Drone Field Spraying in Australia: A Practical Guide
Updated: 3 days ago
Drone field spraying is applying herbicide, pesticide, fungicide or liquid fertiliser from a large multirotor drone rather than a boom spray, plane or backpack. Today's field spray drones carry between 25L and 100L per fill, fly GPS-guided swaths of 6m to 11m and can cover up to 60 hectares an hour on the biggest machines. Terrain-following radar keeps the aircraft at a set height over uneven ground.
The biggest reason growers look at drones is getting onto paddocks that are too wet for anything else. When it's been raining, and a boom or tractor can't get on without cutting the paddock up, a drone can still spray, which is why demand jumps every wet season. Beyond that, a drone costs a lot less to run than a plane or helicopter, gets through many jobs faster than a tractor, and it can handle steep or timbered country and treat only the parts of a paddock that need it. This guide covers how it works, what the rules are and how to choose a machine.
How drone field spraying works
The job breaks down into four stages, which we tend to describe as map, plan, mix and fly. You map the paddock boundary first (on foot, from the remote control or with the drone), the flight software plans swath lines the same way you'd plan boom runs, you mix and load at the trailer or ute, and the drone flies the plan on its own. It comes back when the tank gets low, or a battery needs changing. One person can run the whole operation, flying the drone and swapping batteries and refilling between runs.
Tank size is the main decision when you're comparing drones for spraying fields. A 25L machine refills more often but costs less to buy. A 100L tank means fewer trips back to the trailer on big programs. Nozzle setup comes second. The standard centrifugal nozzles handle most broadacre chemical work, and a mist or atomised nozzle package roughly doubles the litres per minute the drone can put out, which is useful when you need higher water rates.
What can you apply with a spray drone?
Anything you'd put through a boom, as long as the product label allows it, including knockdown and residual herbicides, insecticides, fungicides and liquid fertiliser. Swap the tank for a spreading hopper and the same drone spreads granular fertiliser, seed and bait. Before you buy, read the labels on the products you use most. Aerial application instructions and buffer zones still apply to drones, and some labels set specific requirements for water rate and droplet size.
What licences do you need for drone field spraying?
This is the question we get asked more than any other, and the answer has two layers to it, because CASA covers the aviation side and your state covers the chemicals.
Spraying your own land
Under CASA's landholder pathway, you can operate a single spray drone over land you own or lease for spraying, spreading and mapping without holding an operator's certificate (ReOC), as long as nobody is paying you to do it. The pilot still needs a remote pilot licence (RePL) rated for the aircraft's weight class, the drone must be registered with CASA, and the standard operating conditions apply.
Spraying for payment
If you're spraying other people's properties as a service, you need to operate under a ReOC (your own or your employer's) as well as holding a RePL. This is the contractor pathway, and it's how the operators in our approved contractor network work.
State chemical licences
Aviation approval doesn't cover chemicals, so you'll also need to deal with your state, which runs its own agricultural chemical licensing, and drone application is generally treated as aerial application. Victoria, for example, requires an aircraft operator licence for RPA chemical spraying, and one of the conditions is no application before sunrise or after sunset. Check with your state agriculture department before your first job, and allow for licence fees and any chemical accreditation (an AgVet chemical course, for instance) in your setup budget.
Blanket, spot and variable rate: three different jobs
Blanket coverage is treating the whole paddock at one rate, and drones handle this well, particularly on wet or rough country where a ground rig can't get in.
Spot spraying is a different job altogether, where you fly a survey first with an enterprise camera drone, generate a weed map, and the spray drone only treats the patches on that map. Depending on how patchy the weeds are, this can cut chemical use by around 70% compared with blanket spraying. On a large glyphosate program, that adds up to a lot of money, and the rest of the paddock isn't getting chemical it doesn't need.
Variable rate application is different again, and it starts with a multispectral survey that picks up crop stress you can't see yet and turns it into a prescription map. The drone then applies more where the crop needs it and less where it doesn't. For a lot of growers, this is where the drone pays for itself fastest, sometimes in a single spread or spray program, because you stop putting product on ground that was never going to return it.
As a rough guide for weeds, if they cover less than a third of the paddock then spot spraying is worth the survey. Above that, blanket coverage is usually quicker, and the mapping step stops making sense.
Choosing a field spray drone
The main thing is to match the tank to the program you're running, and for most farms and contractors that means one of the three main Agras machines. The T50 ($15,000 ex GST on current pricing) covers roughly 20 to 30 hectares an hour of liquid application and is the proven mid-sized option, with the T55 due to follow it soon. The new T70P ($18,500) and the T100 ($24,199) with its 100L tank are the machines for broadacre and contracting, where fewer refills per hundred hectares means more country covered in a day, and the T100 will go past 60 hectares an hour in the right conditions. At the smaller end, the DJI Agras T25P ($10,000 on current pricing) suits landholders doing their own knockdown and pasture work.
Whatever airframe you go with, budget for at least two spare batteries, a generator for charging in the paddock and a nozzle package matched to the products you use most. In our experience, it's the support gear, not the drone, that limits how much a new operator gets done in a day.
Not ready to buy? We can connect you with a contractor
We no longer run contracting ourselves, but we still take spraying enquiries and pass them on to operators in our approved contractor network, most of whom bought and trained on their drones through us. Plenty of growers hire a contractor for a season, see how the workflow fits their country, then buy once they know how many hours a machine would fly on their place.
Frequently Asked Questions
Can I legally spray my neighbour's paddock as a favour?
This is one to be careful with, because CASA's landholder pathway only covers land you own or lease, with no payment or compensation for the work. Spraying someone else's property, even informally, generally falls outside it and puts you into ReOC territory, and state chemical licensing applies on top. If a neighbour arrangement is on the cards, talk to your training provider first.
How much does drone field spraying cost per hectare?
As a contracted service, rates vary with the chemical, the terrain and how far the contractor has to travel. If you're buying, work backwards from your annual sprayed hectares. Chemical savings from targeted application plus the contractor fees you no longer pay usually decide the payback period, not the sticker price.
What weather can a spray drone work in?
The same drift rules apply as for any other application, so wind, temperature inversions and delta T all matter, and product labels set the limits. Drones cope with wet paddocks better than ground rigs because nothing touches the soil, but there's no exemption from spray drift conditions, and state rules like Victoria's sunrise to sunset window still apply.
How long does it take to get licensed?
A RePL course typically runs about a week (theory and practical), then you'll need a type rating on your specific aircraft for machines over 25kg. If you need a ReOC for commercial work, allow several more weeks for the application and operations manual. State chemical licensing runs alongside. Starting the paperwork a season before you want to fly is the comfortable way to do it.
Do I need special insurance for drone spraying?
You'll want hull cover for the aircraft and public liability that specifically covers aerial chemical application, because general farm policies often exclude it. We arrange insurance options written for agricultural drone operations as part of the sale, so cover starts the same day the drone does.
