Direct-drill distributor John Dale is advocating a controlled traffic farming system (CTF) for Zero Till drill users.

Designed to minimise traffic on cropped areas so that soil structure is maintained, CTF requires all field traffic – cultivating, drilling, spraying and harvesting machinery – to use the same wheel marks.

Assisted by GPS guidance, Mr Dale says the wheel marks used by the combine harvester should be the ones used by successive passes.

This, he says would require subsequent tractor-powered operations to be performed with tractors running with 3m wheel spacings – a situation which can be achieved, he suggests, by running with dual wheels, but with the inner wheels at very low pressure.

Mr Dale has also introduced an 8m direct drill which has its steerable depth/transport wheels 3m apart. Employing the company’s Seed Hawk tine assemblies, 64 coulters place seed in adjustable bands from 2cm to 10cm wide.

When direct-drilling, the tungsten-tipped tines create a zone of tilled soil into which the seed is placed.

The claimed benefits for using CTF include increased crop yields, better drainage, reduced fuel costs, better weed control and improved soil structure to allow direct drilling in a wider range of conditions.

Mr Dale concedes that adoption of CTF is not without its problems – not least the accurate following of wheel marks in all weather and soil conditions. There is also a question whether or not GPS, void of an on-farm base station, will be sufficiently accurate for tracking to be maintained – signal drift could be a problem.

Even so, there is clearly some logic in confining traffic to specific routes – it is, in effect, large scale bed farming.

John Dale now offers the option of its own home-built coulters in place of the Canadian Seed Hawk tine assemblies used previously.

Each of the new units carries two tine coulters on a parallel-linkage frame supported by a pair of rubber depth/press wheels.

Main advantages of this set-up are said to be improved contour-following regardless of frame height and a significant cost saving – the 6m drill costs £40,000 when equipped with the new coulter assemblies, a saving of £5000 over the Seed Hawk equipped units.