Mechanical weeders fell out of fashion during the 1950s as new selective herbicides offered cheap and safe weed control, but they are now making a comeback.
This resurgence is not just the domain of organic farmers, they are also being increasingly used by mainstream growers who face a diminishing range of herbicides. And there are many additional benefits such as an improved water infiltration and better rooting.
But the next generation weeder is an automated system that can work in fields by itself and promises to revolutionise the way farmers manage weeds.
Looking to launch its own system is French weeding and cultivation specialists Carré, with its Anatis autonomous weeder. Bernoit Carré, who played a key role in its development, offers his future vision of weed control for modern agriculture.
Mechanical weeding has been around for many years, so why is there such interest in an old technology?
"We have been manufacturing inter-row weeders since 1975 and are seeing growing demand. We are now manufacturing a total of 300-600 machines a year. Back when my grandfather was young, farmers commonly used mechanical weeders to manage weeds. Then in my father’s time, chemicals solved the weed problem.
Now with my generation, farmers are under pressure from society to reduce pesticide use and are more aware of the environment. But while they are looking to use fewer chemicals than in my father’s time, they still need to deal with weeds. On top of this, they face the problem of herbicide resistance. The idea is not to get rid of chemistry, but to keep using it as effectively as possible along with mechanical methods."
Why did you build autonomous weeder Anatis?
"Robots are creating a lot of excitement, but we did not set out to build a robot. Instead, we set out to produce a weeder that was automated. We have been manufacturing inter-row weeders since 1975 and the next step was a camera-guided, tractor-mounted system, which we developed 15 years ago. These guided weeders will typically work at 8-10kph. However, farmers don’t want to spend hours on a tractor with a weeder, as it is a boring job and they are under pressure to reduce labour costs."
Other companies are developing robotic weeders. What makes yours different?
"A key element is being able to adjust the weeder tines. Other [robotic] weeders tend to have the hoes/tines mounted underneath, but you can’t adjust the rows, which is why it is mounted behind on a mini three-point linkage. This also means you can change implements and are able to use a variety from our existing range of tractor-pulled machines. For example, farmers have the flexibility to create their own combination of tines followed by a star wheel."
How does it work?
"The robot uses Trimble GPS guidance to navigate in the field, while the camera guides the weeder. We originally considered [using solely] camera guidance, but this requires crop cover for the robot to guide itself. So by using GPS, it can be used to harrow before drilling or soon after drilling before emergence."
What has been the key challenge in developing the system?
"A lot of time has been taken to check that everything works together and to the required accuracy. But more importantly, the key challenge has been safety, as there are a lack of EU regulations, so we have put in much effort to ensure the system is safe by developing lots of safety systems.
There are 3 different operating modes:
- First is a manual mode, where you drive the unit using the remote control.
- Then there is the automatic setting. It prompts you to check there is no one in the field and confirm that there is boarding around the field preventing people gaining access before it will operate.
- Finally, there is the semi-automatic setting which has a safety button that you have to constantly press for it to operate. If there is a problem, you let go and it immediately stops.
In addition, its normal working speed is 4kph and you can walk faster than that. Therefore, you can easily get out of the way. The legislation in France for cars defines that a speed greater than 6kph creates risk, so we have opted for 4kph. Finally, it weighs 800kg, so is no heavier than a horse."
Do you see it being used in broad-acre crops?
"Initially, it is being marketed for vegetable growers, but it can also work in broad-acre crops. We have one farmer who has used it in barley drilled with seven-and-a-half inch (19.05cm) rows and a farmer is planning to use it in sugar beet this summer."
Costing from €80,000 (£70,429), is it economic and what does it offer to farmers?
"They are cost effective, but the return will depend on the farm, crop and soil. However, it is not just paying cost – the main benefit automation brings to farmers is the added value. Spending 8 hours in a tractor cab, reading a newspaper as the tractor steers by itself using GPS has no real value. Value is spending more time managing crops.
One analogy is robotic milkers. When they first came out 15-20 years ago, farmers responded in 2 ways. First, there were those who said: "I no longer need to look after my cows." The second group saw it as an opportunity to spend more time with their cows and it is these businesses that are profitable.
I see the same with robots in fields, enabling farmers to do the more important tasks. Robots can also collect data. For example, if you have the system running for 10 years and have seen 2 to 3 wet springs, then you will have the data to help you manage crops when it occurs again.
Currently, it measures weed percentage and if for example, a farmer wants less than 7% weeds in the field, it will map those areas that are above the 7% threshold and produce colour maps. In the future, sensors will collect other information."
Can I buy a machine?
"We have already done hundreds of tests in the field and now want to validate the system with the 5 farmers who have bought the units. They are mostly vegetable farmers, but one is looking to use it his in sugar beet. Then in 2019, we will ramp up production and push for the export market."
What are the limitations to its use?
"The key limitation is battery life, which is 4 hours on one charge, but technology is advancing all the time and this will increase. It fits well with farms who generate their own renewable energy. We did consider panels on the machine itself, but it would not generate enough power for the system."
Do you see machines getting bigger?
"At the moment, I don’t see the units getting larger [beyond the 2m working width] like the driverless tractors, because of the road regulations. Instead, I see farmers having several smaller machines. This also reduces the risk of breakdowns. If you have one large driverless tractor and it breaks down, you cannot do any weeding, while the farmer with 5 smaller machines can still do work with 4."