Who won last year?

GJ Agri’s self-propelled stone picker – Complex category winner

The Stonebine, built by Jack Bailey and his colleagues at Dorset-based contractor and engineer GJ Agri, was our 2020 Farm Inventions Competition champion.

GJ Agri’s self-propelled stone picker © Fototek

The quirky converted combine was designed to harvest an unusual crop – flint from fields north of Lyme Regis.

Having scoured the market for a suitable stone-picker, they could only find machines that used spring-loaded tines to flick rocks into a big hopper.

However, these were no good for the farm’s building-grade flint stone – worth £65/t in good condition – as they tend to deliver a dirty sample. The sprung tines also have a habit of cracking the flint, obliterating its sell-on value and leaving razor-sharp shards across the field. 

So, after five years of planning, the team at GJ Agri got to work building their own hopper-less version.

The priority was a self-propelled machine with a side cab that would leave ample space for the elevator to run under the engine, so when a 1970s Massey Ferguson 500-series combine came up for sale, they snapped it up.

The donor machine, on a little under 4,000 hours, was stripped almost bare – the only major components that remained unmoved were the engine, front axle and hydrostatic drive.

Major surgery included fitting chassis rails that extended the combine to form enough space for the screening system.

The picking and processing elements include a second-hand Reekie 300 SA digging rotor and web, and an Extec 5000 elevator. One of the biggest expenses was a trommel screen, which was home-built because there was nothing reasonably priced on the second-hand market.

Power to a new triple-stack hydraulic pump arrangement comes via the combine’s old threshing drum drive belts. This runs oil to separate hydraulic motors on the auxiliary services, including the trommel and front and rear elevators.

The flow to each can be altered using an external control valve, and functions can be turned on and off via in-cab switches.

In work, the engine runs at full chat – roughly 2,100rpm – and forward speed is determined by the quantity of stone.

Lifting rowed-up flint from a 7m band limits progress to roughly 1kph, but it can get up to 3kph when picking straight from the ground across its 2m working width.

To give an idea of output, it lifted roughly 1,250t of flint from a 4ha field in one day, some of which was already raked into a line.

The version pictured at the top of this article had come straight out of the workshop, but the team has since fitted guards to all the components and shot-blasted and painted it.

Roger Page’s sward-slitter dribble bar – Intermediate category winner

Intermediate category top spot was taken by Roger Page’s sward-slitter dribble bar.

Roger Page’s sward-slitter dribble bar © James Andrews

Following a number of customer requests to combine sward slitting and slurry application into a single operation, Powys contractor Mr Page came up with a custom dribble bar design.

His original attempt at combining the two processes involved mounting his Opico sward slitter on the front linkage and running with his 6m trailing shoe at the rear.

However, the sward slitter proved too hard for the tractor’s auto-steer system to overrule, so he went in search of another solution.

He initially looked for an off-the-shelf dribble bar, but none of these had the correct pipe spacing to line up with the slitter’s rotors.

Therefore, he set about making his own in the farm workshop. The starting point was to mount a three-point linkage on the slitter for the dribble bar to hang from.

The dribble bar frame was then constructed with a central section that carries a Vogelsang macerator and a telescopic towing arm for the umbilical pipe. This is designed to push the pipe out of the way during headland turns and has a drop-down foot for gathering it up at the end of the job.

The pipe outlets are mounted off box-section wings on both sides and these fold hydraulically with the frame of the slitter. According to Mr Page, this was the trickiest part of the build to get right, as there was so much pipework to deal with.

It was built in the winter of 2017 using all new metal, and it took about 70 hours to complete. Total build cost was about £7,000, including the £2,000 macerator.

No changes have been made to the design since then and about 60% of Mr Page’s umbilical work is now carried out with it. The rest is split between trailing shoe and splash plate.

Robert Schwier’s seed bag cradle – Simple category winner

Winner of the hotly contested simple category was Robert Schwier’s seed bag cradle.

Robert Schwier’s seed bag cradle © Robert Schwier

After a 1t seed bag strap broke, narrowly missing the operator and damaging the drill’s Avadex unit, Essex farmer Mr Schwier decided to come up with a safer alternative to lifting live weights above workers’ heads.

Safety and ease of use were paramount, and his cradle design removes any reliance on the bag’s strap and instead rests the full weight on the heavy-duty box section of the cradle.

The bag is lifted into the box and a bar is put through the strap loops. This doesn’t take any of the weight, but stops it from falling through the bottom when it’s empty.

The cradle is lifted via pallet fork slots underneath, which helps to keep the centre of gravity much lower than before, while also extending the reach of the farm’s articulated loader.

It is easier to see when travelling on tracks and following vehicles, as the bag isn’t swinging around and blocking the driver’s view, says Mr Schwier. It took about a day to knock up and cost very little, as all the metal was already on the farm.

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