In the Netherlands a total of 11 Ferrari Remoweeds and 14 Robovators are currently operational. They are being used by cauliflower, cabbage, celeriac and lettuce growers.

Lettuce easy to recognise by a machine

Their application in lettuce works very well: lettuce is quite homogeneous and relatively easy to recognise by a machine. In addition, in lettuce there are fewer alternatives available. Chemical agents can not be used, and earthing using a common mechanical hoe has a very negative effect on the crops.

According to the supplier of Ferrari, Marten Hulzebos from Agri Evolution, using these new machines is therefore more a mindset matter. “The technology is available, but growers have to learn to think differently,” he says.

Teun Laan demonstrates how the Robovator can be adjusted. The machine creates a smooth field, thanks to the extra rake teeth. - Photos: Marga van der Meer
Teun Laan demonstrates how the Robovator can be adjusted. The machine creates a smooth field, thanks to the extra rake teeth. - Photos: Marga van der Meer

The supplier of Robovator, Nanna Kooiman, foresees possibilities in changing and adapting components. According to him, the best results will be achieved by combining old technology with new technology. “One big advantage is that they are open machines; you can see what is happening inside.”

Agents don’t do the trick anymore

Growers that are now switching to a mechanical hoe are very much focussing on the latest generation of equipment. Erik Botman says: “Spraying gave us little to no results. Then you have to use a stronger agent, but that has a negative effect on the crops. Besides, some weeds are immune to agents altogether.”

After a year of experimenting with the Robovator that was still being developed, Botman opted for the Ferrari. “For me it’s an advantage that the computer is easy to operate. All settings are displayed using numbers and images. Choosing a program takes little time, and anyone can operate the machine.”

That said, Botman is not fully satisfied yet when it comes to the effectiveness of the machine. He would like that to be 100%, each percent less than that is one too many for him.

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Choosing the right moment for mechanical weeding

According to Hulzebos, the main challenge lies in choosing the right moment for mechanical weeding. As far as he is concerned the sooner, the better – two weeks after planting the crops have settled firmly enough, and germinating weeds are still under the surface. Botman on the other hand prefers to wait until the weeds surface.

The machine works fine and is simple enough to operate, but we’re not quite there yet

Other growers who have experience using these machines have found that the ideal moment is in general a lot sooner than they are used to. The main thing is to prevent the weeds from rooting again. Therefore, behind the camera-controlled hoe there are 2 series of goose foot hoes; first a flat one, and then a round one. These remove the weeds from between the rows and earth the soil at the same time.

Plant recognition

When it comes to plant recognition – that still leaves something to be desired, according to Botman. For instance, when cabbage is showing suboptimal growth, too small or damaged crops, the camera does not recognise it. The camera can also be confused by yellow or too brightly coloured leaves. Also, the weeds may not be too big, because then the camera is not able to separate the crop from weeds. Botman concludes: “The machine works fine and is simple enough to operate, but we’re not quite there yet.”

On Erik Botman's Ferrari Remoweed the camera-controlled hoes are followed by goose foot hoes, that earth the soil. However, any specification is possible.
On Erik Botman's Ferrari Remoweed the camera-controlled hoes are followed by goose foot hoes, that earth the soil. However, any specification is possible.

According to the suppliers the solution to these problems is learning how to use the different settings in an optimal way. Using the Ferrari Remoweed, Botman drives at a speed of 1.5 tot 1 km per hour in cabbage (5 rows) and 3.5 to 4 km/h in cauliflower.

One kilometre away, on the field of Maatschap P&M Laan, the Robovator has been put to work. The camera-controlled hoeing mechanism is almost identical to that of the Ferrari. The distance to the crop and the speed with which the blades are being driven in the soil can be adjusted, leaving the soil appearing in a square or a diamond-shape around the crop untouched.

Robovator not more complex than Ferrari Remoweed

User Teun Laan dismisses the suggestion that the Robovator is more complex to operate than its Ferrari counterpart. Laan opted for Kooiman as his supplier, because Kooiman delivers the machine according to Laan’s specifications. This has resulted in a design where first a series of goose foot hoes work their way throughout the rows, followed by the rake teeth that Kooiman designed.

“These tumble the weeds once more,” he explains. The wheel behind the machine measures the distance that has been covered and makes sure the blades remain at the same depth.

The grower decides with which specifications we deliver the machine

Laan is more than satisfied with his Robovator, he says. “It allows us to drive a bit faster, 3 to 5 km/h, and the level of adjustment is better. The result is a nice, even field. The paths between the rows are also worked, so water can be drained easily.”

Supplier Kooiman also developed new stems for the outer blades, which can be swung inside, so the transport width of the machine is limited to 2.75 metres. Hulzebos, who supplies the Ferrari Remoweed, says this is also possible on his machine. “The grower decides with which specifications we deliver the machine.”

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An investment of at least € 70.000

The various growers who witness the demonstration are lively discussing the machines and their alternatives as they walk behind them, watching them work. After all, the camera-controlled mechanical weeders require an investment of at least € 70.000. Many growers still use chemical agents and have adjusted their conventional weeder (spring-tine teeth and goose foot) in order to get the best earthing result.

GPS

By using GPS on the tractor it is, according to one grower, possible to hoe using just your eyes. Grower René Verdonk takes it a step further. He uses GPS on both his tractor and his mechanical weeder. “Camera-controlled mechanical weeders are too slow for my liking,” he explains. Others have switched to a Weedfix or Steketee. Kees Buijsman puts it in perspective: “Like everything else, it’s a matter of proper engineering and, above all, correct fine-tuning.”

Specifications

The Remoweed and Robovator are very much alike when it comes to their major components. The number of elements can be adapted to the number of rows. Each element has its own camera that detects a plant based on shape, location and colour. In this process recognition of chlorophyll (any of several related green pigments found in plants) is key. Settings that the grower must adjust are: incidence of light, minimum crop size, distance to the crop and the speed with which the hoes open and shut. These open when the crop is detected, and they shut when weed or just soil is seen. The machines are equipped with a hydraulic sideshift, which pushes the blades to the left or right to be able to follow curves in the row or to correct steering errors by the driver. This is done automatically using infrared, which makes GPS superfluous.

Marga van der Meer

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