Robocrop helps with weed removal

When you recall it was less than a decade ago that inter-row hoeing was an intensely demanding two-man operation performed at snail’s pace, you have to say things have moved quite dramatically.

Today, it is possible to use a hoe equipped with an automatic guidance system which requires only one man to operate, is incredibly accurate and can be driven at speeds that would horrify the old guard.

It is a development that has not only allowed greater efficiency in the weed control of vegetable crops but has also opened up new possibilities for vast reductions in pesticide use on other crop types.

This is a particularly significant move for organic farmers who can now achieve a useful degree of weed control in their chosen crops – cereals, sugar beet, oilseed rape and so on.

But while this may be so, one of the failings of the system is that it cannot remove weeds that grow directly in the crop row which, for high value vegetable crops, means that labour needs to be employed to pull unwanted plants by hand.

Within the next two years this could all change when a development by two ex-Silsoe researchers reaches fruition.

Dr Nick Tillett and Dr Tony Hague of THT Technology, who were responsible for the original design of what has now become the Garford Robocrop precision hoe, are working on a system that will automatically take out weeds between plants.

“It will be an extension of the current system and will use a similar sensing technology as inter-row guidance,” explains Dr Tillett.

Put simply, this involves a camera sending images of a number of crop rows to a computer which then matches them up with a pre-programmed template.

Any deviation from the template activates the system to side shift the hoe to keep it on course.

“Much of the early work to develop this technology was performed with the help of Garford Farm Machinery,” he says.

“We had the ability to develop the technology and Garford had the expertise in hoe development.”

The company is also closely involved in the new intra-row project and will, no doubt be looking forward to marketing it when it is ready.

So, how does a hoe running at speed between crop rows set about taking out weeds growing between individual plants?

“Let me say from the start that this is only for crops such as lettuce or say, cabbages, which are planted at intervals in excess of 30cm – it won’t work with cereals, for example,” says Dr Tillett.

At the heart of the system is a hydraulically-powered rotating horizontal disc which is best described as a half circle but in reality is more kidney-shaped.

As before, a camera looks ahead and sends images of the plants to the computer which notes where they are and the speed at which they are approaching.

This information is used to set the rotational speed of the half-disc which, when it is about to meet a plant is turned so its straight side is against the side of the plant to miss it and, when the plant is passed, turned so the disc is between the plants to remove any weeds.

In practice, the disc is constantly rotating – its speed automatically adjusting to compensate for changes in the distance between plants.

Dr Tillett points out that the half-disc system is not a totally new idea – a similar system was used many years ago to thin sugar beet before the advent of the mono-seed and precision drills.

What is new is the control system and this is the part which has taken the time to develop.

“Unlike the inter-row guidance system, which only requires one camera to look at a few rows, there will need to be a number of cameras.

Plant spacing within each row needs to be monitored.”

Still very much in its development stage, Dr Tillett says he hopes to have a working prototype ready for the spring of next year with production starting shortly after that.

In terms of economics, he is convinced that put against the cost of labour for hand weeding and the reduction in the cost of herbicides, the price of the intra-row hoe will make sense for vegetable growers.