The new Autostreamer dribble bar from Essex-based Billericay Farm Services (BFS) finally brings variable-rate application to users of liquid fertilisers.
Up to now growers have had to leave the cab and manually change the setting on variable-rate dribble bars. This made the system totally impractical for modern precision-farming systems. There was an option to change the forward speed of the sprayer to change application rates, but was inefficient and difficult to control.
The ingenious new system from BFS means that application rates can now be altered simply by changing the pressure in the spray line. This can be easily controlled by modern spray controllers and means that N-sensors and yield maps can now be used with liquid fertiliser application systems to offer true variable-rate spreading.
The Autostreamer allows the flow through each dribble bar outlet to vary between 0.6-6.0 lit/min by simply changing the operating pressure between 1-3 bar.
There’s no doubt that the Autostreamer is a major breakthrough. Liquid fertiliser makes up about 16% of the UK market, with uptake especially high among larger farmers, so the ability to offer variable-rate applications was a high priority on BFS’ R&D programme. It may seem quite logical that increasing the pressure in a sprayer will increase the flow, but in fact it’s not quite so straightforward.
Toricelli’s law, which rules the flow rate of fluids in a pressurised system, restricts the effect of increasing pressure. No matter how high you increase the pressure, the flow will increase by no more than 1.7. To create the Autostreamer, BFS had to find a way to overcome the laws of fluid dynamics.
The company found its solution by introducing simple valves into its dribble bar system. Each nozzle is large enough to deliver the highest flow rate that a grower might want at a pressure of 3 bars, but if you reduce the pressure below that level the valve restricts the flow and application rates reduce proportionally.
The system brings another benefit that will appeal to all liquid fertiliser users. Traditional dribble bars continue to dribble fertiliser onto the ground – as any fertiliser in the unit leaks out – after spraying stops at the headland. This is not only a contamination risk, but when you consider the number of dribble bars on today’s wide sprayer booms, the financial cost can be high as well. The valves in the new Autostreamer mean that the flow stops immediately that pressure is removed from the nozzles. That means a clean stop and start to spraying and no costly leaks on the headland.
For more information visit: www.bfs.uk.com.
