22 May 1998

Dutch inter-row hoe can handle in-row weeds…

By Henk Lohuis

INTER-ROW hoeing sugar beet to control weeds is not new but its limitation has always been the control of weeds actually growing in the sugar beet row.

Now a Dutch electronics engineer believes he has perfected a system which will enable these weeds to be removed – and at operating speeds of up to 6mph.

Developed at the Department Agro Environment and System Technology of the Agricultural University at Wageningen, Netherlands, Kees van Asselts system employs electronic sensors to detect weeds – rather than sugar beet plants – and uses a vertically rotating blade to remove them.

"We use three beams and a sensor to detect the weeds and ascertain their position in the row," explains Mr van Asselt. "The information is computed through the use of a special chip – the Digital Signal Processor."

Once it was possible to achieve this level of information Mr van Asselt was faced with the problem of designing a hoe which could be operated at a sufficiently high speed and accuracy.

"We looked at the possibilities of using laser rays, water jets, high voltage electric, burning and so on," he says. "But we finally decided on a mechanical system."

It was a decision not with out its problems. Mr van Asselt realised that if such a system was to work quickly, the machinery needed to be positioned in the row, rather than outside it. This led to the development of the vertically rotating blade hoe, which works across the row at right angles.

In operation the hoes spring loaded extended blades are in work all the time until a sugarbeet plant is detected. This causes the blades – still spinning – to be retracted briefly until the plant has been passed, and then extend again to resume hoeing.

Mr Van Asselt concedes there is still a considerable amount of testing to be done before a machine is ready for the commercial market, but he is confident the system has much to offer, particularly in terms of cutting herbicide costs.

Inter-row weeding with the Dutch-developed machine could result in a reduction of sugar beet herbicides. Note the vertically spinning hoe, with its spring-loaded hoeing blades.

Three-row planting in a single bed with this Konings machine imported by Burdens. Using an identical planting system as the existing two-row machine, Konings has added a middle seeding unit. Currently a prototype, trial work this year could see it available for the 1999 season.