4 April 1997

He played the one-pass game – and scored

One-pass cultivation and drilling would appear to be the "in" way of doing things these days – that is, if you can bear to see uncultivated stubbles until the day drilling commences. Andy Collings takes a look at a new farmer-invented one-pass system

THERE are power harrow/drill combinations, cultivator/drill combinations and there are plough/cultivator/drill combinations. All of which have been designed to turn, in one timeless swoop, an uncultivated field into a drilled seed-bed. And then you shut the gate.

The challenge, if you like, is to devise a machine which can beat the system of the traditional plough, disc, drill, harrow and roll operations which for generations have been successfully employed to establish crops.

Most, however, recognise that with modern tractor power and implement design such tedious, time consuming sequences should be limited to one, or at least two passes. But not, it is fervently hoped, at the expense of excessive weed problems, poor establishment and unjustifiable investment in expensive machinery.

In short, a system to be universally accepted, has to work reliably in a wide range of soil conditions, be capable of reasonable daily outputs and be inexpensive to purchase, maintain and operate.

Latest contender in the frame for that clearly lucrative prize, comes from a farmer based near Goole, East Yorks.

The Wonpas cultivation machine is the product of John Gossops cranium activity – although he would not admit to being the author of its pun bearing designation.

At first sight, one could be forgiven for believing the machine to be little more than a modified potato harvester – extensive use of webs and lifting shares certainly lead the uninitiated in this direction. But a closer inspection reveals more.

Designed to work directly into stubble, soil, to a depth of about 12.5cm (5in) is first lifted by shares on to a conveyor; the machine has a working width of 2m (6ft 6in).

The soil, along with surface straw, arrives at a height of about 1.8m (6ft) and, with a fair velocity, hits a vertical web, its face travelling upwards. This action mixes the soil and straw residues and allows the finer particles to drop through onto the ground.

Soil not able to pass through the first web lands on a second horizontal web which acts as a moving sieve, allowing larger clods to fall onto the ground. Finally, clods of soil still unable to make it through the webs are thrown off the end of the web.

All clear so far? Probably not. The important point to understand is the sequence in which graded soil is allowed to return to terra firma.

As the machine moves forward large clods are dropped at the base of the seed-bed, seconds are dropped on top of these and finer particles land on these – the icing on the cake.

A seeder unit attached to the rear of the machine places seed in with the surface soil and the whole width is then firmed up by a bank of tyre presses – wheels on which the machine is supported at the rear.

Still in its prototype format, but nonetheless working, Mr Gossop is pleased with progress so far.

"All the drives to the conveyor and webs are mechanical," he explains. "Future versions could see hydrostatic drives which would enable individual component speeds to be changed to accommodate different soil conditions."

Current soil conveyor speed is set at 6kph which tends to dictate the speed of the tractor pulling it. At this speed, output, in theory, would be about 3ha/hour (3 acres). Mr Gossop uses an 80hp Case tractor to power the machine: "More than enough power," he says.

Working depth is controlled by adjusting the height of the front roller using a screw jack, with the front of the machine lifted clear for headland turns using the tractors lower linkage.

Watching the machine perform in previously ploughed land, it is easy to see the potential of the design, as soil is graded and deposited in layers. But its real test will come later this year when it is asked to work in stubble.

"It should be an interesting time – particularly as we only chop and spread our straw," says Mr Gossop. "I feel confident the machine will perform well."

On the downside, history has demonstrated that soil, moving parts and bearings are not generally a marriage made in heaven, but the use of modern designs and materials could conceivably overcome this – after all, potato harvesters appear to run the course.

"The overall advantage of the Wonpas is that it is relatively cheap to build and operate," explains Mr Gossop.

"There is little moisture loss from the soil, and straw residues and soil are thoroughly mixed – the straw is not deposited in the bottom of a plough furrow."

Future plans, as well as refining the appearance of the machine, include the development of a 3m (9ft 9in) version which should have greater appeal to large scale growers.

John Gossop with his Wonpas cultivator drill.

Wonpas in action. Note the separation of the different sizes of soil particle, with the largest landing at the front and the finest at the rear where the seed is placed.