As spray booms continue to grow, now reaching 54.5metres, operators are enjoying being able to cover more ground in the available weather window in a short period of time.
However, the tip-to-tip speed difference across a wide, turning boom is also driving the need for a fast, precise nozzle control technology.
As Hardi Australia's product manager for large sprayers Steve Lancaster points out, the outer tip of a 54-metre boom travels considerably faster than the inner tip in every turn - leading to significant under- and over-dosing around headlands or any obstacle in the paddock.
"Hardi solves this problem by combining multi-tiered spraying with its H-Select system to provide accurate target-rate control over the widest possible speed range," he said.
The H-Select system calculates the speed of the sprayer and co-ordinates up to four different nozzles on each nozzle body to spray accordingly at the required target rate across the boom and speed range.
This rapid, blended switching between nozzle combinations means H-Select can achieve a target rate accuracy of 90 per cent or better over the entire paddock - virtually eliminating patches of over- or under-dosage.
The nozzle switching is controlled by a solenoid-activated air pressure system, which also enables constant fluid recirculation and lets the boom be operated in unlimited sections, though 18 sections is standard.
Air switching frees the system from the electrical losses incurred by electronic platforms when the wire runs exceed about 18 metres per side, or 36 metres overall.
"The H-Select's nozzle combinations ensure the operator can set droplet sizes at a precise amount and be confident they will not change with rate adjustments," Mr Lancaster said.
"That said, the operator can adjust the droplet size throughout the day to manage wind speed, temperature and humidity changes, using Hardi's complementary Nozzle Watch desktop application."
The software automatically calculates the optimum nozzle selection for a desired droplet size, target rate and speed range. Alternatively, operators can specify nozzles or specify fewer than four (keeping one position free for a fertilizer nozzle, for example). Nozzle Watch then displays nozzle combinations and speed bands, plus overall rate accuracy.
Steve Lancaster is sure that H-SELECT is the solution that large-scale spray operators have been waiting for.
"Farmers can also use a coarse droplet to spray the paddock perimeter, then change to a finer setting once they're away from the fence lines," he said.
"We believe the combination of air switching and multi-tier nozzle selection makes H-Select an effective nozzle control technology for booms 36 metres and above.
"With so much riding on sprayer productivity, these big booms are the way of the future."
H-SELECT is currently available on Hardi Rubicon and Saritor62 Active self-propelled machines, and Hardi Commander trailed sprayers. The system integrates with the on-board ISOBUS.