SPREAD SPOT ON TARGET

6 November 1999




SPREAD SPOT ON TARGET

Easy adjustment to prevent fertiliser being cast into hedges, ditches and streams is a key issue with new spreaders. Peter Hill picks the years highlights.

APART from being wasteful, spreading fertiliser into the bottom of hedges, across ditches and into streams contradicts any attempts to practice intensive arable farming with a sympathetic eye to the environment.

Come spring, farmers and their tractor drivers will be urged to angle or adjust their spreaders to avoid such pollution. And those using two of the latest machines will be hard pressed to come up with an excuse for not doing so.

With the Trend system fitted to KRM-Bogballe spreaders, all it takes is the pull of a lever. And all users of Kuhn Axera-H spreaders have to do is manipulate the hydraulic controls. Both machines can be set-up for headland spreading without the operator leaving the comfort of his cab.

As spreader coverage grows ever wider, so the problem of fertiliser misplacement becomes more difficult to put right. Solutions so far include:

&#8226 tilting the spreader away from the field border to induce a sharper cut-off to the spread pattern on one side

&#8226 fitting vanes (either individually or complete with disc) that do not throw the material so far

&#8226 attaching shields to prevent fertiliser going where it is not wanted.

KRM-Bogballe spreaders have previously used the second of those solutions, so operators have had to replace the standard vanes with special headland designs. Being a quick-fit – Click-Lock – design, this does not take long. But the Danish manufacturer clearly felt that a quicker solution would encourage operators to be more environmentally responsible.

With the Trend system, the same vanes are used for both field and headland spreading, but they have quite different spreading characteristics depending on which direction the discs rotate.

Conventionally, the vanes provide the length needed to accelerate the material sufficiently for wide spreading – up to 36m in the case of the EX model. But in the opposite direction, a gap through which the fertiliser can pass effectively shortens vane length, and so the material is not spread so far.

Trend vanes are standard on all three models in the KRM-Bogballe range:

&#8226 M1: 6m-15m; 700 and 1,200 litre capacities;

&#8226 DZ: 6m-24m; 750 to 3,200 litre capacities;

&#8226 EX: 12m-36m; 1,000 to 3,200 litre capacities.

The change in direction is achieved using a gearbox in the pto drive-train to the two discs, and this can be operated from within the tractor cab.

On Kuhns Axera-H, spreading width from the disc nearest the field border is achieved by slowing its rotation speed. And because there is individual hydraulic drive to each disc, this is easily done.

Disc position is also altered (to trim the fertiliser feed-on point) and, thanks to electronic monitoring of these two functions, all it takes is the flick of a switch.

In extreme situations, feed to either of the discs can be discontinued altogether.

The Kuhn Axera-H comes as an 1,100 litre spreader with extensions taking that progressively to 2,800 litres. The standard disc set gives spreading widths between 12m and 24m, although the machine will also work at up to 36m, with hydraulic drive eliminating the need to run the tractor at constant revs to maintain disc speed and the resulting spread width and pattern.

Lelys latest Centerliner spreader uses the tried-and-tested Supabowl feed mechanism which accelerates the fertiliser before releasing it on to the disc to reduce shatter. But the newer model has a stronger chassis to support bigger – and distinctively styled – hoppers giving much bigger load capacities.

While the current Centerliner SE peaks at 2,500 litres, the SX range capacities are 2,360 litres, 2,730 litres and 3,150 litres so work can progress with fewer stops for fill-ups. Spread widths from the twin disc double-double overlap spreading mechanism are up to 24m.

The divided hopper, which ensures even feed and side-to-side weight distribution on slopes as the fill level falls, has plastic corner finishing panels which not only help protect the steel hopper panels but also house the standard-fit road lights.

Centronic electronic controls can be added, and the spreaders can also be used with Lelys Centermatic three-point linkage-mounted weighing system.

Increased hopper capacities also feature with Sulkys new spreader range from Rustons Engineering.

The Prima and Expert models replace the Sulky DPX Series 5 range and use the same spreading mechanism. This includes an adjustable feed-on spout for each disc to alter spread width and balance the overall pattern of distribution.

There are just two base models but a choice of eight capacities between 900 and 2,400 litres thanks to a selection of profiled steel extensions that are bolted to cast steel corners for security and rigidity.

While the Prima is a relatively basic mechanical spreader, the Expert version can be had with two electronic control systems. MS provides electronic rate setting and 10% rate changes in the field, while DPB maintains application rate regardless of forward speed and interface with digital map systems for GPS-guided variable rate application.

Vicons Rotaflow range of twin disc fertiliser broadcasters is being extended with new models at either end of the technology scale.

For smaller farms, wanting a twin disc spreader of modest specification and working widths up to 18m, the RS-C offers 650 and 1,200 litre sizes, waist-high loading height, and plastic vanes that are simply cut to length for the required spread width.

At the other extreme, the RS-EDW has built-in load cells to automate initial calibration and provide continuous check calibrations in work.

Both machines share the spreading mechanism, in that fertiliser is metered into a rotating chamber in the bottom of the hopper, from where it flows horizontally on to the vanes. But while the RS-C has positive operation of the metering slide by using a double-acting hydraulic ram (instead of relying on spring pressure for closure), the more sophisticated machine has an electric actuator so that application rate can be matched to forward speed or to instructions from a digital application map.

There are five load cells: four carry the weight of the hopper and its contents, while the fifth carries a known load so that the system can automatically compensate for the effects of working across slopes or up and down hills.


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