PHOTO: KVERNELAND
PHOTO: KUHN PHOTO: BOGBALLE
FERTILISER TECHNOLOGY ▶▶▶ T
Weigh-cell calibration brings precision to spreaders
he development of reliable and high- ly accurate on-board weighing sys- tems has made it easier to calibrate fertiliser spreaders with gravity-fed
broadcasting discs and maintain accurate cali- bration settings as spreading continues through the day. For many operators, the abili- ty to calibrate the spreader automatically sim- ply by entering the desired application rate, will be reason enough to opt for a machine with this facility. This applies especially on farms growing several different crops. Or dif- ferent varieties of the same crop – potatoes for example – that require individual regimes re- sulting in frequent changes of fertiliser type and associated calibration.
Make the most of bought-in crop nutrients with technologies designed to maintain accurate applicator calibration, achieve the target application rate, ensure an even spread pattern and minimise wastage.
But weighing on the move is the real prize here. This enables the control electronics to calculate the flow rate of material at regular intervals – maybe as many as 100 times a sec- ond – to compare the actual application rate with the target rate. And alter the hopper out- let slides as necessary, to compensate for any variance. Changes in fertiliser flow rate through a hopper outlet may result from a
subtle change in physical properties (especial- ly in bulk and blended fertiliser products) or from changes in flow characteristics due to ambient conditions. Fertiliser applied on a chill, dewy morning will flow differently once the sun bursts through the cloud in the after- noon. Automatic calibration then ensures that any fine-tuning adjustments are carried out.
Boundary spreading deflection GPS section control
Modifying the discharge pattern from disc spreaders enables ma- chines to open up fields without sending fertiliser into neigh- bouring crops, hedgerows or water courses. It can be achieved in a number of ways: by deploy- ing manually or hydraulically-en- gaged deflectors; by altering the position of the spreading disc
vanes; or by reversing the disc ro- tation, so that fertiliser passes through a slot that reduces the throw of the system. With hy- draulically-driven discs, there is also scope to change the rotation speed on one side or to disen- gage drive altogether, in addition to using a deflector.
Automatic spreading width ad- justment minimises wasteful du- plicate application where spreading bouts converge in ir- regular shaped fields. At its most basic, this may reduce working width in four sections – two ei- ther side – across the full work- ing width available with the ma- terial being applied. But the most sophisticated systems can now provide multiple steps, or
even infinitely variable width ad- justment. Avoiding the potential effects on crops of over- or under-dosing is one benefit. So too is the reduc- tion in operator workload and skill demands. There is also po- tential to reduce the amount of fertiliser applied. This depends on field size and shape, but 5-8% is fairly typical of the results seen in European trials.
Border spreading device deployed on a Kverneland CL spreader to modify the distribution on one side of the machine.
22 ▶ FUTURE FARMING | 24 May 2019
A Kuhn illustration of when section control improves fertiliser spread- ing operations in field with irregular shapes.
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