The short version
A drone sprays an acre in a few minutes with around 10 litres of water and nobody in the field. A knapsack sprayer takes a worker an hour or more per acre with 150 to 200 litres of water and puts that worker inside the spray. A tractor-mounted boom is fast on open, flat, row crops but cannot enter tall or closed canopies and compacts the soil. Per acre, the operator's fee for a drone is similar to hiring a spray crew; the difference is in time, water, labour, exposure and what can be sprayed at all.
Side by side
| Drone | Knapsack (manual) | Tractor boom | |
|---|---|---|---|
| Time for 10 acres | 1 to 2 hours | 1 to 2 days for two workers | 2 to 3 hours |
| Water per acre | 8 to 10 litres | 150 to 200 litres | 80 to 120 litres |
| Labour | Pilot and helper at the edge | Two to four workers in the crop | Driver |
| Exposure to chemical | None for the farmer | Direct: drift, wet foliage, leaking tanks | Low |
| Trampling | None | Lanes through the crop | Wheel tracks |
| Tall or closed crops | Yes, from above | Not once the crop closes | No |
| Wet or flooded fields | Yes | Slow and unpleasant | No |
| Small or scattered plots | Yes; operators batch neighbours | Yes | Poorly |
| Cost per acre (fee only) | Comparable to a hired crew | Labour rate × hours | Lowest on large open fields |
Where the drone wins clearly
- Time-critical sprays: a blight alert, a pest crossing threshold, a narrow dry window in the monsoon. Covering the block in one morning is the whole point.
- Tall and closed crops: grown sugarcane, banana, maize past knee height, mature cotton and orchards, where nobody can walk with a lance.
- Water-scarce areas: a fraction of the water means no tanker, no repeated refills from a distant source.
- Safety: nobody breathes drift or carries a leaking tank. Chemical exposure is the leading occupational hazard of farm labour.
Where a knapsack still makes sense
- Spot treatment of a few plants or a small patch
- Very small kitchen gardens below the operator's minimum booking
- Spraying inside polyhouses and under nets
- Products or crops where the label does not yet permit drone application
What it costs
On Sky Spray you name the price per acre and a nearby operator accepts it; typical accepted ranges and what moves them are on the cost page. Compare against the full cost of a manual spray: the daily wage of each worker, the water and its transport, the extra product wasted in run-off from high-volume spraying, and the yield lost when a spray happens three days late because labour was busy.
Sources
Scheme amounts, approved lists and rules change. This guide was last revised on 2026-09-26; check the official source before acting on a figure.
