12 December 1998


Tracks or tyres? At Clopton Hall Farms in Suffolk, manager Mark Thompson has the luxury of being able to choose whichever is the most suitable for the task. Peter Hill reports.

BIG farms looking to trim machinery and labour costs by trading up to US-style, big horsepower prairie tractors face some fundamental questions.

Go for bulky but basic wheeled tractors like the Case Steiger and New Holland Versatile? Or expensive but potentially lighter treading Claas/Caterpillar Challenger and Case Quadtrac tracklayers?

Mark Thompson, manager at Clopton Hall Farms, Wickhambrook, Suffolk, understands the dilemma. He has both types at his disposal and knows that each has its strengths and weaknesses.

"Our Versatile is the better of the two in terms of sheer lugging power and heavy traction performance," he reckons. "But the Challenger is the better bet when it comes to top work and jobs like moling that need a steady pull."

These two big tractors carry out the bulk of tillage and drilling work across the 1,420ha of arable land cropped by Clopton Hall Farms. Most of the land, south-east of Newmarket, is Hanslope series chalky boulder clay, with some 162ha of fen skirt soils further north.

These soils impose a short season for autumn cultivation and drilling so, with a need for plenty of output, the company has a history of using big horsepower tillage tractors. The Caterpillar Challenger 65E was bought new nine years ago; the New Holland 9680 Versatile was acquired as an ex-demonstrator two years ago.

Tillage power

They are the power behind a tillage programme that includes ploughing land destined for second and third wheats, winter barley, peas and beans, and using discs and tines across the bigger acreage going into first wheats (after rape and pulses) and winter oilseeds (after barley).

"The Versatile is our principal heavy cultivations tractor," explains Mark Thompson. "It does all the ploughing, using an 11-furrow Gregoire-Besson we bought new this year, and most of the stubble busting using a Simba Mono combination of discs, soil loosening tines and subsoiler legs thats still going strong after more than 12 years."

Running on super single radial tyres (dual wheels are reckoned to make the tractor too awkward to move around), the Versatile gets lots of traction on stubbles that provide a firm footing.

"Powershift has transformed this type of tractor – we had a manual gearbox FW60 before – but its still a big, basic tractor thats designed to deliver lots of drawbar pull," says Mark Thompson. "Its just the job on the Mono, which takes a lot of pulling, and it has also done well this year with the big plough. And were happy that, on these big tyres, were getting an acceptable level of ground pressure in good conditions."

Lack of wheelings and surface scuffing ahead of the drill is the Challengers strongest suit, he says.

"In terms of out-and-out traction on stubble, the Challenger does not do as well as the Versatile, especially on barley stubble or when you get a wet, slippery surface," he says. "But it does better than the wheeled machine on a loose surface, which makes it ideal as a drilling tractor."

Pulling a 6m Simba Freeflow cultivator tine drill is therefore the Challengers principal role. The big rubber tracks keep it on top and soil is not displaced or flicked up as it would be by the flexing tyres of the Versatile.

"You get a nice level finish that lets the drill do its job properly, and with no serious compaction to restrict seedling shoot and root development," notes Mark Thompson.

But the big Cat is not entirely limited to top work, since it also gets on with discing barley stubbles straight after the combine to prepare the way for winter oilseed rape, and provides a steady, level pull to get mole drains drawn evenly through the clay soils.

"Ultimately, the Cat has the greater versatility of the two tractors," says Mark Thompson. "It can handle any of the implements and perform any of the tasks that the Versatile is used for, though not so well as the wheeled tractor in many situations. But we think it is significantly better as a top work tractor."

As the Challenger approaches its 10th year on the farm and clocks up repair and maintenance bills at an accelerating rate, these considerations have clearly been thought through before.

"What we do in future is obviously something we have been mulling over," says Clopton Hall Farms director Chris Hollingsworth. "Cost management is crucial as we work with lower crop prices, neither tractor is being fully utilised at 750 to 800 hours a year apiece because of the tight autmun workload, and the Challenger is now costing us a fair bit."

Rising costs

Bills for the past six years tot up to the equivalent of £6,700 a year, even though the tractor is used well within its capabilities and rarely on heavy, demanding work. Those costs include fitting a new engine exhaust manifold, two sets of replacement tracks, a major undercarriage overhaul to extend the working life of the machine, and repairs and modifications to the track suspension and drive wheels.

"The track work means were committed to running the tractor for a while longer yet but who knows how things will work out? In future, we may have to consider something radical like chopping out one of the big tractors and running the remaining one on a 24-hour schedule," says Mr Hollingsworth.

Mark Thompson hopes it will not come to that; he likes having the two tractors around – especially in an autumn like this years – not only for the flexibility and combined work capacity they represent but so that he can capitalise on their respective characteristics and strengths to complete whatever job needs doing in the best way possible.

But if it came to the crunch and one of the giants had to go?

"It would have to be the Versatile," says Mr Thompson. "The Challenger may not be up to its capabilities on primary cultivation but for seed-bed preparation and drilling – where precision and quality affect the performance of the crop – I would accept that limitation in return for the Cats top work ability."

Tasks and tackle

Caterpillar Challenger 65E

Task: Breaking stubbles after winter barley for oilseed rape; discing on the plough to create a cereal seed bed.

Tackle: 6.5m Simba 2B trailed offset discs and double ring press roll.

Task: Drilling oilseed rape and cereals.

Tackle: 6m Simba Freeflow trailed cultivator tine drill.

Task: Mole draining.

Tackle: Single-leg Miles trailed mole plough.

New Holland 9680 Versatile

Task: Primary cultivation and subsoiling in cereal and rape stubbles.

Tackle: 4m Simba Mono disc/tine/subsoiler/roll combination.

Task: Ploughing rape, pea and bean stubbles for first wheats.

Tackle: 11-furrow Gregoire-Besson semi-mounted reversible plough.