Optical sprayer technology returns on investment

Nov. 24, 2023 | 5 Min read
Sky rocketing machinery prices have left many growers wondering whether new technologies like optical spot sprayers are profitable and can pay their way.

Sky rocketing machinery prices have left many growers wondering whether new technologies like optical spot sprayers are profitable and can pay their way.

Planfarm farm business consultant and WeedSmart western extension agronomist Peter Newman has been busy running the figures for boomspray purchase decisions and has found the benefits, often outweigh the upfront cost of weed detection technology.

“Generally, optical sprayers will pay for themselves through herbicide savings in situations where a grower is doing at least one pass for summer weed control and spraying broadleaf weeds in cereals.

“Our growers are often contending with high levels of resistance in broadleaf weeds such as wild radish in cereals. “While the numbers are low due to good management over many years resistant individuals cost a fortune to control,” Mr Newman said.

If growers are still achieving good broadleaf weed control in cereals with cheap (e.g. $10/ha) herbicides, green-on-green weed detection in crop may not pay its way.

Some growers are also starting to notice an increase in glyphosate-resistant ryegrass numbers, weed detection cameras will help control survivors with alternative knockdown herbicides registered for use at higher rates through optical sprayers.

The analysis was based on an ‘average WA farm’ from the 2022 Planfarm Benchmarks -4600 ha, growing 2400 ha of cereals and 1200 ha of break crops with the remaining 1000ha winter-fallowed or pasture.

The assumed cost of a summer spray was $15/ha and the four levels of broadleaf weed control in cereals ranged from a cheap single spray of $10/ha, to a high-cost two-spray strategy at $45/ha, just for herbicides.

The initial investment to fit weed detection cameras or sensors from Bilberry, Weed-It, WeedSeeker or See and Spray Select to a 36 m boom was set at $150,000 and the analysis included the ongoing algorithm fees (for the Bilberry system).

These systems can save around 90 per cent of herbicide cost for both green-on-brown and green-on-green (in-crop) spraying, but for the analysis Mr Newman used an 85 per cent saving.

He depreciated the equipment at 10 per cent per year and included $2 to $4 per ha for repairs depending on the type of boomspray.

The results of the average farm analysis suggested summer spraying the whole 4600 ha farm with a blanket application will cost $69,000.

Swapping to a spot sprayer reduces the herbicide cost by 85 per cent to $10,350 if using a green-on-brown system such as Weed-It, WeedSeeker or See and Spray Select.

If using the Bilberry system and taking into account the annual algorithm fee, the cost is $21,850.

Optical sprayers are useful for the second or third knock in fallow systems to control surviving weeds including glyphosate resistant weeds.

Assuming wild radish is hard to kill in cereals, the analysis is based on blanket spraying one-third of the 2400 ha cereal crops with herbicide costing $21/ha, one-third costing $35/ha and one-third costing $45/ha, giving a total herbicide cost for broadleaf weeds in-crop of $80,000.

Only the Bilberry system can detect weeds in-crop (green-on-green).

Assuming the spot-sprayer reduces chemical usage by 85 per cent, the herbicide cost is $12,000 plus the annual algorithm fee of $19,000.

Across this average farm, chemical savings with a WeedSeeker, Weed-It or See and Spray Select system for summer spraying are about $58,000.

If using a Bilberry system for summer spraying and controlling wild radish in cereals, the saving is $96,000 per year.

“If a grower has a summer weed problem and is using an expensive broadleaf spray over a low density of weeds in cereals, the worst thing they can do is simply buy a new SP boomspray and continue to blanket spray their whole area,” he said.

Although optical sprayer technology involves a high initial outlay the return on investment is rapid in the right situation.

While green-on-green detection is currently limited to select broadleaf weeds in cereals, there are other algorithms in development for detecting weeds in break crops such as lupins, canola and lentils.

This will add to the return on investment in the future.

If you are looking at buying a new sprayer, it is definitely worth running the numbers to see if this technology is beneficial.

Spray efficacy is one of the WeedSmart big six tactics to ensure every drop of herbicide applied is effective, underpinning profitable crop production.


WeedSmart’ is the industry voice delivering science-backed weed control solutions to enhance on-farm practices and promote the long term, sustainable use of herbicides in Australian agriculture. WeedSmart has support from the Grains Research and Development Corporation (GRDC), major herbicide, machinery and seed companies, and university and government research partners, all of whom have a stake in sustainable farming systems. The GRDC is a Platinum investor in WeedSmart to ensure Australian grain growers have access to world class research in strategies to mitigate weeds and control herbicide resistance.
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