The 120ha (300 acres) of potatoes that George Moate used to grow on his South Yorkshire farm at Clayton near Doncaster provided the inspiration for an implement that got him into the machinery making business.

Ironically, potatoes are no longer grown on the farm because he and the farm staff who man the metal-cutting, bending and welding equipment in the workshop are too busy building equipment for other growers.

“It all started in the very wet spring of 2000 when I hired in three tractors, drivers and single bed tillers to prepare ground for our potatoes,” Mr Moate recalls. “When it rained hard, I was paying out £120 an hour and not get anything done.”

That was the spur to develop a bigger capacity tiller wide enough to form three potato beds in one go. Demonstrating the first production machine, which is still doing 240ha (600 acres) a year with its current owner, spurred initial orders for half a dozen more and now there are many more examples working in different parts of the country.

“We now have a range spanning single- to four-bed machines,” says Mr Moate. “The biggest is quite a monster at 7.2m wide and weighing 7.5t.”

The tillers are built to a common format using a headstock, folding frame assembly and rotor tubes sourced from an Italian manufacturer. Walterscheid driveshafts and a Bondioli & Pavesi gearbox from Germany and Italy, respectively, are also used but most other components are either made in-house or bought locally.

“Chapmans of Sheffield produce the ridging bodies, shares and blades, and the star wheels used on the latest machine are also made locally,” says George Moate. “I like to include as much local content as possible.”

With the farm team also producing a range of front- and rear-mounted haulm toppers, the machinery business keeps everyone busy between the demands of the farm’s 688ha (1,700 acres) of cereals.

They are going to be kept even busier if George Moate’s latest idea takes off: A bed tiller that separates and buries stone and clod to leave a good depth of well-tilled soil ready for the planter.

“The idea came to me when I was working with a stone burier we import from Italy,” says Mr Moate. “This machine clears a shallow depth of soil in beds for vegetable production and I wanted something to shuffle stones away from the rotor.

“It struck me that fitting star rollers behind a tine rotor could separate stone and clod from a bed of soil and bury it across the working width, rather than concentrating it between the beds,” he adds. “Cutting out a separate operation with an expensive machine would make tremendous savings in costs and manpower.”

Two years’ experimentation with this patented combination has produced the Tillerstar. Like the stone burier, but in contrast to a regular tiller, its bladed rotor turns against the working direction of travel. That leaves a void just behind rotor as the blades whizz round at 300rpm with a tip speed of 9m/sec.

Soil and stones are thrown on to four rollers formed from flexible stars. These rotate forwards to transport the stone and any sizeable clods into that void where they are subsequently buried by the friable soil passing between the stars.

“The angle of the star rollers is adjustable to fine-tune the effect and they can also be adjusted up and down, and forward and back to change their position relative to the rotor,” explains Mr Moate. “If you’re separating stone, the rollers can be set away from the rotor to give them room to drop into the void; in cloddy soils, they are set closer so the clods get chopped and put into the bed.”

Fitting a hydraulic motor on the end of each roller is a costly drive solution but one that eliminates chains and shafts and makes few demands on the tractor – just oil at 24-litres/min per set or 75-litres/min in total on a triple bed version.

More importantly, hydraulic drive makes the rollers easy to swap when damaged or a different star spacing is needed to suit a change of soil type or conditions, or the finish required for different crops.

Experience so far shows the Tillerstar will not only work effectively on ploughed or bed-formed ground but also direct into stubble – ideally after subsoiling to remove any compaction caused during field operations for the preceding crop.

“During one session with our single bed Tillerstar demonstrator running at 4kph on a 110hp tractor, it produced a bed for onions with 6in of clean soil,” George Moate adds. “I’ve also noticed there’s very little tip wear on the star fingers; I guess because unlike on a de-stoner, where the stars are conveying a deep bed of soil, they are just filtering the soil and conveying a few stones and clods.”

The machine has also worked effectively in conditions that defeated a conventional separator, he maintains, and in many situations could operate without forming beds first.

“One grower suggested it will open up potato land where farmers don’t like the way conventional separation techniques concentrate the stone rows,” Mr Moate says. “And I suppose it would be useful for multi-row harvesting systems where stone separated into channels gets in the way.”

A handful of growers have certainly been convinced by what they have seen, placing orders for triple-bed Tillerstar implements for use next spring.

“I haven’t invented some new technology, just combined existing technology in a different way,” George Moate adds. “As one grower commented after seeing a demonstration – it’s a wonder no-one’s thought of it before.”